Heterogeneity of cycloid psychoses: a latent class analysis

Background. Three hypotheses have been proposed in regard to the origin of cycloid psychoses: (1) they are an independent nosological entity; (2) they are atypical cases of affective disorders; and (3) they are a heterogeneou s group of disorders. This study examined the heterogeneity hypothesis by a ttempting to delineate distinct affective and non-affective subgroups. Methods. In 60 cases drawn from a classic study of cycloid psychoses by Per ris (1974), latent class analysis was used to delineate subgroups. Results. Two classes were identified in the analysis: one characterized by the convergence of affective symptoms and family history of affective disor ders and the other by the relative paucity of such features. Conclusions. Cycloid psychoses are composed of at least two subgroups, dist inguishable on the basis of symptoms and family history.