Examining serotonin function: A modified technique for rapid tryptophan depletion

behavior, cognitive functioning, and impulsivity. Milder forms of pervasive developmental disorders may be misdiagnosed, or emphasis may be placed on other deficits in communication and socialization. Asperger's syndrome, a category of pervasive developmental disorder, has received increasing scrutiny. Wing ( 1981 ), Nagy and Szatmari (1986), and Tantam (1988), have delineated the characteristics of this disorder, including impairment in empathy, an extreme degree of social isolation, and difficulty understanding appropriate social rules. We present flmr cases of Asperger's syndrome presenting in later life, referred to us with behavioral symptoms of hyperactivity, poor impulse control, and attentional difficulties. Neuropsychological evaluation suggested dysfunctions in sociability, verbal and nonverbal expressiveness, and engrossing and idiosyncratic interests and clumsiness, all of which represent the current DSM-IV diagnosis of Asperger's syndrome. We present four cases at differing ages of diagnosis, their demographics, and their phenomenological findings. We hope to alert readers to clinical pitfalls and call attention to the existence of this little-known and fascinating disorder.