Seasonal influences on first-episode admission in affective and non-affective psychosis.

Background: Since bipolar affective disorder has been recorded, clinicians treating patients with this disorder have noted the cyclic nature of episodes, particularly an increase in mania in the spring and summer months and depression during winter.

Objective: The aim of this study was to investigate seasonality in symptom onset and service admissions over a period of 10 years in a group of patients (n= 359) with first-episode (FE) mania (n= 133), FE schizoaffective disorder (n= 49) and FE schizophrenia (n= 177).

Method: Patients were recruited if they were between 15 and 28 years of age and if they resided in the geographical mental health service catchment area.