@Pookah83
Is it not at all clear that all mental illnesses arise from the brain or some effect on it? The various disorders are definitely different from each other but I mainly object to the idea that mental disorders aren't neurological. What are they then? Moral failings?
Why would you say moral failings? That seems to make for quite a narrow set of possibilities.
Neurological disorders are damage or malfunctioning of the brain and nervous system.
We really don't know that all things classed as mental illness fall under that definition. This idea that people had that depression, for example, was caused by a chemical imbalance, was never very solidly founded.
There is some reason to think, from the evidence of brain scans, that psychiatric and neurological disorders aren't really the same kind of thing. What that means isn't clear and may be different for different problems.
However, what is clear is that some disorders, like schizophrenia, seem to behave like we'd expect in terms of an illness with a clear physiological basis. They seem to look similar, and follow a similar course, and affect a similar group of people, everywhere. Whereas others, like anorexia, may appear in some places but not others, or may seem to have a totally different origin, or manifest very differently, or effect a different group of people.