Posted: Nov 19, 2010 3:19 am
A "disease" is just a state of unhealthiness. All mental disorders are diseases, but this doesn't mean that it's a biological problem. The term "mental illness/disease" was changed to "mental disorder" specifically because this is a common mistake that people made - thinking that the cause of the problem was necessarily biological. And "psychosis" is just a vague term that applies to a number of vastly different disorders that only have a few things in common; namely hallucinations, delusions and lack of insight, and that these things are "significant". So psychosis is just a state of disconnect from reality that is more extreme than would be normally expected, and the cause can be biological or environmental (or both).
And even if it were a physical problem in the brain that results in abnormal functioning, this doesn't even mean we should conclude that medication is the best solution. Given what we know about autism, we can be reasonably sure that the cause is genetic but the only treatment we have for it (and an incredibly successful one at that) is behavioral therapy.