Can Deep Brain Stimulation in the Bed Nucleus of the Stria Terminalis Help Patients with Severe OCD?

What you need to know

• Deep brain stimulation (DBS) is a promising treatment for severe, treatment-resistant obsessive-compulsive disorder (OCD).
• This study explored stimulating a specific brain region called the bed nucleus of the stria terminalis (BST) in OCD patients.
• While group results weren’t statistically significant, some individual patients experienced benefits from BST stimulation.

Understanding OCD and Deep Brain Stimulation

Obsessive-compulsive disorder (OCD) is a challenging mental health condition that affects about 2% of the population. People with OCD experience persistent, intrusive thoughts (obsessions) and feel compelled to perform repetitive behaviors (compulsions) to alleviate their anxiety. While many patients benefit from medication or cognitive-behavioral therapy, about 10% of OCD sufferers remain severely affected despite these treatments.

For these treatment-resistant cases, deep brain stimulation (DBS) has emerged as a potential option. DBS involves surgically implanting electrodes in specific areas of the brain and delivering electrical pulses to modulate brain activity. It’s like a pacemaker for the brain. While DBS for OCD is still considered an experimental treatment, early results have been encouraging for some patients.

The Bed Nucleus of the Stria Terminalis: A New Target?

This study focused on a specific brain region called the bed nucleus of the stria terminalis (BST). The BST is part of the brain’s extended amygdala system, which plays a crucial role in processing emotions, particularly fear and anxiety. Previous research in both animals and humans has suggested that the BST might be involved in anxiety disorders and OCD.

The researchers wanted to know if stimulating the BST could help alleviate OCD symptoms. They were also curious about whether stimulating just one side of the brain (unilateral stimulation) might be effective, as most DBS treatments stimulate both sides (bilateral stimulation).

Study Design: Putting BST Stimulation to the Test

The study involved nine patients with severe OCD who had already received DBS treatment. These patients underwent a carefully designed experiment:

1. Patients were shown a series of images, some neutral and some that triggered their OCD symptoms.
2. They rated their levels of anxiety, depression, obsessions, compulsions, avoidance, and overall well-being after viewing these images.
3. This process was repeated under different stimulation conditions:
   • Their usual stimulation settings
   • No stimulation
   • Left BST stimulation only
   • Right BST stimulation only
   • Bilateral BST stimulation

The patients and the psychiatrist evaluating them didn’t know which stimulation condition was being used during each trial, making this a “double-blind” study.

Results: A Mixed Picture

The overall results of the study were not as clear-cut as the researchers might have hoped:

1. On average, bilateral BST stimulation seemed to perform slightly better than no stimulation, but the difference wasn’t statistically significant for the group as a whole.

2. There was no evidence that stimulating just one side of the BST was more effective than bilateral stimulation.

3. When the researchers looked more closely at individual patients, they found that some did experience noticeable benefits from BST stimulation. This was particularly true for patients who still had moderate to severe OCD symptoms with their usual stimulation settings.

4. Two patients actually chose to switch their regular DBS settings to the BST stimulation used in the study because they found it more effective.

Challenges and Limitations

The study faced several challenges that may have affected the results:

1. Small sample size: With only nine patients, it’s difficult to detect subtle effects or generalize the findings to all OCD patients.

2. Variability among patients: The severity of OCD symptoms and response to treatment varied widely among the participants.

3. Experimental design: Some patients found the computer-based task itself stressful, which may have overshadowed the effects of the different stimulation conditions.

4. Side effects: Adjusting to new stimulation settings sometimes caused temporary side effects like feeling uncomfortably warm or sweaty, which may have influenced patients’ ratings.

Implications for OCD Treatment

While the study didn’t provide strong statistical evidence for the superiority of BST stimulation, it did offer some valuable insights:

1. Personalized approach: The results highlight the importance of individualized treatment. What works best can vary significantly from patient to patient.

2. New options for non-responders: For patients who haven’t achieved satisfactory results with standard DBS settings, trying BST stimulation might be worth considering.

3. Streamlining the adjustment process: Using brain anatomy to guide electrode placement and stimulation settings could potentially make it easier and faster to find effective DBS parameters for each patient.

Conclusions

• While group-level results weren’t statistically significant, some individual patients experienced meaningful benefits from BST stimulation.
• The study suggests that targeting the BST could be a viable option for DBS in treatment-resistant OCD, particularly for patients who haven’t responded well to other stimulation targets.
• More research with larger groups of patients is needed to fully understand the potential of BST stimulation for OCD treatment.

This study represents an important step in refining DBS treatment for severe OCD. By exploring new brain targets and stimulation approaches, researchers hope to improve outcomes for patients who have struggled to find relief through other treatments. While BST stimulation may not be a magic bullet for all OCD patients, it could become a valuable tool in the growing arsenal of personalized treatment options for this challenging disorder.