0636 Examination of longitudinal chronotype stability in individuals with bipolar disorder and healthy controls

Abstract

Abstract Introduction Introduction: Circadian rhythms have long been conceptualized as central to the pathophysiology of bipolar disorder (BD). Numerous cross-sectional analyses have demonstrated associations of eveningness with BD and greater severity of mood symptoms. Longitudinal studies that evaluate stability of chronotype and its association with mood symptoms are lacking. Methods 88 BD2) from the Prechter Longitudinal Study of BD. Participants completed an average of 10 years of longitudinal assessments of depression (PHQ-9) and mania (Altman Self-Reported Mania Scale) every 2 months, and chronotype (Munich ChronoType Questionnaire) annually. Chronotype was assessed using both a single item from the MCTQ in which seven possible chronotypes were presented (from extreme early to extreme late type), and the calculation of midpoint of sleep on work-free days, sleep-corrected (MSFsc). We calculated (in)stability using the mean square successive difference (MSSD) and assessed the relationship between mood, age, sex, medication, and stability using mixed effects models. Results Results: Individuals with BD1 and BD2 reported later chronotypes compared to HC. Individuals with BD1 had later MSFsc as well as greater instability in chronotype and MSFsc compared to HC. Greater instability in chronotype was associated with higher depression and mania symptom severity. Treatment with mood stabilizers was associated with less instability in MSFsc, while antidepressant treatment was associated with greater instability in MSFsc. Conclusion Discussion: These results provide the strongest evidence to date of later chronotypes in individuals with BD. This is the largest examination of longitudinal stability of chronotype and results indicate that only BD1 is associated with greater instability over time. This instability, in part, reflects changes in mood symptoms over time, as well as in medication use. These data highlight the importance of assessment and treatment of circadian disruption in individuals BD. Support (if any) Heinz C. Prechter Bipolar Research Program