In 2009, A&E introduced the United States to Hoarders. While many of us know a hoarder – or someone who "has a problem with clutter," as one person euphemistically put it to ABC – Hoarders was the first time a light was shed on the mental illness. By its definition, hoarders are people who excessively collect items and cannot bring themselves to throw them out.

As of 2010, Hoarders was A&E's top-rated show among adults who are 18 to 49 years old, and 25 to 54 year olds. It goes without saying that Hoarders is still on the air, fascinating and reviling viewers who glimpse people's homes, littered with paper, food and sometimes animals.

Psychologists previously thought hoarders were untreatable, thinking that the underlying cause of the condition was obsessive-compulsive disorder (OCD), an anxiety disorder in which people have unceasing thoughts about something or are driven to behaviors that cause them to do something. Brain scans have uncovered a different clue about the causes of hoarding, indicating that hoarding is not a result of OCD at all. The answer to the cause of hoarding may indicate that hoarding is a treatable condition after all.

Yale University's David Tolin and his team took brain scans of 43 people who had been diagnosed with a hoarding disorder, 31 with OCD and 33 healthy controls. Each participant in the study was asked to bring a stack of unsorted paper from their house, like newspaper or junk mail, which was intermixed with experimenters' own paper. Subjects had to choose whether to keep or destroy 50 items of theirs and 50 of the experimenters' objects. In the end, the objects that subjects chose to destroy were shredded in front of them so that they could feel the permanence of their decision.

Healthy controls chose to shred, on average, 40 of 50 items that they had brought. People with OCD let go of 37 items. People with hoarding disorders discarded a comparatively paltry 29 items. At 2.3 seconds versus 2.8 seconds, it also took hoarders slightly longer than healthy controls to make the decision. People with hoarding disorders also reported feeling anxious and sad about the decision.

Hoarders' fMRI readings for the anterior cingulate cortex and the mid- to anterior insula showed irregularities. Those portions of the brain detect mistakes during unsure situations and assess risk, respectively.

Surprisingly, hoarders' brain activity when forced to make decisions about other people's things were lower. When faced with making a decision about their own things, hoarders' brains fired off far greater signals than the other groups.

As Tolin says, hoarders are not necessarily interested in keeping all of the things that they possess, but their brains are not as well-equipped to handle decision making. They also associate far more risk with the decisions that they do make.

The research indicates that hoarding has been treated the incorrect way because it was associated with OCD. It also explains why, when the clutter is removed from hoarders' homes, they begin to amass new clutter all over again. Hoarders have found some success with selective serotonin reuptake inhibitors (SSRIs), which is also given to patients with OCD. Hopefully with the new research, hoarders can receive new, adequate treatment, and start throwing things in the trash.