Background: Maintenance electroconvulsive therapy (m-ECT) is effective in preventing recurrences of depressive episodes. There is little information on long-term m-ECT extending over several years and its impact on cognitive functions. This study was an attempt to determine the efficacy and side effects of long-term m-ECT.
Method: Depressive episodes and admissions before m-ECT for a period equal to the duration of m-ECT and during m-ECT were compared using medical records. Cognitive functions assessed by Mini-Mental State Examination (MMSE) before and after m-ECT were compared along with the review of Neuropsychiatry Unit Cognitive Assessment Tool (NUCOG).
Results: 17 patients had m-ECT that extended from 6 to 153 months (mean 39, SD=44.46). The average number of episodes before and during m-ECT was 2.47 (SD=2.23) and 0.88 (SD=1.31) respectively (Wilcoxon ranked test Z=3.06, r=0.55, two-tailed p=0.002). Average number of admissions dropped from 2.05 (SD=1.88) to 0.23 (SD=0.43) during m-ECT (Z=3.471, r=0.71, p=0.001). The average time to recurrence was 24.24 months (SD=25.20) with longest depression free survival of 105 months. There was no significant difference in MMSE score before and after the commencement m-ECT or progressive deterioration in NUCOG score.
Limitations: This study was limited by retrospective nature of data collection, small sample size, confounding effects of antidepressants along with m-ECT and absence of a highly sensitive cognitive screening tool that can capture all types of cognitive impairments following m-ECT.
Conclusions: In a naturalistic setting the efficacy of m-ECT may extend over several years while cognitive functions remain largely unaffected.
Keywords: Cognitive deficits; Depression; ECT; Electroconvulsive therapy; Maintenance ECT.
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