Doesnt it seem like mental disorders are heavily dependent on the society you live in. Usually one of the main and most important things that are required in order to say you have a mental disorder is that it must cause distress on a daily basis. So the best example of this would be ADHD. If we lived in an Agrarian society where most people farmed would ADHD really cause them distress on a daily basis? Unless its EXTREMELY severe it seems like it would have little to no distress as you are constantly doing physical tasks and arent sitting in a class room for hours needing to listen to someone. Also it begs the question how common are things like depression, is it mostly a problem because of modern society? if you had a huge family and lived in a village where people all supported each other doing physical tasks all day would depression be extremely rare?