From experience, the brain is basically processing inputs (perceptions) and then outputs thoughts or actions. The issue is when either the inputs are distorted

From experience, the brain is basically processing inputs (perceptions) and then outputs thoughts or actions. The issue is when either the inputs are distorted or the processing is being interfered with. Caffeine for instance can induce psychosis in some people by indirectly effecting dopaminergic response (via its action on adenosine receptors). Other drugs can do the same. (we all know that marijuana can induce "bad trips"). But really, everything we perceive are inputs that can startup brain work. And some inputs are stored in memory. One thing that can work is metathinking, i.e. awareness of one's own brain processing (observing one thoughts and bodily sensations for instance, basically meditation). That's the processing part but one should also avoid distortions by avoiding psychoactive substances (alcohol, tea or coffee included). Psychiatry doesn't work too well because it is underfunded and is stuck on alleviating symptoms. Psychiatrists are the first to admit that they don't really know how things work. There are some weird stuff that can be discovered at the brain level once someone monitors their own thoughts/ brain chatter but this is somewhat esoteric. That's the realm of yogis, qigong practionners etc but there is too much folklore and I won't delve into that. Doesn't seem scientifically proven although I have my own experiences.