Early life adversity, oxytocin system alterations, and addiction vulnerability: a narrative review

Prenatal and early-life stress (ELS) reprogram the hypothalamic-pituitary-adrenal (HPA) axis and intersecting neurotransmitter circuits, producing long-lasting alterations in the oxytocin (OXT) system. Accumulating clinical and pre-clinical evidence links these neurobiological changes to increased vulnerability for addiction. This narrative review synthesizes recent (2005-2025) literature on: how ELS disrupts the maturation of OXT neurons and receptors; the consequent cross-talk with glutamatergic, GABAergic and HPA-peptide signaling that biases the mesocorticolimbic reward network toward addiction; and the emerging therapeutic potential of exogenous OXT. Rodent models of maternal separation, limited bedding or gestational restraint reveal OXT-system hypofunction-marked by OXTR hyper-methylation, reduced hypothalamic OXT mRNA and diminished receptor density in the amygdala and nucleus accumbens. Parallel human studies report analogous epigenetic signatures in cord blood and peripheral tissues of stress-exposed offspring. Functionally, OXT curtails presynaptic glutamate release in the ventral tegmental area, augments tonic GABA_A currents in medial prefrontal cortex, and attenuates AVP-driven CRH output, thereby normalizing reward- and stress-circuit activity. These adaptations translate into lower drug intake, reduced cue-induced reinstatement and blunted withdrawal anxiety in animal models. Early clinical trials corroborate these findings; intranasal OXT reduces craving and withdrawal severity, with the largest effect sizes observed in individuals exhibiting low baseline plasma OXT or high OXTR methylation. It can be concluded that prenatal stress is a potent risk factor for later substance use disorders (SUDs), in part via durable disruption of the developing OXT system. Targeted OXT pharmacotherapy-alone or combined with stress-axis modulators-holds promise for a precision-medicine approach to addiction, particularly in ELS-exposed subpopulations.