Effective treatments for major depressive disorder have been in high demand since medieval times. Antidepressant prescription drugs first became available in the twentieth century, yet still are not effective for many patients and often cause multiple side effects. Alternative treatments such as electroconvulsive therapy (ECT) have lesser-known detrimental features. Some patients may experience memory loss and confusion, as Brenda Griffith describes in the Scientific American article, "Fighting Depression with Magnets." Griffith has tried over twelve different antidepressant medications and ECT, all of which brought negative side effects and no relief for her depression. Finally, Griffith began transcranial magnetic stimulation (TMS) as a last line of treatment and saw drastic improvements in her depressive symptoms.
The process of TMS involves an electromagnetic coil placed against the head of a patient, usually at a location specific to their condition. Repetitive TMS provides stimulation through induced electrical current in axons. While the process provides electrical stimulation in cortical areas, deep brain structures such as the hippocampus are inaccessible through TMS. Regions demonstrating increased fMRI connectivity with specific deeper cortical structures are not always the same as the outer cortex areas stimulated, meaning that locations directly above the targeted area do not necessarily correlate with what lies directly underneath them.
TMS is not only useful for lessening symptoms of depression, but also beneficial for strengthening memory ability. Dr. Joel Voss, a neurology researcher at Northwestern University, focuses his work on memory improvement and recently held a lecture at Loyola University Chicago on the manipulation of memory ability through TMS. Voss's study compares success of a spatial memorization task with measures of precision of a simple memory task. In older adults with declining memory, he compares both item recognition and source recognition. His results show that source memory significantly improved (by as much as 30 percent) in participants who received TMS treatment, and the memory increase remained relatively better up to one week later after initial treatment in experimental group participants. Voss chose to electrically stimulate the hippocampal-cortical network in order to best reach the hippocampus, as it is a deep structure and not easily accessible through TMS.
Overall, transcranial magnetic stimulation is becoming more successful and common in treating various cognitive abnormalities such as depression and memory-related disorders. However, TMS must be used frequently over a substantial time period in order to prove successful in patients. The cost of many treatments can range from $300-$500 and adds up quickly in its typical thirty to forty sessions. Medical insurance has been recognizing and covering TMS costs much more frequently than before, and hopefully will continue to become more affordable for individuals in order to greatly stabilize and improve their daily lives.
- Joel Voss lecture
- Picture: https://en.wikipedia.org/wiki/Transcranial_magnetic_stimulation
- https://blogs.scientificamerican.com/observations/fighting-depression-with-magnets/
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