Epidemiology of cycloid psychosis.

The incidence and risk of cycloid psychosis were investigated in the 1947 cohort of the Lundby Study. No male cases were found. For women the incidence rate (per 100 observation years) was 0.016%. The cumulative probability, i.e. risk up to 60 years of age, was 0.7%. These figures are about half of those for schizophrenia in women in the same population. It is concluded that cycloid psychosis constitutes a substantial part of psychotic disorders among women.