There is no consensus on what the root causes of major depression are; there are probably many causes. Dopamine can definitely affect happiness, but giving a ch

There is no consensus on what the root causes of major depression are; there are probably many causes. Dopamine can definitely affect happiness, but giving a chronically depressed patient L-DOPA once per day generally won't treat their depression for very long. On that same note, people with ADHD are often missing dopamine in many parts of the brain, but ADHD isn't necessarily correlated strongly with depression. And quick dopamine-releasing drugs like amphetamine (Adderall/Dexedrine/Vyvanse), or dopamine reuptake inhibitors like methylphenidate (Ritalin/Concerta), tend not to be great treatments for depression, either. They can be a short term treatment by giving you a euphoric high the first few times you take them, or if you take big doses, but that's not a good long term treatment strategy.