Seasonal affective disorder (SAD) is defined as depression that occurs with seasonality -typically occurring in the autumn and winter months and remitting in spring and summer. It is thought to be pathophysiologically related to circadian misalignment and can often be effectively treated, or even prevented, with light therapy and/or bupropion. Given that SAD may therefore be avoidable, it would be of great benefit if we could predict those at risk for this disorder. In this study, the authors investigated the prevalence of SAD in 467 subjects (age 35 years or younger) with early-onset major depressive disorder (MDD), bipolar disorder I (BDI), bipolar disorder II (BDII), and healthy controls. It was found that individuals with early-onset mood disorders had a higher occurrence of seasonality versus healthy controls. Moreover, patients with BDII had a significantly elevated risk of SAD compared to other mood disorders (Figure). These data indicate that individuals with early-onset mood disorders, and particularly those with BDII, may have a higher risk of circadian misalignment that makes for a more difficult time adapting to seasonal changes. In light of this evidence, it is suggested that patients with early-onset mood disorders be screened for SAD and, conversely, that patients with SAD be screened for mood disorders (particularly BDII).
Figure. Proportion of Early-Onset Mood Disorder Patients with SAD
MDD: major depressive disorder; BDI: bipolar disorder I; BDII: bipolar disorder II
Yeom JW et al. Depress Anxiety 2021; Epub ahead of print. Abstract
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