Is There Evidence That Stimulus Parameters and Electrode Placement Affect the Cognitive Side Effects of Electroconvulsive Therapy in Patients with Schizophrenia and Schizoaffective Disorder? A Systematic Review

Seventy percent of patients with treatment-resistant schizophrenia do not respond to clozapine. Electroconvulsive therapy (ECT) can potentially offer significant benefit in clozapine-resistant patients. However, cognitive side effects can occur with ECT and are a function of stimulus parameters and electrode placements. Thus, the objective of this article is to systematically review published clinical trials related to the effect of ECT stimulus parameters and electrode placements on cognitive side effects. We performed a systematic review of the literature up to July of 2020 for clinical studies published in English or German examining the effect of ECT stimulus parameters and/or electrode placement on cognitive side effects in patients with schizophrenia or schizoaffective disorder. The literature search generated 3 randomized, double-blind, clinical trials, 1 randomized, nonblinded trial, and 1 retrospective study. There are mixed findings regarding whether pulse width and stimulus dose impact on cognitive side effects. One study showed less cognitive side effect for right unilateral (RUL) than bitemporal (BT) electrode placement, and 2 studies showed a cognitive advantage for bifrontal (BF) compared with BT ECT. Only 1 retrospective study measured global cognition and showed post-ECT cognitive improvement with all treatment modalities using Montreal Cognitive Assessment in comparison to pre-ECT Montreal Cognitive Assessment scores. Current data are limited, but evolving. The evidence suggests that RUL or BF ECT have more favorable cognitive outcomes than BT ECT. Definitive larger clinical trials are needed to optimize parameter and electrode placement selection to minimize adverse cognitive effects.