1. Neurodevelopmental Disorder
1.1. Intellectual Disabilities
1.2. Communication Disorders
1.2.1. Language Disorder
1.2.2. Speech Sound Disorder
1.2.3. Childhood-Onset Fluency Disorder (Stuttering)
1.2.4. Social (Pragmatic) Communication Disorder
1.3. Autism Spectrum Disorder
1.4. Attention-Deficit/Hyperactivity Disorder
1.5. Specific Learning Disorder
1.6. Motor Disorders
1.6.1. Developmental Coordination Disorder
1.6.2. Stereotypic Movement Disorder
1.6.3. Tic Disorders
The neurodevelopmental disorders are a group of conditions with onset in the
developmental period. The disorders typically manifest early in development, often before
the child enters grade school, and are characterized by developmental deficits that
produce impairments of personal, social, academic, or occupational functioning. The
range of developmental deficits varies from very specific limitations of learning or control
of executive functions to global impairments of social skills or intelligence. The neurodevelopmental
disorders frequently co-occur; for example, individuals with autism spectrum
disorder often have intellectual disability (intellectual developmental disorder), and
many children with attention-deficit/hyperactivity disorder (ADHD) also have a specific
learning disorder. For some disorders, the clinical presentation includes symptoms of excess
as well as deficits and delays in achieving expected milestones. For example, autism
spectrum disorder is diagnosed only when the characteristic deficits of social communication
are accompanied by excessively repetitive behaviors, restricted interests, and insistence
on sameness.
Intellectual disability (intellectual developmental disorder) is characterized by deficits
in general mental abilities, such as reasoning, problem solving, planning, abstract thinking,
judgment, academic learning, and learning from experience. The deficits result in impairments
of adaptive functioning, such that the individual fails to meet standards of personal
independence and social responsibility in one or more aspects of daily life, including commimication,
social participation, academic or occupational functioning, and personal independence
at home or in community settings. Global developmental delay, as its name
implies, is diagnosed when an individual fails to meet expected developmental milestones
in several areas of intellectual functioning. The diagnosis is used for individuals who are
imable to undergo systematic assessments of intellectual functioning, including children
who are too young to participate in standardized testing. Intellectual disability may result
from an acquired insult during the developmental period from, for example, a severe head
injury, in which case a neurocognitive disorder also may be diagnosed.
Tlie communication disorders include language disorder, speech sound disorder, social
(pragmatic) communication disorder, and childhood-onset fluency disorder (stuttering).
The first three disorders are characterized by deficits in the development and use of
language, speech, and social communication, respectively. Childhood-onset fluency disorder
is characterized by disturbances of the normal fluency and motor production of
speech, including repetitive sounds or syllables, prolongation of consonants or vowel
sounds, broken words, blocking, or words produced with an excess of physical tension.
Like other neurodevelopmental disorders, communication disorders begin early in life
and may produce lifelong functional impairments.
Autism spectrum disorder is characterized by persistent deficits in social communication
and social interaction across multiple contexts, including deficits in social reciprocity,
nonverbal communicative behaviors used for social interaction, and skills in developing,
maintaining, and understanding relationships. In addition to the social communication
deficits, the diagnosis of autism spectrum disorder requires the presence of restricted, repetitive
patterns of behavior, interests, or activities. Because symptoms change with development
and may be masked by compensatory mechanisms, the diagnostic criteria may
be met based on historical information, although the current presentation must cause significant
impairment.
Within the diagnosis of autism spectrum disorder, individual clinical characteristics
are noted through the use of specifiers (with or without accompanying intellectual impairment;
with or without accompanying structural language impairment; associated with a
known medical/genetic or environmental/acquired condition; associated with another
neurodevelopmental, mental, or behavioral disorder), as well as specifiers that describe
the autistic symptoms (age at first concern; with or without loss of established skills; severity).
These specifiers provide clinicians with an opportunity to individualize the diagnosis
and communicate a richer clinical description of the affected individuals. For example, many
individuals previously diagnosed with Asperger's disorder would now receive a diagnosis
of autism spectrum disorder without language or intellectual impairment.
ADHD is a neurodevelopmental disorder defined by impairing levels of inattention, disorganization,
and/or hyperactivity-impulsivity. Inattention and disorganization entail inability
to stay on task, seeming not to listen, and losing materials, at levels that are inconsistent
with age or developmental level. Hyperactivity-impulsivity entails overactivity, fidgeting, inability
to stay seated, intruding into other people's activities, and inability to wait—symptoms
that are excessive for age or developmental level. In childhood, ADHD frequently overlaps
with disorders that are often considered to be "externalizing disorders," such as oppositional
defiant disorder and conduct disorder. ADHD often persists into adulthood, witii resultant
impairments of social, academic and occupational functioning.
The neurodevelopmental motor disorders include developmental coordination disorder,
stereotypic movement disorder, and tic disorders. Developmental coordination disorder
is characterized by deficits in the acquisition and execution of coordinated motor
skills and is manifested by clumsiness and slowness or inaccuracy of performance of motor
skills that cause interference with activities of daily living. Stereotypic movement disorder
is diagnosed when an individual has repetitive, seemingly driven, and apparently
purposeless motor behaviors, such as hand flapping, body rocking, head banging, selfbiting,
or hitting. The movements interfere with social, academic, or other activities. If the
behaviors cause self-injury, this should be specified as part of the diagnostic description.
Tic disorders are characterized by the presence of motor or vocal tics, which are sudden,
rapid, recurrent, nonrhythmic, sterotyped motor movements or vocalizations. The duration,
presumed etiology, and clinical presentation define the specific tic disorder that is diagnosed:
Tourette's disorder, persistent (chronic) motor or vocal tic disorder, provisional
tic disorder, other specified tic disorder, and unspecified tic disorder. Tourette's disorder
is diagnosed when the individual has multiple motor and vocal tics that have been present
for at least 1 year and that have a waxing-waning symptom course.
Specific learning disorder, as the name implies, is diagnosed when there are specific deficits
in an individual's ability to perceive or process information efficiently and accurately. This
neurodevelopmental disorder first manifests during the years of formal schooling and is
characterized by persistent and impairing difficulties with learning foimdational academic
skills in reading, writing, and/or math. The individual's performance of the affected academic
skills is well below average for age, or acceptable performance levels are achieved only with
extraordinary effort. Specific learning disorder may occur in individuals identified as intellectually
gifted and manifest only when the learning demands or assessment procedures (e.g.,
timed tests) pose barriers that cannot be overcome by their innate intelligence and compensatory
strategies. For all individuals, specific learning disorder can produce lifelong impairments
in activities dependent on the skills, including occupational performance.
The use of specifiers for the neurodevelopmental disorder diagnoses enriches the clinical
description of the individual's clinical course and current symptomatology. In addition
to specifiers that describe the clinical presentation, such as age at onset or severity
ratings, the neurodevelopmental disorders may include the specifier "associated with a
known medical or genetic condition or environmental factor." This specifier gives clinicians
an opportunity to document factors that may have played a role in the etiology of the
disorder, as v^^ll as those that might affect the clinical course. Examples include genetic
disorders, such as fragile X syndrome, tuberous sclerosis, and Rett syndrome; medical conditions
such as epilepsy; and environmental factors, including very low birth weight and
fetal alcohol exposure (even in the absence of stigmata of fetal alcohol syndrome).
The essential features of intellectual disability (intellectual developmental disorder) are
deficits in general mental abilities (Criterion A) and impairment in everyday adaptive
functioning, in comparison to an individual's age-, gender-, and socioculturally matched
peers (Criterion B). Onset is during the developmental period (Criterion C). The diagnosis
of intellectual disability is based on both clinical assessment and standardized testing of
intellectual and adaptive functions.
Criterion A refers to intellectual functions that involve reasoning, problem solving,
planning, abstract thinking, judgment, learning from instruction and experience, and
practical understanding. Critical components include verbal comprehension, working
memory, perceptual reasoning, quantitative reasoning, abstract thought, and cognitive efficacy.
Intellectual functioning is typically measured with individually administered and
psychometrically valid, comprehensive, culturally appropriate, psychometrically sound
tests of intelligence. Individuals with intellectual disability have scores of approximately
two standard deviations or more below the population mean, including a margin for measurement
error (generally +5 points). On tests with a standard deviation of 15 and a mean
of 100, this involves a score of 65-75 (70 } 5). Clinical training and judgment are required
to interpret test results and assess intellectual performance.
Factors that may affect test scores include practice effects and the "Flynn effect' (i.e.,
overly high scores due to out-of-date test norms). Invalid scores may result from the use of
brief intelligence screening tests or group tests; highly discrepant individual subtest scores
may make an overall IQ score invalid. Instruments must be normed for the individual's sociocultural
background and native language. Co-occurring disorders that affect communication,
language, and/or motor or sensory function may affect test scores. Individual
cognitive profiles based on neuropsychological testing are more useful for understanding
intellectual abilities than a single IQ score. Such testing may identify areas of relative
strengths and weaknesses, an assessment important for academic and vocational planning.
IQ test scores are approximations of conceptual functioning but may be insufficient to
assess reasoning in real-life situations and mastery of practical tasks. For example, a person
with an IQ score above 70 may have such severe adaptive behavior problems in social
judgment, social understanding, and other areas of adaptive functioning that the person's
actual functioning is comparable to that of individuals with a lower IQ score. Thus, clinical
judgment is needed in interpreting the results of IQ tests.
Deficits in adaptive functioning (Criterion B) refer to how well a person meets community
standards of personal independence and social responsibility, in comparison to others of similar
age and sociocultural background. Adaptive functioning involves adaptive reasoning in
three domains: conceptual, social, and practical. The conceptual (academic) domain involves
competence in memory, language, reading, writing, math reasoning, acquisition of practical
knowledge, problem solving, and judgment in novel situations, among others. The social domain
involves awareness of others' thoughts, feelings, and experiences; empathy; interpersonal
communication skills; friendship abilities; and social judgment, among others. The
practical domain involves learning and self-management across life settings, including personal
care, job responsibilities, money management, recreation, self-management of behavior, and
school and work task organization, among others. Intellectual capacity, education, motivation,
socialization, personality features, vocational opportunity, cultural experience, and coexisting
general medical conditions or mental disorders influence adaptive functioning.
Adaptive functioning is assessed using both clinical evaluation and individualized,
culturally appropriate, psychometrically sound measures. Standardized measures are
used with knowledgeable informants (e.g., parent or other family member; teacher; counselor;
care provider) and the individual to the extent possible. Additional sources of information
include educational, developmental, medical, and mental health evaluations.
Scores from standardized measures and interview sources must be interpreted using clinical
judgment. When standardized testing is difficult or impossible, because of a variety of
factors (e.g., sensory impairment, severe problem behavior), the individual may be diagnosed
with unspecified intellectual disability. Adaptive functioning may be difficult to
assess in a controlled setting (e.g., prisons, detention centers); if possible, corroborative information
reflecting functioning outside those settings should be obtained.
Criterion B is met when at least one domain of adaptive functioning—conceptual, social,
or practical—is sufficiently impaired that ongoing support is needed in order for the
person to perform adequately in one or more life settings at school, at work, at home, or in
the community. To meet diagnostic criteria for intellectual disability, the deficits in adaptive
functioning must be directly related to the intellectual impairments described in Criterion
A. Criterion C, onset during the developmental period, refers to recognition that
intellectual and adaptive deficits are present during childhood or adolescence.
Intellectual disability is a heterogeneous condition with multiple causes. There may be
associated difficulties with social judgment; assessment of risk; self-management of behavior,
emotions, or interpersonal relationships; or motivation in school or work environments.
Lack of communication skills may predispose to disruptive and aggressive behaviors. Gullibility
is often a feature, involving naivete in social situations and a tendency for being easily
led by others. Gullibility and lack of awareness of risk may result in exploitation by others
and possible victimization, fraud, unintentional criminal involvement, false confessions,
and risk for physical and sexual abuse. These associated features can be important in criminal
cases, including Atkins-type hearings involving the death penalty.
Individuals with a diagnosis of intellectual disability with co-occurring mental disorders
are at risk for suicide. They think about suicide, make suicide attempts, and may die
from them. Thus, screening for suicidal thoughts is essential in the assessment process. Because
of a lack of awareness of risk and danger, accidental injury rates may be increased.
Intellectual disability has an overall general population prevalence of approximately 1%, and prevalence rates vary by age. Prevalence for severe intellectual disability is approximately 6 per 1,000
Intellectual disability occurs in all races and cultures. Cultural sensitivity and knowledge are needed during assessment, and the individual's ethnic, cultural, and linguistic background, available experiences, and adaptive functioning within his or her community and cultural setting must be taken into account.
Overall, males are more likely than females to be diagnosed with both mild (average maleifemale ratio 1.6:1) and severe (average male:female ratio 1.2:1) forms of intellectual disability. However, gender ratios vary widely in reported studies. Sex-linked genetic factors and male vulnerability to brain insult may accoimt for some of the gender differences.
Disorders of communication include deficits in language, speech, and communication.
Speech is the expressive production of sounds and includes an individual's articulation,
fluency, voice, and resonance quality. Language includes the form, function, and use of a
conventional system of symbols (i.e., spoken words, sign language, written words, pictures)
in a rule-governed manner for communication. Communication includes any verbal
or nonverbal behavior (whether intentional or unintentional) that influences the behavior,
ideas, or attitudes of another individual. Assessments of speech, language and communication
abilities must take into account the individual’s cultural and language context,
particularly for individuals growing up in bilingual environments. The standardized measures
of language development and of nonverbal intellectual capacity must be relevant for
the cultural and linguistic group (i.e., tests developed and standardized for one group may
not provide appropriate norms for a different group). The diagnostic category of communication
disorders includes the following: language disorder, speech sound disorder,
childhood-onset fluency disorder (stuttering), social (pragmatic) communication disorder,
and other specified and unspecified communication disorders.
The core diagnostic features of language disorder are difficulties in the acquisition and use
of language due to deficits in the comprehension or production of vocabulary, sentence
structure, and discourse. The language deficits are evident in spoken communication,
written communication, or sign language. Language learning and use is dependent on
both receptive and expressive skills. Expressive ability refers to the production of vocal, gestural,
or verbal signals, while receptive ability refers to the process of receiving and comprehending
language messages. Language skills need to be assessed in both expressive
and receptive modalities as these may differ in severity. For example, an individual's expressive
language may be severely impaired, while his receptive language is hardly impaired
at all.
Language disorder usually affects vocabulary and grammar, and these effects then
limit the capacity for discourse. The child's first words and phrases are likely to be delayed
in onset; vocabulary size is smaller and less varied than expected; and sentences are
shorter and less complex with grammatical errors, especially in past tense. Deficits in comprehension
of language are frequently underestimated, as children may be good at using
context to infer meaning. There may be word-finding problems, impoverished verbal definitions,
or poor understanding of synonyms, multiple meanings, or word play appropriate
for age and culture. Problems with remembering new words and sentences are
manifested by difficulties following instructions of increasing length, difficulties rehearsing
strings of verbal information (e.g., remembering a phone number or a shopping list),
and difficulties remembering novel sound sequences, a skill that may be important for
learning new words. Difficulties with discourse are shown by a reduced ability to provide
adequate information about the key events and to narrate a coherent story.
The language difficulty is manifest by abilities substantially and quantifiably below
that expected for age and significantly interfering with academic achievement, occupational
performance, effective communication, or socialization (Criterion B). A diagnosis of
language disorder is made based on the synthesis of the individual's history, direct clinical
observation in different contexts (i.e., home, school, or work), and scores from standardized
tests of language ability that can be used to guide estimates of severity.
A positive family history of language disorders is often present. Individuals, even children, can be adept at accommodating to their limited language. They may appear to be shy or reticent to talk. Affected individuals may prefer to communicate only with family members or other familiar individuals. Although these social indicators are not diagnostic of a language disorder, if they are notable and persistent, they warrant referral for a full language assessment. Language disorder, particularly expressive deficits, may co-occur with speech sound disorder.
Speech sound production describes the clear articulation of the phonemes (i.e., individual sounds) that in combination make up spoken words. Speech sound production requires both the phonological knowledge of speech sounds and the ability to coordinate the movements of the articulators (i.e., the jaw, tongue, and lips,) with breathing and vocalizing for speech. Children with speech production difficulties may experience difficulty with phonological knowledge of speech sounds or the ability to coordinate movements for speech in varying degrees. Speech sound disorder is thus heterogeneous in its underlying mechanisms and includes phonological disorder and articulation disorder. A speech sound disorder is diagnosed when speech sound production is not what would be expected based on the child's age and developmental stage and when the deficits are not the result of a physical, structural, neurological, or hearing impairment. Among typically developing children at age 4 years, overall speech should be intelligible, whereas at age 2 years, only 50% may be understandable.
Language disorder, particularly expressive deficits, may be found to co-occur with speech
sound disorder. A positive family history of speech or language disorders is often present.
If the ability to rapidly coordinate the articulators is a particular aspect of difficulty,
there may be a history of delay or incoordination in acquiring skills that also utilize the
articulators and related facial musculature; among others, these skills include chewing,
maintaining mouth closure, and blowing the nose. Other areas of motor coordination may
be impaired as in developmental coordination disorder. Verbal dyspraxia is a term also
used for speech production problems.
Speech may be differentially impaired in certain genetic conditions (e.g.. Down syndrome,
22q deletion, FoxPZ gene mutation). If present, these should also be coded.
The essential feature of childhood-onset fluency disorder (stuttering) is a disturbance in the normal fluency and time patterning of speech that is inappropriate for the individual's age. This disturbance is characterized by frequent repetitions or prolongations of sounds or syllables and by other types of speech dysfluencies, including broken words (e.g., pauses within a word), audible or silent blocl^g (i.e., filled or unfilled pauses in speech), circumlocutions (i.e., word substitutions to avoid problematic words), words produced with an excess of physical tension, and monosyllabic whole-word repetitions (e.g., 'T-I-I-I see him"). The disturbance in fluency interferes with academic or occupational achievement or with social communication. The extent of the disturbance varies from situation to situation and often is more severe when there is special pressure to communicate (e.g., giving a report at school, interviewing for a job). Dysfluency is often absent during oral reading, singing, or talking to inanimate objects or to pets.
Fearful anticipation of the problem may develop. The speaker may attempt to avoid dysfluencies
by linguistic mechanisms (e.g., altering the rate of speech, avoiding certain
words or sounds) or by avoiding certain speech situations, such as telephoning or public
speaking. In addition to being features of the condition, stress and anxiety have been
shown to exacerbate dysfluency.
Childhood-onset fluency disorder may also be accompanied by motor movements
(e.g., eye blinks, tics, tremors of the lips or face, jerking of the head, breathing movements,
fist clenching). Children with fluency disorder show a range of language abilities, and the
relationship between fluency disorder and language abilities is unclear.
In addition to being features of the condition, stress and anxiety can exacerbate dysfluency. Impairment of social functioning may result from this anxiety.
Social (pragmatic) communication disorder is characterized by a primary difficulty with pragmatics, or the social use of language and communication, as manifested by deficits in understanding and following social rules of verbal and nonverbal communication in naturalistic contexts, changing language according to the needs of the listener or situation, and following rules for conversations and storytelling. The deficits in social communication result in functional limitations in effective communication, social participation, development of social relationships, academic achievement, or occupational performance. The deficits are not better explained by low abilities in the domains of structural language or cognitive abihty.
The most common associated feature of social (pragmatic) communication disorder is language impairment, which is characterized by a history of delay in reaching language milestones, and historical, if not current, structural language problems (see ''Language Disorder" earlier in this chapter). Individuals with social communication deficits may avoid social interactions. Attention-deficit/hyperactivity disorder (ADHD), behavioral problems, and specific learning disorders are also more common among affected individuals.
The essential features of autism spectrum disorder are persistent impairment in reciprocal
social communication and social interaction (Criterion A), and restricted, repetitive patterns
of behavior, interests, or activities (Criterion B). These symptoms are present from
early childhood and limit or impair everyday functioning (Criteria C and D). The stage at
which functional impairment becomes obvious will vary according to characteristics of
the individual and his or her environment. Core diagnostic features are evident in the
developmental period, but intervention, compensation, and current supports may mask
difficulties in at least some contexts. Manifestations of the disorder also vary greatly depending
on the severity of the autistic condition, developmental level, and chronological age;
hence, the term spectrum. Autism spectrum disorder encompasses disorders previously referred
to as early infantile autism, childhood autism, Kanner's autism, high-functioning
autism, atypical autism, pervasive developmental disorder not otherwise specified, childhood
disintegrative disorder, and Asperger's disorder.
The impairments in communication and social interaction specified in Criterion A are
pervasive and sustained. Diagnoses are most valid and reliable when based on multiple
sources of information, including clinician's observations, caregiver history, and, when
possible, self-report. Verbal and nonverbal deficits in social communication have varying
manifestations, depending on the individual's age, intellectual level, and language ability,
as well as other factors such as treatment history and current support. Many individuals
have language deficits, ranging from complete lack of speech through language delays,
poor comprehension of speech, echoed speech, or stilted and overly literal language. Even
when formal language skills (e.g., vocabulary, grammar) are intact, the use of language for
reciprocal social communication is impaired in autism spectrum disorder.
Deficits in social-emotional reciprocity (i.e., the ability to engage with others and share
thoughts and feelings) are clearly evident in young children with the disorder, who may
show little or no initiation of social interaction and no sharing of emotions, along with reduced
or absent imitation of others' behavior. What language exists is often one-sided,
lacking in social reciprocity, and used to request or label rather than to comment, share
feelings, or converse. In adults without intellectual disabilities or language delays, deficits
in social-emotional reciprocity may be most apparent in difficulties processing and responding
to complex social cues (e.g., when and how to join a conversation, what not to
say). Adults who have developed compensation strategies for some social challenges still
struggle in novel or unsupported situations and suffer from the effort and anxiety of consciously
calculating what is socially intuitive for most individuals.
Deficits in nonverbal communicative behaviors used for social interaction are manifested
by absent, reduced, or atypical use of eye contact (relative to cultural norms), gestures,
facial expressions, body orientation, or speech intonation. An early feature of autism
spectrum disorder is impaired joint attention as manifested by a lack of pointing, showing,
or bringing objects to share interest with others, or failure to follow someone's pointing or
eye gaze. Individuals may learn a few functional gestures, but their repertoire is smaller
than that of others, and they often fail to use expressive gestures spontaneously in communication.
Among adults with fluent language, the difficulty in coordinating nonverbal
communication with speech may give the impression of odd, wooden, or exaggerated
"body language" during interactions. Impairment may be relatively subtle within individual
modes (e.g., someone may have relatively good eye contact when speaking) but
noticeable in poor integration of eye contact, gesture, body posture, prosody, and facial expression
for social communication.
Deficits in developing, maintaining, and understanding relationships should be
judged against norms for age, gender, and culture. There may be absent, reduced, or atypical
social interest, manifested by rejection of others, passivity, or inappropriate approaches
that seem aggressive or disruptive. These difficulties are particularly evident in
young children, in whom there is often a lack of shared social play and imagination (e.g.,
age-appropriate flexible pretend play) and, later, insistence on playing by very fixed rules.
Older individuals may struggle to understand what behavior is considered appropriate in
one situation but not another (e.g., casual behavior during a job interview), or the different
ways that language may be used to communicate (e.g., irony, white lies). There may be an
apparent preference for solitary activities or for interacting with much younger or older
people. Frequently, there is a desire to establish friendships without a complete or realistic
idea of what friendship entails (e.g., one-sided friendships or friendships based solely on
shared special interests). Relationships with siblings, co-workers, and caregivers are also
important to consider (in terms of reciprocity).
Autism spectrum disorder is also defined by restricted, repetitive patterns of behavior,
interests, or activities (as specified in Criterion B), which show a range of manifestations
according to age and ability, intervention, and current supports. Stereotyped or repetitive
behaviors include simple motor stereotypies (e.g., hand flapping, finger flicking), repetitive
use of objects (e.g., spinning coins, lining up toys), and repetitive speech (e.g., echolalia,
the delayed or immediate parroting of heard words; use of "you" when referring to
self; stereotyped use of words, phrases, or prosodic patterns). Excessive adherence to routines
and restricted patterns of behavior may be manifest in resistance to change (e.g., distress
at apparently small changes, such as in packaging of a favorite food; insistence on
adherence to rules; rigidity of thinking) or ritualized patterns of verbal or nonverbal behavior
(e.g., repetitive questioning, pacing a perimeter). Highly restricted, fixated interests
in autism spectrum disorder tend to be abnormal in intensity or focus (e.g., a toddler
strongly attached to a pan; a child preoccupied with vacuum cleaners; an adult spending
hours writing out timetables). Some fascinations and routines may relate to apparent hyper-
or hyporeactivity to sensory input, manifested through extreme responses to specific
sounds or textures, excessive smelling or touching of objects, fascination with lights or
spinning objects, and sometimes apparent indifference to pain, heat, or cold. Extreme reaction
to or rituals involving taste, smell, texture, or appearance of food or excessive food
restrictions are common and may be a presenting feature of autism spectrum disorder.
Many adults with autism spectrum disorder without intellectual or language disabilities
learn to suppress repetitive behavior in public. Special interests may be a source of
pleasure and motivation and provide avenues for education and employment later in life.
Diagnostic criteria may be met when restricted, repetitive patterns of behavior, interests,
or activities were clearly present during childhood or at some time in the past, even if
symptoms are no longer present.
Criterion D requires that the features must cause clinically significant impairment in social,
occupational, or other important areas of current functioning. Criterion E specifies that
the social communication deficits, although sometimes accompanied by intellectual disability
(intellectual developmental disorder), are not in line with the individual's developmental
level; impairments exceed difficulties expected on the basis of developmental level.
Standardized behavioral diagnostic instruments with good psychometric properties,
including caregiver interviews, questionnaires and clinician observation measures, are
available and can improve reliability of diagnosis over time and across clinicians.
Many individuals with autism spectrum disorder also have intellectual impairment and/or language impairment (e.g., slow to talk, language comprehension behind production). Even those with average or high intelligence have an uneven profile of abilities. The gap between intellectual and adaptive functional skills is often large. Motor deficits are often present, including odd gait, clumsiness, and other abnormal motor signs (e.g., walking on tiptoes). Selfinjury (e.g., head banging, biting the wrist) may occur, and disruptive/challenging behaviors are more common in children and adolescents with autism spectrum disorder than other disorders, including intellectual disability. Adolescents and adults with autism spectrum disorder are prone to anxiety and depression. Some individuals develop catatonic-like motor behavior (slowing and "freezing" mid-action), but these are typically not of the magnitude of a catatonic episode. However, it is possible for individuals with autism spectrum disorder to experience a marked deterioration in motor symptoms and display a full catatonic episode with symptoms such as mutism, posturing, grimacing and waxy flexibility. The risk period for comorbid catatonia appears to be greatest in the adolescent years.
In recent years, reported frequencies for autism spectrum disorder across U.S. and nonU.S. countries have approached 1% of the population, with similar estimates in child and adult samples. It remains unclear whether higher rates reflect an expansion of the diagnostic criteria of DSM-IV to include subthreshold cases, increased awareness, differences in study methodology, or a true increase in the frequency of autism spectrum disorder.
Cultural differences will exist in norms for social interaction, nonverbal communication, and relationships, but individuals with autism spectrum disorder are markedly impaired against the norms for their cultural context. Cultural and socioeconomic factors may affect age at recognition or diagnosis; for example, in the United States, late or underdiagnosis of autism spectrum disorder among African American children may occur.
Autism spectrum disorder is diagnosed four times more often in males than in females. In clinic samples, females tend to be more likely to show accompanying intellectual disability, suggesting that girls without accompanying intellectual impairments or language delays may go unrecognized, perhaps because of subtler manifestation of social and communication difficulties.
In young children with autism spectrum disorder, lack of social and communication abilities may hamper learning, especially learning through social interaction or in settings with peers. In the home, insistence on routines and aversion to change, as well as sensory sensitivities, may interfere with eating and sleeping and make routine care (e.g., haircuts, dental work) extremely difficult. Adaptive skills are typically below measured IQ. Extreme difficulties in planning, organization, and coping with change negatively impact academic achievement, even for students with above-average intelligence. During adulthood, these individuals may have difficulties establishing independence because of continued rigidity and difficulty with novelty. Many individuals with autism spectrum disorder, even without intellectual disability, have poor adult psychosocial functioning as indexed by measures such as independent living and gainful employment. Functional consequences in old age are unknown, but social isolation and communication problems (e.g., reduced help-seeking) are likely to have consequences for health in older adulthood.
The essential feature of attention-deficit/hyperactivity disorder (ADHD) is a persistent
pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or
development. Inattention manifests behaviorally in ADHD as wandering off task, lacking
persistence, having difficulty sustaining focus, and being disorganized and is not due to
defiance or lack of comprehension. Hyperactivity refers to excessive motor activity (such as
a child running about) when it is not appropriate, or excessive fidgeting, tapping, or talkativeness.
In adults, hyperactivity may manifest as extreme restlessness or wearing others
out with their activity. Impulsivity refers to hasty actions that occur in the moment without
forethought and that have high potential for harm to the individual (e.g., darting into the
street without looking). Impulsivity may reflect a desire for immediate rewards or an inability
to delay gratification. Impulsive behaviors may manifest as social intrusiveness
(e.g., interrupting others excessively) and/or as making important decisions without consideration
of long-term consequences (e.g., taking a job without adequate information).
ADHD begins in childhood. The requirement that several symptoms be present before
age 12 years conveys the importance of a substantial clinical presentation during childhood.
At the same time, an earlier age at onset is not specified because of difficulties in establishing
precise childhood onset retrospectively. Adult recall of childhood symptoms
tends to be unreliable, and it is beneficial to obtain ancillary information.
Manifestations of the disorder must be present in more than one setting (e.g., home and
school, work). Confirmation of substantial symptoms across settings typically cannot be
done accurately without consulting informants who have seen the individual in those settings.
Typically, symptoms vary depending on context within a given setting. Signs of the
disorder may be minimal or absent when the individual is receiving frequent rewards for
appropriate behavior, is under close supervision, is in a novel setting, is engaged in especially
interesting activities, has consistent external stimulation (e.g., via electronic screens),
or is interacting in one-on-one situations (e.g., the clinician's office).
Mild delays in language, motor, or social development are not specific to ADHD but often cooccur.
Associated features may include low frustration tolerance, irritability, or mood lability.
Even in the absence of a specific learning disorder, academic or work performance is often impaired.
Inattentive behavior is associated with various underlying cognitive processes, and individuals
with ADHD may exhibit cognitive problems on tests of attention, executive
function, or memory, although these tests are not sufficiently sensitive or specific to serve as diagnostic
indices. By early adulthood, ADHD is associated with an increased risk of suicide attempt,
primarily when comorbid with mood, conduct, or substance use disorders.
No biological marker is diagnostic for ADHD. As a group, compared with peers, children
with ADHD display increased slow wave electroencephalograms, reduced total
brain volume on magnetic resonance imaging, and possibly a delay in posterior to anterior
cortical maturation, but these findings are not diagnostic. In the uncommon cases where
there is a known genetic cause (e.g.. Fragile X syndrome, 22qll deletion syndrome), the
ADHD presentation should still be diagnosed.
Population surveys suggest that ADHD occurs in most cultures in about 5% of children and about 2.5% of adults.
Differences in ADHD prevalence rates across regions appear attributable mainly to different diagnostic and methodological practices. However, there also may be cultural variation in attitudes toward or interpretations of children's behaviors. Clinical identification rates in the United States for African American and Latino populations tend to be lower than for Caucasian populations. Informant symptom ratings may be influenced by cultural group of the child and the informant, suggeshng that culturally appropriate practices are relevant in assessing ADHD.
ADHD is more frequent in males than in females in the general population, with a ratio of approximately 2:1 in children and 1.6:1 in adults. Females are more likely than males to present primarily with inattentive features.
ADHD is associated with reduced school performance and academic attainment, social rejection, and, in adults, poorer occupational performance, attainment, attendance, and
higher probability of unemployment as well as elevated interpersonal conflict. Children
with ADHD are significantly more likely than their peers without ADHD to develop conduct disorder in adolescence and antisocial personality disorder in adulthood, consequently increasing the likelihood for substance use disorders and incarceration. The risk of
subsequent substance use disorders is elevated, especially when conduct disorder or antisocial personality disorder develops. Individuals with ADHD are more likely than peers
to be injured. Traffic accidents and violations are more frequent in drivers with ADHD.
There may be an elevated likelihood of obesity among individuals with ADHD.
Inadequate or variable self-application to tasks that require sustained effort is often interpreted by others as laziness, irresponsibility, or failure to cooperate. Family relationships may be characterized by discord and negative interactions. Peer relationships afe
often disrupted by peer rejection, neglect, or teasing of the individual with ADHD. On average, individuals with ADHD obtain less schooling, have poorer vocational achievement,
and have reduced intellectual scores than their peers, although there is great variability. In
its severe form, the disorder is markedly impairing, affecting social, familial, and scholastic/occupational adjustment.
Academic deficits, school-related problems, and peer neglect tend to be most associated with elevated symptoms of inattention, whereas peer rejection and, to a lesser extent,
accidental injury are most salient with marked symptoms of hyperactivity or impulsivity
Specific learning disorder is a neurodevelopmental disorder with a biological origin that is
the basis for abnormalities at a cognitive level that are associated with the behavioral signs
of the disorder. The biological origin includes an interaction of genetic, epigenetic, and environmental
factors, which affect the brain's ability to perceive or process verbal or nonverbal
information efficiently and accurately.
One essential feature of specific learning disorder is persistent difficulties learning keystone
academic skills (Criterion A), with onset during the years of formal schooling (i.e., the developmental
period). Key academic skills include reading of single words accurately and
fluently, reading comprehension, written expression and spelling, arithmetic calculation, and
mathematical reasoning (solving mathematical problems). In contrast to talking or walking,
which are acquired developmental milestones that emerge with brain maturation, academic
skills (e.g., reading, spelling, writing, mathematics) have to be taught and learned explicitly.
Specific learning disorder disrupts the normal pattern of learning academic skills; it is not simply
a consequence of lack of opportunity of learning or inadequate instruction. Difficulties
mastering these key academic skills may also impede learning in other academic subjects (e.g.,
history, science, social studies), but those problems are attributable to difficulties learning the
underlying academic skills. Difficulties learning to map letters with the sounds of one's language—^
to read printed words (often called dyslexia)—is one of the most common manifestations
of specific learning disorder. The learning difficulties manifest as a range of observable,
descriptive behaviors or symptoms (as listed in Criteria A1-A6). These clinical symptoms may
be observed, probed by means of the clinical interview, or ascertained from school reports, rating
scales, or descriptions in previous educational or psychological assessments. The learning
difficulties are persistent, not transitory. In children and adolescents, persistence is defined as
restricted progress in learning (i.e., no evidence that the individual is catching up with classmates)
for at least 6 months despite the provision of extra help at home or school. For example,
difficulties learning to read single words that do not fully or rapidly remit with the provision of
instruction in phonological skills or word identification strategies may indicate a specific
learning disorder. Evidence of persistent learning difficulties may be derived from cumulative
school reports, portfolios of the child's evaluated work, curriculum-based measures, or clinical
interview. In adults, persistent difficulty refers to ongoing difficulties in literacy or numeracy
skills that manifest during childhood or adolescence, as indicated by cumulative evidence
from school reports, evaluated portfolios of work, or previous assessments.
A second key feature is that the individual's performance of the affected academic skills is
well below average for age (Criterion B). One robust clinical indicator of difficulties learning
academic skills is low academic achievement for age or average achievement that is sustainable
only by extraordinarily high levels of effort or support. In children, the low academic skills
cause significant interference in school performance (as indicated by school reports and
teacher's grades or ratings). Another clinical indicator, particularly in adults, is avoidance of
activities that require the academic skills. Also in adulthood, low academic skills interfere with
occupational performance or everyday activities requiring those skills (as indicated by self-report
or report by others). However, this criterion also requires psychometric evidence from an
individually administered, psychometrically sound and culturally appropriate test of academic
achievement that is norm-referenced or criterion-referenced. Academic skills are distributed
along a continuum, so there is no natural cutpoint that can be used to differentiate
individuals with and without specific learning disorder. Thus, any threshold used to specify
what constitutes significantly low academic achievement (e.g., academic skills weU below age
expectation) is to a large extent arbitrary. Low achievement scores on one or more standardized
tests or subtests within an academic domain (i.e., at least 1.5 standard deviations [SD] below
the population mean for age, which translates to a standard score of 78 or less, which is
below the 7th percentile) are needed for the greatest diagnostic certainty. However, precise
scores will vary according to the particular standardized tests that are used. On the basis of
clinical judgment, a more lenient threshold may be used (e.g., 1.0-2.5 SD below the population
mean for age), when learning difficulties are supported by converging evidence
from clinical assessment, academic history, school reports, or test scores. Moreover, since
standardized tests are not available in all languages, the diagnosis may then be based in
part on clinical judgment of scores on available test measures.
A third core feature is that the learning difficulties are readily apparent in the early
school years in most individuals (Criterion C). However, in others, the learning difficulties
may not manifest fully until later school years, by which time learning demands have increased
and exceed the individual's limited capacities.
Another key diagnostic feature is that the learning difficulties are considered "specific,"
for four reasons. First, they are not attributable to intellectual disabilities (intellectual
disability [intellectual developmental disorder]); global developmental delay;
hearing or vision disorders, or neurological or motor disorders) (Criterion D). Specific
learning disorder affects learning in individuals who otherwise demonstrate normal levels
of intellectual functioning (generally estimated by an IQ score of greater than about 70
[}5 points allowing for measurement error]). The phrase "unexpected academic underachievement"
is often cited as the defining characteristic of specific learning disorder in
that the specific learning disabilities are not part of a more general learning difficulty as
manifested in intellectual disability or global developmental delay. Specific learning disorder
may also occur in individuals identified as intellectually "gifted." These individuals
may be able to sustain apparentiy adequate academic functioning by using compensatory
strategies, extraordinarily high effort, or support, until the learning demands or assessment
procedures (e.g., timed tests) pose barriers to their demonstrating their learning or
accomplishing required tasks. Second, the learning difficulty cannot be attributed to more
general external factors, such as economic or environmental disadvantage, chronic absenteeism,
or lack of education as typically provided in the individual's community context.
Third, the learning difficulty cannot be attributed to a neurological (e.g., pediatric stroke)
or motor disorders or to vision or hearing disorders, which are often associated with problems
learning academic skills but are distinguishable by presence of neurological signs.
Finally, the learning difficulty may be restricted to one academic skill or domain (e.g., reading
single words, retrieving or calculating number facts).
Comprehensive assessment is required. Specific learning disorder can only be diagnosed
after formal education starts but can be diagnosed at any point afterward in children, adolescents,
or adults, providing there is evidence of onset during the years of formal schooling (i.e.,
the developmental period). No single data source is sufficient for a diagnosis of specific learning
disorder. Rather, specific learning disorder is a clinical diagnosis based on a synthesis of
the individual's medical, developmental, educational, and family history; the history of the
learning difficulty, including its previous and current manifestation; the impact of the difficulty
on academic, occupational, or social functioning; previous or current school reports;
portfolios of work requiring academic skills; curriculum-based assessments; and previous or
current scores from individual standardized tests of academic achievement. If an intellectual,
sensory, neurological, or motor disorder is suspected, then the clinical assessment for specific
learning disorder should also include methods appropriate for these disorders. Thus, comprehensive
assessment will involve professionals with expertise in specific learning disorder and
psychological/cognitive assessment. Since specific learning disorder typically persists into
adulthood, reassessment is rarely necessary, unless indicated by marked changes in the learning
difficulties (amelioration or worsening) or requested for specific purposes.
Specific learning disorder is frequently but not invariably preceded, in preschool years, by
delays in attention, language, or motor skills that may persist and co-occur with specific
learning disorder. An uneven profile of abilities is common, such as above-average abilities
in drawing, design, and other visuospatial abilities, but slow, effortful, and inaccurate
reading and poor reading comprehension and written expression. Individuals with specific
learning disorder typically (but not invariably) exhibit poor performance on psychological
tests of cognitive processing. However, it remains unclear whether these cognitive
abnormalities are the cause, correlate, or consequence of the learning difficulties. Also, although
cognitive deficits associated with difficulties learning to read words are well documented,
those associated with other manifestations of specific learning disorder (e.g.,
reading comprehension, arithmetic computation, written expression) are underspecified
or unknown. Moreover, individuals with similar behavioral symptoms or test scores are
found to have a variety of cognitive deficits, and many of these processing deficits are also
found in other neurodevelopmental disorders (e.g., attention-deficit/hyperactivity disorder
[ADHD], autistic spectrum disorder, communication disorders, developmental coordination
disorder). Thus, assessment of cognitive processing deficits is not required for
diagnostic assessment. Specific learning disorder is associated with increased risk for suicidal
ideation and suicide attempts in children, adolescents, and adults.
There are no known biological markers of specific learning disorder. As a group, individuals
with the disorder show circumscribed alterations in cognitive processing and
brain structure and function. Genetic differences are also evident at the group level. But
cognitive testing, neuroimaging, or genetic testing are not useful for diagnosis at this time.
Specific learning disorder occurs across languages, cultures, races, and socioeconomic conditions but may vary in its manifestation according to the nature of the spoken and written symbol systems and cultural and educational practices. For example, the cognitive processing requirements of reading and of working with numbers vary greatly across orthographies. In the English language, the observable hallmark clinical symptom of difficulties learning to read is inaccurate and slow reading of single words; in other alphabetic languages that have more direct mapping between sounds and letters (e.g., Spanish, German) and in non-alphabetic languages (e.g., Chinese, Japanese), the hallmark feature is slow but accurate reading. In English-language learners, assessment should include consideration of whether the source of reading difficulties is a limited proficiency with English or a specific learning disorder. Risk factors for specific learning disorder in Englishlanguage learners include a family history of specific learning disorder or language delay in the native language, as well as learning difficulties in English and failure to catch up with peers. If there is suspicion of cultural or language differences (e.g., as in an Englishlanguage learner), the assessment needs to take into account the individual's language proficiency in his or her first or native language as well as in the second language (in this example, English). Also, assessment should consider the linguistic and cultural context in which the individual is living, as well as his or her educational and learning history in the original culture and language.
Specific learning disorder is more common in males than in females (ratios range from about 2:1 to 3:1) and cannot be attributed to factors such as ascertainment bias, definitional or measurement variation, language, race, or socioeconomic status.
The diagnosis of developmental coordinahon disorder is made by a clinical synthesis of the
history (developmental and medical), physical examination, school or workplace report, and
individual assessment using psychometrically sound and culturally appropriate standardized
tests. The manifestation of impaired skills requiring motor coordination (Criterion A) varies
with age. Young children may be delayed in achieving motor milestones (i.e., sitting, crawling,
walking), although many achieve typical motor milestones. They also may be delayed in developing
skills such as negotiating stairs, pedaling, buttoning shirts, completing puzzles, and
using zippers. Even when the skill is achieved, movement execution may appear awkward,
slow, or less precise than that of peers. Older children and adults may display slow speed or inaccuracy
with motor aspects of activities such as assembling puzzles, building models, playing
ball games (especially in teams), handwriting, typing, driving, or carrying out self-care sldlls.
Developmental coordination disorder is diagnosed only if the impairment in motor
skills significantly interferes with the performance of, or participation in, daily activities in
family, social, school, or community life (Criterion B). Examples of such activities include
getting dressed, eating meals with age-appropriate utensils and without mess, engaging
in physical games with others, using specific tools in class such as rulers and scissors, and
participating in team exercise activities at school. Not only is ability to perform these actions
impaired, but also marked slowness in execution is common. Handwriting competence
is frequently affected, consequently affecting legibility and/or speed of written output
and affecting academic achievement (the impact is distinguished from specific learning
difficulty by the emphasis on the motoric component of written output skills). In adults,
everyday skills in education and work, especially those in which speed and accuracy are
required, are affected by coordination problems.
Criterion C states that the onset of symptoms of developmental coordination disorder
must be in the early developmental period. However, developmental coordination disorder is
typically not diagnosed before age 5 years because there is considerable variation in the age at
acquisition of many motor skills or a lack of stability of measurement in early childhood (e.g.,
some children catch up) or because other causes of motor delay may not have fully manifested.
Criterion D specifies that the diagnosis of developmental coordination disorder is
made if the coordination difficulties are not better explained by visual impairment or attributable
to a neurological condition. Thus, visual function examination and neurological
examination must be included in the diagnostic evaluation. If intellectual disability (intellectual
developmental disorder) is present, the motor difficulties are in excess of those expected
for the mental age; however, no IQ cut-off or discrepancy criterion is specified.
Developmental coordination disorder does not have discrete subtypes; however, individuals
may be impaired predominantly in gross motor skills or in fine motor skills, including
handwriting skills.
Other terms used to describe developmental coordination disorder include childhood
dyspraxia, specific developmental disorder of motor function, and clumsy child syndrome.
Some children with developmental coordination disorder show additional (usually suppressed) motor activity, such as choreiform movements of unsupported limbs or mirror movements. These "overflow" movements are referred to as neurodevelopmental immaturities or neurological soft signs rather than neurological abnormalities. In both current literature and clinical practice, their role in diagnosis is still unclear, requiring further evaluation.
The prevalence of developmental coordination disorder in children ages 5-11 years is 5%- 6% (in children age 7 years, 1.8% are diagnosed with severe developmental coordination disorder and 3% with probable developmental coordination disorder). Males are more often affected than females, with a maleifemale ratio between 2:1 and 7:1.
Developmental coordination disorder occurs across cultures, races, and socioeconomic conditions. By definition, "activities of daily living" implies cultural differences necessitating consideration of the context in which the individual child is living as well as whether he or she has had appropriate opportunities to learn and practice such activities.
Developmental coordination disorder leads to impaired functional performance in activities of daily living (Criterion B), and the impairment is increased with co-occurring conditions. Consequences of developmental coordination disorder include reduced participation in team play and sports; poor self-esteem and sense of self-worth; emotional or behavior problems; impaired academic achievement; poor physical fitness; and reduced physical activity and obesity.
The essential feature of stereotypic movement disorder is repetitive, seemingly driven,
and apparently purposeless motor behavior (Criterion A). These behaviors are often
rhythmical movements of the head, hands, or body without obvious adaptive function.
The movements may or may not respond to efforts to stop them. Among typically developing
children, the repetitive movements may be stopped when attention is directed to
them or when the child is distracted from performing them. Among children with neurodevelopmental
disorders, the behaviors are typically less responsive to such efforts. In
other cases, the individual demonstrates self-restraining behaviors (e.g., sitting on hands,
wrapping arms in clothing, finding a protective device).
The repertoire of behaviors is variable; each individual presents with his or her own individually
patterned, "signature" behavior. Examples of non-self-injurious stereotypic
movements include, but are not limited to, body rocking, bilateral flapping or rotating
hand movements, flicking or fluttering fingers in front of the face, arm waving or flapping,
and head nodding. Stereotyped self-injurious behaviors include, but are not limited to, repetitive
head banging, face slapping, eye poking, and biting of hands, lips, or other body
parts. Eye poking is particularly concerning; it occurs more frequently among children
with visual impairment. Multiple movements may be combined (e.g., cocking the head,
rocking the torso, waving a small string repetitively in front of the face).
Stereotypic movements may occur many times during a day, lasting a few seconds to
several minutes or longer. Frequency can vary from many occurrences in a single day to
several weeks elapsing between episodes. The behaviors vary in context, occurring when
the individual is engrossed in other activities, when excited, stressed, fatigued, or bored.
Criterion A requires that the movements be "apparently" purposeless. However, some
functions may be served by the movements. For example, stereotypic movements might
reduce anxiety in response to external stressors.
Criterion B states that the stereotypic movements interfere with social, academic, or
other activities and, in some children, may result in self-injury (or would if protective measures
were not used). If self-injury is present, it should be coded using the specifier. Onset
of stereotypic movements is in the early developmental period (Criterion C). Criterion D
states that the repetitive, stereotyped behavior in stereotypic movement disorder is not attributable
to the^physiological effects of a substance or neurological condition and is not
better explained by another neurodevelopmental or mental disorder. The presence of
stereotypic movements may indicate an undetected neurodevelopmental problem, especially
in children ages 1-3 years.
Simple stereotypic movements (e.g., rocking) are common in young typically developing children. Complex stereotypic movements are much less common (occurring in approximately 3%-4%). Between 4% and 16°/«of individuals v^ith intellectual disability (intellectual developmental disorder) engage in stereotypy and self-injury. The risk is greater in individuals with severe intellectual disability. Among individuals with intellectual disability living in residential facilities, 10%-15% may have stereotypic movement disorder with self-injury.
Stereotypic movement disorder, with or without self-injury, occurs in all races and cultures. Cultural attitudes toward unusual behaviors may result in delayed diagnosis. Overall cultural tolerance and attitudes toward stereotypic movement vary and must be considered.
Tic disorders comprise four diagnostic categories: Tourette's disorder, persistent (chronic)
motor or vocal tic disorder, provisional tic disorder, and the other specified and unspecified
tic disorders. Diagnosis for any tic disorder is based on the presence of motor and/or vocal
tics (Criterion A), duration of tic symptoms (Criterion B), age at onset (Criterion C), and absence
of any known cause such as another medical condition or substance use (Criterion D).
The tic disorders are hierarchical in order (i.e., Tourette's disorder, followed by persistent
[chronic] motor or vocal tic disorder, followed by provisional tic disorder, followed by the
other specified and unspecified tic disorders), such that once a tic disorder at one level of the
hierarchy is diagnosed, a lower hierarchy diagnosis cannot be made (Criterion E).
Tics are sudden, rapid, recurrent, nonrhythmic motor movements or vocalizations. An
individual may have various tic symptoms over time, but at any point in time, the tic repertoire
recurs in a characteristic fashion. Although tics can include almost any muscle group
or vocalization, certain tic symptoms, such as eye blinking or throat clearing, are common
across patient populations. Tics are generally experienced as involuntary but can be voluntarily
suppressed for varying lengths of time.
Tics can be either simple or complex. Simple motor tics are of short duration (i.e., milliseconds)
and can include eye blinking, shoulder shrugging, and extension of the extremities.
Simple vocal tics include throat clearing, sniffing, and grunting often caused by
contraction of the diaphragm or muscles of the oropharynx. Complex motor tics are of longer
duration (i.e., seconds) and often include a combination of simple tics such as simultaneous
head turning and shoulder shrugging. Complex tics can appear purposeful, such
as a tic-like sexual or obscene gesture (copropraxia) or a tic-like imitation of someone else's
movements (echopraxia). Similarly, complex vocal tics include repeating one's own sounds
or words {palilalia), repeating the last-heard word or phrase (echolalia), or uttering socially
unacceptable words, including obscenities, or ethnic, racial, or religious slurs (coprolalia).
Importantly, coprolalia is an abrupt, sharp bark or grunt utterance and lacks the prosody
of similar inappropriate speech observed in human interactions.
The presence of motor and/or vocal tics varies across the four tic disorders (Criterion
A). For Tourette's disorder, both motor and vocal tics must be present, whereas for persistent
(chronic) motor or vocal tic disorder, only motor or only vocal tics are present. For
provisional tic disorder, motor and/or vocal tics may be present. For other specified or unspecified
tic disorders, the movement disorder symptoms are best characterized as tics but
are atypical in presentation or age at onset, or have a known etiology.
The 1-year minimum duration criterion (Criterion B) assures that individuals diagnosed
with either Tourette's disorder or persistent (chronic) motor or vocal tic disorder
have had persistent symptoms. Tics wax and wane in severity, and some individuals may
have tic-free periods of weeks to months; however, an individual who has had tic symptoms
of greater than 1 year's duration since first tic onset would be considered to have persistent
symptoms regardless of duration of tic-free periods. For an individual with motor
and/or vocal tics of less than 1 year since first tic onset, a provisional tic disorder diagnosis
can be considered. There is no duration specification for other specified and unspecified tic
disorders. The onset of tics must occur prior to age 18 years (Criterion C). Tic disorders
typically begin in the prepubertal period, with an average age at onset between 4 and 6
years, and with the incidence of new-onset tic disorders decreasing in the teen years. New
onset of tic symptoms in adulthood is exceedingly rare and is often associated with exposures
to drugs (e.g., excessive cocaine use) or is a result of a central nervous system insult
(e.g., postviral encephalitis). Although tic onset is uncommon in teenagers and adults, it is
not uncommon for adolescents and adults to present for an initial diagnostic assessment
and, when carefully evaluated, provide a history of milder symptoms dating back to childhood.
New-onset abnormal movements suggestive of tics outside of the usual age range
should result in evaluation for other movement disorders or for specific etiologies.
Tic symptoms cannot be attributable to the physiological effects of a substance or another
medical condition (Criterion D). When there is strong evidence from the history,
physical examination, and/or laboratory results to suggest a plausible, proximal, and
probable cause for a tic disorder, a diagnosis of other specified tic disorder should be used.
Having previously met diagnostic criteria for Tourette's disorder negates a possible diagnosis
of persistent (chronic) motor or vocal tic disorder (Criterion E). Similarly, a previous
diagnosis of persistent (chronic) motor or vocal tic disorder negates a diagnosis of
provisional tic disorder or other specified or unspecified tic disorder (Criterion E).
Tics are common in childhood but transient in most cases. The estimated prevalence of Tourette's disorder ranges from 3 to 8 per 1,000 in school-age children. Males are more commonly affected than females, with the ratio varying from 2:1 to 4:1. A national survey in the United States estimated 3 per 1,000 for the prevalence of clinically identified cases. The frequency of identified cases was lower among African Americans and Hispanic Americans, which may be related to differences in access to care.
Tic disorders do not appear to vary in clinical characteristics, course, or etiology by race, ethnicity, and culture. However, race, ethnicity, and culture may impact how tic disorders are perceived and managed in the family and community, as well as influencing patterns of help seeking, and choices of treatment.
Males are more commonly affected than females, but there are no gender differences in the kinds of tics, age at onset, or course. Women with persistent tic disorders may be more likely to experience anxiety and depression.
Many individuals with mild to moderate tic severity experience no distress or impairment in functioning and may even be unaware of their tics. Individuals with more severe symptoms generally have more impairment in daily living, but even individuals with moderate or even severe tic disorders may function well. The presence of a co-occurring condition, such as ADHD or OCD, can have greater impact on functioning. Less commonly, tics disrupt functioning in daily activities and result in social isolation, interpersonal conflict, peer victimization, inability to work or to go to school, and lower quality of life. The individual also may experience substantial psychological distress. Rare complications of Tourette's disorder include physical injury, such as eye injury (from hitting oneself in the face), and orthopedic and neurological injury (e.g., disc disease related to forceful head and neck movements).