Scientists say they have discovered new evidence on why obsessive compulsive disorder (OCD) runs in families, according to a report in Australia's Daily Telegraph.
Researchers from the University of Cambridge studied people with OCD and their close family members and found they shared distinctive patterns in their brain structure.
The findings, published in the journal Brain, could help predict risk of OCD and lead to more accurate diagnosis of OCD, the researchers said.
OCD is known to run in families but little is known about how genes contribute to the disorder, although one theory is they may influence brain structure, the study offered as background.
Cambridge researchers tried to determine whether there were biological markers of genetic risk for developing OCD.
Using magnetic resonance imaging (MRI), they took pictures of the brains of 31 people with OCD as well as scans of 31 healthy close relatives (such as a brother, sister or parent).
A second group of 31 healthy people acted as controls.
The results showed that OCD sufferers and their families had less grey matter in the areas of their brain associated with suppressing responses.
The researchers concluded they had found "substantial evidence that variation in motor inhibitory control" was correlated with grey matter density changes in parts of the brain.
Lara Menzies from the Brain Mapping Unit at the University of Cambridge said, "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."
OCD sufferers experience recurrent thoughts about subjects such as contamination and germs.
They may also take part in rituals, such as repeated hand-washing, checking windows are locked or lining items up in a specific order.