Long-term clinical efficacy of maintenance electroconvulsive therapy in patients with treatment-resistant schizophrenia on clozapine.

Electroconvulsive therapy (ECT) has been suggested as a treatment for augmenting the response to clozapine in patients that do not respond well to clozapine alone and maintenance ECT (M-ECT) had also been recommended to sustain improvement. This retrospective study of up to 2 years of observation was conducted to explore whether M-ECT is beneficial for long-term maintenance of the symptom remission elicited by acute ECT. Positive and Negative Syndrome Scale (PANSS) were plotted for each patient and compared using a linear mixed-effect model. A total of thirty-eight patients were followed and classified into three groups: (1) clozapine alone (CZP, n = 15), (2) acute ECT only (A-ECT, n = 11), and (3) acute ECT with M-ECT (M-ECT, n = 12). The mean number and interval of ECT sessions during the maintenance period in the M-ECT group were 39.0 ± 26.7 and 15.6 ± 8.4 days, respectively. The slope of the M-ECT group eventually declined, but that of the A-ECT group gradually increased back to the pre-ECT level. No persistent or serious adverse effects were observed. In conclusion, A-ECT augmented the effect of clozapine, but M-ECT was required for sustaining symptom improvement.