High-dose Magnetic Seizure Therapy on rhesus monkeys results in benign acute cognitive side-effect profile relative to Electroconvuslive therapy. This is in line with earlier reports. This time a more powerful MST device was used.
Rhesus monkeys received 4 weeks of daily high-dose MST (6 × seizure threshold), ECT (2.5 × seizure threshold), and sham (anesthesia alone).
In randomized order, subjects received 20 days of ECT, high-dose MST, and sham treatment (anesthesia alone). A recovery phase, with a minimum of 20 days and a maximum of 30 days, immediately followed each treatment phase. The length of the recovery period was determined by a return to baseline performance.
The monkeys 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.
This research showed that chronic treatment with high-dose MST resulted in less cognitive impairment than ECT and that high-dose MST did not significantly differ from the effects of anesthesia alone.
These results support the feasibility and safety of high-dose MST for subsequent work in humans to assess its efficacy in the treatment of depression.
Limitations of the study:
- the small sample size
- the limited number of cognitive domains assessed
- the risk of carry-over effects
- practice effects
- all three monkeys were males
Advantages of MST
Magnetic seizure therapy (MST) is under development as an alternative convulsive technique to minimize the neurocognitive adverse effects of convulsive therapy while maintaining antidepressant efficacy. Preclinical testing suggests that MST might have several advantages over ECT, including increased precision of stimulation, greater control of intracerebral spatial distribution, lack of susceptibility to impedance from surface tissues, and the sparing of deep brain structures