Methylphenidate therapy for aggression in a man with ring 22 chromosome. Report and literature review.

A 28-year-old mentally retarded man with ring 22 chromosome [r(22)] had deterioration of mood and behavior, decreased speech, bradykinesia, and decline of fine motor skills over a three-year period, which were further exacerbated by treatment with phenothiazines. A trial of methylphenidate hydrochloride resulted in rapid improvement of mood, behavior, and to a small extent, motor function. This finding suggests that dopamine depletion may play a role in the behavioral deterioration seen in this disorder. The possibility that genes that control dopamine metabolism may be present on chromosome 22 is raised. The phenotype of this patient is compared with the 25 reported cases of r(22).