Course of residual symptoms according to the duration of euthymia in remitted bipolar patients

Although many studies showed the negative impact of residual symptoms on the course of bipolar disorder (BD), there is a need to examine potential differences in residual symptoms according to the duration of euthymia in remitted BD patients.

This was a large cross-sectional study of 525 euthymic BD out-patients. A multivariate analysis of covariance was conducted to compare depressive and manic residual symptoms, sleep disturbances and cognitive complaints among three patient groups on the basis of duration of euthymia (A. 6 months to <1 year; B. 1 year to <3 years; C. 3 years to ≤5 years).

A significant difference between the three groups was found in residual symptoms [Pillai's Trace: F(8942) = 4.659, P < 0.001]. Tukey post hoc analysis indicated that patients from Group C presented lower residual depressive symptoms, higher sleep quality and better perceived cognitive performance compared with Group A. Group B also presented better sleep and cognitive outcomes than Group A. In addition, Group C showed the lowest incidence of functional impairment.

This study suggests that the intensity of residual symptoms and functional impairment in remitted BD patients is negatively related to the duration of euthymia.