F—— Magnets, How Do They Work?

in News
February 1st, 2011

It has been said “The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ but ‘That’s funny…’” (Isaac Asimov), and a recent observation by a Harvard Medical School lab studying the brain chemistry of Bipolar Disorder has researchers uttering that precise phrase…as well as the one alluded to in the title of this post.

The initial study prompting such observations recruited patients suffering specifically from Bipolar Disorder, also known as Manic-Depression, for 20-minute brain scans in an MRI.  MRI scans subject patients to a harmless magnetic field and pulses of radio waves to create detailed structural images of various body parts, in this case, the brain.  While the procedure is painless and relatively short, it can be unpleasant for reasons wholly unrelated to the magnets and radio signals; patients frequently report unrelated bodily discomfort or claustrophobia.  For this reason it was all the more surprising, according to one researcher, that patients participating in the study started to report mood elevations (that for some lasted days or even a week) following the scan.  One patient even subtly suggested that the researchers had slipped her something without her permission.

Patient undergoing TMS treatment for depression

The use of magnets to improve the effects of depression is not uncharted territory in neuroscience and it might even sound familiar to some.  Transcranial magnetic stimulation, or TMS, is another technique that has recently been adapted to depression therapy, yet it is more akin to electroconvulsive, or “electroshock”, therapy (ECT) than MRI.

TMS uses a magnetic field to induce a relatively small electric current, without causing seizure or loss of consciousness, to stimulate the left prefrontal cortex, the area thought to be under-active in depression.  Whereas ECT treatments are utilized only in the most extreme depression cases because of the risk of seizure and necessity of sedation, TMS carries much fewer risks and can be used for more mild depression. While the exact mechanisms are still not known, particularly the roll of seizure for the antidepressant effects, both ECT and TMS have been cleared by the FDA.

But the magnet employed in MRI does not excite specific brain regions (if it did the entire imaging method of functional magnetic resonance imaging, fMRI, would be ineffective) and it is certainly not strong enough to induce seizures.  After observing the curious side-effects of their initial study, the aforementioned researchers set up a small preliminary study with both bipolar and normal controls who confirmed respectively that the effects were not placebo, and that even those without depression can experience the mood-boosting effects of MRI.

So could a new depression treatment soon be joining the ranks of such accidental scientific breakthroughs as penicillin and Post-It notes?  At this point it really is unclear.  The actual mechanism of the mood-boosting effects of MRI on depressed patients is not yet understood, nor have the effects been generalized to unipolar depression.  However, the safety of exposure to MRI has been confirmed by the FDA and a lack of total understanding regarding what causes the “miraculous” effects of that other magnet-based depression treatment, TMS, as well as a host of other medical treatments (including lithium for Bipolar Disorder) certainly has not prevented their use.

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