Cycloid psychosis and affective disorder: borderland cases.

A subsample of untreated cycloid psychoses satisfying the requirements for major affective disorder according to DSM-III was compared with a subsample of cycloid psychoses getting other DSM-III diagnoses. The concept of cycloid psychosis applied thus was wider than permitted by the criteria stipulated by Perris and Brockington with respect to the prominence of the mood component. Since it could be demonstrated that no decisive differences prevailed with respect to frequencies of single features tested, a modified discriminant analytic procedure was applied. In this analysis, 76% of cases were correctly assigned. On average affective cases were more similar to the score profile derived from the nonaffective group than nonaffective cases were to the same profile, i.e. to themselves. Symptomatologically the affective cases had their main point in a distinctive confusion syndrome.