@invisiblegorilla, I think this is a valuable piece. I ran a class on exactly this issue this summer. There are several resources from that listed on the Second Session, Afternoon sections on this page
https://sites.google.com/site/gswnaturalscience2016/home/neuroscience
It might be helpful to draw the distinction between a disease (which has a known cause and possibly treatments) and a syndrome, which is just a pattern of symptoms. AIDS was a syndrome; HIV is a disease caused by a virus. Everything in the current edition of the DSM is a syndrome. Things like schizophrenia will become diseases when we learn more, just like Huntington's and Parkinson's are diseases because we know what causes them. Towards that end, the NIH is hoping to replace the DSM with another scheme that focuses more on cause and effect, but as this paper shows, it is very much a work in progress.
http://journal.frontiersin.org/article/10.3389/fnhum.2016.00309/full
Thanks for your response, plotbot2015. The problem with your HIV comparison is that, unlike schizophrenia, there are laboratory tests to determine whether someone is afflicted by HIV. Before you can study the etiology of a particular ailment, you have to demonstrate that it is both valid and can be reliably diagnosed. Neither of which is the case for schizophrenia.
Yes, you are correct. At this moment in time, there's no test. In the early 1980s, there was no test for HIV, either. That's why they called it a syndrome.
https://www.aids.gov/hiv-aids-basics/hiv-aids-101/aids-timeline/
But we'll get there, eventually. I realize that is not much comfort to the people suffering now.