Heavy substance use (SU) and substance use disorders (SUD) have complex etiologies and often severe consequences. Certain personality traits have been associated with an increased risk for SU(D), but far less is known about personality changes related to SU(D). This review aims to synthesize the existing literature on this research question. A systematic literature search was conducted from November 2022 to February 2023 in PubMed, EbscoHost, and Web of Science. Peer-reviewed original papers on SU(D)-related personality changes were included. Of 55 included studies, 38 were observational population-based studies and 17 were intervention studies. Overall, personality and SU measures, samples, study designs, and statistical approaches were highly heterogenous. In observational studies, higher SU was most consistently related to increases in impulsivity-related traits and (less so) neuroticism, while interventions in the context of SU(D) were mostly associated with increases in conscientiousness and self-efficacy and lasting decreases in neuroticism. Findings for traits related to extraversion, openness, conscientiousness, and agreeableness were mixed and depended on SU measure and age. Studies on bidirectional associations suggest that personality and SU(D) both influence each other over time. Due to their strong association with SU(D), impulsivity-related traits may be important target points for interventions. Future work may investigate the mechanisms underlying personality changes related to SU(D), distinguishing substance-specific effects from general SU(D)-related processes like withdrawal, craving, and loss of control. Furthermore, more research is needed to examine whether SU(D)-related personality changes vary by developmental stage and clinical features (e.g. initial use, onset, remission, and relapse).
Keywords: addiction; drugs; misuse; personality development; personality traits.