Lithium prophylaxis of schizoaffective disorders: a prospective study.

A prospective study was carried out in order to provide an answer to the following questions. (1) Is lithium effective as a prophylactic agent in broadly defined schizoaffective disorders? (2) Taking for granted that schizoaffective disorders represent a heterogeneous group of conditions, in which schizoaffective patients is lithium effective? (3) Are there any clinical, historical or biological predictors of response to lithium prophylaxis in schizoaffective patients? (4) What are the minimum plasma lithium levels required for effective prophylaxis in schizoaffective disorders? The study confirmed the efficacy of lithium prophylaxis in broadly defined schizoaffective disorders, but showed that this treatment is relatively ineffective in schizoaffective patients with a prominent schizophrenic-like component in their clinical picture and in those diagnosed cross-sectionally as schizodepressive. The only successful predictor of response was a previous bipolar course of the illness (which was associated with a positive outcome of prophylaxis). Plasma lithium levels in the range of 0.45-0.60 mEq/l did not prove to be useful for prophylactic purposes in schizoaffective disorders.