Comorbidity of seasonal affective disorders with schizophrenia in the extreme North

Abstract

The purpose of this study was to provide estimates of the prevalence of seasonal affective disorder (SAD) among Alaska residents with schizophrenia and to evaluate the relation of SAD symptoms to symptoms of general depression, negative schizophrenia, and alcohol abuse. Nine (33%) of the subjects exceeded cut-off criteria for SAD. Assessment of depression supported the diagnostic classification of respondents who met cut-off criteria for SAD as depressed, but also supported conceptualizations of SAD as a syndrome separate from unipolar depression. Evaluation of negative symptoms of schizophrenia validated the divergence of SAD and depression symptoms from negative symptoms. Implications of this study are discussed in terms of a potential heightened vulnerability to SAD among people with schizophrenia. SAD is prevalent among general population residents in the northern latitudes. Therefore, a heightened risk for comorbid SAD is a potential issue for clinical management among people with schizophrenia in the North.