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Depression and your brain

There are lots of theories about what causes depression. Let’s explore what happens in your brain when you feel depressed.

Teen girl looking sad, with a brain behind her

Theory number 1: Depression could be related to your stress response and saving energy

Depression and your stress response

When you experience stress, your brain has an automatic ‘stress response’. Usually this is your ‘fight/flight/freeze’ response. This evolved to help you in danger. 

In theory, when you experience a lot of stress, or long lasting stress, your brain might go into depression mode for three reasons:

  • Depression could be an alternate stress response. Rather than fight/flight/freeze, some theories suggest depression could be a different way for you to withdraw from a stressful environment you can’t escape.
  • Feeling anxious or stressed uses a lot of energy. It’s not possible to run on high energy forever! Because depression is technically a way to save energy, feeling depressed might be a way to help recharge your batteries.
  • Your brain might interpret long-term stress as a famine. Depression might be designed to help you conserve energy when food is scarce or you are at risk of starvation – kind of like hibernating.

Check out these articles to learn more about the brain!

“One of the main symptoms of feeling depressed or having depression is a lack of balance between the parts of your brain that control your ability to regulate your emotions and motivate yourself or achieve goals.”

– Amanda, Kids Helpline Counsellor

Theory number 2: Depression could be related to problem-solving

Negative thoughts might help us with problem-solving

Many people who feel depressed experience ‘negative rumination' (overthinking about negative things). But this overthinking about bad stuff could actually help us solve important, complex problems!

According to this theory, we might experience changes in our brain or body that stop us getting distracted, so we can focus on our stressful problems. 

These changes include some familiar symptoms of depression – like low energy and no interest in things we used to enjoy.
If this theory is right, these periods of ‘negative rumination’ were evolved to last a short time, and once we solved a problem, we would start to feel better.

But modern life is very complicated! If people are trying to deal with overwhelming problems they can’t solve for a long period of time, they might get ‘stuck’ and feel depressed long-term. 

Theory number 3: Depression could be an immune response to inflammation

Firstly… what’s an immune response?

Your immune response is how your body defends itself against bacteria, viruses, and other stuff it perceives as harmful.

Your body’s immune response to illness or injury is called ‘inflammation’.

Now think about the last time you were sick with a cold or flu. Besides the flu symptoms, like a runny nose or cough, you probably experienced some of these…

  • Feeling down/flat mood
  • No interest in usual interests or hobbies
  • Brain fog
  • Lack of energy
  • Tiredness or fatigue
  • Sleeping lots
  • Changes in appetite
  • Withdrawing from friends or social activities

Looks a bit like depression, doesn’t it?

There is actually a scientific theory that inflammation may play a role in depressive symptoms.

Inflammation and depression

Your body responding to inflammation mimics how it might respond to a contagious virus. This might explain some symptoms of depression, like feeling tired and withdrawing from social activities. These symptoms might:

Help you get rest, so you can fight off disease

Prevent the spread of an illness if it’s contagious

Avoid stress, because stress can make your immune system less effective

Stop you from catching other illnesses when your immune system is already weakened

“Illness, injury, stress and eating unhealthy foods are some of the things that can increase inflammation in the body.”

– Amanda, Kids Helpline Counsellor

What else might cause depression?

There are many more theories about depression. There’s a lot we still don’t know! Other things that might cause or play a role in depression include:

  • your personality
  • your genes
  • your previous experiences
  • your learned behaviours
  • your environment
  • …and many more!

These factors affect different people differently.

Why are theories important?

The three theories above might help explain why depression exists. It’s possible that all three theories are wrong or right in different ways or for different people.

Theories have limitations. Things can be linked but not cause each other. Or depression may cause inflammation, rather than the other way around. Or, there could even be a third factor that causes both things that we don’t know about yet.

Figuring out the cause of depression is important because it determines prevention and treatment.

If you’re feeling depressed, we’re here for you.

Even when you don’t know what to say or how to express what you’re going through, contact us and we’ll support you through it.

Give us a call, start a WebChat or send us an email anytime, for any reason.

This content was last reviewed 23/04/2020

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