According to Dr. David Tolin, director of the Anxiety Disorders Center at the Institute of Living at Hartford Hospital, some people hoard because of perfectionism. "They don't necessarily color-code their closets, but they have that perfectionistic streak that bites them when it gets too bad," he says. "They have the mentality that, 'If I can't make this decision perfectly, I won't do it at all.' And that's where the hoarding comes in. They become so frightened that they will make a mistake, that they become paralyzed and just allow the clutter to build up."

Other people hoard because they are afraid that they will accidentally throw away something that is useful. "People with hoarding problems will often think of all kinds of ways that they could use something, or they think of people that might want that object, so they keep it," Dr. Tolin says. "The irony, however, is that in most cases, they never actually use the object in the way they thought of. They don't actually give the object to the person they thought of. So these reasons for keeping things don't turn out to be good reasons after all."

Still other people save things because they feel a sense of emotional attachment to the objects in their home. "All of us get attached to things some of the time," Dr. Tolin says. "We have things that remind us of people we love, or they remind us of happy times. But for people with hoarding problems, the attachment to objects becomes very intense—sometimes more intense than the attachment to actual people. And instead of feeling attached to one thing, like a scrapbook or a favorite sweater, they can become attached to hundreds, even thousands, of things. Some people have told me that all of the things in their homes feel like their friends or family members, so they can't bear to throw them out."

• Learn more at CompulsiveHoarding.org

From The Oprah Winfrey Show Inside the Secret Lives of Hoarders