Subtypes of mania determined by grade of membership analysis

Classical descriptions of mania subtypes extend back to Kraepelin; however, in marked contrast to the study of depression subtypes, validation of mani a subtypes by multivariate statistical methods has seldom been attempted. W e applied Grade of Membership (GOM) analysis to the rated clinical features of 327 inpatients with DSM-III-R mania diagnoses. GOM is a type of latent structure multivariate analysis, which differs from others of this type in making no a priori distributional assumptions about groupings. We obtained 5 GOM Pure Types with good face validity. The major Kraepelinian forms of " hypomania," "acute mania," "delusional mania," and "depressive or anxious m ania" were validated. The major new finding is of two mixed mania presentat ions, each with marked lability of mood. The first of these displayed a dom inant mood of severe depression with labile periods of pressured, irritable hostility and paranoia, and the complete absence of euphoria or humor. The second mixed mania Pure Type displayed a true, incongruous mixture of affe cts: periods of classical manic symptoms with euphoria, elation, humor, gra ndiosity, psychosis, and psychomotor activation, switching frequently to mo derately depressed mood with pressured anxiety and irritability. This multi variate analysis validated classical clinical descriptions of the major sub types of mania. Two distinct forms of mixed manic episodes were identified. DSM-III-R criteria did not reliably identify either of these two natural g roups of mixed bipolar patients. As occurs in depression, this clinical het erogeneity of mania may influence response to drug treatments. (C) 2001 Ame rican College of Neuropsychopharmacology. Published by Elsevier Science Inc .