Randomized controlled trial of the cognitive side-effects of magnetic seizure therapy (MST) and electroconvulsive shock (ECS).

Magnetic seizure therapy (MST) is under development as a means of improving the cognitive side-effect profile of electroconvulsive therapy (ECT) by inducing more spatially delimited seizures that spare cortical regions involved in memory. We tested whether MST had a cognitive side-effect profile distinct from electroconvulsive shock (ECS) in a non-human primate model, using the Columbia University Primate Cognitive Profile, which has been shown to be sensitive to the cognitive effects of ECS. Using a within-subject cross-over design, daily ECS, MST, and sham (anaesthesia-only) interventions were administered in 5-wk blocks. Rhesus macaques (n = 2) were trained on a long-term memory task, an anterograde learning and memory task, and a combined anterograde and retrograde task where learning and memory were evaluated for new and previously learned 3-item lists. Acutely following each intervention, monkeys were tested on the cognitive battery twice daily, separated by a 3-h retention interval. Overall, monkeys were least accurate following ECS (p's < 0.05) compared to sham and MST. This effect was most marked for long-term memory of a constant target, short-term memory of a variable target and recall of previously learned 3-item lists. Monkeys were slowest to complete all tasks following ECS (p's = 0.0001). Time to task completion following MST did not differ from sham. These findings suggest that MST results in a more benign acute cognitive side-effect profile than ECS in this model, consistent with initial observations with human MST.