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Most of us struggle with clutter. Your friend calls to say they're coming over, and suddenly you're scrambling to put things away and make your place at least a little bit presentable.

But when people take this to the extreme, it can be a little mystifying. Like, you definitely do not need all your junk mail going back to 1997. It's easy to make hoarding a punchline -- it's managed to sustain at least 9 seasons of reality.

TV. But the thing is, hoarding is a real problem, and it's not as rare as you might think. It's thought that about 2-6% of people have what's called hoarding disorder.

And while we still have a lot to learn about it, neuroscientists think something quite distinct is happening in the brains of those who have it. People with hoarding disorder accumulate stuff, even things others would say are worthless, because it's hard for them to part with their possessions. It often pains them to throw things out -- there's an intense feeling of loss if they do.

And they may not want to get rid of stuff in case they might need it later. Many also seek out new objects, whether they're freebies or purchases. This is different from collecting because even if you're collecting something hardly anyone else wants, like hotel key cards, collectors usually focus on one thing, and they keep everything organized.

That's not what happens with hoarders. Stuff builds up, and when it starts to take over, sometimes people can't use their kitchens anymore to make food. Or, they find that half of their bed is coated in stuff, making it hard for them to sleep.

In short, clutter is no longer just clutter — it's interfering with their lives. In severe cases, hoarding can become dangerous, because people can't move through their homes easily, and the space can become unsanitary and a fire hazard. Those extreme cases are what they usually show on TV.

But it's a lot easier to see what's happening in someone's home than it is to see inside their head. Back in the 1990s, psychologists thought hoarding was a subtype of obsessive compulsive disorder, or OCD, a disorder where people can become fixated on things, or do certain behaviors repetitively. This idea made sense: hoarding was one symptom used to diagnose OCD, and anywhere from 20-40% of people with OCD do some hoarding.

Plus, it's easy to see how hoarding could be related to an obsessive fear of being wasteful or getting rid of important items. But 80% of hoarders, beyond their accumulation of stuff, have no other symptoms of OCD. And there are some telltale differences between how people with OCD usually feel about their compulsions and the feelings that come with hoarding.

People with OCD tend to be bothered by their compulsions, whereas hoarders usually aren't — beyond embarrassment if someone comes into their house. And unlike with OCD compulsions, hoarders aren't generally thinking about hoarding all the time. Neuroscientists have also noticed that the activity patterns in the brains of people who hoard look different from those in people with OCD.

In one 2012 study of 107 volunteers, which included hoarders, people with OCD, and controls, researchers imaged people's brains while they decided whether they should keep or shred newspapers and pieces of mail. As you'd expect, hoarders struggled with the task, and were more anxious and indecisive. And when the items came from their own homes, they had much higher activity in two parts of their brains than people in the other groups.

These regions, the anterior cingulate cortex and the insula, are important for decision-making and emotion. Researchers think this abnormal brain activity makes it hard for hoarders to respond appropriately to objects — basically because they overvalue them, so it's hard for them to throw things out. Since those responses aren't seen in people with OCD, it doesn't seem like the disorders are really all that similar, even though there can be some overlap.

In 2013, the authors of the fifth and latest edition of the Diagnostic and Statistical. Manual of Mental Disorders, or DSM, agreed, and officially recognized hoarding disorder as its own thing — although it's still in the same category as OCD. Now, even though we have some idea as to what's going on in the brains of hoarders, we don't really understand why the disorder starts in certain people and not in others.

We do know that there are some risk factors. First, hoarding disorder often runs in families, and some twin studies suggest that at least part of it is genetic. And about 75% of hoarders also have some other mental health problem, like depression, anxiety, or ADHD.

Many people with the disorder have also experienced traumatic events or had traumatic childhoods. For example, an abusive relationship or the death of someone the person is close to can make hoarding worse or sometimes even trigger it. It's not clear why this is, but some psychologists think that after traumatic events, people may feel safer attaching themselves to objects rather than people, who might hurt or abandon them.

It's like the clutter gives them comfort. We also know that middle-aged or older adults are more likely to be affected, possibly because the disorder gets worse over time. So, even though hoarding symptoms usually start early, like in the person's teens, it might take a few decades or more for things to really get out of hand.

There's no full-on cure for hoarding disorder, but cognitive behavioral therapy, or CBT, can help treat it. Therapists help the patient question why they want to acquire more things, or why they can't get rid of something. They come up with a set of questions to make it easier to tell whether an object is worth buying or keeping, like, ‘Do I really need this right now?' or, ‘What's the worst thing that can happen if I get rid of this box of old toys?' By learning to recognize the hoarding behaviors, and by talking through their feelings with someone as they practice sorting and throwing things out, people can begin to change.

Successfully treating hoarding is not easy. It involves reshaping a fundamental part of how you perceive the world and live your life. But understanding more about where your thoughts and behaviors come from can go a long way toward giving you agency over them — even if change seems impossible or scary at first.

That's what psychology is all about. It's also why we do what we do here at SciShow Psych. The human brain is amazing and weird, and if you're watching this right now, odds are you have a human brain.

So if you're interested in learning more about the weird quirks that make us who we are, you can go to youtube.com/scishowpsych to subscribe. [♪ OUTRO ].