Seasonal and nonseasonal depression: how do they differ? Symptom profile, clinical and family history in a general population sample.

BACKGROUND: A small number of studies have previously compared the symptom profiles and clinical and family history patterns of patients with seasonal and nonseasonal depression. However, previous research has tended to be conducted in secondary and tertiary care populations. Little comparative data is available for seasonal and nonseasonal depression in general population samples.
METHODS: Patients aged 18-64 registered on a primary care database in North Wales were screened via post for the presence of SAD via the Seasonal Patterns Assessment Questionnaire (SPAQ) and depression via the Beck Depression Inventory (BDI). Interview-confirmed cases of SAD (n=25) and major depression (n=43) were compared in terms of symptom profile, clinical history and family history of psychiatric disorder.
RESULTS: Seasonal depression was found to be associated with lower occupational and cognitive impairment and psychiatric intervention than nonseasonal depression. The symptoms of hopelessness and weight loss were particularly predictive for nonseasonal depression. LIMITATIONS: The study was conducted at only one geography. CLINICAL RELEVANCE: Seasonal depression's discrete symptom profile may be used to distinguish cases of seasonal and nonseasonal depression in primary care patients.
CONCLUSIONS: SAD appears to be a relatively mild variant of depression, but this finding should not detract from the need for improved identification and treatment of SAD in primary care populations.