The effects of electroconvulsive therapy on cognition: an exploratory retrospective study

Electroconvulsive therapy (ECT) is one of the most effective treatments for depression, but worries about cognitive side effects remain. This retrospective study evaluated cognitive outcomes and the antidepressant efficacy of ECT in a real-life sample of patients with treatment-resistant uni- or bipolar depression.

We included 90 depressed inpatients aged 49 ± 13.8 (SD) years who underwent 10 ± 2.1 (SD) unilateral or bitemporal ECT treatments and completed an extensive pre- and post-treatment psychological test battery. The Hamilton Depression Rating Scale (HAMD) and the Mini-Mental State Examination (MMSE) were evaluated as main outcomes pre-/post-ECT treatment.

There was no significant change in MMSE scores between pre-/post-treatment assessments (β = 0.10, 95% confidence interval [CI] [-0.44, 0.25], p = 0.58), indicating no negative effect on global cognition. A minority of patients (N = 3) experienced a reduction of ≥5 points in the MMSE. Most cognitive tests showed no difference; however, some domains revealed statistically significant improvements (visual learning and motoric reaction time), whereas one domain showed a significant decline (verbal learning). Higher age and higher stimulus doses predicted worse outcomes in some cognitive domains. While ECT significantly reduced depressive symptoms measured by HAMD (β = -5.51, 95% CI [-7.08, -3.94], p < 0.001), depressive symptoms were not associated with cognitive outcomes.

No major cognitive changes were observed. While test results indicated deterioration in verbal learning and improvement in visual learning and motoric reaction time, effect sizes were small, and other cognitive tests showed no significant changes. The main limitation is the absence of retrograde memory assessment.