Co-occurring SAD symptomatology and schizophrenia at high latitude: a pilot study.

OBJECTIVES: Recent research investigates major depression with seasonal pattern, also called seasonal affective disorder (SAD), depression in schizophrenia and seasonality in schizophrenia, but there exits limited research investigating SAD in schizophrenia. This study documents co-occurring SAD symptomatology in patients with schizophrenia at high latitude. STUDY DESIGN: Clinical cross-sectional study of patients with schizophrenia attending treatment centres in Alaska. METHOD: Twenty-eight patients completed a structured interview assessing seasonal patterns in mood, depression, negative symptoms of schizophrenia and alcohol use. RESULTS: Thirty-six percent of patients with schizophrenia met the criteria for SAD used in previous general population research on SAD in Alaska. When a presence of major depressive episode was confirmed using a structured clinical interview for depression in schizophrenia, the rate was 25%. Severity of SAD symptoms was greatest among patients with alcohol-abuse history. CONCLUSIONS: Co-occurring SAD symptomatology was identified in this extreme latitude sample of patients with schizophrenia. The frequency and severity of symptomatology was greater than found in a general population study of SAD conducted in Alaska using identical criteria. SAD may be under-diagnosed in schizophrenia at moderate and extreme latitudes, highlighting clinical assessment considerations, potential utility of bright light therapy and the need for additional research.