[Cycloid psychoses as atypical manic-depressive disorders. Results of a family study]

Whereas a growing body of evidence suggests that cycloid psychoses have to be separated from schizophrenic psychoses, their relations to bipolar affective disorder are less clear.

In a controlled family study, we recruited 46 patients with cycloid psychosis (CP), 33 with manic-depressive illness (MDI), and 27 controls. Three hundred fifty-six of 389 living first-degree relatives were personally examined by experienced psychiatrists blinded to the diagnosis of the index proband.

The relatives of CP patients showed significantly lower morbidity risk of functional psychoses than relatives of patients with MDI in Kaplan-Meier life table calculation. The morbidity risk for functional psychoses in relatives of patients with CP did not differ significantly from that in relatives of controls.

These results suggest that CP are etiologically different from bipolar affective psychoses and cannot be integrated into the spectrum of bipolar affective disorders. The findings provide further evidence for a nosological independence of CP.