If compulsive drug-seeking and drug-taking behavior are often not motivated by either the desire to obtain pleasure or by the desire to relieve withdrawal, then what motivates addictive behavior in these instances? Why do addicts compulsively seek drugs? We have attempted to address these questions by proposing the concept of “incentive-sensitization”.3,30 Tire basic thesis of the incentive-sensitization view of addiction can be summarized in four points.
(1) Potentially addictive drugs share the ability to produce long-lasting adaptations in neural systems (i.e. addictive drugs change the brain).
(2) The brain systems that are changed include those normally involved in the process of incentive motivation and reward.
(3) The critical neuroadaptations for addiction render these brain reward systems hypersensitive (“sensitized”) to drugs and drug- associated stimuli.
(4) The brain systems that are sensitized do not mediate the pleasurable or euphoric effects of drugs (drug “liking”), but instead they mediate a subcomponent of reward we have termed incentive salience or
“wanting”. It is the psychological process of incentive salience specifically that is responsible for instrumental drug-seeking and drug-taking behavior (drug “wanting”).
We have hypothesized that when sensitized, this incentive salience process produces compulsive patterns of drug-seeking behavior. Through associative learning the enhanced incentive value becomes focused specifically on drug-related stimuli, leading to more and more compulsive patterns of drug-seeking and drugtaking behavior. Furthermore, the persistence of neural sensitization is hypothesized to leave addicts susceptible to relapse even long after the discontinuation of drug use. In die following we will review some of the evidence for incentive-sensitization, and elaborate some of the major features of this view of addiction.
References
Robinson, Terry E., and Kent C. Berridge. 2000. “The psychology and neurobiology of addiction: An incentive-sensitization view.” Addiction 95 (8s2): 91–117. doi:10.1046/j.1360-0443.95.8s2.19.x.