Pervasive Developmental Disorders are characterised by severe and pervasive impairment in several areas of development: reciprocal social interaction skills, communication skills, or the presence of stereotyped behaviour, interests and activities. The qualitative impairments that define these conditions are distinctly deviant relative to the individual's developmental level or mental age.
AUTISTIC DISORDER
DIAGNOSTIC FEATURES
The essential features of Autistic Disorder are the presence of markedly abnormal or impaired development in social interaction and communication and a markedly restricted repertoire of activity and interests. Manifestations of the disorder vary greatly depending on the developmental level and chronological age of the individual. Autistic Disorder is sometimes referred to as Early Infantile Autism, Childhood Autism or Kanner's Syndrome.
The impairment in reciprocal social interaction is gross and sustained. There may be marked impairment in use of multiple non-verbal behaviours (eg: eye-to-eye gaze, facial expression, body postures and gestures) to regulate social interaction and communication. (Criterion A1a). There may be failure to develop peer relationships appropriate to developmental level (Criterion A1b) that may take different forms at different ages. Younger individuals may have little or no interest in establishing friendships. Older individuals may have an interest in friendship but lack understanding of the conventions of social interaction. There may be a lack of spontaneous seeking to share enjoyment, interests, or achievments with other people (eg: not showing, bringing or pointing out objects they find interesting) (Criterion A1c). Lack of social or emotional reciprocity may be present (eg: not actively participating in simple social play or games, preferring solitary activities, or involving others only as tools or mechanical aids) (Criterion A1d). Often, an individual's awareness of others is markedly impaired. Individuals with this disorder may be oblivious to other children (including siblings), may have no concept of the needs of others, or may not notice another person's distress.
The impairment in communication is also marked and sustained and affects both verbal and non-verbal skills. There may be delay in, or total lack of, the development of spoken language (Criterion A2a). In individuals who do speak, there may be marked impairment in the ability to initiate or sustain a converstaion with others. (Criterion A2b), or a stereotyped and repetitive use of language or idiosyncratic language (Criterion A2c). There may also be a lack of varied, spontaneous, make-believe play or social imitative play appropriate to developmental level (Criterion A2d). When speech does develop, the pitch, intonation, rate, rhythm or stress may be abnormal (eg: tone of voice may be monotonous, or contain question-like rises at the end of statements). Grammatical structures are often immature and include stereotyped and repetitive use of language (eg: repetition of words or phrases regardless of meaning; repeating jingles or commercials) or metaphorical language (ie: language that can only be understood clealrly by those familiar with the individual's communication style). A disturbance in the comprehension of language may be evidenced by an inability to understand simple questions, directions or jokes. Imaginative play is often absent or markedly impaired.
These individuals also tend not to engage in simple imitation games or routines of infancy or early childhood, or do so only out of context or in a mechanical way.
Individuals with Autistic Disorder have restricted, repetitive, and stereotyped patterns of behaviour, interests and activities. There may be an encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus (CriterionA3a); an apparently inflexible adherence to specific, nonfunctional routines or rituals (Criterion A3b); stereotyped and repetitive motor mannerisms (Criterion A3c); or a persistent preoccupation with parts of objects (Criterion A3d). Individuals with Autistic Disorder display a markedly restricted range of interests and are often preoccupied with one narrow interest (eg: with amassing facts about meteorology or baseball). They may line up an exact number of play things in the same manner over and over again or repetitively mimic the actions of a television actor. They may insist on sameness and show resistance to or distress over trivial changes (eg: a younger child may have a catastrophic reaction to a minor change in the environment such as a new set of curtains or a change in place at the dinner table).
There is often an interest in nonfunctional routines or rituals or an unreasonable insistence on following routines (eg: taking the same route to school every day). Stereotyped body movements include the hands (clapping, finger-flicking) or whole body (rocking, dipping and swaying). Abnormalities of posture (eg: walking on tiptoe, odd hand movements and body postures) may be present. These individuals show a persistent preoccupation with parts of objects (buttons, parts of the body). There may also be a fascination with movement (eg: the spinning wheels of toys, the opening and closing of doors, an electric fan or other rapidly revolving object). The person may be highly attached to some inanimate object (eg: a piece of string or a rubber band).
The disturbance must be manifest by delays or abnormal functioning in at least one of the following areas prior to age 3 years: social interaction, language as used in social communication, or symbolic or imaginative play (CriterionB). There is typically no period of unequivocally normal development, although 1 or 2 years of relatively normal development has been reported in some instances. In a minority of cases, parents report regression in language development, generally manifest as the cessation of speech after a child has acquired from 5 to 10 words. By definition, if there is a period of normal development, it cannot extend past age 3 years. The disturbance must not be better accounted for by Rett's Disorder or Childhood Disintegrative Disorder (Criterion C).
ASSOCIATED FEATURES AND DISORDERS
Associated descriptive features and mental disorders: In most cases, there is an associated diagnosis of Mental Retardation, commonly in the moderate range (IQ 35-50). Approximately 75% of children with Autistic Disorder function at a retarded level. There may be abnormalities in the development of cognitive skills. The profile of cognitive skills is usually uneven, regardless of the general level of intelligence (eg: a 4 1/2 year old girl with Autistic Disorder may be able to read, ie: hyperlexia). In many higher-functioning children with Autistic Disorder, the level of receptive language (ie: language comprehension) is below that of expressive language (ie: vocabulary). Individuals with Autistic Disorder may have a range of behavioural symptoms, including hyperactivity, short attention span, impulsivity, aggressiveness, self-injurious behaviours and, particularly in young children, temper tantrums. There may be odd responses to sensory stimuli (eg: a high threshold for pain, oversensitivity to sounds or being touched, exaggerated reactions to light or odours, fascination with certain stimuli). There may be abnormalities in eating (eg: limiting diet to a few foods, Pica) or sleeping (eg: recurrent awakening at night, with rocking). Abnormalities of mood or affect (eg: giggling or weeping for no apparent reason, an apparent absence of emotional reaction) may be present. There may be a lack of fear in response to real dangers and excessive fearfulness in response to harmless objects. A variety of self-injurious behaviours may be present (eg: head banging or finger, hand or wrist biting). In adolescence or early adult life, individuals with Autistic Disorder who have the intellectual capacity for insight may become depressed in response to the realisation of their serious impairment.
Associated laboratory findings: When Autistic Disorder is associated with a general medical condition, laboratory findings consistent with the general medical condition will be observed. There have been reports of group differences in measures of serotonergic activity, but these are not diagnostic for Autistic Disorder. Imaging studies may be abnormal in some cases, but no specific pattern has been clearly identified. EEG abnormalities are common even in the absence of seizure disorders.
Associated physical examination findings and general medical conditions: Various nonspecific neurological symptoms or signs may be noted (eg: primitive reflexes, delayed development of hand dominance) in Autistic Disorder. The condition is sometimes observed in association with a neurological or other general medical condition (eg: encephalitis, phenylketonuria, tuberous sclerosis, fragile x syndrome, anoxia during birth, maternal rubella). Seizures may develop (particularly in adolescence) in as many as 25% of cases.
SPECIFIC AGE AND GENDER FEATURES
The nature of the impairment in social interaction may change over time in Autistic Disorder and may vary depending on the developmental level of the individual. In infants, there may be a failure to cuddle; an indifference or aversion to affection or physical contact; a lack of eye contact, facial responsiveness or socially directed smiles; and a failure to respond to their parents' voices. As a result, parents may be concerned initially that the child is deaf. Young children with this disorder may treat adults as interchangeable or may cling mechanically to a specific person. Over the course of development, the child may become more willing to be passively engaged in social interaction and may even become more interested in social interaction. However, even in such instances, the child tends to treat other people in unusual ways (eg: expecting other people to answer ritualised questions in specific ways, having little sense of other peoples' boundaries and being inappropriately intrusive in social interaction). In older individuals, tasks involving long-term memory (eg: train timetables, historical dates, chemical formulas, or recall of the exact words of a song heard years before) may be excellent, but the information inappropriate to the social context. Rates of the disorder are four to five times higher in males than in females. Females with the disorder are more likely, however, to exhibit more severe mental retardation.
PREVALENCE
Epidemiological studies suggest rates of Autistic Disorder of 2 - 5 cases per 10 000 individuals.
COURSE
By definition, the onset of Autistic Disorder is prior to age 3 years. In some instances, parents will report that they have been worried about the child since birth or shortly afterward because of the child's lack of interest in social interaction. Manifestations of the disorder in infancy are more subtle and difficult to define than those seen after age 2 years. In a minority of cases, the child may be reported to have developed normally for the first year (or even 2 years) of life. Autistic Disorder follows a continuous course. In school-age children and adolescents, developmental gains in some areas are common (eg: increased interest in social functioning as the child reaches school age). Some individuals deteriorate behaviourally during adolescence, whereas others improve. Language skills (eg: presence of communicative speech) and overall intellectual level are the strongest factors related to ultimate prognosis. Available follow-up studies suggest that only a small percentage of individuals with the disorder go on as adults to live and work independently. In about one-third of cases, some degree of partial independence is possible. The highest functioning adults with Autistic Disorder typically continue to exhibit problems in social interaction and communication along with markedly restricted interests and activities.
FAMILIAL PATTERN
There is an increased risk of Autistic Disorder among siblings of individuals with the disorder.
DIFFERENTIAL DIAGNOSIS
Periods of developmental regression may be observed in normal development, but these are neither as severe nor as prolonged as in Autistic Disorder. Autistic Disorder must be differentiated from other Pervasive Developmental Disorders. Rett's disorder differs from Autistic Disorder in its characteristic sex ratio and pattern of deficits. Rett's Disorder has been diagnosed only in females, whereas Autistic Disorder occurs much more frequently in males. In Rett's Disorder, the is a characteristic pattern of head-growth deceleration, loss of previously acquired purposeful hand skills, and the appearance of poorly coordinated gait or trunk movements, particularly during the pre-school years. Individuals with Rett's Disorder may exhibit difficulties in social interaction similar to those observed in Autistic Disorder, but these tend to be transient. Autistic Disorder differs from Childhood Disintegrative Disorder, which has a distinctive pattern of developmental regression following at least two years of normal development. In Autistic Disorder, developmental abnormalities are usually noted within the first year of life. When information on early development is unavailable or when it is not possible to document the required period of normal development, the diagnosis of Autistic Disorder should be made. Asperger's Disorder can be distinguished from Autistic Disorder by the lack of delay in language development. Asperger's Disorder is not diagnosed if criteria are met for Autistic Disorder.
Schizophrenia with childhood onset usually develops after years of normal, or near normal, development. An additional diagnosis of Schizophrenia can be made if an individual with Autistic Disorder develops the characteristic features of Schizophrenia with active-phase symptoms of prominent delusions or hallucinations that last for at least one month. In Selective Mutism, the childs usually exhibits appropriate communication skills in certain contexts and does not have the severe impairment in social interaction and the restricted patterns of behaviour associated with Autistic Disorder. In Expressive Language Disorder and Mixed Receptive-Expressive Language Disorder, there is language impairment, but it is not associated with the presence of a qualitative impairment in social interaction and restricted, repetitive and stereotyped patterns of behaviour. It is sometimes difficult to determine whether an additional diagnosis of Autistic Disorder is warranted in an individual with Mental Retardation, especially if the mental retardation is severe or profound. An additional diagnosis of Autistic Disorder is reserved for those situations in which there are qualitative deficits in social and communicative skills and the specific behaviours characteristic of Autistic Disorder are present. Motor stereotypes are characteristic of Autistic Disorder. An additional diagnosis of Stereotypic Movement Disorder is not given when these are better accounted for as part of the presentation of Autistic Disorder.
DIAGNOSTIC CRITERIA FOR AUTISTIC DISORDER
A. A total of six (or more) items from (1), (2), and (3), with at least two from (1), and one each from (2) and (3).
1) qualitative impairment in social interaction, as manifested by at least two of the following:
(a) marked impairment in the use of multiple nonverbal behaviours such as eye-to-eye gaze facial expression, body postures, and gestures, to regulate social interaction;
(b) failure to develop peer relationships appropriate to developmental level;
(c) a lack of spontaneous seeking to share enjoyment, interests or achievments with other people (eg: by a lack of showing, bringing or pointing out objects of interest);
(d) lack of social or emotional reciprocity.
2) qualitative impairments in communication as manifested by at least one of the following:
(a) delay in, or total lack of, the development of spoken language (not accompanied by an attempt to compensate through alternative modes of communication such as gesture or mime);
(b) in individuals with adequate speech, marked impairment in the ability to initiate or sustain a conversation with others;
(c) lack of varied, spontaneous, make-believe play or social imitative play appropriate to developmental level;
3) restricted, repetitive and stereotyped patterns of behaviour, interests and activities, as manifested by at least one of the following:
(a) encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus;
(b) apparently inflexible adherence to specific nonfunctional routines or rituals;
(c) stereotyped and repetitive motor mannerisms (eg: hand or finger flapping or twisting, or complex whole-body movements);
(d) persistent preoccupation with parts of objects.
B. Delays or abnormal functioning in at least one of the following areas, with onset prior to age 3 years: (1) social interaction, (2) language as used in social communication, or (3) symbolic or imaginative play.
C. The disturbance is not better accounted for by Rett's Disorder or Childhood Disintegrative Disorder.
DIAGNOSTIC CRITERIA FOR AUTISM DISORDER (ICD-10) (WHO 1992)
At least 8 of the 16 specified items must be fulfilled.
a)Qualitative impairments in reciprocal social interaction, as manifested by at least three of the following five:
1)failure adequately to use eye-to-eye gaze, facial expression, body posture and gesture to regulate social interaction.
2)failure to develop peer relationships.
3)rarely seeking and using other people for comfort and affection at times of stress or distress and/or offering comfort and affection to others when they are showing distress or unhappiness.
4)lack of shared enjoyment in terms of vicarious pleasure in other peoples' happiness and /or spontaneous seeking to share their own enjoyment through joint involvement with others.
5)lack of socio-emotional reciprocity.
b)Qualitative impairments in communication: 1)lack of social usage of whatever language skills are present. 2)impairment in make-believe and social imitative play. 3)poor synchrony and lack of reciprocity in conversational interchange. 4)poor flexibility in language expression and a relative lack of creativity and fantasy in thought processes. 5)lack of emotional response to other peoples' verbal and non-verbal overtures. 6)impaired use of variations in cadence or emphasis to reflect communicative modulation. 7)lack of accompanying gesture to provide emphasis or aid meaning in spoken communication.
c)Restricted, repetitive and stereotyped patterns of behaviour, interests and activities, as manifested by ate least two of the following six: 1)encompassing preoccupation with stereotyped and restricted patterns of interest. 2)specific attachments to unusual objects. 3)apparently compulsive adherence to specific, non-functional routines or rituals. 4)stereotyped and repetitive motor mannerisms. 5)preoccupations with part-objects or non-functional elements of play material. 6)distress over changes in small, non-functional details of the environment.
d)Developmental abnormalities must have been present in the first three years for the diagnosis to be made.
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ASPERGER'S DISORDER
DIAGNOSTIC FEATURES
The essential features of Asperger's Disorder are severe and sustained impairment in social interaction (Criterion A) and the development of restricted, repetitive patterns of behaviour, interests, and activities (Criterion B). The disturbance must cause clinically significant impairment in social, occupational, or other important areas of functioning (Criterion C). In contrast to Autistic Disorder, there are no clinically significant delays in language (eg: single words are used by age 2 years, communicative phrases are used by age 3 years) (Criterion D). In addition, there are no clinically significant delays in cognitive development or in the development of age-appropriate self-help skills, adaptive behaviour (other than in social interaction), and curiosity about the environment in childhood (Criterion E). The diagnosis is not given if the criteria are met for any other specific Pervasive Developmental Disorder or for Schizophrenia (Criterion F).
ASSOCIATED FEATURES AND DISORDERS
Asperger's Disorder is sometimes observed in association with general medical conditions. Various nonspecific neurological symptoms or signs may be noted. Motor milestones may be delayed and motor clumsiness is often observed.
PREVALENCE
Information on the prevalence of Asperger's Disorder is limited, but it appears to be more common in males.
COURSE
Asperger's Disorder appears to have a somewhat later onset than Autistic Disorder, or at least to be recognised somewhat later. Motor delays or motor clumsiness may be noted in the preschool period. Difficulties in social interaction may become more apparent in the context of school. It is during this time that particular idiosyncratic or circumscribed interests (eg: a fascination with train schedules) may appear or be recognised as such. As adults, individuals with the condition may have problems with empathy and modulation of social interaction. This disorder apparently follows a continuous course and, in the vast majority of cases, the duration is lifelong.
FAMILIAL PATTERN
Although the available data are limited, there appears to be an increased frequency of Asperger's Disorder among family members of individuals who have the disorder.
DIFFERENTIAL DIAGNOSIS
Asperger's Disorder is not diagnosed if criteria are met for another Pervasive Developmental Disorder or for Schizophrenia. Asperger's Disorder must also be distinguished from Obsessive-Compulsive Disorder and Schizoid Personality Disorder. Asperger's Disorder and Obsessive-Compulsive Disorder share repetitive and stereotyped patterns of behaviour. In contrast to Obsessive-Compulsive Disorder, Asperger's Disorder is characterised by a qualitative impairment in social interaction and a more restricted pattern of interests and activities. In contrast to Schizoid Personality Disorder, Asperger's Disorder is characterised by stereotyped behaviours and interests and by more severely impaired social interaction.
DIAGNOSTIC CRITERIA FOR ASPERGER'S DISORDER (DSM IV)
A) Qualitative impairment in social interaction, as manifested by at least two of the following: 1) marked impairment in the use of multiple nonverbal behaviours such as eye-to-eye gaze, facial expression, body postures, and gestures to regulate social interaction; 2) failure to develop peer relationships appropriate to developmental level; 3) a lack of spontaneous seeking to share enjoyment, interests or achievments with other people (eg: by a lack of showing, bringing, or pointing out objects of interest to other people); 4) lack of social or emotional reciprocity.
B) Restricted repetitive and stereotyped patterns of behaviour, interests, and activities, as manifested by at least one of the following: 1) encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus; 2) apparently inflexible adherence to specific, nonfunctional routines or rituals; 3) stereotyped and repetitive motor mannerisms (eg: hand or finger flapping or twisting, or complex whole-body movements); 4) persistent preoccupation with parts of objects
C) The disturbance causes clinically significant impairment in social, occupational, or other important areas of functioning.
D) There is no clinically significant general delay in language (eg: single words used by age 2 years, communicative phrases used by age 3 years).
E) There is no clinically significant delay in cognitive development or in the development of age-appropriate self-help skills, adaptive behaviour (other than social interaction), and curiosity about the environment in childhood.
F) Criteria are not met for another specific Pervasive Developmental Disorder, or Schizophrenia.
DIAGNOSTIC CRITERIA FOR ASPERGER'S DISORDER (GILLBERG, 1991)
A)Severe impairment in reciprocal social interaction as manifested by at least two of the following four: 1)inability to interact with peers. 2)lack of desire to interact with peers. 3)lack of appreciation of social cues. 4)socially and emotionally inappropriate behaviour.
B)All-absorbing narrow interest, as manifested by at least one of the following three: 1)exclusion of other activities. 2)repetitive adherence. 3)more rote than meaning.
C)Speech and language problems, as manifested by at least three of the following five: 1)delayed development of language. 2)superficially perfect expressive language. 3)formal, pedantic language. 4)odd prosody, peculiar voice characteristics. 5)impairment of comprehension, including misinterpretations of literal/implied meanings.
D)Non-verbal communication problems, as manifested by at least one of the following five: 1)limited use of gestures. 2)clumsy/gauche body language. 3)limited facial expression. 4)inappropriate expression. 5)peculiar, stiff gaze.
E)Motor clumsiness, as documented by poor performance on neurodevelopmental examination.
DIAGNOSTIC CRITERIA FOR ASPERGER'S DISORDER (SZATMARI, ET AL. 1989)
A)Solitary, as manifested by at least two of the following four: 1)no close friends. 2)avoids others. 3)no interest in making friends. 4)a loner.
B)Impaired social interaction, as manifested by at least one of the following five: 1)approaches others only to have own needs met. 2)a clumsy social approach. 3)one-sided responses to peers. 4)difficulty sensing feelings of others. 5)detached from feelings of others.
C)Impaired non-verbal communication, as manifested by at least one of the following seven: 1)limited facial expression. 2)unable to read emotion from facial expressions of child. 3)unable to give messages with eyes. 4)does not look at others. 5)does not use hands to express oneself. 6)gestures are large and clumsy. 7)comes too close to others.
D)Odd speech, as manifested by at least two of the following six: 1)abnormalities in inflection. 2)talks too much. 3)talks too little. 4)lack of cohesion to conversation. 5)idiosyncratic use of words. 6)repetitive patterns of speech.
E)Does not meet criteria for Autistic Disorder.
DIAGNOSTIC CRITERIA FOR ASPERGER'S DISORDER (ICD-10, WHO, 1992)
A)A lack of any clinically significant general delay in language or cognitive development. Diagnosis requires that single words should have developed by two years of age and that communicative phrases be used by three years of age or earlier. Self-help skills, adaptive behaviour and curiosity about the environment during the first three years should be at a level consistent with normal intellectual development. Motor milestones may be somewhat delayed and motor clumsiness is usual (although not a necessary feature).
B)Qualitative impairment in reciprocal social interaction. (Criteria as for autism, see above).
C)Restricted, repetitive, and stereotyped patterns of behaviour, interests and activities. (Criteria as for autism, see above).
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PERVASIVE DEVELOPMENTAL DISORDER NOT OTHERWISE SPECIFIED, INCLUDING ATYPICAL AUTISM
This category should be used when there is a severe and pervasive impairment in the development of reciprocal social interaction, or verbal and nonverbal communication skills, or when stereotyped behaviour, interests, and activities are present, but the criteria are not met for a specific Pervasive Developmental Disorder, Schizophrenia, Schizotypal Personality Disorder, or Aviodant Personality Disorder. For example, this category includes "atypical autism" -- presentations that do not meet the criteria for Autistic Disorder because of late age at onset, atypical symptomatology, or subthreshold symptomatology, or all of these