Mixed affective states and the natural history of manic-depressive psychosis.

Since neither the unipolar nor the bipolar theories of manic-depressive psychosis explain all its features, an alternative model was tested. The hypotheses are that mixed affective psychoses represent a superimposition on hypomania of a second type of depression which can sometimes develop from the depressive phase of manic-depressive psychosis, and that schizophrenia occurring in the course of a manic-depressive illness is an alternative to mixed affective psychosis. From an examination of the clinical histories of a random sample of people with bipolar manic-depressive psychosis, evidence was found to support both ideas.