Can Transcranial Magnetic Stimulation Effectively Treat Obsessive-Compulsive Disorder?

What you need to know

• Transcranial magnetic stimulation (TMS) appears to be an effective treatment option for obsessive-compulsive disorder (OCD), particularly when applied to certain brain regions.
• Both low-frequency and high-frequency TMS stimulation can reduce OCD symptoms.
• TMS is generally safe, with only mild side effects reported in most studies.
• More research is needed to determine the optimal TMS parameters and identify which patients are most likely to benefit.

What is transcranial magnetic stimulation?

Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique that uses magnetic fields to activate specific areas of the brain. During a TMS session, an electromagnetic coil is placed against the scalp. The coil generates magnetic pulses that pass through the skull and induce small electrical currents in targeted brain regions, temporarily altering brain activity.

TMS can be applied in different ways:

• Repetitive TMS (rTMS): Delivers repeated magnetic pulses to a specific brain area. Low-frequency rTMS (≤1 Hz) is thought to decrease brain activity in the targeted region, while high-frequency rTMS (≥5 Hz) is believed to increase activity.

• Deep TMS (dTMS): Uses a specialized coil that can stimulate deeper brain structures compared to standard TMS coils.

• Theta burst stimulation (TBS): Delivers bursts of high-frequency pulses in a specific pattern. Continuous TBS is thought to inhibit brain activity, while intermittent TBS may increase activity.

How might TMS help with OCD?

Obsessive-compulsive disorder (OCD) is a mental health condition characterized by recurring, intrusive thoughts (obsessions) and repetitive behaviors or mental acts (compulsions) that a person feels driven to perform. OCD affects about 2-3% of the population and can significantly impair daily functioning and quality of life.

Research suggests that OCD involves abnormal activity in certain brain circuits, particularly the cortico-striato-thalamo-cortical (CSTC) circuit. This circuit includes several brain regions that are involved in cognitive and emotional processing, movement control, and habit formation. In people with OCD, parts of this circuit may be overactive.

TMS aims to modulate activity in these brain circuits. By applying magnetic stimulation to specific brain areas involved in OCD, TMS may help normalize brain activity and reduce symptoms. The most commonly targeted brain regions for OCD treatment with TMS include:

• Dorsolateral prefrontal cortex (DLPFC): Involved in executive functions like planning and decision-making
• Supplementary motor area (SMA): Important for movement planning and control
• Orbitofrontal cortex (OFC): Plays a role in emotional processing and decision-making
• Medial prefrontal cortex (mPFC): Involved in self-referential thinking and emotion regulation
• Anterior cingulate cortex (ACC): Important for error detection and conflict monitoring

What does the research show?

This review examined 12 meta-analyses on the use of TMS for OCD, which collectively included data from hundreds of patients across many individual studies. Here are the key findings:

Effectiveness

• Most meta-analyses found that TMS significantly reduced OCD symptoms compared to sham (placebo) treatment.
• The average effect sizes reported were in the moderate to large range, suggesting TMS has a meaningful clinical impact for many patients.
• Stimulation of the dorsolateral prefrontal cortex (DLPFC) and supplementary motor area (SMA) showed the most consistent benefits across studies.
• Both low-frequency and high-frequency TMS protocols appeared effective.

Safety

• TMS was generally well-tolerated with only mild side effects reported in most studies.
• The most common side effects were headache, scalp discomfort, and neck pain.
• Dropout rates in TMS studies were low, suggesting most patients found the treatment acceptable.

Factors affecting treatment response

• Patients with less severe or treatment-resistant OCD may respond better to TMS.
• The total number of TMS sessions and pulses delivered may impact effectiveness.
• Combining TMS with exposure to OCD triggers may enhance its effects in some cases.

Limitations of the research

• There was significant variation in results across studies, likely due to differences in TMS protocols, patient characteristics, and study designs.
• Many studies had small sample sizes.
• Publication bias may have inflated the reported effectiveness of TMS in some meta-analyses.

What are the implications for patients?

For patients with OCD who have not responded well to standard treatments like medication and psychotherapy, TMS may be a promising option to consider. The research suggests TMS can provide meaningful symptom relief for many patients while being generally safe and well-tolerated.

However, it’s important to note that TMS is not a cure for OCD and does not work for everyone. The optimal treatment parameters (e.g. brain target, stimulation frequency, number of sessions) are still being determined. Patients should discuss the potential benefits and limitations of TMS with their healthcare provider to determine if it’s an appropriate treatment option for their individual situation.

Some practical considerations for patients interested in TMS:

• TMS typically involves multiple treatment sessions (often daily) over several weeks.
• It’s usually used as an add-on to ongoing medication and/or psychotherapy rather than a standalone treatment.
• TMS is not widely available everywhere and may not be covered by all insurance plans.
• The effects of TMS may be temporary, so ongoing or maintenance treatment may be needed.

Conclusions

• Transcranial magnetic stimulation appears to be a promising treatment option for obsessive-compulsive disorder, with most studies showing it can significantly reduce symptoms.
• TMS is generally safe and well-tolerated, with only mild side effects in most cases.
• More research is needed to determine the optimal TMS parameters and identify which patients are most likely to benefit.
• For OCD patients who haven’t responded well to standard treatments, TMS may be worth discussing with a healthcare provider as a potential treatment option.