How Does Depression Affect The Brain? What Happens?

Depression can cause bad feelings, overreactions, a drop in intelligence, and a general feeling of being down. These symptoms can be mild to severe, with suicidal thoughts showing up in the worst cases. All of these, though, are just signs of depression. The causes of depression and the most important things to learn about it have more to do with the changes depression can make to the brain.

What Happens to the Brain During Depression?

When a person is depressed, chemicals flood the brain and matter is lost. This causes the brain to change in many ways. In this section, we talk about the three most important things that happen to a person’s brain when they are depressed.

Brain Shrinkage

One of the most common changes is brain shrinkage. The duration and severity of the depression will affect the shrinkage.

This shrinking is caused by a cortisol imbalance, also known as the stress hormone. Depression makes the hippocampus make more cortisol, which slows the growth of new neurons in the brain. The loss of function of a part of the brain is closely linked to the shrinking of its circuits.

High cortisol levels cause other parts of the brain to shrink, but the amygdala grows. Since the amygdala controls emotions, this could lead to trouble sleeping, mood swings, and other problems with hormones. Bipolar disorder is also associated with having an amygdala that is too big.

Brain Inflammation

Brain inflammation is linked to major depression. Experts don’t know for sure if depression causes brain inflammation or if it’s the other way around, but researchers think the two are linked. Studies have shown that people with depression for more than ten years have 30% more inflammation in their brains than people with depression for less than ten years.

Since inflammation in the brain kills neurons, it can cause a lot of problems. When neurons and neurotransmitters die, the brain may shrink and lose its ability to change as the person ages. This is called neuroplasticity. The inability to form new connections between neurons and the release of new neurotransmitters causes cognitive impairment.


Researchers haven’t found a clear link yet, but people with major depression may take in less oxygen. The most popular theory is that depression changes the way you breathe, which can lead to a lack of oxygen or hypoxia.

Brain function can be impaired by even mild hypoxia. People with mild hypoxia have trouble making decisions, lose motor skills, and forget things. If you don’t get enough oxygen for a long time, it can cause inflammation and damage to brain cells.

Changes in behavior and thought occur when communication between different parts of the brain is disrupted. Some of the most important changes that show how depressed someone feels are as given below:

  • Increase in anxiety
  • Memory problems
  • Guilt
  • Hopelessness
  • Trouble thinking straight
  • Overreaction to situation
  • Sleep issues
  • Negative emotions
  • Changed speech patterns
  • Appetite issues

Are the changes going to last?

Researchers are still looking into the duration of clinical depression and its anticipated effects. But research shows that the effects may last for a long time.

Clinical depression might affect the brain, but the effects of depression that lasts for a long time or keeps coming back can be especially bad. There is mounting evidence that the brain alterations associated with depression (such as those in the hippocampus) can have a cumulative effect over time, suggesting that they may be persistent years after an initial depressive episode even in patients with major depressive disorder.

People with depression also have more translocator proteins in their bodies. Scientists have discovered a connection between these neurochemicals and brain inflammation,

  • Damage or kill brain cells
  • stop new ones from coming up.
  • stop you from thinking
  • Accelerate brain aging

Temporary reductions in new growth and a rise in aging, even if levels eventually recover to normal, may nevertheless have lasting effects. Persistent depression almost certainly results in noticeable, lasting brain changes.

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