| Paper authors: | Tyler Kaster, Jonathan Downar, Fidel Vila-Rodriguez, Kevin Thorpe, Kfir Feffer, Yoshihiro Noda, Peter Giacobbe, Yuliya Knyahnytska, Sidney Kennedy, Raymond Lam, Zafiris Daskalakis, Daniel Blumberger |
| Year of paper publication: | 2019 |
| Post authors: | Alice Erchov, Sarah Kesler Fidel Vila-Rodriguez |
| Download the research article: | Kaster (2019) Trajectories of Response to Dorsolateral Prefrontal rTMS in Major Depression: A THREE-D Study |
Introduction
Repetitive Transcranial Magnetic Stimulation (rTMS) is a safe, non-invasive, and effective treatment for depression, even when it doesn’t respond to antidepressant medications (i.e., is treatment-resistant). However, 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 for three reasons:
- It could help predict how someone will respond to rTMS
- It could help plan and optimize the number or intensity of treatments to improve outcomes
- It could help us understand depression itself. Different responses to treatment could reflect differences in the illness or its biology.
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.
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. Data from a total of 388 people with depression was used in this study. To be eligible, all participants had to have tried 1-2 antidepressants in the past without improvement. This means that their depression was considered treatment-resistant.
rTMS was delivered daily, on weekdays (5 days/week) for 4-6 weeks total. Participants all received either the standard rTMS protocols (37.5 min treatments) or its accelerated version, iTBS (3.5 min treatments).
Results
Four unique response trajectories were found:
- Rapid response (73 people, 19% total): near-maximum improvement by weeks 2-3, followed by a relative plateau to week 6
- Less severe symptoms at the start with steady improvement (154 people, 40% total)
- More severe symptoms at the start with steady improvement (118 people, 30% total)
- Non-responders (43 people, 11% total): minimal improvement over treatment
These differences could be detected as early as 1 week into treatment. Whether or not people were receiving rTMS or iTBS did not appear to affect their response trajectories or likelihood of improvement.
People were more likely to be rapid responders if they were older, had less severe depression before the start of treatment, and were NOT taking benzodiazepine medications (e.g, Xanax, Ativan, Valium, etc.).
Conversely, people were more likely to be non-responders if they were younger, had more severe depression before the start of treatment, and were taking benzodiazepine medications.
Conclusion
This study found that there were 4 unique trajectories of improvement for those with treatment-resistant depression undergoing rTMS: rapid response, no response, and then two groups in between. People were most likely to have a rapid response if they were older, had less severe depression, and were not using benzodiazepines. This knowledge may help clinicians and patients decide if rTMS is right for them, and how they might expect their symptoms to respond over several weeks of a treatment course.