Abstract
BACKGROUND: Biological rhythm disturbance is common in bipolar patients and seems to affect the course and prognosis of the illness negatively. The main aim of the current study was to assess biological rhythms in remitted bipolar patients. We also assessed whether there was an association between clinical variables or functioning and biological rhythms in remitted bipolar participants. METHODS: The Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN) was used to assess biological rhythm disturbance. It is an 18-item interviewer-administered instrument which allows us to investigate the main areas related to circadian rhythm disturbance (sleep/social, activities, and eating pattern) in bipolar disorder. RESULTS AND DISCUSSION: Bipolar patients (n = 107) experienced greater biological rhythm alterations than the control group (n = 100) (BRIAN total scores 35.36 ± 7.11 vs. 32.48 ± 6.10, t = 6.912, p = 0.002, Cohen's d = 0.43, r = 0.21). In particular, patients were more impaired than the control group with regard to sleep/social (14.67 ± 4.14 vs. 13.49 ± 2.91, t = 10.61, p = 0.018, Cohen's d = 0.33, r = 0.16) and activity (8.49 ± 2.51 vs. 7.07 ± 2.13, t = 3.90, p = 0.001, Cohen's d = 0.61, r = 0.29) domains. Furthermore, a significant correlation was found between biological rhythms with residual depressive symptoms (r = 0.459, p < 0.001) and functioning (r = 0.432, p < 0.001). These findings suggest a potential link between biological rhythms and the pathophysiology of bipolar disorder. It highlights the importance of novel instruments (e.g., BRIAN) which allow us to assess biological rhythm disturbance in psychiatry. Finally, specific psychosocial interventions focused on lifestyle regularity may be considered as a supplemental treatment of bipolar illness episodes.