| Paper authors: | Ruiyang Ge, Elizabeth Gregory, Jian Wang, Nicholas Ainsworth, Wei Jian, Chunlin Yang, Gang Wang, Fidel Vila-Rodriguez |
| Year of paper publication: | 2021 |
| Post authors: | Alice Erchov, Lisa Ridgway, Fidel Vila-Rodriguez |
| Download the research article: | Ge (2021) Magnetic seizure therapy is associated with functional and structural brain changes in MDD: Therapeutic versus side effect correlates |
Introduction
Magnetic Seizure Therapy (MST) is similar to rTMS: it is a safe, painless, effective, and non-invasive way to treat even severe depression that hasn’t improved with antidepressants. MST also uses a device placed on the scalp to deliver a magnetic field that disrupts the brain’s electrical activity. However, MST is stronger. In fact, it is intended to elicit a closely-monitored seizure that is then thought to rewire the brain for the better, with less side effects than electroconvulsive therapy (ECT).
MST is also capable of treating even more severe depression than rTMS. Between a large 30%-60% of people who receive MST have their depression remit — and this can be accomplished in as little as 6 days!
How MST works on a brain level is less clear. Some studies suggest it increases blood flow to important regions of the brain for thinking and feeling. Others suggest it increases brain matter. It is also possible that it changes the way our brain regions communicate with each other.
As mentioned in another recent article, 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 (i.e., are coordinated) are said to have “functional connectivity”.
The researchers of the current study were wondering if changes in the brain structure (size) and function (activity) were related to improvements in depression after MST.
Methods
This study included 15 people with moderate or severe treatment-resistant depression. There were also 10 “healthy controls” (people without depression or other illnesses) that were used as a comparison group. Data for this analysis was taken from a previous MST trial done at the NINET Lab at UBC.
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: https://youtu.be/4UOeBM5BwdY?si=qVcXgGJy2kDmiqSj.
There were 2 areas of the brain the researchers were primarily interested in:
- The hippocampus, our memory center, is thought to be related to deficits in memory and cognition (thinking) in people with depression. It is also a region that is consistently found to have decreased in size in people with depression.
- The subgenual anterior cingulate cortex (sgACC) is located deep in the lower front of our brain. The sgACC is thought to help with our decision-making and emotion regulation. This region is shown to change its activity after a course of electroconvulsive therapy (ECT), and that these changes were related to improvements in depression.
Individuals with depression received MST on 6 consecutive weekdays, under general anesthesia.
Results
- Patients had an average 57% reduction in depressive symptoms and a 62% reduction of anxiety symptoms after MST
- Patients also had improvements in their memory and cognition after MST
- There was an increase in grey matter and volume in two regions located near the outer-top of the brain called the bilateral paracentral lobule and the left postcentral gyrus
- People with a hippocampus that had a decrease in functional connectivity (fired in a less coordinated way) with regions in the front-top of the brain saw less improvements in their memory
- The sgACC had an increase in functional connectivity (fired in a more coordinated way) with regions in the mid-back of the brain called the parietal lobe
- This greater this change, the more depressive symptoms improved
- Interestingly, these deeper brain regions are not where the MST coil can target directly from the scalp. This means that MST is capable of creating brain-wide changes, far beyond its local and surface-level targets.
Conclusion
MST appears very effective in treating people with depression in as little as 6 days. Not only does it improve mood, it also strengthens memory and cognition among people with depression. This study found that these positive changes may be due to the effect that it has on the structure and function of our brain. Specifically, more coordinated activity between the sgACC and other regions of the brain appeared to be closely related to improvements in depression. Conversely, people who had a hippocampus that fired in a less coordinated manner with other regions of the brain did not appear to benefit as much from MST. These findings may be used to specify which treatment is right for a specific individual in the future. It also helps us better understand the unique ways that MST and other treatments like rTMS and ECT work to treat depression.