Concordant response to pharmacotherapy in monozygotic twins with schizoaffective disorder.

BACKGROUND: Schizoaffective disorder (SAD) represents one of the most confusing and controversial concepts in psychiatry. Prevalence is less than 1%, but despite that it has a major influence on an individual and community. There is an increased risk for schizophrenia and mood diorders in first degree relatives with SAD, according to DSM IV. This paper describes the concordant clinical response of a pair of monozygotic twins with SAD when treated with risperidon and valproic acid. We found that their clinical symptoms were very similar and both brothers expressed hipomanic and depressive episode prior to full onset of SAD-psychotic symptoms with correlations of elevated mood, and first psychiatric hospitalization at the age of 19 (patient A) and 18 (patient B). Their response to the combined treatment with risperidon and valproic acid has been also similar both in intensity and in the pattern of symptoms that have improved.