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May 2017 TMS Newsletter : How Does TMS works?
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It has become clear that TMS treatment is an effective method for treating Major Depressive Disorder (MDD), a serious health issue in this country.
The National Institute of Health (NIH) reports that, "the lifetime prevalence of major depressive disorder is high, around 16.9% in the United States," [but, the] "treatment outcome of depression is suboptimal. The use of currently available antidepressants is limited by their side effects, slow response, and inadequate treatment efficacy," [and,] "full remission is difficult to be achieved." [1]
As a result, alternative methods of treating MDD are on the rise, which has led to the exploration of the specific neurological responses behind the treatments. In the case of TMS, there is still quite a bit to learn. As stated in an article published by the NIH, "The mechanism about how TMS works on depression is still unclear." [2]
There is precedence for this partial mystery as the brain is a highly complex and nuanced system that scientists all over the world are still working to completely understand. Even the effectiveness and mechanism of action of selective serotonin reuptake inhibitors (SSRIs), the most commonly prescribed form of antidepressant, is not universally agreed upon.
Given this, it is critical to delve into the science and begin putting the pieces together, because when it comes to treating patients suffering from major depressive disorder, the more we know, the more we can help.
Although the mechanism of action is unknown, it is hypothesized that the NeuroStar TMS Therapy System causes neuronal depolarization and changes in brain functional activity that may be associated with various physiologic changes in the brain associated with symptomatic relief of depression in the indicated population.Research has indicated that TMS treatment may be working in one or more of the following ways:
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Neurogenesis (i.e. brain growth, specifically the development of new tissues) Stimulation: "Over time, antidepressant response was associated with a near significant increase in left amygdala volume (6.58%)." [3]
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Serotonin and Dopamine Modulation: TMS may, "facilitate serotonin transmission in the hippocampus and induce dopamine release in the striatum of patients with depression indicating that rTMS [repetitive transcranial magnetic stimulation] might have indirect effects on the HPA axis ["a complex set of direct interactions and reciprocal loops of negative feedback between the frontal cortex... the hypothalamus, the pituitary gland, and the adrenal gland"] activity." [4]
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Neural Network Connectivity Repair: "TMS selectively modulates functional connectivity both within and between the CEN [central executive network] and DMN [medial prefrontal-medial parietal default mode network], and modulation of subgenual cingulate connectivity may play an important mechanistic role in alleviating depression." [6]
Although the exact mechanism for how rTMS works is notknown, doctors around the country have been using the standard protocol as determined by the FDA approval for Major Depression in 2008, and we know that is works for most patients. The next big question is,what changes can we make to the standard protocol, in terms of the best treatment location, pulse pattern, intensity level, number of pulses per treatment and length of treatment course?This question and others like it are currently being studied at many facilities and university hospitals around the country, and the results will help further our knowledge about rTMS and lead to better, more effective treatment for our patients.
What is certain today is that the brain is responding positively to TMS, and people across the country who suffer from major depression are finally beginning to feel some relief.
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[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5405587/#B102
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5405587/#B102
[4] https://www.ncbi.nlm.nih.gov/pubmed/22784443
[5] http://www.brainstimjrnl.com/article/S1935-861X(14)00400-8/abstract
[6] https://academic.oup.com/ijnp/article-lookup/doi/10.1017/S1461145702002791
[7] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4209727/
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About Author:
Erin Ginder-Shaw
Freelance Writer
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