I nearly went tot he doc for something as I was depressed. My mate said try a few things first, one of which was run around the lake in Khon Kaen 3 times a week, which I did and the depression went.
Buy a dog, mind you it's depressing when they die, mine just did, after 12 years.
If it's clinical, see a doc, fk your brother and others who are ignorant.