Personality and seasonal affective disorder: Results from the CAN-SAD study

Background: Personality factors have been implicated in seasonal affective disorder (SAD). The present study investigated the relationship between the five-factor model of personality (neuroticism, extraversion, openness, agreeableness, conscientiousness) and SAD. Methods: Ninety-five patients with SAD completed personality measures before and after treatment in a clinical trial and during the summer months. The personality scores of the SAD patients were compared with a matched group of non-seasonal depressed patients and published normative data. Stability and change in personality scores with changes in mood state were assessed. Personality dimensions were evaluated as possible predictors of treatment outcome. Results: SAD patients showed elevated openness scores relative to both non-seasonal depressed patients and norms. Their neuroticism scores were lower than non-seasonal depressed patients, but higher than norms. All personality dimensions showed large and highly significant test-retest correlations but several personality dimensions, particularly neuroticism and extraversion, also showed considerable change with changing mood state. None of the personality dimensions were significantly associated with treatment outcome. Limitations: Personality assessment relied on self-report. Conclusions: The personality profile of SAD patients differs from both non-seasonal depressed patients and norms. Elevated openness scores appear to be a unique feature of patients with SAD. Since mood state has a significant impact on personality scores, assessment of personality in SAD patients should ideally be conducted when they are in remission. Further investigation of the relationship between personality and SAD, especially the potential significance of elevated openness scores, is warranted.