Mental illness, brain studies, and disease risk
That abnormalities in brain function are related to mental illness really isn't much of a surprise. But researchers have recently localized malfunctioning to a specific area of the brain in people with OCD and their relatives.
Obesessive-compulsive disorder is a brain disease in which the sufferer is held captive by unwanted obsessions, and usually by accompanying compulsions to help mitigate the anxieties caused by the obsessions. I have OCD (although it is currently in remission- my horrific anxiety is now more generalized rather than specific), and if I was worried about germs and AIDS, then I would wash my hands repeatedly, until they were red and raw and cracked and bleeding. When that didn't relieve the anxiety, I switched to Clorox.* If I was worried about hitting a pedestrian or small animal with my car, I would drive around the block searching for bodies in the road and refusing to watch TV thinking the police would be looking for me.
In a recent study published in Science, researchers found abnormalities on PET scans of OCD sufferers in the orbitofrontal cortex (see picture). The OFC is one of the "least understood" regions of the primate and human brain, and is thought to be involved with such things as "representing the affective value of reinforcers, and in decision-making and expectation. In particular, the human OFC is thought to regulate planning behavior associated with sensitivity to reward and punishment."In people with OCD (and their unaffected relatives), this part of the brain didn't activate as usual. An MSNBC news story interview with the lead author of the study said this:
The study included 14 people with OCD and 12 immediate relatives without the disorder who were asked to complete a task requiring them to be flexible in making certain decisions — something people with the condition have difficulty doing.
Brain activity was normal in volunteers without the disorder.
"If this part of the brain isn't acting as it should it predisposes you to OCD," Chamberlain said. "Previous studies had only shown this in patients, not the unaffected relatives."
The findings could help identify people at risk to provide treatment before symptoms emerge, and lead to a biological marker to determine who is at greatest risk, he added.
To me, the significance wasn't just in localizing brain malfunction in OCD to a specific area, but rather finding this same abnormality in unaffected relatives. Clearly, something genetic is going on here. Questions remain, however. If the same area of the brain is malfunctioning, why do some people have clinical illness while others don't? What is serving to mitigate disease? Can we target drugs to this area?
Given the huge database of people in the AN Genetics Study, I would love to see this similar tests performed on people with eating disorders.
*Note: don't do this on raw skin. It hurts. A lot.
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