Individual differences underlying susceptibility to addiction: Role for the endogenous oxytocin system

Substantial individual differences exist in basal oxytocin levels and reactivity of the system. The endogenous oxytocin system changes and matures over time as part of normal development. This paper postulates that individual factors and early external influences (i.e. parenting, stress and illness) affect the developing endogenous oxytocin system and its connectivity with other systems affecting oxytocin levels and alter responsiveness of the oxytocin system. When an individual is exposed to alcohol and drugs in adolescence, these individual differences in the endogenous oxytocin system can affect reward seeking and drug use behaviour. It is postulated that for example drug use may be more rewarding resulting in an escalation of use; an imbalance between natural and drug rewards could affect the attractiveness of excessive drug use; individuals may be more susceptible to stress-induced relapse to drug use.