| Paper authors: | Ruiyang Ge, Afifa Humaira, Elizabeth Gregory, Golnoush Alamian, Erin MacMillan, Laura Barlow, Rebecca Todd, Sean Nestor, Sophia Frangou, Fidel Vila-Rodriguez |
| Year of paper publication: | 2022 |
| Post authors: | Alice Erchov, Lisa Ridgway, Fidel Vila-Rodriguez |
| Download the research article: | Ge (2022) Predictive Value of Acute Neuroplastic Response to rTMS in Treatment Outcome in Depression: A Concurrent TMS-fMRI Trial |
Introduction
Did you know that your brain is always working, even when you’re not thinking or doing anything in particular? In fact, different areas of our brain are always in “conversation” – coordinating their activity in order to do everything from seeing, talking, breathing, and even dreaming! Areas of our brain that are active or quiet at the same time are said to have “functional connectivity”.
Functional connectivity can be measured at rest (“resting state functional connectivity”) or while we are engaging in a certain task (“task-based functional connectivity”). For example: doing a math equation, performing a memory game, or receiving a neuromodulation treatment like rTMS.
rTMS is a safe, non-invasive neurostimulation technique used to treat depression. It works by applying a coil to the scalp, which then delivers magnetic pulses that disrupts the way the brain functions in depression. Importantly, it is effective even for people who did not benefit from antidepressants. Predicting who might benefit best from rTMS is an important topic for researchers: it can help direct patients and clinicians to whatever treatments would be best for them.
The researchers of the current study were wondering if how the brain reacts to rTMS can be used to predict whether someone with depression would benefit from this treatment. Specifically, how the functional connectivity between brain areas changes with rTMS.
Methods
38 people with depression completed this study. Everyone had to have tried, and not benefited from, at least one antidepressant in the past. This means their depression was treatment-resistant.
Brain activity was measured using something called functional magnetic resonance imaging (fMRI). Each person lies down in a tube-like scanner. This scanner uses very strong magnets and tracks how different molecules in the brain react to it. Areas of our brain that are very active use a lot of blood and oxygen for energy, when compared to areas of our brain that are not active. The fMRI detects these differences in blood and oxygen to determine what brian areas are working at any given time. For an additional video that explains how MRIs and fMRIs work, you can see here.
Participants in this study received an fMRI while not doing anything (resting state) that was then compared to an fMRI taken while they received an rTMS treatment. Then, for the complete treatment course, rTMS was delivered every week day for 4 weeks (20 treatments total). This study used a specific, low frequency rTMS treatment that has a lower likelihood of disrupting the fMRI images.
Results
- Overall, this study found functional connectivity between many regions of the brain could predict response to rTMS. These areas were widespread, but are generally related to our emotional response and regulation.
- Interestingly, the areas of the brain that responded to rTMS were spread throughout the whole brain. This shows that rTMS can influence brain function far beyond the one area that is directly targeted by the treatment.
- Overall, functional connectivity was reduced when participants’ depression improved with treatment. This shows that rTMS may work through reducing problematic activity across different brain regions.
Conclusion
rTMS appears to treat depression through widespread changes across the brain. How the brain reacts to rTMS may help predict whether someone would benefit from this specific treatment. More research is needed before we can have a complete understanding of how we can predict, and ultimately prescribe, what treatment is best for a specific individual.