Medium range cognitive impairment (MeRCI) hypothesis for psychosis formation: Evidence from epidemiological studies and recent molecular genetic developments

摘要

Psychotic episodes are a collection of heterogeneous mental states in which patients experience delusions and hallucinations. Delusions are classically defined as "false beliefs based on incorrect inferences about external reality that are firmly sustained despite what almost everyone else believes,"1 and hallucinations are perceptions without objects. Although psychotic episodes are characterized by several other symptoms (e.g., disordered thinking, disorganized behaviours), delusions and hallucinations are the most salient and puzzling aspects of the psychotic experience. The terms that are often used to define psychosis are philosophically very loaded. What are beliefs and external reality and how we make sound inferences have all been and still are some of the most difficult questions in the history of philosophy and science. For some, reality is out there; it does not need to be defined. The expression "losing touch with reality," often used to describe psychosis, is grounded in this conception of reality. For others, reality is coextensive to being human and having expectations, desires and fears.