Compulsive hoarding—such as sharing your one-room apartment with the last 50 years' worth of the local newspaper—is considered a kind of obsessive-compulsive disorder. But some psychiatrists think that hoarding is actually a different disorder from OCD. Indeed, hoarders are less likely to do well when they take the drugs that usually help OCD patients. Researchers at UCLA looked for the answer in 62 OCD patients' brains.

What the researchers wanted to know: Do compulsive hoarders have different brain activity than other obsessive-compulsive people?

What they did: Researchers recruited people in the Los Angeles area using advertisements. Forty-five had obsessive-compulsive disorder, and the other 17 were normal. Twelve of the OCD patients were compulsive hoarders. The subjects were tested to find out how bad their symptoms were, including hoarding. They also got a brain scan; each was injected with radioactive glucose, which lights up the most active parts of the brain during the PET scan.

What they found: Hoarders and nonhoarding OCD patients had significantly different patterns of brain activity (they were also different from the normal brains). For example, hoarders had less activity in a part of the brain that handles things like motivation, emotional self-control, and choosing between conflicting options. They also had less activity in parts of the brain that—according to earlier studies—are often less active in people who don't respond well to antidepressants, which may explain why standard OCD treatments don't work well on hoarders.

What it means to you: Not all obsessive compulsive disorders are created the same.

Caveats: This study was originally designed to compare obsessive compulsive disorder, major depressive disorder, and normal subjects, not to look at hoarding and nonhoarding. It's often dangerous to draw conclusions that a study wasn't designed to look for.

Find out more: Do you have a problem with compulsive hoarding? The Bio-Behavioral Institute lists some symptoms of this disease.

Read the article: Saxena, S. et al. "Cerebral Glucose Metabolism in Obsessive-Compulsive Hoarding." American Journal of Psychiatry. June 2004, Vol. 161, pp. 1038–1048.

Abstract online: http://ajp.psychiatryonline.org/