Excessive Grooming in Mice = Mental Illness

It's safe to say that my face almost hit the keyboard as I was reading the article Bone marrow transplants cure mental illness – in mice in The Guardian today. Apparently, Nobel prize for medicine winner, Mario Capecchi, conducted a study which consisted breeding "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." Because this excessive grooming is similar to trichotillomania, a disorder in which people pull out their hair, it somehow means that OCD, depression, autism, and schizophrenia may be caused by immune deficiencies.

Wait...what?

"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."

By now, I really hope you see problems with this. For one, the scientists bred mice with a mutated gene which could have had numerous different effects, and because the resulting effect was excessive grooming, they linked it to a sort of spectrum disorder, without acknowledging the possibility that the mutated gene may have made the mice excessively, well, itchy.

Second, the team takes this behavior and somehow links it to other disorders such as depression, autism, and schizophrenia. Tell me, did the mice hum as a result of the mutated gene as well?

However, these issues do not stop Capecchi from concluding: "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."

Of course, right in the middle of the article, Capecchi comes out with it: "The recognition that many neuropsychiatric diseases have a direct connection to the immune system emphasises that we should be taking immune deficiencies associated with neuropsychiatric disease much more seriously. We know a lot more about the immune system and how to treat immune deficiencies than we know about how our brain works and what the drugs used to treat neuropsychiatric disorders are doing."

As with a previous blog post, the Mind Over Meds Reaction, it would appear that the goal of psychiatry is ultimately how to figure out what type of medication to assign to the individual based on assumed biological predisposition.

The article did assuage my immediate, overwhelming concern by adding as a final comment: "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. '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."