Substance-Induced Psychosis: Diagnostic Challenges and Phenomenological Insights

Abstract

Substance-induced psychosis (SIP) is an increasingly prevalent and complex condition that presents significant diagnostic and therapeutic challenges. With the rising use of novel psychoactive substances (NPSs) and potent traditional compounds like cannabis and cocaine, particularly among adolescents and young adults, understanding the mechanisms and clinical manifestations of SIP has become more critical. This review examines the psychopathological characteristics of SIP, focusing on the differentiation between substance-induced and primary psychotic disorders. Two key concepts are explored: Gaëtan de Clérambault’s “mental automatism”, which describes involuntary thoughts and sensations experienced as alien to the self, and the “twilight state” of consciousness, characterized by an altered perception of space, time, and social interaction. These phenomena are essential in understanding how substance use triggers psychotic processes and how SIP differs from endogenous psychosis. This review also highlights the clinical and phenomenological distinctions between acute and chronic psychotic episodes, emphasizing the potential transition from SIP to persistent psychosis, especially in cases of frequent and potent substance use. It discusses the diagnostic and therapeutic importance of recognizing specific psychopathological markers such as alterations in temporality, spatiality, and intersubjectivity. Understanding these features enhances the clinician’s ability to accurately differentiate SIP from primary psychotic disorders, which is often complicated by the widespread use of substances that may not be easily detectable in standard tests. This review concludes by advocating for a clinical–phenomenological approach to empathically engage with patients and provide a solid diagnostic framework for improved treatment strategies, particularly for those at risk of transitioning to chronic psychosis.