Is Asperger's Syndrome Too Vaguely Defined?

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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 behavior, 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 or deviances in language acquisition (e.g.,single non-echoed words are used communicatively by age 2 years, and spontaneous communicative phrases are used by age 3 years)(Criterion D), although more subtle aspects of social communication (e.g.,typical give and take in conversation) may be affected. In addition, during the first 3 years of life, there are no clinically significant delays in cognitive development as manifested by expressing normal curiosity about the environment or in the acquisition of age-appropriate learning skills and adaptive behaviors (other than in social interaction)(Criterion E). Finally, the criteria are not met for another specific Pervasive Developmental Disorder or for Schizophrenia (Criterion F). This condition is also termed Asperger's Syndrome.

The impairment in reciprocal social interaction is gross and sustained. There may be marked impairment in the use of multiple nonverbal behaviors (e.g.,eye-to-eye gaze, facial expression, body postures and gestures) to regulate social interaction and communication (Criterion A1). There may be failure to develop peer relationships appropriate to developmental level (Criterion A2) 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 of understanding the conventions of social interaction. There may be a lack of spontaneous seeking to share enjoyment, interests, or achievements with other people (e.g.,not showing, bringing, or pointing out objects they find interesting) (Criterion A3). Lack of social or emotional reciprocity may be present (e.g.,not actively participating in simple social play or games, preferring solitary activities, or involving others in activities only as tools or "mechanical" aids)(Criterion A4). Although the social deficit in Asperger's Disorder is severe and is defined in the same way as in Autistic Disorder, the lack of social reciprocity is more typically manifest by an eccentric and one-sided social approach to others (e.g.,pursuing a conversational topic regardless of other' reactions) rather than social and emotional indifference.

As in Autistic Disorder, restricted, repetitive patterns of behavior, interests, and activities are present (Criterion B). Often these are primarily manifest in the development of encompassing preoccupations about a circumscribed topic or interest, about which the individual can amass a great deal of facts and information (Criterion B1). These interests and activities are pursued with great intensity often to the exclusion of other activities.

The disturbance must cause clinically significant impairment in social adaptation, which in turn may have a significant impact on self-suffiency or on occupational or other important areas of functioning (Criterion C). The social deficits and restricted patterns of interests, activities, and behavior are the source of considerable disability.

In contrast to Autistic Disorder, there are no clinically significant delays in early language (e.g.,single words are used by age 2, communicative phrases are used by age 3)(Criterion D). Subsequent language may be unusual in terms of the individual's preoccupation with certain topics and his or her verbosity. Difficulties in communication may result from social dysfunction and the failure to appreciate and utilize conventional rules of conversation, failure to appreciate nonverbal cues, and limited capacities for self-monitoring.

Individuals with Asperger's Disorder do not have clinically significant delays in cognitive development or in age-appropriate self-help skills, adaptive behavior (other than in social interaction), and curiosity about the environment in childhood (Criterion E). Because early language and cognitive skills are within normal limits in the first 3 years of life, parents or caregivers are not usually concerned about the child's development during that time, although upon detailed interviewing they may recall unusual behaviors. The child may be described as talking before walking, and indeed parents may believe the child to be precocious (e.g.,with a rich or "adult" vocabulary). Although subtle social problems may exist, parents or caregivers often are not concerned until the child begins to attend a preschool or is exposed to same-age peers may become apparent.

By definition the diagnosis is not given if the criteria are met for any other specific Pervasive Developmental Disorder or for Schizophrenia (although the diagnosis of Asperger's Disorder and Schizophrenia may coexist if the onset of the Asperger's Disorder clearly preceded the onset of Schizophrenia)(Criterion F).
Associated Features and Disorders

In contrast to Autistic Disorder, Mental Retardation is not usually observed in Asperger's Disorder, although occasional cases in which Mild Mental Retardation is present have been noted (e.g.,when the Mental Retardation becomes apparent only in the school years, with no apparent cognitive or language delay in the first years of life). Variability of cognitive functioning may be observed, often with strengths in areas of verbal ability (e.g.,vocabulary, rote auditory memory) and weaknesses in non-verbal areas (e.g.,visual-motor and visual-spatial skills). Motor clumsiness and awkwardness may be present but usually are relatively mild, although motor difficulties may contribute to peer rejection and social isolation (e.g.,inability to participate in group sports). Symptoms of overactivity and inattention are frequent in Asperger's Disorder, and indeed many individuals with this condition receive a diagnosis of Attention Deficit/Hyperactivity Disorder prior to the diagnosis of Asperger's Disorder. Asperger's Disorder has been reported to be associated with a number of other mental disorders, including Depressive Disorders.

Specific Age and Gender Features

The clinical picture may present differently at different ages. Often the social disability of individuals with the disorder becomes more striking over time. By adolescence some individuals with the disorder may learn to use areas of strength (e.g.,rote verbal abilities) to compensate for areas of weakness. Individuals with Asperger's Disorder may experience victimization by others; this, and feelings of social isolation and an increasing capacity for self-awareness, may contribute to the development of depression and anxiety in adolescence and young adulthood. The disorder is diagnosed much more frequently (at least five times) in males than in females.

Prevalence

Definitive data regarding the prevalence of Asperger's Disorder are lacking.

Course

Asperger's Disorder is a continuous and lifelong disorder. In school-age children, good verbal abilities may, to some extent, mask the severity of the child's social dysfunction and may also mislead caregivers and teachers - that is, caregivers and teachers may focus on the child's good verbal skills but be insufficiently aware of problems in other areas (particularly social adjustment). The child's relatively good verbal skills may also lead teachers and caregivers to erroneously attribute behavioral difficulties to willfulness or stubbornness in the child. Interest in forming social relationships may increase in adolescence as the individuals learn some ways of responding more adaptively to their difficulties - for example, the individual may learn to apply explicit verbal rules or routines in certain stressful situations. Older individuals may have an interest in friendship but lack understanding of the conventions of social interaction and may more likely make relationships with individuals much older or younger than themselves. The prognosis appears significantly better than in Autistic Disorder, as follow-up studies suggest that, as adults, many individuals are capable of gainful employment and personal self-sufficiency.

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. There may also be an increased risk for Autistic Disorder as well as more general social difficulties.

Differential Diagnosis

Asperger's Disorder must be distinguished from the other Pervasive Developmental Disorder, all of which are characterized by problems in social interaction. It differs from Autistic Disorder in several ways. In Autistic Disorder there are, by definition, significant abnormalities in the areas of social interaction, language, and play, whereas in Asperger's Disorder early cognitive and language skills are not delayed significantly. Furthermore, in Autistic Disorder, restricted, repetitive, and stereotyped interests and activities are often characterized by the presence of motor mannerisms, preoccupation with parts of objects, rituals, and marked distress in change, whereas in Asperger's Disorder these are primarily observed in the all-encompassing pursuit of a circumscribed interest involving a topic to which the individual devotes inordinate amounts of time amassing information and facts. Differentiation of the two conditions can be problematic in some cases. In Autistic Disorder, typical social interaction patterns are marked by self-isolation or markedly rigid social approaches, whereas in Asperger's Disorder there may appear to be motivation for approaching others even though this is then done in a highly eccentric, one-sided, verbose, and insensitive manner.

Asperger's Disorder must also be differentiated from Pervasive Developmental Disorders other than Autistic Disorder. Rett's Disorder differs from Asperger's Disorder in its characteristic sex ratio and pattern of deficits. Rett's Disorder has been diagnosed only in females, whereas Asperger's Disorder occurs much more frequently in males. In Rett's Disorder, there 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. Rett's Disorder is also associated with marked degrees of Mental Retardation and gross impairments in language and communication.

Asperger's Disorder differs from Childhood Disintegrative Disorder, which has a distinctive pattern of developmental regression following at least 2 years of normal development. Children with Childhood Disintegrative Disorder also display marked degrees of Mental Retardation and language impairment. In contrast, in Asperger's Disorder there is no pattern of developmental regression and, by definition, no significant cognitive or language delays.

Schizophrenia of childhood onset usually develops after years of normal, or near normal, development, and characteristic features of the disorder, including hallucinations, delusions, and disorganized speech, are present. In Selective Mutism, the child usually exhibits appropriate communication skills in certain contexts and does not have the severe impairment in social interaction and the restricted patterns of behavior associated with Asperger's Disorder. Conversely, individuals with Asperger's Disorder are typically verbose. In Expressive Language Disorder and Mixed Receptive-Expressive Language Disorder, there is language impairment but no associated qualitative impairment in social interaction and restricted, repetitive, and stereotyped patterns of behavior. Some individuals iwth Asperger's Disorder may exhibit behavioral patterns suggesting Obsessive-Compulsive Disorder, although special clinical attention should be given to the differentiation between preoccupations and activities in Asperger's Disorder and obsessions and compulsions in Obsessive-Compulsive Disorder. In Asperger's Disorder these interests are the source of some apparent pleasure or comfort, whereas in Obsessive-Compulsive Disorder they are the source of anxiety. Furthermore, Obsessive-Compulsive Disorder is typically not associated with the level of impairment in social interaction and social communication seen in Asperger's Disorder.

The relationship between Asperger's Disorder and Schizoid Personality Disorder is unclear. In general, the social difficulties in Asperger's Disorder are more severe and of earlier onset. Although some individuals with Asperger's Disorder may experience heightened and debilitating anxiety in social settings as in Social Phobia or other Anxiety Disorders, the latter conditions are not characterized by pervasive impairments in social development or by the circumscribed interests typical of Asperger's Disorder. Asperger's Disorder must be distinguished from normal social awkwardness and normal age-appropriate interests and hobbies. In Asperger's Disorder, the social deficits are quite severe and the preoccupations are all-encompassing and interfere with the acquisition of basic skills.

For example, it is probably fair to say that Asperger's syndrome, as diagnosed in the United Kingdom, is on average less severe than Asperger's syndrome diagnosed in the United States and Canada.