Since bipolar affective disorder (BPAD) has been recorded, clinicians treating the illness have noted the cyclic nature of episodes, symptoms and vulnerability to environmental changes. In particular, a significant increase in manic episodes has been noted in Spring and Summer months and depressive episodes in Autumn and Winter. Numerous studies have examined this trend in patients with mania and associated illnesses but many of these studies have fundamental design flaws. For example, some do not differentiate bipolar I and II patients, some include those with schizoaffective disorder and few studies investigate the timing of symptom onset and treatment initiation, which may vary markedly. The aim of this study was to investigate seasonality in symptom onset and service admissions in a group of patients with first episode mania, schizoaffective disorder and schizophrenia.
The study involved 177 patients with schizophrenia, 49 patients with schizoaffective disorder and 133 patients with bipolar disorder recruited for a geographical catchment area over a period of 10 years. Patients were recruited into the service only if their age was between 15 and 28 years and they had a first episode of psychosis. Diagnosis was made by either SCID or the Royal Park Multidiagnostic Interview for Psychosis. The results were analysed by monthly and seasonal variation and revealed a significant seasonal change in onset of symptoms only in patients with bipolar disorder. In terms of seasonality of time of service entry (i.e. probable peak illness state) the results indicate a high overall seasonality (particularly in males), which was reflected by seasonality in both the schizoaffective and bipolar groups.
The results of this analysis indicate that even in first episode, patients with bipolar disorder display a characteristic seasonality of both symptom onset and admission to the service. This provides further evidence that systems mediating the entrainment of biological rhythms to the environment may be abnormal in bipolar disorder. These results may further facilitate facilities preparedness for patients at different times of the year.