| Paper authors: | Jonathan Hsu, Jonathan Downar, Fidel Vila-Rodriguez, Zafiris Daskalakis, Daniel Blumberger |
| Year of paper publication: | 2019 |
| Post authors: | Alice Erchov, Lisa Ridgway, Fidel Vila-Rodriguez |
| Download the research article: | Hsu (2019) Impact of prior treatment on remission with intermittent theta burst versus high-frequency repetitive transcranial magnetic stimulation in treatment resistant depression |
Introduction
Depression, on its own, can have severe and harmful impacts on an individual’s life. While there have been great advancements in psychiatry’s ability to treat the illness through antidepressants, these do not work for everyone. This phenomenon is called “treatment-resistant depression” and is especially severe for those affected.
Interestingly, the likelihood to respond (i.e., improve) with antidepressants is thought to decrease with every attempt. To illustrate: someone who did not respond to one antidepressant may be less likely to respond to a second. If they do not respond to a second, the chance that they will respond to a third is increasingly slim.
However, antidepressants are not the only route of treatment for those with depression. Emerging neurostimulation treatments such as repetitive transcranial magnetic stimulation (rTMS) is effective even in severely treatment-resistant depression! rTMS is becoming increasingly researched, and new improvements have been able to shorten treatments to only ~3.5 minutes in length, without sacrificing its ability to treat depression. This shortened treatment is called iTBS.
Knowing who might benefit most from neurostimulation therapies can help clinicians and patients understand the best treatment route for them. It is still unclear whether someone’s past history with antidepressants affects the likelihood for someone to respond to rTMS or iTBS in the future.
Methods
This paper is an analysis of a past study done by the NINET Lab at UBC and collaborations with the Center for Addiction and Mental Health (CAMH) and the United Health Network (UHN) of Toronto, Ontrario. A total of 385 participants with depression completed 4-6 weeks of either iTBS or rTMS. To see more details about the original study, you can refer to that infographic and summary here.
Results
| Number of participants | Number of failed antidepressant trials | Average likelihood of remission |
| 217 (52%) | 0-1 | 29% |
| 116 (28%) | 2 | |
| 81 (20%) | 3 | 17% |
| People who failed 3 antidepressant trials were less likely to remit in response to rTMS/iTBS when compared to those who failed only 2 or less | ||
Remission = symptoms fall below a “clinically-relevant” severity (i.e., are so low that it is likely no longer enough to classify as depression)
- Those who failed 3 antidepressants were less likely to have their depression remit in response to rTMS/iTBS when compared to those who only failed 2 or less
- There was no difference in the likelihood of remission between those who received rTMS or the accelerated counterpart, iTBS
Conclusion
This study suggests that those who did not improve with 2 or less antidepressant trials may be more likely to have their depression remit in response to rTMS/iTBS than those who tried 3 or more. Additionally, short iTBS treatments have been shown to be no less effective than the lengthier rTMS protocol. This means that patients may benefit from a shortened time commitment without sacrificing their chance of improvement.
This finding might help guide clinical decisions. If public access and knowledge of neurostimulation treatments was to improve, it is possible that people could receive rTMS/iTBS earlier in their depression treatment course. It is also possible that those who do not improve with either antidepressants or rTMS/iTBS may have a unique underlying illness that might make it harder to treat. Researching why people may respond or not respond to a particular approach can help us better understand depression and, ultimately, improve our ability to treat it.