Adverse Psychosocial Relationships and Substance Use Disorder: a Narrative Review

Abstract

Introduction: Substance abuse is recognized as a brain disorder that primarily affects two systems: the motivation-reward system and the defense system. The former is responsible for modulating behaviors aimed at obtaining pleasurable reinforcers such as social interactions and food. Frequent drug use diminishes the response of this system, leading to tolerance to hedonic effects. The defense system, oriented towards safeguarding the individual’s physical integrity, responds to threatening stimuli by generating sensations of fear or anxiety and displays an antifragile nature. Objective: to describe the interaction between these systems, which is altered by frequent drug use. This leads to a diminished response of the motivation-reward system and an increased response of the defense system, as well as the effect of adverse social interactions between the two. Method: recent scientific articles published in PubMed were browsed and critically reviewed; both human and animal studies were included. Discussion and conclusions: adverse social interactions, such as neglectful parenting and child abuse, promote an allostatic load and strengthen the antifragile nature of the defense system, favoring and maintaining drug consumption. In animal models, it has been observed that maternal care deprivation in the early days of life leads to maladaptive behaviors in adulthood and increased alcohol consumption. Similarly, subordinate animals consume more drugs than their dominant counterparts. These findings suggest a complex relationship between early adverse experiences, the development of the reward and defense systems, and vulnerability to addiction.