Probably at least a few of those sub-disorders are actually nutritional deficiencies. We have this myth (perpetuated by MDs who have ZERO training in nutrition) that we don't have nutritional deficiencies in America. In fact, the American diet is horrible, and we all know it. B12 deficiencies are common (which is one of the reasons shots are often prescribed), as are deficiencies in magnesium, along with numerous other vitamins and minerals. Since the mid 90's, the FDA has mandated "enrichment" of foods, but the forms of the additives are NOT the biologically active forms, so some people have trouble processing them. For instance, MTHFR gene defects are common (my wife and I have different ones, and she has the really bad C677T defect), making folic acid (which is artificial) range from useless to poisonous to some people who need to take methylfolate instead. In fact, since the mid 90's a lot of people have reported declines in their health, which may be correlated with that FDA mandate (although without a more complete study, we have to assume this is anecdotal and COULD be correlated more strongly with something else).
Anyhow, my point is that many psychological disorders, such as bipolarism, are associated with vitamin deficiencies. If you look at the symptoms lists of various B vitamin deficiencies, for instance, you'll see that it is already established what kinds of psychological effects can occur in cases of "extreme" deficiencies. If we can get past the idea that nobody in America can have extreme vitamin deficiencies (you can have plenty of some vitamin but still be anemic if you can't USE it in that form), then we can start treating mental disorders using carefully controlled diets and supplement schedules. I'm sure it won't work on everyone, but it would be insane to not try it in place of loading people up on antipsychotics because the "doctors" are mental hospitals have no fucking clue about nutrition.
And just to reinforce, folic acid is basically poison to about 10% of humans. Different vegetables contain methylfolate and/or folinic acid, NOT folic acid. Defects in the genes that code enzymes that convert folinic acid and folic acid are more common than most food allergies, making this a serious problem!
One interesting side-effect of this is the proliferation of the bad genes. People with homozygous C677T mutation have about a 30% conversion rate from folic acid to methylfolate. (Meanwhile the unconverted folic acid itself interferes with the methylation cycle.) If a woman gets pregnant and takes folic acid in large quantities (which is what doctors instruct), the fetus will take all of the methylfolate, and the mother will get very sick. Meanwhile the fetus will be allowed to develop when otherwise it would have naturally aborted due to an inability on its own to convert folinic acid that you get from food. As a result, we have more people born with this defect, while people in the FDA and the medical profession are too ignorant of the consequences to deal with them properly. Mind you, if they were to take more methylfolate, the viability of this defect would increase, but at least the mothers wouldn't get as sick.