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.

      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.

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

      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.

      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.