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Altered Brain Activity in Those With Obsessive-Compulsive Disorder

Posted on: Monday, 21 July 2008, 07:18 CDT

Researchers at Cambridge University in Britain have found that people with obsessive-compulsive disorder (OCD), as well as their close relatives, show less activity in a particular part of their brain compared to those without the condition. 
 
identified differences in the way brains of people with obsessive-compulsive disorder (OCD) work. The scientists found that brain scans of those with OCD, as well as their close relatives, revealed less activity in a particular part of the brain.

The researchers said the finding could potentially improve diagnosis of the condition, which provokes recurrent irrational thoughts such as fears of accidents or contamination, and a compulsion to follow certain rituals.

Experts believe between 2% and 3% of the general population will experience some kind of OCD during their lives.

And while the condition tends to run in families, suggesting a genetic component, such a gene has not yet been identified.  At present, the disease is typically diagnosed after a psychiatric review.

In conducting their study, the Cambridge researchers used a type of scan called a functional MRI, or fMRI, which displays activity in different parts of the brain in real time. The study’s participants, including some diagnosed with OCD, their immediate relatives, and some with no family history of the illness, all received the fMRI scans.

To incite an "OCD" response, the researchers asked each participant to choose between pictures on two screens displayed side by side, one of which was randomly selected as the "target". The pictures would alternate between left and right, and the participant was given periodic feedback about whether they were selecting the proper target.

The test was intended to stimulate "behavioral flexibility", a known challenge for those with OCD. In volunteers with neither OCD nor a family history of the condition, the test caused activity in an area of the brain known as the orbitofrontal cortex. However, in both those diagnosed with OCD and their relatives, the amount of activity in this area was significantly lower.

Although previous research has revealed differences in the brain structure of those with OCD compared to those without the disease, the current study is thought to be the first time such differences have been recorded.

"Impaired function in brain areas controlling flexible behavior probably predisposes people to developing the compulsive rigid symptoms that are characteristic of OCD,” Dr Samuel Chamberlain, who led the study, told BBC News.

"This study shows that these brain changes run in families, and represent a candidate vulnerability factor."

Dr. Chamberlain said the scan could augment current methods of diagnosing OCD.

Psychologist Dr Rob Willson, an OCD specialist, told BBC News he was excited by the potential of fMRI, even though its high cost made it unfeasible for diagnosing cases.

"What it could do is help test the effectiveness of interventions for OCD, and the more we learn about which parts of the brain are being activated, the more chance we have of understanding the condition better," he said.

The Cambridge University study appears in the journal Science. An abstract can be viewed at http://www.sciencemag.org/cgi/content/abstract/321/5887/421.

Source: redOrbit staff and wire reports

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