Obsessive compulsive disorder linked to brain activity

WASHINGTON, July 17 (Xinhua) -- Measuring activity in a region of the brain could help identify people at risk of developing obsessive compulsive disorder (OCD), researchers have discovered.

The new findings, made by researchers from the University of Cambridge in Britain, were published in the U.S. journal Science on Thursday.

As the current diagnosis of OCD is based on clinical interviews and often does not occur until the disorder has progressed, this latest discovery could enable earlier, more objective detection and intervention, the study said

The research team discovered that people with OCD and their close family members show under-activation of brain areas responsible for stopping habitual behaviour. This is the first time that scientists have associated functional changes in the brain with familial risk for the disorder.

OCD is a debilitating condition that affects 2-3 percent of the population at some point in life. Patients suffer from recurrent intrusive thoughts (obsessions) that are distressing and hard to suppress. Examples include fears of contamination, or that something terrible will happen to a loved one.

They also suffer from repetitive rituals (compulsions), which are often designed to neutralize those thoughts. Examples include hand-washing and checking gas hobs. These symptoms cause distress and can occupy hours during the day, interfering with quality of life and the ability to work.

Although OCD tends to run in families, genetic factors responsible for the condition are not known. Genes may pose a risk for OCD by influencing how the brain develops.

The researchers used functional magnetic resonance imaging (fMRI) to measure brain activity in the lateral or bitofrontal cortex (OFC) during a designed test. Located in the frontal lobes, the lateral OFC is involved in decision-making and behavior.

Fourteen volunteers without a family history of OCD, 14 people with OCD and 12 immediate relatives of these patients took the test.

Comparison of fMRI images of their brain activity throughout showed under-activation in the lateral OFC and other brain areas in both the OCD patients and their family members.

Impaired function in brain areas controlling flexible behaviour probably predisposes people to developing the compulsive rigid symptoms that are characteristic of OCD, said the researchers.

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

Since the current diagnosis of OCD is subjective, improved understanding of the underlying causes of the condition could lead to more accurate diagnosis and improved clinical treatments, said the study.