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

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