MRI scans reveal OCD alters the brain’s decision-making mechanisms
Researchers have scanned the brains of adolescents with obsessive-compulsive disorder, OCD, while they performed decision-making tasks and identified the specific areas affected by the condition. The study sheds light on the biological basis of OCD and could be used to provide more targeted, effective treatment.
OCD is considered one of the most debilitating psychiatric illnesses. Characterized by a pattern of distressing and unwanted thoughts and fears (obsessions) that trigger time-consuming repetitive behaviors (compulsions), the disorder often has a profound effect on social functioning and quality of life. OCD usually presents during childhood or adolescence.
New research by the University of New South Wales Sydney has examined the biological basis of OCD in adolescents, shedding light on how the disorder affects how the brain makes decisions and controls behavior.
“These repetitive actions, obsessions and compulsions aren’t completely under the control of someone with OCD,” said Iain Perkes, lead author of the study. “Otherwise, they would simply choose not to do them. So, there was good reason to think that those decision-making mechanisms in the brain go awry in the case of OCD.”
The researchers recruited 20 adolescents with OCD and 21 healthy adolescents and asked them to complete decision-making tasks to gain small food rewards while inside an MRI scanner that measured blood flow in the brain. For example, one activity involved playing a computer game where they tilted a vending machine in different directions, each corresponding to a different snack.
“We make decisions every day based on environmental cues – for example, stop signals and go signals that we see at traffic lights,” Perkes said. “These cues allow us to predict the circumstances around us.”
Before one of the decision-making tasks, the ‘value’ of the food was reduced by participants being shown a video of insects – such as a cockroach – crawling over the food.
“We wanted to see how changing the value of the reward would change the choice of action for healthy young people, versus young people with OCD,” said Perkes.
Adolescents with OCD struggled to make choices and control their behavior to gain food rewards compared to the control group and reducing the value of the food had little influence on their behavior during tasks.
“People with OCD experience difficulties using reward signals to guide their choices in an adaptive way,” Perkes said. “Those behavioral difficulties are associated with changes in the brain.”
MRI scans showed different patterns of brain activity in adolescents with OCD compared to controls. The differences were particularly strong in the orbitofrontal cortex (OFC), a region in the frontal lobe involved in decision-making and behavioral control.
During decision-making tasks, the lateral OFC showed hypoactivity in participants with OCD, whereas the medial OFC showed hyperactivity. The researchers also found that hyperactivity was linked to the severity of OCD symptoms, supporting the connection between decision-making performance and the disorder.
The researchers say their findings provide a greater understanding of the biological basis for OCD, which may reduce the stigma associated with the disorder.
“As we understand the biological reality and underpinnings of mental health conditions like OCD, it helps to reduce stigma,” said Perkes. “It shifts the dialogue from ‘Just pull your socks up, work harder’ to ‘There are changes in the brain; that’s a real health condition.’”
The findings also have the potential to lead to better treatments. For example, it may lead to more targeted transcranial magnetic stimulation, a treatment that uses magnetic fields to stimulate nerve cells in the brain.
“We know that for one-third of people living with OCD, they don’t respond to first-line treatments,” Perkes said. “There is a real need to continue discovering new and better treatment paradigms.”
The study was published in the journal Biological Psychiatry Global Open Science.
Source: UNSW Sydney