Compulsive behaviors are prevalent worldwide, with millions of people coping with them even without a formal diagnosis. Despite how common these behaviors are, the mechanisms that drive them are still poorly understood. But a new study out of Boston University has taken the first step toward better understanding the drivers of obsessive-compulsive behaviors — and has perhaps uncovered a new drug-free method of treating them.

The study, published Jan. 18 in Nature Medicine, found that using a method of high-frequency neuromodulation, a type of painless electrical stimulation, led to a marked improvement in the reduction of obsessive-compulsive behavior. 

Researchers conducted an experiment using 60 participants who had shown obsessive-compulsive behavior but did not have a formal OCD diagnosis. The participants were otherwise healthy individuals who “exhibited obsessive-compulsive behaviors in a wide range,” according to Shrey Grover, a doctoral student in the department of psychological and brain sciences at Boston University and an author of the study.

The researchers focused on a kind of technology called non-invasive neuromodulation, which enables a clinician to modulate or change brain activity patterns without having to access the brain directly. A subset of techniques within this family of technologies is called trans-cranial alternating current stimulation, which the researchers utilized for this study, and involves applying an alternating current to the scalp in such a manner that the current propagates to a certain brain region and modifies the activity of that region.

Each participant received a personalized non-invasive, painless trans-cranial neuromodulation treatment for 30 minutes a day for five consecutive days, and had their behavior tracked for three months after the treatment. The study found that obsessive-compulsive behaviors were reduced by about 28% and that the reduction remained consistent for three months following the treatment.

The researchers were impressed by “how robust the effects were” of this initial study, Grover said.

“This definitely is something which is quite motivating for us, because it suggests that there may be some potential in this form of intervention,” Grover added. “This may be something that can be extended to perhaps clinical populations.”

The study focused on obsessive-compulsive behaviors due to how they are linked to the reward center of the brain, Grover said. It’s an area of the brain that has certain high-frequency rhythms and activities that the researchers hypothesize might be linked to the development of obsessive-compulsive behaviors, in addition to being linked to reward-based learning. The treatment aimed to modulate these rhythms.

The study highlighted how this sort of personalized neuromodulation on a repeated schedule can benefit patients, Grover said, and that the combination of personalization and repetition is something that could be potentially adapted into other kinds of non-invasive neuromodulation protocols.

Grover noted that the overall field of non-invasive neuromodulation is still in its infancy, meaning that there’s still significant work to be done to understand the mechanisms that make it work, in addition to how well it can work as a treatment.

“There are lots of knowledge gaps with regards to what makes this technique effective and how sustainable it is,” Grover said. “Eventually, if we would like an intervention to be adapted into a clinical setting, we want the effects to be as strong and as sustainable as possible.”

Future studies may examine how well the non-invasive neuromodulation techniques fare against other existing treatments for OCD, such as medications, psychotherapy, deep brain stimulation, and surgical treatments. Additionally, further studies may examine how well it works as a treatment for other kinds of compulsive disorders, such as substance use disorders, gambling disorders, and compulsive eating disorders, Grover said.

But a next immediate step for this team will be seeking to better understand the mechanism by which non-invasive neuromodulation functions for patients.

“We’ve been able to see that if people have this intervention, the obsessive-compulsive behavior reduces. But how exactly that happens, and what’s exactly happening in the brain — that’s a question that we haven’t been able to conclusively answer,” Grover said. “We have speculations about it, which we discuss in our paper, but we haven’t been able to conclusively answer it yet. We’re looking at additional experiments which would give us a better sense of how exactly neuromodulation impacts obsessive-compulsive behavior.”

The article, “High-frequency neuromodulation improves obsessive–compulsive behavior,” was published on Jan. 18 in Nature Medicine. It was authored by Shrey Grover, John Nguyen, Vighnesh Viswanathan and Robert Reinhart, all of Boston University.