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Magnetic Seizure Therapy (MST) can Treat Depression by Changing the Structure and Function of our Brains
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. 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.
Memory-Related Regions of the Brain Function Differently in Those with Treatment-Resistant Depression
Depression doesn’t just affect the way people feel, it also affects the way people think. Specifically, a lot of people with depression notice that their memory might have become worse: they may have difficulty studying for school exams, misplace their things, or forgetting what they needed from the store. Many studies have looked into why this might be, looking particularly at the structure of our brain’s memory center, but not its function. The researchers of the current study were wondering if changes in the brain structure (size) and function (activity) were related to differences in memory among people with treatment-resistant depression, when compared to those without.
How the Brain Reacts to rTMS can Predict Who Will Benefit Most From this Depression Treatment
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.
Memory can improve after rTMS treatment for those with depression-related cognitive symptoms
Did you know that poor mood is not the only way to diagnose depression? In fact, cognitive impairment – worsened thinking, concentration, and decision making – is one of nine criteria for the disorder. This impairment is even more common and severe among those who have treatment-resistant depression: a particular case where someone does not improve with standard antidepressant medications. This study assessed changes to cognition 3 months post-rTMS among a group of people with treatment-resistant depression and compared it to people without depression.
Not Just Your Brain: iTBS-related Changes in Heart Function
It is no question that neurostimulation treatments like rTMS change your brain for the better. Because of this, rTMS is capable of treating depression even when people did not benefit from antidepressants. However, less is known about how rTMS affects other parts of the body: primarily, the heart. It is possible that heart rate could be used to help pinpoint the target of iTBS for a more precise, effective treatment.
Four Paths of Response to rTMS in Treatment-Resistant Depression
rTMS treatment outcomes are very diverse. Some may improve almost instantly, others may require a higher number or intensity of treatments, and others may not respond at all. Understanding the diversity of rTMS treatment responses can be important in order for clinicians and patients to find the best, personalized treatment approach for their depression. The aim of this study was to describe the number and pattern of unique pathways (i.e., trajectories) of improvement to rTMS among a large group of people with treatment-resistant depression.
People are most likely to respond to rTMS if they have attempted less than 3 trials of antidepressants in the past, without success
Interestingly, the likelihood to respond (i.e., improve) with antidepressants is thought to decrease with every attempt. It is unclear whether someone’s past history with antidepressants affects the likelihood for someone to respond to rTMS or iTBS in the future. Knowing who might benefit most from neurostimulation therapies can help clinicians and patients understand the best treatment route for them.
LEFT and RIGHT-handed people with treatment-resistant depression improve equally with rTMS
Interestingly, handedness (i.e., whether an individual is right or left handed) might indicate which side of the brain/body is more dominant. Potentially, this could affect the intensity of stimulation that left or right-handed people need. Additionally, rTMS is delivered to the left side of an individual’s head. This region of the brain controls the right side of your body — raising the question as to whether rTMS is equally effective for left and right-handed people. This could have important impacts for depression treatment.
Towards Competency-Based Medical Education in Neurostimulation
Competency-based medical education (CBME) is an emerging model of training for medical students. Instead of relying simply on the time spent in residency, CBME focuses on having residents achieve necessary skills such that they would be able to perform competently (successfully) and independently in their selected specialties. A group of residents, academic faculty, and clinical faculty at the University of British Columbia (UBC) have come together to create a roadmap as to how to apply CBME specifically to interventional psychiatry – which includes the practice of electroconvulsive therapy and rTMS.
Who may be most likely to benefit from repetitive transcranial magnetic stimulation (rTMS)?
Even though repetitive transcranial magnetic stimulation (rTMS) is largely effective at treating depression even for those who do not respond to antidepressants, there is still a fraction of individuals who do not improve with rTMS. Predicting who may respond best to rTMS may help clinicians and patients make better choices as to what treatments to pursue, with the ultimate hope to better treat depression. Trevizol et al. (2020) used data from a clinical trial run by the NINET Lab at UBC called THREE-D to determine if there are characteristics that can help predict whether someone would benefit from rTMS.