Thoughts that lead to compulsive behavior in obsessive-compulsive disorder (OCD) correspond with physiological changes in the brain, according to a new case study. The article is published ahead of print in the Journal of Neurophysiology (JNP).
OCD is a mental health condition consisting of patterns of unreasonable thoughts and fears (obsessions) that trigger affected people to have repetitive thoughts and actions (compulsions). Without treatment, OCD compulsions can often interrupt a person's daily routine and may interfere with personal and professional relationships. Medications and cognitive behavioral therapy are standard treatments for OCD but in some cases are not enough to manage symptoms. Deep brain stimulation, which delivers electrical impulses to targeted areas of the brain to change its activity has become a therapeutic option for hard-to-treat OCD.
For this case study, researchers observed a 64-year-old man with OCD whose compulsions involved personal hygiene. His symptoms were not responsive to medication. Researchers explored how the brain physiologically reacts to OCD compulsions by performing deep brain stimulation and provoking compulsive behavior while the man was awake during surgery. The research team recorded from and stimulated a region of the brain called the nucleus accumbens-;a collection of nerve cells (neurons) that play an important role in the brain's reward circuitry.
The researchers designed a provocation test based on the man's self-reported obsession with cleanliness. They placed a microelectrode in two different sites close to the nucleus accumbens. The researchers gave the man a toothbrush and asked him to "imagine brushing your teeth with this dirty toothbrush." One site showed an increase in neuronal activity during the provocation while the other site showed a relative decrease. This could be due to the different types of neurons in the two sites and their different reactions to the verbal trigger. However, the broader "finding that provocation of the patient's contamination obsession induced physiological changes in [the nucleus accumbens] is an initial step forward to better understand how obsessions are processed in the human brain," the researchers wrote.