What happens to the course of bipolar disorder after electroconvulsive therapy?

Background Bipolar disorder (BD) encompasses manic and depressive episodes and an illness-free interval. Treatments used in BD patients may influence the ill phases with different actions on the illness-free interval. Methods We performed a naturalistic mirror-image retrospective study analyzing the number of episodes and admissions in 41 BD patients for the same period of time of 5 years before and after electroconvulsive therapy (ECT). Furthermore, we assessed the duration of free intervals before and after ECT as a sign of prolonged well-being. Univariate analysis with t-test was used to compare differences before and after ECT, while analysis of variance was used to compare factors possibly associated with the efficacy on free-interval of ECT. Results Comparing the 5-year periods before and after ECT, we found significantly longer [13.2±9.0 months before ECT to 25.1±19.1 after treatment (t=3.8; p<0.0001)] free intervals, as well as significant reductions in the number of episodes [5.9±3.0 before ECT to 1.0±1.7 after treatment (t=9.3; p<0.0001)], and in the number of admissions [2.2±1.3 before ECT to 0.2±0.5 after treatment (t=9.4; p<0.0001)]. Limitations The main limitations of this study consisted in the relatively small sample size, the mirror-image retrospective naturalistic study design and possibly patient selection bias. Conclusions Electroconvulsive therapy seemed to increase free-intervals and reduced number of BD episodes and admissions. It is plausible that ECT, along with suspending antidepressant treatment, might carry intrinsic stabilizing effect on the course of BD.