Differential effects of high-dose magnetic seizure therapy and electroconvulsive shock on cognitive function

Background: Magnetic seizure therapy (MST) is under investigation as an alternative form of convulsive therapy that induces more focal seizures and spares cortical regions involved in memory. With a newly expanded version of the Columbia University Primate Cognitive Profile, we compared the cognitive effects of high-dose MST delivered at 100 Hz (6 x seizure threshold) with electroconvulsive shock (ECS) delivered at 2.5 x seizure threshold. Methods: Daily high-dose MST, ECS, and sham (anesthesia-only) were administered for 4 weeks each in a within-subject crossover design. Rhesus macaques (n = 3) were trained on five cognitive tasks assessing automatic memory, anterograde learning and memory, combined anterograde and retrograde simultaneous chaining, and spatial and serial working memory. Acutely after each intervention, monkeys were tested on the cognitive battery twice daily, separated by a 3-hour retention interval. Results: Subjects were slower to complete criterion tasks (p values <.0001) after ECS, compared with sham and high-dose MST. Moreover, time to task-completion after high-dose MST did not differ from sham. Of six measures of accuracy, treatment effects' were found in four; in all of these, ECS but not MST fared worse than sham. On all accuracy and time to completion measurements, subjects performed as well after high-dose MST as subjects from a previous study on moderate-dose MST. Conclusions: These findings provide evidence that high-dose MST results in benign acute cognitive side-effect profile relative to ECS and are in line with our previous studies.