Paul Salkovskis, clinical director of the Maudsley Hospital Centre

Paul Salkovskis, clinical director of the Maudsley Hospital Centre Naomi Fineberg, a consultant psychiatrist at Queen Elizabeth II Hospital in Welwyn Garden City, said the work was a major development. "This finding is clearly important in directing research in new directions for OCD and OCD-spectrum disorder treatments. Given the intransigence of OCD symptoms, synchronous motor and the fact that roughly one third of treated OCD patients fail to make a good recovery, new treatment directions in this field are sorely needed."

In the study, Capecchi's team bred mice that carried a mutation in a gene called Hoxb8 that causes faulty immune cells to grow in the bone marrow. Mice that carry the defective gene groom themselves too often and for too long, leaving them with bare patches and skin wounds.

Writing in the US journal Cell, the team describe how transplanting healthy bone marrow into the mice cured them of the grooming disorder. In later operations, the scientists induced the disorder in healthy mice by giving them bone marrow from affected mice.

"We're showing there is a direct relationship between a psychiatric disorder and the immune system, specifically cells named microglia that are derived from bone marrow," Capecchi said. There are two kinds of microglial cells in the brain. Around 60% form in the brain in the earliest stages of human development, while the remaining 40% originate in bone marrow and then move to the brain.

"This is immensely important and incredibly exciting. It's definitely something people will want to follow up," said Douglas Blackwood, professor of psychiatric genetics at Edinburgh University. "Current treatments for these kinds of conditions are not incredibly effective and there's a massive need for alternatives."

Other researchers were more cautious about the work. Paul Salkovskis, clinical director of the Maudsley Hospital Centre for Anxiety Disorders and Trauma in London, said it was impossible to draw strong conclusions about the role of the immune system in human mental illnesses from the study. synchronous motor "Excessive grooming in mice is not a good model for obsessive-compulsive disorder in humans, a condition that can be treated effectively with cognitive behavioural therapy," he said.