Can daily actigraphic profiles distinguish between different mood states in inpatients with bipolar disorder? An observational study.

Background: Criterion A changes for bipolar disorder (BD) in the Diagnostic and Statistical Manual of Mental Disorders-Fifth Edition yield new difficulties in diagnosis. Actigraphy has been used to capture the activity features of patients with BD. However, it remains unclear whether long-term actigraphic data could distinguish between different mood states in hospitalized patients with BD. Methods: In this observational study, 30 hospitalized patients with BD were included. Wrist-worn actigraphs were used to monitor motor activity. The patients were divided into bipolar disorder-depression (BD-D), bipolar disorder-mania (BD-M), and bipolar disorder-mixed state (BD-MS) groups. Motor activity differences were estimated using non-parametric analyses between and within the three groups. Results: The mean 24 h activity level differed between the groups. In the between-group analysis, the intra-individual fluctuation and minute-to-minute variability in the morning and the mean activity level and minute-to-minute variability in the evening significantly differed between the BD-M and BD-MS groups. In the within-group analysis, the BD-M group showed a disrupted rhythm and reduced activity complexity at night. Both the BD-D and BD-MS groups demonstrated significant differences between several parameters obtained in the morning and evening. Conclusion: The mean activity levels during the relatively long monitoring period and the intra-day variation within the groups could reflect the differences in motor activity. Sustained activity monitoring may clarify the emotional states and provide information for clinical diagnosis.