Almost everyone collects something at some point in his or her life—from stamps to vinyl records to Pokemon cards. But sometimes collecting can get out of hand. Now scientists have found a specific part of the brain that might be involved.


Tracking the hoarding instinct. I'm Bob Hirshon and this is Science Update.

Pack rats take note: The tendency to collect useless junk may be due to a brain malfunction. That's according to Steven Anderson and his fellow neurologists at the University of Iowa.

They found a link between indiscriminate hoarding and injuries to the brain's right mesial prefrontal cortex.


This part of the brain where we've identified the abnormality seems to be a part of the brain that helps guide humans to collect things that are of emotional or aesthetic or monetary value. That's the system that's gone awry in these patients.

As a result, the patients can no longer judge what they need or even want. The findings could shed light on other conditions, like obsessive-compulsive disorder, which can trigger hoarding without an injury. I'm Bob Hirshon for AAAS, the science society.

Making Sense of the Research

The brain is an incredibly complex organ. Often, in brain research, looking at the effects of an injury can suggest how the brain normally functions. It's kind of like taking parts out of a DVD player to see how it works without them. If you take out a part, and you lose the sound but not the picture, you know that part had something to do with the sound.

Obviously, scientists can't go around taking parts out of people's brains to see what happens. But they can study people who happen to have brain injuries. They can look at a bunch of patients with the same kind of brain injury, and look for common symptoms. Or they can look at patients with similar symptoms, and see if they have similar brain injuries. Either way, if they find a pattern, they can draw some conclusions about how the brain works.

Here, Dr.Anderson's team looked at dozens of patients who had focal brain lesions—very specific injuries to small areas of the brain. They divided them into two groups: those who developed compulsive hoarding habits after they were injured, and those who did not. When they compared the brain injuries of the hoarders to the non-hoarders, they spotted an area in the prefrontal cortex that appeared to make the difference.

Why would a brain injury make people collect junk? Anderson suspects this doesn't just happen randomly. All humans seem to have some kind of built-in tendency to collect things. This may harken back to an earlier point in our evolution: many animals hoard things, especially food. But somewhere along the way, Anderson suggests, this little spot on our prefrontal cortex put the brakes on hoarding. For those patients unlucky enough to get injured in this spot, the controls come off, and they start hoarding anything they can get their hands on.

If his suspicions are correct, this wouldn't be the only example of a prefrontal cortex injury unleashing some kind of primitive behavior. The prefrontal cortex is the most "advanced" part of the brain; only mammals have it, and it's more developed in humans than in any other animal. Patients with other prefrontal cortex injuries often lose control of their basic impulses, resulting in everything from inappropriate vocal outbursts to anti-social or violent behavior.

Understanding how this area of the brain works may also help doctors treat other patients who hoard things. Although hoarding isn't as destructive as some psychiatric problems, it can still make your life very messy and unmanageable. If scientists could find a way to artificially control the hoarding instinct in these patients, they could focus their energies on their families, jobs, and hobbies again.

Now try and answer these questions:

  1. Why do you think humans have a tendency to collect things?
  2. What's the difference between normal collecting and compulsive hoarding?
  3. If you could examine the brain of a patient who was a compulsive hoarder, but who never had a major head injury, what might you expect to find?
  4. What are the limitations of brain injury studies? What are they NOT able to prove?

For Educators

Read an article on Hoarding on ScienCentralnews.com.

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