Chronotype in bipolar disorder: an 18-month prospective study

Abstract

Objective: Circadian dysregulation plays an important role in the etiology of mood disorders. Evening chronotype is frequent in these patients. However, prospective studies about the influence of chronotype on mood symptoms have reached unclear conclusions in patients with bipolar disorder (BD). The objective of this study was to investigate relationship between chronotype and prognostic factors for BD. Methods: At the baseline, 80 euthymic BD patients answered a demographic questionnaire and clinical scales to evaluate anxiety, functioning and chronotype. Circadian preference was measured using the Morningness-Eveningness Questionnaire, in which lower scores indicate eveningness. Mood episodes and hospitalizations were evaluated monthly for 18 months. Results: Among the BD patients, 14 (17.5%) were definitely morning type, 35 (43.8%), moderately morning, 27 (33.7%) intermediate (neither) and 4 (5%) moderately evening. Eveningness was associated with obesity or overweight (p = 0.03), greater anxiety (p = 0.002) and better functioning (p = 0.01), as well as with mood episodes (p = 0.04), but not with psychiatric hospitalizations (p = 0.82). This group tended toward depressive episodes (p = 0.06), but not (hypo)mania (p = 0.56). Conclusion: This study indicated that evening chronotype predicts a poor prognostic for BD. It reinforces the relevance of treating rhythm disruptions even during euthymia to improve patient quality of life and prevent mood episodes.

Late chronotype predicts more depressive symptoms in bipolar disorder over a 5 year follow-up period

“…Our results suggest that late chronotype predominantly increases the risk for a depressive mood course rather than a hypomania/mania mood course. One previous study also reported that late chronotypes had more anxiety symptoms during follow up (Melo et al 2020), but this effect was not detected in the current study possibly due to the smaller number of GAD-7 assessments. Both previous studies only included individuals who were euthymic at baseline, whereas in the current study all participants were included and baseline mood was adjusted for in the analyses.…”

“…While higher doses of melatonin taken at bedtime have been tested in people with bipolar disorder as a sleep aid (Baandrup et al 2011) and to improve cardiometabolic health (Mostafavi et al 2017), it remains to be determined if melatonin, when used to phase advance circadian timing, can improve mood course in people with bipolar disorder. While the five years of follow up in this study is meaningfully longer than the previous studies (Takaesu et al 2017;Melo et al 2020), the granularity and frequency of the data collection nonetheless remains modest. The gathering of self-reported mood symptoms every two months and an in-person clinical assessment every two years may still have not accurately captured the nuanced daily to weekly variability in mood in people with bipolar disorder.…”

“…This result raises the interesting possibility that late chronotype could be protective against manic relapse and symptoms, which should be explored in further research (Table 5). This study of the impact of chronotype on subsequent mood course in people with bipolar disorder is the largest study to date, in a sample three times that of previous studies and with a follow up period more than three times as long (Takaesu et al 2017;Melo et al 2020). In Fig.…”

“…The other study examined baseline chronotype in 80 euthymic individuals with bipolar disorder and measured their subsequent anxiety, behavioral function, and number of mood episodes every month across an 18-month period. Eveningness at baseline significantly predicted poorer behavioral function, increased anxiety levels and a greater number of mood episodes (Melo et al 2020 ). These results suggest that assessing chronotype in individuals with bipolar disorder may help identify patients at higher risk for adverse outcomes.…”

“…These results suggest that assessing chronotype in individuals with bipolar disorder may help identify patients at higher risk for adverse outcomes. As the authors of these previous studies acknowledged, 12–18-months were relatively short periods to assess mood course and the sample sizes were relatively small (Takaesu et al 2017 ; Melo et al 2020 ). Therefore, the aim of the current study was to further examine baseline chronotype as a potentially important predictor of mood-related outcomes in a larger sample of individuals with bipolar disorder over a longer follow up period.…”