August 6, 2012 -- Psychologists have classified hoarding disorder as a type of OCD for years, but new brain imaging research shows that information is, well, garbage.
A new study in the Journal of the American Medical Association shows that patients with hoarding disorder show different brain activity during decision making than patients with OCD, pinpointing a biological distinction between the two disorders for the first time.
"A hoarder is not a pack rat. A hoarder is not a slob. A hoarder is not lazy," Dr. Jeff Szymanski, the executive director of the International OCD Foundation, told ABCNews.com after he read the study. "A part of their brain doesn't work the way your brain works."
Dr. David Tolin and his team at the Institute of Living in Hartford, Conn. used brain imaging (fMRI) to test how 107 people reacted when asked whether they wanted to keep a piece of junk mail or discard it. Sometimes, it was junk mail that belonged to the patient, and sometimes, it belonged to someone else. Forty-three participants had hoarding disorder and another 31 had OCD or obsessive compulsive disorder, according to the study.
When the junk mail had a hoarding patient's name on it, certain parts of that patient's brain lit up, showing "abnormal activity" in the decision-making regions (the anterior cingulated cortex and the insula), according to the study. When the mail listed someone else's name, the same parts of the hoarder's brain were abnormally quiet.
Only hoarding patients showed this kind of activity, Tolin said. OCD patients did not.
"It's a very clean, well-done study," Szymanski said.
Tolin told ABCNews.com he and his colleagues embarked on the study because they were dissatisfied with the idea that hoarding was part of OCD and should be treated that way.
"The more that we got to know people who hoard…they didn't really resemble people with OCD all that much," he said. "The more basic information you know about a particular disorder, the better equipped you're going to be."
Szymanski said the brain imaging study could mean that hoarders are not treatment-resistant, as doctors originally suspected; they were just being treated for the wrong disorder because they were being treated for OCD. He said the study illustrates why exposure-based therapy, in which therapists help OCD patients deal with fear by exposing them to things that cause anxiety, doesn't work for hoarders.
"Danger isn't really what's going on with hoarders," he said, explaining that if it was, a different region of the brain would light up. "We need to teach them how to properly and effectively categorize… You think hoarding is about piles and piles of garbage, but it's not about piles and piles of garbage. It's about how that person doesn't have the proper decision-making skills or the proper prioritizing skills."
Szymanski said the study comes just as the American Psychiatric Association debates whether to separate hoarding disorder from OCD in the next edition of the Diagnostic and Statistical Manual of Mental Disorders. The "DSM," as they call it, is the guide psychiatrists and psychologists use to diagnose their patients.
He said the separation of hoarding and OCD is likely, but not definite. The newest edition will come out next year.
Tolin said the study also shows why people with hoarding disorder don't seem to grasp the gravity of their problem: When they have to face a decision that isn't meaningful to them, they have significantly "underpowered" activity in the decision-making part of the brain.
"These regions of the brain are part of what makes you bothered by it," he said.
Lee Shuer, who lives in Easthampton, Mass., had a hoarding problem for about five years before his wife urged him to participate in a study for "people who had problems with clutter." It happened to be one of Tolin's earlier studies, but Shuer said it was the "first piece of the puzzle" toward getting help.
"I was never diagnosed, and there still isn't a diagnosis," he said, though his apartment was filled with bobbleheads and other items from 2000 to about 2005.
Once he had his breakthrough, he was able to deal with the problem with his wife by his side. Now, he leads self-help groups using the tools he learned during his own recovery process.
He said that many of his group members go to him before turning to a therapist for their hoarding disorder.
"Some people tried to work on this with their therapists, but the therapists aren't really trained in helping this situation," Shuer told ABCNews.com. "Some people are bringing what they learned in group back to their therapists."
Dr. Tiffany Chao of the ABC News Medical Unit contributed to this report.