OCD Linked to Low Activity in Brain Area
> 7/23/2008 12:31:50 PM

An examination of brain activity may lead to more effective ways of diagnosing obsessive compulsive disorder (OCD), as new research from the July issue of Science indicates. Researchers from the University of Cambridge used brain imaging technology to show that a particular part of the brain, the lateral orbitofrontal cortex, may be less active in individuals with OCD and in those more likely to have the anxiety disorder.

The researchers measured patterns of brain activity in 14 individuals with OCD, 12 of their family members, and 14 control subjects with no family history of OCD. All of the subjects took a visual test that examined their ability to alter their behavior in response to feedback. They were presented with two different images, one of which had been designated a “target.” After picking the picture they believed to be the target, the subjects were told if they had guessed correctly or incorrectly, and they were then allowed to choose again. When the subjects had given six correct answers in a row, the other picture became the target, and the subjects would have to change their answer in order to identify the target. Control subjects displayed normal brain activity throughout this process, but those with OCD and those with a family history of OCD both had low levels of activity in the lateral orbitofrontal cortex.

Individuals with OCD experience obsessions—intrusive and distressing ideas or impulses—and often try to counteract these unwanted thoughts with compulsions—repetitive rituals. Someone who persistently thinks that everything around them is contaminated with germs, for instance, might feel the need to wash their hands often as a way to prevent or reduce the anxiety caused by their obsession. As this study demonstrates, activity in the orbitofrontal cortex, which is located in the frontal lobes and aids in decision-making, might influence this type of behavior. Low levels of activity in this brain region could interfere with the ability to stop actions that have become habitual, contributing to the rigid thoughts and behaviors associated with OCD.

Many genetic and environmental factors likely play a role OCD, and this study may point to just one biological mechanism involved. Further research is necessary so that we can understand why some people with impairments in the orbitofrontal cortex develop OCD while others do not. The symptoms of OCD interfere with an individual’s life and can be debilitating, but as we learn more about the factors underlying this disorder, we may be able to identify those at risk early on and ensure that they receive treatment as soon as necessary.

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