Association Between Bipolar Disorder and Seasonal Affective Disorder
Yes, bipolar disorder is strongly associated with seasonal affective disorder (SAD), with individuals with bipolar disorder showing 3-4 times higher rates of SAD compared to the general population, and bipolar II disorder demonstrating the highest prevalence among all mood disorders. 1, 2
Prevalence and Strength of Association
- Bipolar disorder patients have a 27% prevalence of SAD, yielding an adjusted odds ratio of 3.73 (95% CI: 2.64-5.27) compared to primary care populations 2
- Bipolar II disorder shows the highest SAD prevalence among all early-onset mood disorders, with significantly higher odds ratios for SAD when compared to both major depressive disorder and bipolar I disorder 1
- All bipolar subtypes (I and II) demonstrate significantly higher Global Seasonality Scores than healthy controls, indicating greater seasonal mood variation 3, 1
Seasonal Patterns in Bipolar Disorder
- Longitudinal studies confirm that individuals with bipolar I and II exhibit significant seasonal effects on mood symptoms, with decreased depressive symptoms and increased manic symptoms during longer daylight months 3
- High seasonality scores are associated with greater variance in mood symptoms across the year in bipolar patients 3
- The seasonal pattern can apply to both depressive and manic episodes in bipolar disorder, making it a specifier for the diagnosis in DSM-5 4, 5
Clinical Implications
- Thorough assessment of seasonality in bipolar disorder is warranted for personalized treatment and proactive prevention of mood episodes, particularly in bipolar II disorder where the association is strongest 1
- Interventions such as light therapy during seasons of heightened risk could be beneficial for managing seasonal mood fluctuations in bipolar patients 3
- Vigilance for seasonal symptom recurrence in bipolar disorder is important for management and relapse prevention, given the 3-4 fold increased risk compared to general populations 2
Mechanistic Context
- One study suggests that the BDNF Val66Met polymorphism may be involved in seasonal affective patterns, as Met allele carriers were more likely to develop postpartum depressive symptoms if they delivered in fall or winter, hinting at BDNF's potential role in seasonal affective disorders 6
- Seasonal changes in CNS function involve melatonin secretion, dopamine and serotonin neurotransmitters, and the hypothalamic-pituitary-adrenal axis, with "clock genes" playing significant roles in circadian and circannual processes 5
Risk Factors for SAD in General Population
- Risk factors for SAD include family history, female sex, living at northern latitudes, and young adulthood (18-30 years), though these apply broadly and not specifically to the bipolar-SAD association 4