I think it has as much to do with population as it does with mental health. When a population reaches its carrying capacity and then continues to overflow, as seen with China, India, Japan, and now the USA, problems begin to manifest in their own negative and often violent ways. There really is no answer to population control at this point though, and so that means there is absolutely no answer to what's going on in terms of "mental health", because that kind of quantity has already been breached.
I truly believe we are just going to have to live with a more fucked up world where more and more countries become penetrated with problems and danger, until the full capacity of the Earth comes to halt and the population can dwindle a bit. We are truly on the cusp of the highest rapid expansion of people the world has ever seen and we can neither sustain that many more, nor afford (or want) to lose that many on a regular schedule basis.
It's just a bunch of shit and I hope everyone realizes that about our shit world by now. ^_^