Daily Actigraphy Profiles Distinguish Depressive and Interepisode States in Bipolar Disorder

Disruptions in activity are core features of mood states in bipolar disorder (BD). In this study, we sought to identify activity patterns that discriminate between mood states in BD. Locomotor activity was collected by using actigraphy for 6 weeks in participants with interepisode BD Type I ( n = 37) or participants with no lifetime mood disorders ( n = 39). The 24-hr activity pattern of each participant-day was characterized and within-person differences in activity patterns were examined across mood states. Results showed that among participants with BD, depressive days are distinguished from other mood states by an overall lower activity level and a pattern of later activity onset, a midday elevation of activity, and low evening activity. No distinct within-person activity patterns were found for hypomanic/manic days. Given that activity can be monitored noninvasively for extended time periods, activity pattern identification may be leveraged to detect mood states in BD, thereby providing more immediate delivery of care.