Objective: 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.
Method: 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).
Results: 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.
Conclusion: This study suggests that the intensity of residual symptoms and functional impairment in remitted BD patients is negatively related to the duration of euthymia.
Keywords: bipolar disorder; clinical aspects; treatment.
© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.