Prophylactic lithium and personality variables. An international collaborative study

61 patients - 28 suffering from bipolar, and 33 from unipolar psychotic affective disorders - completed two personality inventories, one before and one about 6 months after starting lithium treatment to prevent relapses. On the basis of empirical observations it had been assumed that personality characteristics would change more in bipolar than in unipolar patients and that these changes would concern mainly those personality characteristics which reflect sociability and impulsivity. The inventories used were the EPI and the MNT. The results were in agreement with the predictions. Moreover, a significant decrease in N-scores was found both in bipolar and unipolar patients. It is assumed that these changes reflect both the therapeutic effect of lithium and an effect upon the personality characteristics of patients who suffer from bipolar or unipolar affective disorders.