(condition thought to be neurological in etiology is immunological??? Rick, it's those microglia once again!)

http://news.sciencemag.org/scienceno...could-be-.html

a study of mice suggests that faulty immune cells prompt such compulsive behaviors. The results raise the possibility of treating obsessive-compulsive disorder by targeting the immune system rather than the brain...


...When Capecchi and colleagues began looking for the Hoxb8-making cells in the mouse brain, they expected to find that the source was neurons that control grooming. To their surprise, the only cells producing Hoxb8 were microglia, immune cells that guard against pathogens. Although some microglia start out in the brain, others are born in the bone marrow and move in. Overall, adult mice with faulty Hoxb8 harbored about 15% fewer microglia in the brain than normal.

To test whether defective microglia provoke mice to feats of extreme cleanliness, the researchers performed bone marrow transplants. Transferring marrow from Hoxb8-lacking mice into healthy rodents provoked compulsive grooming, the researchers report in the 28 May issue of Cell. And when mice deficient in Hoxb8 received marrow from healthy animals, they cut back on their ablutions. Before this finding, “nobody would say you can cure a [pathological] behavior with a bone marrow transplant,” Capecchi says.

... Previous studies have implied a link between the immune system and obsessive-compulsive disorder and other neuropsychiatric conditions, Capecchi says. “Here, we say there is a direct connection.”

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