On the question of whether "mental illnesses" are diseases or simply arise from behaviour (as discussed in comments below). My personal theory is that they are

On the question of whether "mental illnesses" are diseases or simply arise from behaviour (as discussed in comments below). My personal theory is that they are neither. Most mental illnesses are actually social illnesses. That is: we've engineered a society that is hostile to a set of (perfectly healthy) behavioural phenotypes. It's already known that within different cultures and environments, those with certain "mental illnesses" fare better or worse. Nobody with cancer "thrives" depending on their cultural environment, but if you're an engineer on the Autistic spectrum, you might. If you're an artist with ADHD, you thrive. Even schizophrenics do well in some cultural environments. Force someone who was born bipolar, or with attention deficit in a society that demands them to sit in an office (or classroom) for 8-10 hours a day, every day, at the same time, and focus on the same thing, and sure... they will become "disordered". Just as most people would go crazy in the sort of fluid or even chaotic environment that those people would thrive in. * * * A Thought Experiment: Imagine you were born into a world where the predominant behavioural phenotype is bipolar or ADHD: there are no set work hours, only goal posts. Teams work in frenzies of 24 - 36 sleepless hours, followed by a day or two off. Maybe one week there's no work, but then for a month it's crunch time. Some days you work nights, some days you work early in the morning. Everyone wears many hats, otherwise they'd become bored; and you're expected to do the same. To everyone, this is just the way things are. To you... your stress levels are through the roof, you can't focus in such an environment, yet everyone is wondering what's this guy's problem? Why does he have such a hard time working in a fluid environment? Why does he need special treatment and be given evenly-distributed work at predictable hours? Clearly there's some sort of disorder going on here. So you read some pamphlets and you see a Doctor... maybe there is something wrong with you, you think. It's so natural for everyone else, yet you can barely function in society. Luckily for you, there is "help": the standard treatment for Rigid Thought Pattern Disorder is a 50mc dose of LSD every three days. Sure, it makes you not quite feel like yourself, but look at how much you've been improving since you started treatment! You no longer sleep regular hours like you used to, you're no longer displaying Rigid Thought Patterns. Just give the treatment some time and you'll get used to the side effects. * * * I have no science to back this up of course. Just something I think about sometimes at 3 in the morning while I'm having a particularly productive night... (Yes it's likely that this would be a rather inefficient world in many ways, so it makes sense for the predominant behavioural phenotype to be more predictable and stable. The point being, in both cases the non-neurotypical individual can have a positive impact if they're not regarded as deficient, but if instead we see these differences in behaviour the same way we see differences in height, strength, or any other physical attribute.)