We all know people who are messy.

Then there are the extreme cases, the ones where they can’t actually walk through their home because it’s filled with garbage or their kitchen is filled with rotten food and garbage and they sleep on a chair because their bedroom is uninhabitable. You can tell you are approaching the house because the smell permeates the entire street. These are people with a hoarding disorder.

“It is a mental disorder,” says Dr. David Tolin, Ph.D., Director of the Anxiety Disorders Center at the Institute of Living. “It’s not just sloppy, or someone being lazy. The people with hoarding disorder really do have a psychiatric condition that has made them at least partially lose control of their behavior.

“So we need to recognize it for what it is. This is not something that the person necessarily signed up for. It’s not like this is how people want to live their lives. They have just lost control of themselves.”

Hoarding has been researched systematically only for the past 20 years, with an increased focus in the last decade. Studies at the Institute of Living have focused on trying to understand what makes discarding any item so hard for those with the disorder.

“We have been doing research here at the Anxiety Disorders Center, looking at brain function,” says Dr. Tolin, “trying to understand what is happening as they decide whether to keep or discard things. What we see is there is a very strong reaction in the brain to the very idea of discarding. Even simulating discarding triggers a very strong neuro reaction that is really different from what people without hoarding disorder experience.”

Dr. Tolin says that though it’s a new diagnosis, it’s not a new problem.

“This behavior begins very early,” he says. “So we can see that something is off by this child’s behavior by late childhood, early adolescence. Something is off, and it is not just routine collecting. Rather, the person is habitually acquiring things, and often it’s things that most people would scratch their head and wonder why they are acquiring this, it’s not valuable. It’s tin cans, or old containers from food.”

Dr. Tolin has put his research on display and in practice on the hit A&E program, “Hoarders.” He has the distinction of being the first psychologist featured on the show, now in its 12th season. But this is not the only time he has brought his research to television. Dr. Tolin started out making regular appearances on “The Oprah Winfrey Show,” as well as being featured on “The OCD Project” and “My Shopping Addiction.”

Currently, there is no cure for Hoarding disorder. The Institute Of Living offers a 16-week therapy program of treatment, but even those who get significantly better, will still suffer from the disorder when finished. Dr. Tolin says the key part is to remember that it all takes time – much more than the week they feature on the show.

“Because we measure the success in part by the cleaning out of a house,” he says, “unless you have the army of people that you see on ‘Hoarders,’ it can’t be done in that short a period of time. It’s going to take a long time for one person, or one person and their family to clear stuff out. It just takes a long time to get there.”