Using brain imaging, researchers have found that obsessive-compulsive disorder affects particular areas of the brain involved in processing certainty during the decision-making process. The findings provide a greater understanding of the processes underlying this enigmatic condition.
Obsessions are defined as repeated thoughts, urges, or mental images that cause a person stress or anxiety. Obsessive thoughts can lead to compulsions or repetitive behaviors to relieve that anxiety. While many people with obsessive-compulsive disorder (OCD) have both obsessions and compulsions, some have one or the other.
There are myths and stereotypes around OCD. Namely, that it’s a personality trait (being uptight, meticulous, neurotic), that people with OCD ‘just need to stop’ their compulsive rituals, or that OCD is all about cleanliness and neatness. However, OCD is a neurological disorder whose underpinnings are not well known.
In a new study led by the University of Cambridge, researchers used brain imaging to gain a greater understanding of the condition and what might cause it. They started with the premise that OCD arises due to difficulty processing uncertainty. It makes sense: decision-making is frequently associated with risk-taking under uncertain conditions, and an elevated intolerance of uncertainty is a critical feature of OCD.
The researchers studied a group of patients with OCD and another group with severe OCD who’d undergone a capsulotomy, a last-resort surgical procedure to relieve symptoms when other treatments haven’t worked. The aim was to investigate brain processing during a task featuring uncertainty.
“We used a simple card gambling task like that commonly used in drinking games,” said Valerie Voon, a corresponding author of the study. “Participants faced with an open card simply bet whether they thought the next card would be higher or lower than the open card. At the extremes, with high or low open cards, certainty is high, but uncertainty was much higher with cards near the middle of the deck.”
The researchers used functional magnetic resonance imaging (fMRI) to focus on areas of the brain associated with decision-making, namely the dorsal anterior cingulate cortex (dACC) and the anterior insula (AI). While they were determining certainty, participants with OCD displayed aberrant behavior in this circuitry compared to healthy controls.
“Critically, patients with OCD showed slower decision-making, but only when the outcomes were more certain,” Voon said. “Because these impairments appeared in both the OCD patients and those who had improved after capsulotomy surgery, that suggests this cognitive mechanism might be a core feature underlying why OCD develops, irrespective of how severe the symptoms might be.”
The findings make clear the condition is one marked by disordered brain processing when it comes to certainty, the researchers say.
“The imaging data may provide a representation of how OCD patients might struggle with their symptoms,” said Voon. “Whereas healthy individuals might be able to say, ‘this is clean’ and stop cleaning, people with OCD might struggle with that sense of certainty, and perhaps spend more time wondering, ‘is this still a bit dirty, or is this clean enough?’ and clean further.”
The study was published in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.
Source: Elsevier