OCD and compulsions: how deep brain stimulation can help

OCD, addiction, and eating disorders share a common denominator: the urge to act despite the risk. Dr. Casey Halpern, a neurosurgeon at the University of Pennsylvania specializing in deep brain stimulation, dedicates his research to understanding and modulating those circuits from inside the brain.

What is deep brain stimulation and how does it work

Deep brain stimulation (DBS) involves implanting a very thin electrode into a specific region of the brain and delivering continuous electrical stimulation through it. While it has been used for decades to treat tremor in Parkinson's disease, the same techniques are being adapted to treat OCD, eating disorders, and addiction.

The nucleus accumbens and reward circuits

The nucleus accumbens is part of the brain's reward circuits. When disrupted, it regulates compulsive behavior: the person seeks rewards despite risk or harm, as happens in drug addiction, OCD, or binge eating. Surgically modulating this area is one of the central targets of Dr. Halpern's team.

Treatment options for severe OCD

OCD is first treated with SSRIs and tricyclic antidepressants. Cognitive behavioral therapy with exposure and response prevention techniques is probably the most effective intervention for patients who respond to it. However, approximately 30% of patients do not respond to any of these treatments and continue to suffer from severe OCD.

When DBS comes into play

For those refractory patients, DBS can offer relief when everything else has failed. Dr. Halpern notes a response rate of approximately 50%, though even responders typically retain some symptoms. The intervention is not curative, but it can significantly reduce the burden of the disease.

Capsulotomy is also used, an ablation that destroys a small area of brain tissue involved in OCD. MRI-guided focused ultrasound makes it possible to perform that ablation without opening the skull, though the optimal target is still under investigation.

Identifying brain signals specific to symptoms

One of the most important advances in this field is the ability to identify cells whose electrical activity correlates with symptoms. In the case of Parkinsonian tremor, surgeons listen in real time to the signal of tremoring cells and confirm electrode placement. Dr. Halpern aims to do something equivalent for obsessions and binge-eating urges.

The eating disorder experiment

In hospitalized patients with implanted devices, the team provokes the emotional state preceding a binge and simultaneously records the electrode's brain signal, the patient's video, and eye tracking. The goal is to detect an electrographic craving signal that the device can autonomously identify and respond to with stimulation before the patient acts.

Non-invasive techniques: TMS and ultrasound

Transcranial magnetic stimulation (TMS) is FDA-approved for depression, OCD, and nicotine addiction. Its limitation is spatial precision and duration of effect. Dr. Halpern views it as a selection tool: if a patient temporarily responds to TMS, they are an appropriate candidate for a DBS study.

MRI-guided focused ultrasound is already approved for tremor and can perform non-invasive brain ablations. Research is exploring its modulatory use and the possibility of opening the blood-brain barrier to deliver drugs to specific brain areas.

Artificial intelligence and early detection

Dr. Halpern is optimistic about the role of machine learning in anticipating compulsive episodes before patients are aware of them. Devices that integrate voice patterns, breathing, and sleep can detect the state preceding a depressive or impulsive episode and alert the patient in advance. Extreme impulsivity, in its most dangerous form such as suicidal ideation, is also a central focus of the lab.

Conclusion

DBS is not the first-line treatment for OCD or eating disorders, but it represents real hope for patients who have exhausted conventional options. Dr. Halpern's research on craving and compulsion circuits is paving the way for more precise treatments, both invasive and non-invasive, for some of the most prevalent conditions of our time.