Etiological theories of addiction: A comprehensive update on neurobiological, genetic and behavioural vulnerability

• Drug addiction is an undesirable aspect of modern society.
• Multiple brain systems, genetic factors, sociocultural context and impulsivity may underlie vulnerability to drug addiction.
• Human ability to develop new drugs may be an evolutionary indicator that will ensure our increasing dependence on drugs.
• Advanced multidisciplinary researches are required to tackle the issue of drug addiction from multiple perspectives.

Currently, about 246 million people around the world have used an illicit drug. The reasons for this use are multiple: e.g. to augment the sensation of pleasure or to reduce the withdrawal and other aversive effects of a given substance. This raises the problem of addiction, which remains a disease of modern society. This review offers a comprehensive update of the different theories about the etiology of addictive behaviors with emphasis on the neurobiological, environmental, psychopathological, behavioural and genetic aspects of addictions, discussed from an evolutionary perspective. The main conclusion of this review is that vulnerability to drug addiction suggests an interaction between many brain systems (including the reward, decision-making, serotonergic, oxytocin, interoceptive insula, CRF, norepinephrine, dynorphin/KOR, orexin and vasopressin systems), genetic predisposition, sociocultural context, impulsivity and drugs types. Further advances in biological and psychological science are needed to address the problems of addiction at its roots.