Authors: Kaili Liang; Hailong Li; Xuan Bu; Xue Li; Lingxiao Cao; Jing Liu; Yingxue Gao; Bin Li; Changjian Qiu; Weijie Bao; Suming Zhang; Xinyu Hu; Haoyang Xing; Qiyong Gong; Xiaoqi Huang · Research
Can Repetitive Transcranial Magnetic Stimulation Help Treat Obsessive-Compulsive Disorder?
A review of studies on using repetitive transcranial magnetic stimulation (rTMS) to treat obsessive-compulsive disorder (OCD)
Source: Liang, K., Li, H., Bu, X., Li, X., Cao, L., Liu, J., Gao, Y., Li, B., Qiu, C., Bao, W., Zhang, S., Hu, X., Xing, H., Gong, Q., & Huang, X. (2021). Efficacy and tolerability of repetitive transcranial magnetic stimulation for the treatment of obsessive-compulsive disorder in adults: a systematic review and network meta-analysis. Translational Psychiatry, 11(1), 332. https://doi.org/10.1038/s41398-021-01453-0
What you need to know
- Repetitive transcranial magnetic stimulation (rTMS) shows promise as a treatment option for obsessive-compulsive disorder (OCD)
- Low-frequency rTMS applied to the dorsolateral prefrontal cortex may be the most effective approach
- More high-quality research is still needed to confirm the benefits of rTMS for OCD
Understanding OCD and Current Treatments
Obsessive-compulsive disorder (OCD) is a mental health condition that affects 2.5-3% of people at some point in their lives. People with OCD experience persistent, intrusive thoughts (obsessions) and feel compelled to perform repetitive behaviors (compulsions) to relieve anxiety. For example, someone might have obsessive thoughts about germs and feel compelled to wash their hands repeatedly.
The main treatments for OCD are:
- Cognitive-behavioral therapy (CBT) - A type of talk therapy that helps people change thought patterns and behaviors
- Medications like selective serotonin reuptake inhibitors (SSRIs)
- A combination of therapy and medication
However, these standard treatments don’t work well for about half of people with OCD. This has led researchers to explore new options, including brain stimulation techniques like repetitive transcranial magnetic stimulation (rTMS).
How rTMS Works
Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive technique that uses magnetic fields to stimulate specific areas of the brain. Here’s how it works:
- A magnetic coil is placed against the scalp
- The coil generates magnetic pulses that pass through the skull
- These pulses create electrical currents in targeted brain regions
- The currents activate neurons (brain cells), altering brain activity
Researchers believe OCD involves abnormal activity in brain circuits connecting areas like the prefrontal cortex, striatum, and thalamus. By modulating activity in these circuits, rTMS may help reduce OCD symptoms.
The effects of rTMS can vary based on the stimulation frequency:
- Low frequency (≤1 Hz): Tends to decrease brain activity in the targeted area
- High frequency (≥5 Hz): Tends to increase brain activity in the targeted area
Reviewing the Evidence on rTMS for OCD
To evaluate how well rTMS works for OCD, researchers conducted a network meta-analysis - a technique that allows comparison of multiple treatments, even if they haven’t been directly compared in studies. They analyzed 22 randomized controlled trials including 698 total participants.
The analysis looked at different rTMS approaches, varying in:
- Target brain area (e.g. dorsolateral prefrontal cortex, supplementary motor area)
- Stimulation frequency (low vs high)
The main outcomes measured were:
- Efficacy: Change in OCD symptom severity (measured by the Yale-Brown Obsessive Compulsive Scale)
- Tolerability: Rate of patients dropping out due to side effects
Key Findings on Efficacy
Three rTMS approaches showed significant benefits compared to sham (placebo) treatment:
- Low-frequency stimulation of the dorsolateral prefrontal cortex
- Low-frequency stimulation of the supplementary motor area
- High-frequency stimulation of the dorsolateral prefrontal cortex
Of these, low-frequency stimulation of the dorsolateral prefrontal cortex appeared to be the most effective based on rankings. However, the overall quality of evidence was considered very low, meaning more research is needed to be confident in these results.
Findings on Tolerability
All rTMS approaches appeared to be similarly tolerable to sham treatment, with no significant differences in dropout rates due to side effects. This suggests rTMS is generally well-tolerated.
Factors Affecting Treatment Response
The analysis found some factors that may influence how well rTMS works for OCD:
- Age: Low-frequency dorsolateral prefrontal cortex stimulation was more effective in people under 35
- Sex: It was more effective in studies with fewer female participants
- Treatment resistance: It worked better in people who had not failed previous OCD treatments
- Brain side: Right-sided stimulation appeared more effective than left-sided
However, these findings are preliminary and need further study.
Limitations and Future Research Needs
While this analysis provides useful insights, there are some important limitations:
- The overall quality of evidence was low, mainly due to small sample sizes and potential biases in study designs
- Most studies only looked at short-term effects, so long-term benefits are unclear
- More research is needed on factors like OCD subtype that could affect treatment response
To strengthen the evidence, researchers recommend:
- Larger, high-quality clinical trials
- Studies directly comparing different rTMS approaches
- Longer follow-up periods to assess lasting effects
- More research on predictors of treatment response
Conclusions
- Low-frequency rTMS of the dorsolateral prefrontal cortex shows the most promise for treating OCD symptoms
- rTMS appears to be well-tolerated with few side effects
- More high-quality research is still needed to confirm the benefits and optimize treatment approaches