When you go through something traumatic, your brain triggers a “flight-or-fight” response. Most people recover on their own, but some get posttraumatic stress disorder. PTSD causes your amygdala — the part of the brain that controls emotions — to be overactive. And it lowers activity in your prefrontal cortex, a decision-making area. It can also shrink your hippocampus, which forms memories.
Depression doesn’t affect just your mood. The disorder can change your brain. Experts say it lessens activity in some brain areas, including your prefrontal lobes, which are involved with things like reasoning, personality, and judgment. One study found that people who were depressed for more than a decade had about 30% more brain inflammation. This may lead to brain cell loss, which would make memory problems and dementia more likely.
Experts think ADHD symptoms, like inattention and hyperactivity, come from brain differences. Research shows there’s less gray and white matter in people with ADHD. Certain areas also take longer to take shape. What’s more, networks of nerve cells work differently. These networks send signals in the brain, and they play a role in attention and focus.