Conventional thinking holds that it takes about 12 weeks for people being treated for obsessive-compulsive disorder (OCD) to show improvement. But a study, published online in Molecular Psychiatry, suggests that a form of intensive cognitive-behavioral therapy can achieve those same results in as little as four weeks.

Sanjaya Saxena, MD, a psychiatrist at the University of California, San Diego, School of Medicine, along with colleagues took PET scans of 10 people with OCD before treatment. He and his colleagues then treated them five days a week for four weeks with a therapy known as "exposure and response prevention," in which clients learn to tolerate their obsessive fears and worries without acting out their compulsions.

After these four weeks, the participants showed significant improvements in their OCD symptoms and ability to function. When Saxena ran PET scans again, he found a decrease in thalamus activity & a pattern seen in other OCD treatments & and an increase of activity in the right dorsal anterior cingulate cortex, which is involved in reappraising and suppressing negative emotions. The same pattern of increased activation has also been observed in people with major depression who receive cognitive-behavioral therapy.

Saxena theorizes that activating this brain region might be required for people to respond to intensive cognitive-behavioral therapy. And not just people with OCD, he says, but also people with other mood and anxiety disorders. Knowing that will help researchers develop more effective therapies, he says.

Saxena hopes his research will help break down the false dichotomy between psychological and biological treatments for psychiatric disorders. Psychological treatments clearly have biological effects, he says.

"Our study reinforced the efficacy of the treatment," Saxena says, "and now we've shown how it works in the brain."

-M. Price