What Causes OCD?
Using a specific type of brain scan (a positron emission tomography or PET), scientists have shown that functioning in some areas of the brain is different between people who have OCD and those who don’t.
Research shows that the disorder may involve communication errors that take place between the orbitofrontal cortex (front part of the brain), the striatum, and the thalamus (deeper parts of the brain). Abnormalities in the serotonin and other neurotransmitter systems—chemicals that send messages between brain cells – also are involved in the disorder.
A study funded by the National Institutes of Health examined DNA, and the results suggest that OCD and certain related psychiatric disorders may be associated with an uncommon mutation of the human serotonin transporter gene (hSERT). People with severe OCD symptoms may have a second variation in the same gene. Other research points to a possible genetic component—about 25% of OCD sufferers have an immediate family member with the disorder.
Some people exhibit symptoms of OCD after a brain injury, which also suggests a connection between brain function impairment and OCD. And some children begin to exhibit symptoms after a severe infection such as strep throat. However, studies suggest the infection doesn’t actually cause OCD, but triggers symptoms in children who are genetically predisposed to the disorder.