Can Deep Brain Stimulation Help Treat Severe OCD?

What you need to know

• Deep brain stimulation (DBS) is an experimental treatment being studied for severe, treatment-resistant obsessive-compulsive disorder (OCD).
• This case study describes how adjusting DBS settings resolved side effects while maintaining benefits for OCD symptoms in one patient.
• The findings suggest stimulating an area called the mesencephalic ventral tegmentum may be effective for OCD, rather than directly stimulating a nearby brain region called the subthalamic nucleus.
• More research is needed to determine the optimal brain targets and stimulation settings for DBS in OCD.

Understanding OCD and deep brain stimulation

Obsessive-compulsive disorder (OCD) is a mental health condition characterized by intrusive, distressing thoughts (obsessions) and repetitive behaviors or mental acts (compulsions) that a person feels driven to perform. For some people with severe OCD that has not responded to standard treatments like medication and psychotherapy, deep brain stimulation (DBS) is being studied as an experimental treatment option.

DBS involves surgically implanting thin wire electrodes into specific areas of the brain. These electrodes are connected to a device implanted under the skin of the chest that sends electrical pulses to stimulate those brain regions. By modulating the activity of brain circuits involved in OCD, DBS aims to reduce symptoms.

However, researchers are still working to determine the optimal brain targets and stimulation settings for DBS in OCD. This case study provides some intriguing clues about which brain areas may be most important to stimulate - and which to avoid - to maximize benefits while minimizing side effects.

A patient’s journey with DBS for severe OCD

The study describes the case of a 52-year-old woman with severe, treatment-resistant OCD. She had suffered from obsessive fears of contamination and compulsive cleaning behaviors since her teenage years. These symptoms severely limited her life, causing her to live in isolation with a very restricted range of activities. Multiple medication trials and psychotherapy attempts over 20 years had not provided sufficient relief.

After careful evaluation, she was identified as a candidate for DBS treatment. She underwent surgery to have DBS electrodes implanted bilaterally (on both sides of the brain) in an area called the superolateral branch of the medial forebrain bundle (slMFB). This is a bundle of nerve fibers that connects several brain regions involved in reward and motivation.

Initial benefits and emergence of side effects

When DBS stimulation was initiated after surgery, the patient experienced rapid improvement in her OCD symptoms. Her score on a standard OCD symptom rating scale (the Yale-Brown Obsessive Compulsive Scale or Y-BOCS) dropped from 31 before surgery to 16 just two days after stimulation began. Over the next several months, her symptoms continued to improve, with her Y-BOCS score reaching as low as 7.

However, as stimulation settings were adjusted over time to maintain effectiveness, the patient began experiencing some side effects. About 16 months after starting DBS, she developed some fine motor disturbances affecting her right side. By 32 months, she was experiencing troublesome involuntary movements (dyskinesias) in her right leg and foot.

These movement-related side effects were likely caused by the electrical stimulation affecting an adjacent brain structure called the anteromedial subthalamic nucleus (amSTN). The subthalamic nucleus plays an important role in motor control, so stimulating it can sometimes produce unwanted movement effects.

Adjusting stimulation to resolve side effects

To address these side effects, the researchers used advanced brain imaging and stimulation modeling techniques to visualize how the electrical stimulation was affecting different brain areas. They then adjusted the stimulation settings to steer the electrical field away from the subthalamic nucleus and more specifically target the mesencephalic ventral tegmentum (MVT).

The MVT is an area that contains the ventral tegmental area, a key node in the brain’s reward and motivation circuitry. By focusing stimulation on this region, they hoped to maintain the anti-OCD effects while avoiding motor side effects.

Remarkably, this adjustment led to rapid improvement. Within hours, the patient’s dyskinesias resolved completely. Her previous fine motor disturbances also disappeared. Importantly, the benefits for her OCD symptoms were maintained even with this change in stimulation target.

Implications for understanding OCD circuits

This case provides some intriguing insights into the brain circuitry involved in OCD and potential DBS treatments:

1. It suggests that stimulation of the MVT area may be sufficient to produce anti-OCD effects, without needing to directly stimulate the nearby subthalamic nucleus.

2. The rapid resolution of side effects when stimulation was shifted away from the subthalamic nucleus, while maintaining OCD symptom improvement, indicates these effects may involve separate neural pathways.

3. It raises the possibility that previous studies showing benefits of stimulating the anteromedial subthalamic nucleus for OCD may have actually been achieving their effects by current spread to the adjacent MVT region.

Limitations and future directions

While this single case report provides valuable insights, it’s important to note its limitations. Findings from one patient may not generalize to all people with OCD. Additionally, longer-term follow-up would be helpful to ensure the benefits are sustained over time.

Larger, controlled studies are needed to more definitively determine the optimal brain targets and stimulation parameters for DBS in OCD. Future research should directly compare stimulation of different targets like the MVT and subthalamic nucleus.

It will also be important to better understand the specific neural circuits and mechanisms by which DBS in these regions affects OCD symptoms. This could potentially allow for even more precise targeting of stimulation in the future.

Conclusions

• Adjusting deep brain stimulation settings resolved movement-related side effects while maintaining benefits for OCD symptoms in this patient.
• Stimulating the mesencephalic ventral tegmentum, rather than the nearby subthalamic nucleus, may be sufficient to improve OCD.
• This case provides clues about the brain circuitry involved in OCD, but more research is needed to optimize DBS treatments.
• DBS remains an experimental treatment for severe OCD, but continued refinements may help improve its effectiveness and tolerability.

While DBS is still considered an experimental treatment for OCD, case studies like this one are helping researchers iteratively improve the technique. For patients with severe, treatment-resistant OCD, continued research into DBS and other novel interventions offers hope for expanding the available treatment options in the future.