By Jeremy Schwab
Millions of Americans, and possibly over a billion people worldwide, suffer from some level of obsessive-compulsive behavior. These behaviors can include obsessive cleaning, eating, shopping, picking skin, itching, hoarding, gambling, or counting and organizing objects. A person could have one or more of these behaviors. Those with the most acute symptoms (an estimated two-to-three percent of the population) are diagnosed with obsessive compulsive disorder (OCD).
Unfortunately for those suffering from obsessions or compulsions, current pharmaceutical and surgical interventions have not been able to dramatically reduce these behaviors. But in January BU Arts & Sciences researchers published a study in Nature Medicine showing that applying onto the scalp very weak electrical currents attuned to a person’s specific brain wave pattern can significantly reduce obsessive-compulsive behaviors. These findings by Assistant Professor of Psychological & Brain Sciences Robert Reinhart and graduate student Shrey Grover pave the way for further studies and eventually clinical applications that could improve the lives of millions.
The findings help confirm what many neuroscientists had begun to suspect: that the same neural mechanisms underlying the processing of rewards from one’s environment also underlie obsessive-compulsive behaviors. Previous research suggested that a certain type of electrical pulses among neurons, called high-frequency rhythms or beta-gamma rhythms, helps us process and learn from rewarding feedback—specifically in the orbital frontal cortex. When we receive rewarding feedback for an action, such as praise or a prize, we exhibit high levels of these beta-gamma rhythms. These brain rhythms, it is thought, help us learn from the rewarding feedback, making us more likely to repeat that action.
“Obsessive-compulsive behaviors are thought to arise from abnormalities in how we process information about rewards and how such information leads us to form habits,” explains Grover.
In envisioning the study, Reinhart hypothesized that applying individually-attuned transcranial alternating current stimulation to the scalp for 30 minutes each day for five straight days would change study participants’ beta-gamma rhythms in a way that would help the orbital frontal cortex maintain an effective rhythm and better communicate with other areas of the brain involved in reward learning and behavior.
To test this hypothesis, the researchers used a video game in which participants learned to make choices that lead to rewarding outcomes and avoid those which lead to punishing outcomes. Using this video game, they identified the beta-gamma frequency in hertz at which this part of the brain fired when a participant won money in the game. Then, they administered the electrical stimulation at that frequency for five days. The results were clear: the 64 volunteers reported an average decline of nearly 30 percent in their obsessive-compulsive tendencies, and this decline either held steady or increased over the course of three months (the length of the study). None of the volunteers had OCD, but all reported varying levels of obsessive-compulsive behavior. Furthermore, those with the highest levels of these behaviors saw the greatest improvement.
A New Way to Access the Brain’s Secrets
The study has generated a lot of interest. In an accompanying commentary, fellow researchers studying obsessive-compulsive behaviors have recognized the clinical implications of this work while highlighting opportunities for future research. A February 24 New York Times article (A Better Way to Zap Our Brains) featuring Reinhart and Grover’s research noted that the techniques they are helping pioneer are opening up new possibilities for both understanding and modifying the human brain.
“This new form of frequency-personalized stimulation may open an entirely new realm of brain science methods that can help us better understand human learning and cognition and its breakdown in mental illnesses,” Reinhart told arts&sciences. Both invasive and non-invasive personalized brain stimulation techniques are already being used to test potential treatments for depression and other conditions.
But the Arts & Sciences researchers don’t want to get ahead of themselves. “The field of non-invasive neuromodulation is in its infancy,” cautions Grover, who works in the Cognitive and Clinical Neuroscience Laboratory, which Reinhart directs. “Studies are being done to see how effective it is. We would need a lot more work with different clinical populations and larger sample sizes to confirm just how reliable this intervention is. We want to make sure that any treatment we come up with produces results that are both robust and sustainable.”
The potential for noninvasive neuromodulation in improving symptoms is being studied for many mental illnesses and conditions. Besides obsessive-compulsive behavior, these techniques are being examined as therapeutic tools for major depressive disorder, schizophrenia, Parkinson’s disease, anxiety disorders as well as age-related cognitive decline. In the future, brain stimulation technology can be potentially paired with existing medicinal and therapeutic treatments to promote healthy mental function.