Effectiveness of lithium prophylaxis in schizoaffective psychoses: application of a polydiagnostic approach.

The effectiveness of lithium prophylaxis has been tested in a group of patients fulfilling the relatively broad ICD-9 definition of schizophrenic psychosis, schizoaffective type, and in each of the subgroups resulting from the application to the same patients of four different sets of diagnostic criteria for schizoaffective or cycloid psychoses. Moreover, a comparison has been made, within the whole patient population, between responders and non-responders to treatment, with respect to some clinical and biological variables. The mean number of morbid episodes and the mean total morbidity have been found significantly reduced during the treatment period, as compared with a control period of the same length, in the whole patient population as well as in subjects meeting RDC and Kendell's criteria for schizoaffective disorder (with special regard to schizomanics) and Perris's criteria for cycloid psychoses. No significant difference between the two periods has been observed in patients diagnosed as schizoaffectives according to Welner et al. Clinical/historical variables (with special regard to those concerning the course of the illness and the family history of major psychoses) have been found the most reliable predictors of response, whereas biological variables did not discriminate between responders and nonresponders to prophylaxis.