Faulty Circuits

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CHRONIC ACUTE ANXIETIES ABOUT SEX, VIOLENCE and contamination are bizarre and debilitating. Sufferers of so-called obsessive-compulsive disorder -- about 2% of populations worldwide -- constantly repeat such simple actions as washing their hands, manically checking doors and stoves, and hoarding newspapers. Scientists who have long suspected that a key problem is a malfunction in the brain's circuitry now have strong evidence to support that idea. According to researchers at the University of California, Los Angeles, successful behavior- modification therapy and drug treatment both have a marked effect on a central region of the brain that governs the learning of habits and routines.

In their study, published in Archives of General Psychiatry, one group of patients was treated by scientists with the drug Prozac while those in the second group met regularly with a therapist who worked on helping them acquire control over their senseless fears and urges through deconditioning exercises. In 10 weeks, about two-thirds of the patients in both groups had improved. Brain scans of responsive patients showed a decrease in metabolic activity in the brain's right caudate nucleus.

Normally, the caudate nucleus filters the flood of anxious feelings and sensations that are relayed from the orbital cortex, an area of the brain just above the eyes, and sends only the significant ones on to the thalamus for further action. But in people with obsessive-compulsive disorder, says neuroscientist Lewis Baxter, who led the team, the caudate nucleus is "a poor executive officer. He's bombarded with messages from worrywarts. But instead of setting priorities, he gets excited about all the messages and passes them on to the dispatcher."