Can Substance-Induced Psychoses (SIP) Shed Light on the Paradigm of Schizophrenia?

Abstract

Substance-induced psychoses (SIP) may offer a useful vantage point for exploring mechanisms underlying psychotic disorders and for examining the phenomenological specificities of schizophrenia. Clinical observations suggest that a clinically relevant subset of patients does not fully recover after an episode of substance-induced psychosis, raising the hypothesis of more persistent psychotic trajectories that may differ from both acute SIP and primary psychotic disorders (PPD). In this context, the proposal of Substance-Related Exogenous Psychosis (SREP) situates exogenous psychoses as conditions related to, yet not fully overlapping with, schizophrenia. Drawing on the tradition of classical psychopathology, from Bonhoeffer’s exogenous model to the concept of lysergic psychoma, and integrating it with recent research on self-disorders, the hypothesis emerges that substance-induced psychoses may function as heuristic phenomenological models useful for exploring the genesis of psychotic phenomena. Examination of ipseity through the EASE interview suggest similarities between SIP and PPD, but also significant differences: SIP are characterized by more superficial and transient alterations of the self, whereas schizophrenia involves deeper and structurally embedded disturbances. From this perspective, the phenomenological comparison of schizophrenia, SIP, and SREP may help delineate with greater precision which dimensions of self-experience are compromised across these psychotic conditions. This conceptual framework is intended as a hypothesis-generating perspective, which may guide future longitudinal studies integrating phenomenology and substance-related mechanisms to refine the boundaries between acute SIP, persistent SIP/SREP trajectories, and schizophrenia spectrum disorders.