Seasonal variation of manic and depressive symptoms in bipolar disorder

Abstract

Objectives Analyses of seasonal variation of manic and depressive symptoms in bipolar disorder in retrospective studies examining admission data have yielded conflicting results. We examined seasonal variation of mood symptoms in a prospective cohort with long-term follow-up: The Collaborative Depression Study (CDS). Methods The CDS included participants from five academic centers with a prospective diagnosis of bipolar I or II disorder. The sample was limited to those who were followed for at least 10 years of annual or semi-annual assessments. Time series analyses and autoregressive integrated moving average (ARIMA) models were used assess seasonal patterns of manic and depressive symptoms. Results A total of 314 individuals were analyzed [bipolar I disorder: (n = 202) and bipolar II disorder: (n = 112)] with both disorders exhibiting the lowest depressive symptoms in summer and highest around the winter solstice, though the winter peak in symptoms was statistically significant only with bipolar I disorder. Variation of manic symptoms was more pronounced in bipolar II disorder, with a significant peak in hypomanic symptomatology in the months surrounding the fall equinox. Conclusions Significant seasonal variation exists in bipolar disorder with manic/hypomanic symptoms peaking around the fall equinox and depressive symptoms peaking in months surrounding the winter solstice in bipolar I disorder.

Seasonal variation of depressive symptoms in unipolar major depressive disorder

“…Thus, we hypothesized that those with MDD would have a peak in depressive symptomatology in the months surrounding the winter solstice (e.g. November, December, January), which would be consistent with our findings in bipolar disorder [29]. Lastly, we attempted to identify whether this pattern would persist over 20 years of follow-up.…”

“…We examined the seasonality of symptom burden in MDD, based on previously defined thresholds of 3 or greater on the major depression LIFE scale (Table 1) or 3/3 on the minor depression LIFE scale (Table 2) [29, 32–35, 39–41]. The ordinal LIFE scales were collapsed into an indicator (dichotomous) variable with a value of one or zero assigned for each day a patient did or did not meet, respectively, at least one of the above thresholds for clinically significant symptomology.…”

“…The models were based on a multinomial distribution with a cumulative logit link, and included the covariates age, gender and treatment. The use of any antidepressant treatment in a given month was identified with an indicator variable as in previous studies [29, 32–35, 39–41]. …”

“…Akin to a prior analysis of participants with bipolar disorder from this sample [29], the timing of relapse over the entire duration of follow-up was additionally explored with the unit of analysis being mood episodes rather than the 298 individual participants constituting the sample. The calendar month of onset of any new depressive episodes (major or minor) was determined following any periods of recovery, defined as eight consecutive weeks with no or only residual symptoms.…”

Bipolar disorders: is there an influence of seasonality or photoperiod?

“…This result underscores the higher probability of admission during the pronounced photoperiod change between spring and summer, which agrees with numerous recent studies confirming a strong seasonal pattern in bipolar disorder. [9][10][11][12][13][14][15][16]21,[34][35][36][37] This finding, in light the DSM-5's focus on seasonal pattern in bipolar disorder, prompted the following question: is seasonality really the most incisive clinical parameter for assessing the onset of bipolar disorder, or is it, rather, greater exposure to sunlight?…”