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Hopefully, by now we all know that depression is about more than sadness. But even if your idea of depression also includes things like hopelessness or apathy, what about irritability or anger?

Does depression make you think of overwhelming guilt? What about memory loss? Because those are all symptoms, too.

There's a lot we still don't understand about depression, especially when it comes to what's happening on the cellular level. But we know that when it comes to the experience of depression, the disorder often shows itself in the form of unhealthy psychological processes. It turns out that some of those thought processes — specifically, self-blame and rumination — can lead to symptoms people might not realize are signs of depression.

And that's too bad, because the result is that we misunderstand those who are suffering from it, sometimes including ourselves. Freud, wrong as he was about a lot of things, pointed out that depression was different from simple sadness because it was associated with guilt, and today psychologists consider self-blame a key symptom of depression. When something bad happens, depressed people tend to blame themselves, and see it as a reflection of their self-worth as a whole.

An example researchers sometimes use is thinking that if you fail at a sports match, it means you're a total failure. What's weird is that this only applies to yourself — depressed people don't usually assign blame to others the same way. Turns out the unusual amount of guilt — and only applying it to yourself — might come from two regions of the brain that don't activate together the way they should.

In a 2012 study, researchers scanned the brains of 25 people who'd previously had depression and 22 people who didn't. When the people who'd never been depressed read descriptions of themselves doing something wrong, it activated both the part of their brain associated with guilt and the part that deals with morality and what's socially appropriate. In people who'd been depressed, that second part wasn't activated as strongly.

This was a small study, so we can't draw too many conclusions from it. But based on the results, the authors suggested that people who are more prone to depression don't get an accurate picture of what they did wrong, so they just feel guilty about everything. So that's one unhealthy thought pattern that can cause symptoms beyond plain old sadness or apathy.

Another is rumination. And it's a big one. Rumination is, basically, brooding — usually unintentionally.

Part of problem-solving involves analyzing the factors surrounding the problem, and that applies to negative emotional experiences, too. But rumination takes that way too far. It's getting stuck thinking about everything that led to and resulted from a negative experience, and it's strongly linked to both depression and anxiety.

It can also explain some of the less straightforward signs of depression, like memory problems. Of all the symptoms of depression, memory problems might seem the most surprising, because we tend to classify depression as emotional, and memory as more a mechanical part of the mind. But this is just a false dichotomy, that's not how the brain works.

Depressive disorders often include problems with cognitive function: the ability to clearly understand, process, and respond to information. And researchers think that has a lot to do with rumination eating up all your brainpower. You need cognitive resources to pay attention and remember things, and when people with depression are using those resources to brood, they have trouble redirecting them toward the task at hand.

They end up struggling with episodic memory, which is the recollection of specific events that happened to you, and working memory, which is how you hold onto information that you're currently using to process other information. Those are both pretty important! It becomes a vicious cycle, where the only way to break out of this pattern of rumination is to redirect your mental resources toward something that might make you feel better.

But that's exactly what rumination makes it so much harder to do! So people get stuck. Rumination can also lead to another common symptom of depression: anger and irritability, which appears in more than half of patients, although it's only used to diagnose the disorder in kids and teens.

But it can be a sign of particularly severe depression. At its core, rumination is a coping strategy people use to help regulate their emotions — it's just not a very good one. Instead of feeling better, when people brood on something that made them angry, they tend to spend more time … angry.

We still have more to learn about how unhealthy thought patterns like self-blame and rumination contribute to depression and its symptoms. But as we study them, we're discovering that they can explain a lot. And there's some good news here, too.

Self-blame may have to do with brain regions not activating the way they should, and rumination may feel like getting stuck. But researchers point out that unhealthy thought patterns like these are exactly what psychotherapy is meant to help with. Cognitive behavioral therapy, especially, is designed to identify the connections between thought patterns and behaviors, and reshape those thought patterns in a healthier way.

So yes, depression is a complicated, difficult illness. But there are therapies and treatments that can help. And recognizing the different ways depression manifests itself is an important step toward getting that help and doing this research.

Thanks for watching this episode of SciShow Psych. If you're interested in learning more about the science of depression, you can check out our video on common misconceptions about antidepressants. And don't forget to subscribe! [♪ OUTRO ].