Depression isn’t just feeling sad—it’s something happening in your brain. It can feel like your mind is working against you, and that’s hard to understand. Scientists say it’s caused by problems with brain chemicals, changes in how your brain adapts, and stress that won’t go away. Let’s break it down with real studies.
Problems with Brain Chemicals: Serotonin and Dopamine
Your mood depends on two brain chemicals: serotonin and dopamine. Serotonin keeps you calm and happy. Dopamine makes you want to do things and enjoy them. In depression, these chemicals get out of balance. A study in The American Journal of Psychiatry (aan het Rot et al., 2009) showed that lowering serotonin in healthy people makes them feel sad and tired. They did this with something called "tryptophan depletion."
What is tryptophan depletion? Tryptophan is like a building block your body uses to make serotonin. If you don’t have enough tryptophan (like from eating less of certain foods or in experiments), your brain makes less serotonin, and you feel down. It’s like taking sugar out of a cookie recipe—it doesn’t turn out right.
Another study in Biological Psychiatry (Dunlop & Nemeroff, 2007) found that people with depression have less dopamine in a brain area tied to pleasure, which is why nothing feels fun.
Neuroplasticity: The Brain That Changes
Your brain can change and learn new things—this is called neuroplasticity. But in depression, those changes can hurt more than help. A study in The Journal of Neuroscience (Duman & Monteggia, 2006) showed that long-term stress stops a brain part (the hippocampus) from making new cells, making you feel hopeless. But a study in Nature Reviews Neuroscience (Duman et al., 2016) found that depression medicines, like ones that boost serotonin, help the brain grow new connections again.
Exercise or talking to a therapist can also fix your brain, according to Translational Psychiatry (Erickson et al., 2011).
Stress That Sticks Around
When you’re stressed all the time, your body makes a hormone called cortisol. A study in Psychoneuroendocrinology (McEwen, 2004) showed that too much cortisol hurts your brain and makes you feel more scared or sad. Research in JAMA Psychiatry (Hammen, 2005) says stress from things like money troubles or fights raises your chance of depression.
The American Psychiatric Association (APA, 2013) explains that this stress also makes it harder to think straight, keeping you stuck in bad thoughts.
How to Get Better
Depression happens because brain chemicals get messy, stress makes it worse, and your brain changes in tough ways. But there’s hope: medicines, exercise, and therapy can fix those changes. Knowing it’s about your brain, not just you, is the first step to feeling better.
Comments