The study investigates how individuals with OCD exhibit abnormal brain activity when processing uncertainty in the dorsal anterior cingulate cortex.
Obsessive-compulsive disorder (OCD), a neurological condition, is characterized by compulsive repeating behaviors like cleaning and checking even when there is clear-cut objective evidence that the environment is tidy, clean, and appropriate.
The condition, though occasionally misdiagnosed as a disorder of “fussiness,” is really brought on by a difficulty processing ambiguity. But the neural underpinnings of that anomalous processing remain a mystery.
Now, a recent study uses brain imaging to examine more closely at the mechanisms behind uncertainty processing in OCD. It was published in the Elsevier journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.
Three groups of persons were studied by the researchers, who were led by Valerie Voon, PhD, of the University of Cambridge: OCD sufferers, OCD sufferers who had received capsulotomy treatment, which is believed to lessen OCD-related brain activity, and healthy controls. In addition to examining processing in OCD, the researchers also sought to understand how capsulotomy influenced processing.
According to Dr. Voon, “We employed a straightforward card gambling assignment similar to that seen in drinking games. When presented with an open card, participants simply placed a wager on whether they believed the subsequent card would be higher or lower than the open card. At the extremes, with high or low open cards, certainty is great, but with cards towards the center of the deck, uncertainty was considerably higher.
The dorsal anterior cingulate cortex (dACC) and anterior insula (AI), two brain regions associated with decision-making, were the main focus of the functional magnetic resonance imaging (fMRI) tests. When determining certainty, OCD participants showed abnormal activity in this circuitry compared to unaffected controls.
Critically, individuals with OCD exhibited slower decision-making, but only when the results were more definite, according to Dr. Voon. The fact that these deficits were present in both OCD patients and those whose symptoms had improved following capsulotomy surgery implies that this cognitive process may be a key factor in how OCD develops, regardless of how severe the symptoms may be.
“The imaging data may represent how OCD patients might struggle with their symptoms,” continued Dr. Voon. People with OCD may struggle with that sense of confidence and may spend more time thinking “is this still a bit dirty, or is this clean enough,” and cleaning further, as opposed to healthy people who may be able to declare, “this is clean,” and finish cleaning.
The results demonstrate that OCD is a condition of faulty brain processing of certainty rather than an excessive cleaning problem.
“This very interesting study provides an important new perspective on the mechanism underlying the disabling symptoms of OCD and suggests that developing new therapies targeting uncertainty processing in the disorder, as well as the neural systems underlying these processes, such as the dACC and AI, may offer new hope to those suffering from this difficult to treat condition,” said Cameron Carter, MD, the journal’s editor.