Depression is predicted to be the second-largest contributor of global disease burden by 2020. Practically everybody is impacted by depression (directly, or indirectly through loved ones). With such a huge impact, it's important to understand how depression happens in the brain so that new treatments can be developed. Approximately 30-60% of the people with depression don’t get better with normal antidepressant or psychotherapy treatments, suggesting something is different about their brains. Being able to identify what this key difference is can let doctors know who should receive standard treatments, and who might better benefit from other treatments, like Transcranial Magnetic Stimulation (TMS). This would lead to a more effective distribution of treatment resources for people with depression, saving the healthcare system money by giving people treatments that likely work better for their unique brains.
Yamile Jasaui, MS Student
Dr. Frank MacMaster
University of CalgaryDr. MacMasters' Website
One feature of the brain that could be different in treatment-resistant depression is the amount of a neurochemical called glutamate. This study investigated if glutamate could be used to figure out who would and would not get better from a TMS treatment. Does TMS possibly help people get better by changing something about glutamate? This study tried to answer that question by giving people with “treatment-resistant depression” TMS therapy, along with a brain scan before and after their TMS treatment. This let researchers discover that TMS increased glutamate levels in a part of the frontal cortex ( which is important for reasoning and planning), corresponded to improvements in depression. Furthermore, the people who didn’t respond to TMS already had high glutamate levels, so that might be why TMS wasn’t effective for them.
About half of the people who receive TMS will respond with at least a 50% decrease in their depressive symptoms. This is fantastic, as all of these people have been told they have treatment-resistant depression (a pretty scary diagnosis - I’m never going to get better?!) but it’s still not enough. Since glutamate was able to identify who would benefit from TMS, this means doctors could potentially use brain scans for a personalized medicine approach to pediatric depression. Additionally, since an increase in glutamate (an excitatory neurotransmitter) was associated with recovery from depression, this suggests TMS might be “jump-starting” the kids' brains towards healing. The prevalence of depression in our society is increasing, with a significant lifestyle and economic burden for individuals and communities. We need to be better able to recognize and treat the different subtypes of depression and be able to give them treatments that work for the way their brain is wired.