Making sure a stovetop isn’t left on or readjusting an askew picture frame is often a natural response when something feels off. Yet, for over two million Americans living with obsessive-compulsive disorder (OCD), this nagging, unsettling feeling is a constant, debilitating presence marked by obsessions, persistent distressing thoughts, and compulsions, which result in repetitive behaviors people feel driven to perform.
Cognitive behavioral therapy and antidepressants can mellow out the obsessions and compulsions that people with OCD experience, but about one-third of those living with OCD don’t see improvement with either therapeutic treatment or medication. These cases are called treatment-resistant OCD, and for these people, there usually isn’t a whole lot that can be done outside of these standard (and unfortunately ineffective) remedies. But a new emerging treatment may provide some much-needed relief. Known as “deep brain stimulation,” this therapy delivers jolts of electricity to the brain in the hopes of fading those persistent, nagging thoughts into a distant memory.
In a study published earlier this month in the journal Neuron, researchers at the University of Pennsylvania used a type of brain stimulation called “responsive deep brain stimulation” to treat a 34-year-old woman with treatment-resistant OCD. Using a brain implant surgically placed to treat her epilepsy, the researchers taught the device to recognize a unique pattern of abnormal brain activity — a potential neural biomarker of OCD — and stimulate it any time it appeared. Within months, the woman’s severe obsessions and compulsions were significantly reduced. Two years after her first treatment, the researchers say her disorder no longer eats up hours of her day.
“This study is a proof-of-principle that we’re very close to finding a marker of OCD that seems to go up and down with effective deep brain stimulation,” Martijn Figee, director of the Mount Sinai Interventional Psychiatry Program, who was not involved in the study, tells Inverse.
Resetting the brain
Since the mid-1980s, deep brain stimulation has been used to treat movement disorders like Parkinson’s disease or severe tremors and, in more recent years, Alzheimer’s disease, severe depression, binge eating, and now treatment-resistant OCD have also seen positive results.
About half of people with treatment-resistant OCD who try deep brain stimulation get much better, but the results aren’t consistent. Much of that has to do with the fact that we don’t fully understand how deep brain stimulation works. What scientists do know is that delivering a continuous electrical current through an electrode implanted in the brain helps reset and normalize communication between different areas involved in OCD. This incomplete understanding leads to challenges in fine-tuning deep brain stimulation in a way that’s effective for people dealing with treatment-resistant OCD.
“We know that when we deliver a therapy continuously, the brain can sort of develop a tolerance to it, and that needs to be changed over time, complicating the therapy,” Casey Halpern, an associate professor of neurosurgery at the University of Pennsylvania who led the study, tells Inverse.
This is where the “responsive” piece of the deep brain stimulation puzzle fits in. Instead of sending electrical signals continuously, responsive deep brain stimulation only stimulates the brain when it picks up certain brain activity. Think of it like a smart thermostat that turns on the heat only when the temperature drops too low. This method of adjusting to the person’s brain activity has been tried before with certain types of epilepsy and depression, so scientists hoped people with treatment-resistant OCD would benefit as well.
A smarter deep brain stimulator
For this new study, Halpern and his team worked with a 34-year-old woman with a history of OCD so severe she couldn’t eat around other people out of fear her own food would get contaminated (seafood was one major trigger). She would wash her hands so much to the point of bleeding, and she couldn’t leave her home or go to bed without checking all the doors and windows. The woman’s OCD took up eight hours of her day, and she was unable to live independently. And like other treatment-resistant OCD cases, therapy and medications didn’t seem to help at all.
In 2019, she had a neurostimulation device called a NeuroPace RNS System implanted on top of her skull with electrodes leading into her brain to manage her seizures. After getting the seizures under control, Halpern and his team set to work finding a particular brain signal they could train the implant to recognize. They recorded brain data as the woman went about her day-to-day tasks and in the lab as she interacted, in real life and in virtual reality, with objects meant to provoke her OCD.
Previous studies with deep brain stimulation and people with OCD found a low-frequency brainwave appearing in the basal ganglia — an area of the brain involved in coordinating movement, cognition, and emotion often targeted by stimulation therapies — whenever someone engaged with their obsessions or compulsions.
Halpern and his colleagues came across the same low-frequency electrical activity with the person they were treating for OCD. Specifically, they identified a brain circuit involving the nucleus accumbens, which is part of the basal ganglia associated with motivation and action, and the ventral pallidum, also located in the basal ganglia and is a central hub in the brain’s reward circuits. The researchers called these two regions the NAc-VeP circuit.
After the first day of treatment targeting this circuit whenever it went haywire, Halpern says her patient saw marked improvement in several OCD tendencies, including her urge to check windows and doors at night.
After 24 weeks, according to the study, her patient with OCD reported a significant drop in her obsessive thoughts and related compulsive actions. After two and a half years, her life had completely transformed: her daily rituals downsized from eight hours to just 30 minutes, and she felt comfortable around previously triggering situations (like being in the presence of seafood). Another big bonus? She no longer had to live with her parents and was getting to work on time.
“What’s particularly exciting is that signal, that biomarker we discovered and reported on, it actually seems to be going away… [suggesting] there’s plasticity in the brain,” says Halpern. “We can actually restore normal to this part of the brain, and that could lead to long-lasting effects that might not need treatment one day.”
A glimmer of hope
While the results are promising, Halpern stresses this is only one case study. Further, the person had epilepsy in addition to OCD, so her results may not necessarily mean others will experience the same success. The biomarker — the unique pattern of abnormal brain activity — might also differ across people with OCD, so testing the efficacy of this stimulation therapy for other individuals will require further study.
“To the best of our ability, we tried to demonstrate that this intervention was in no way impacted by her epilepsy. Of course, because she has epilepsy, it’s really hard to prove that,” says Halpern. “We are very convinced… for example, there was no real overlap between stimulating for her epilepsy and stimulating for her OCD [since] we stimulated for her epilepsy for at least six months before the treatment started.”
Sameer Sheth, a neurosurgeon at Baylor College of Medicine who studies deep brain stimulation but was not involved in the study, tells Inverse it also remains to be seen how responsive deep brain stimulation stacks up against conventional methods since the study participant’s outcomes were on par with what you would expect with continuous deep brain stimulation.
“What [this study] has not shown is what if you just delivered intermittent stimulation, just delivered stimulation throughout the day but not continuously but, say, every one hour? Would you have just as good a result? I bet you would.” says Sheth. “The patient’s outcome [in this study] was good, but we usually see better outcomes. We usually see patients getting better faster within three to six months [versus two years].”
Figee of Mount Sinai acknowledges while the success is modest, the benefit of this proof-of-concept is having that neural biomarker as a starting point to identify a functional change within the brain that corresponds with a disease.
“Because our patients are so severely ill, whatever you’re picking up is probably related to their illness and is probably meaningful, not just for deep brain stimulation, but just for our understanding of the illness and potential future treatments,” he says.
Finding the neural biomarker of just one person could lead to one day bringing meaningful relief to millions.
