Shock and Cure - With Magnets

Electroconvulsive therapy (ECT) is the oldest treatment in psychiatry that's still in use today. ECT uses a brief electrical current to induce a generalized seizure. No-one knows why, but in many cases this rapidly alleviates depression - amongst other things.

The problem with ECT is that it may cause memory loss. It's hotly debated how serious of a problem this is, and most psychiatrists agree that the risk is justified if the alternative is untreatable illness, but it's fair to say that whether or not it's not as bad as some people believe, the fear that it might be, is the main limitation to the use of the treatment.

Wouldn't it be handy if there was a way of getting the benefits of ECT without the risk of side effects? To that end, people have tried tinkering with the specifics of the electrical stimulation - the frequency and waveform of the current, the location of the electrodes, etc. - but unfortunately it seems like the settings that work best, tend to be the ones with the most side effects.

Enter magnetic seizure therapy (MST). As the name suggests, this is like ECT, except it uses powerful magnets, instead of electrical current, to cause the seizures. In fact though, the magnets work by creating electrical currents in the brain by electromagnetic induction, so it's not entirely different.

MST is thought to be more selective than ECT, in that it induces seizures in the surface of the brain - the cerebral cortex - but not the hippocampus, and other structures buried deeper in the brain, which are involved in memory.

It was first proposed in 2001, and since then it's been tested in a number of very small trials in monkeys and people. Now a group of German psychiatrists say that it's as effective as ECT, but with fewer side effects, in a new trial of 20 severely depressed people. Ironically, they work on Sigmund Freud Street, Bonn. I am not sure what Freud would say about this.

The trial was randomized, but not blinded: it's hard to blind people to this because the equipment used looks completely different. Nor was there a placebo group. All the patients had failed to improve with multiple antidepressants, and psychotherapy in almost all cases, and were therefore eligible for ECT. If anything, the MST group were slightly more ill than the ECT group at baseline.

The ECT they used was right unilateral. This is probably not quite as effective as stimulation which targets both sides of the brain (bitemporal or bifrontal), but has fewer side-effects.

So what happened? After 12 sessions, MST and ECT both seemed to work, and they were equally effective on average. Some patients got much better, some only got a bit better.

What about side effects? MST was noticeably "gentler", in that it didn't cause headaches or muscle pain, and people recovered from the seizures much faster (2 minutes vs 8 minutes to reorientation) after MST. This may have been because the seizures (as assessed using EEG) were less intense.

In terms of the all-important memory and cognitive side effects, however, it's not clear what was going on. They used a whole bunch of neuropsychological tests. In some of them, people got worse over the course of the sessions. In others, they got better. But in several, the scores went up and down with no meaningful pattern. If anything the MST group seemed to do a bit better but to be honest it's impossible to tell because there's so much data and it's so messy.

Unfortunately the tests they used have been criticized for not picking up the kinds of memory problems that some ECT patients complain of e.g. the "wiping" of old memories. For some reason they didn't just ask people whether they felt their memory was damaged or not.

Overall, this trial confirms that MST is a promising idea, but it remains to be seen whether it has any meaningful advantages over old school shock therapy...

Kayser S, Bewernick BH, Grubert C, Hadrysiewicz BL, Axmacher N, & Schlaepfer TE (2010). Antidepressant effects, of magnetic seizure therapy and electroconvulsive therapy, in treatment-resistant depression. Journal of psychiatric research PMID: 20951997