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Personalized brain stimulation could relieve a common mental health disorder

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Obsessive compulsive disorder (OCD) is often dismissed as no more than a quirky handwashing obsession, or preoccupation with checking locked doors. But in reality, the mental health condition seriously affects almost a billion people's quality of life every year. Yet effective treatments are limited, and the most common therapy — cognitive behavioral therapy — doesn't work for as many as 40 percent of people with the condition, according to one scientific review.

A new approach proposes taking a different tack: Bringing the treatment for OCD directly to the brain. In a new paper, a team of neuroscientists show how directly stimulating the brain's reward processing center could help curb obsessive compulsive behaviors.

Taking a personalized approach, the researchers show just 30 minutes of stimulation for five days could have lasting effects up to 3 months after treatment. In some study participants, the approach reduced their OCD-related behaviors by 30 percent.

Why it matters — OCD can manifest in many forms, so a personalized treatment has its advantages. But the authors go further — they suggest their personal brain stimulation approach could be used to treat other forms of compulsive behaviors, including overeating, shopping, or gambling.

The findings were published Monday in the journal Nature Medicine.

Here's the background — The brain-stimulation approach used in this study is called transcranial Alternating Current Stimulation (tACS). It works by amplifying the brain's own oscillations to increase certain brain functions. Essentially, it looks like an electrode patch applied to the skull — much like an electrode patch might be applied to your back in order to deliver low-intensity electrical stimulation in physical therapy

By tuning in to the specific beta-gamma frequencies coming from the reward center of the brain, the research team set out to see how amplifying these brainwaves with tACS may improve OCD symptoms.

The research team recruited 124 people with non-clinical levels of OCD and divided them up into control and test groups to see how effective tACS might be in curbing their compulsive behaviors.

What they did — Once divided into the trial groups, the researchers used a common self-reporting metric for OCD, the Obsessive–Compulsive Inventory-Revised (OCI-R), to establish baseline levels of OCD for each participant.

In the first part of the experiment, researchers observed how beta-gamma stimulation via tACS would effect reward or punishment-guided learning when playing a gambling-like game. In separate iterations of this game, randomly selected icons were either associated with an 80 percent chance of reward ($10) or an 80 percent chance of losing $10.

For the second part of the experiment, participants in the experimental groups received tACS for 30-minutes a day over the course of five days to see how it would effect their OCD symptoms and OCI-R score in the following three months

What they discovered — From the first experiment, the team did observe a causal relationship between reward-guided learning and tACS stimulation, namely that stimulation during these trials resulted in more exploratory behavior by participants. Previous research has linked lower levels of exploration during reward-based learning to compulsive disorders, such as alcohol abuse disorder — so more exploration may improve such behavior.

A 3D model of location and intensity of beta-gamma stimulation on the brain during trials.Grover et al. / Nature Medicine

As for the second experiment, the results were even more encouraging. Following participants for three months after their initial 5-day stimulation, the researchers found significant decreases in OCD behavior and up to a 28 percent decrease of OCI-R levels months after treatment. Interestingly, the researchers also note participants who felt the greatest effects had the highest baseline OCI-R levels — meaning that those who show the greatest OCD-related behaviors may benefit most from a treatment like this.

What's next — Right now, the researcher write their findings are at best causal evidence of this treatment's effectiveness, but they hope that future research will further confirm their initial findings with additional neuroimaging.

They also note that while their current research focuses on non-clinical levels of OCD, they believe the results could be similarly replicated in a study group with more severe OCD.

The Inverse Analysis — While the current aim of this research is to treat a disorder that diminishes the quality of life of millions, the researchers also suggest this technique could be used to treat other, more common forms of compulsions as well, including overeating and shopping.

The idea of applying this research beyond the clinic raises uncomfortable questions about what else you may train the brain to do — or not do — with a little stimulation. For example, how might a technique like this be used by bosses, spouses, or even parents to train new behaviors?

Such a dystopian future is remote, but it's an ethical concern to keep in mind as research progresses.

Abstract: Nearly one billion people worldwide suffer from obsessive–compulsive behaviors, yet our mechanistic understanding of these behaviors is incomplete, and effective therapeutics are unavailable. An emerging perspective characterizes obsessive–compulsive behaviors as maladaptive habit learning, which may be associated with abnormal beta–gamma neurophysiology of the orbitofrontal–striatal circuitry during reward processing. We target the orbitofrontal cortex with alternating current, personalized to the intrinsic beta–gamma frequency of the reward network, and show rapid, reversible, frequency-specific modulation of reward- but not punishment-guided choice behavior and learning, driven by increased exploration in the setting of an actor-critic architecture. Next, we demonstrate that chronic application of the procedure over 5 days robustly attenuates obsessive–compulsive behavior in a non-clinical population for 3 months, with the largest benefits for individuals with more severe symptoms. Finally, we show that convergent mechanisms underlie modulation of reward learning and reduction of obsessive–compulsive symptoms. The results contribute to neurophysiological theories of reward, learning and obsessive–compulsive behavior, suggest a unifying functional role of rhythms in the beta–gamma range, and set the groundwork for the development of personalized circuit-based therapeutics for related disorders.
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