This was needed elsewhere, so a quick important distinction:
From Greek:
• psychosis: mind-condition
• in psychosis: temporarily disconnected from reality
• psychopathy: mind-suffering or - disease
• a psychopath: a person with a persistent antisocial personality disorder
they’re unrelated
Hallucinations and delusions are an easy mental illness to mark the barrier on. When you no longer treat them as your imagination running away, and treat them as real it is psychosis.
Notably a lot of people only get them when they hit psychosis.
One of the patterns of psychosis is additional symptoms appearing that were not part of the psychiatric issues before.
Schizo-effective disorder is among the most common to appear under psychosis.