A study by British researchers published in the latest edition of the journal Brain shows that individuals with obsessive compulsive disorder (OCD) and their relatives appear to have distinctive patterns in their brain structure.

The team of scientists at Cambridge University from the Brain Mapping Unit, led by Ed Bullmore, used magnetic resonance scanning of the brains of some 31 OCD patients to measure their ability to perform simple tasks involving brain and hand. The tests were also done on a fist-degree relative of each of the patients, who was not diagnosed with the disorder, and on 31 other healthy people.

The test was designed to objectively measure the ability to stop repetitive behaviors. The findings indicated that relatives of OCD patients did significantly worse than the group of healthy people. Their poor performance was also associated with decreases of grey matter in brain regions important in suppressing responses and habits, such as the orbitofrontal and right inferior frontal regions.

"Impaired brain function in the areas of the brain associated with stopping motor responses may contribute to the compulsive and repetitive behaviors that are characteristic of OCD," said researcher Lara Menzies to BBC. "These brain changes appear to run in families and may represent a genetic risk factor for developing the condition. The current diagnosis of OCD available to psychiatrists is subjective and therefore knowledge of the underlying causes may lead to better diagnosis and ultimately improved clinical treatments."

Obsessive-compulsive disorder is a psychiatric anxiety disorder which affects about 3 percent of the general population. There is still much debate over the exact cause of the illness, but the majority of researchers now think that obsessive-compulsive behavior is caused by abnormalities in the brain, and the disorder is not psychological in nature. Many who suffer from OCD suffer from panic attacks and are exposed to a higher risk of drug addiction.