Question

Explain the positive reward model of drug abuse. What evidence supports this model of addiction?

Answer 1

• The positive reward/reinforcement model focuses on the ability of many abused drugs to serve as positively reinforcing stimuli. This means that consuming the drug strengthens whatever preceding behavior was performed by the organism. The rewarding and reinforcing properties of abused drugs have been demonstrated in numerous animal studies using several different experimental techniques.
• An experimental animal such as a rat, mouse, or monkey is fitted with an intravenous catheter attached to a drug-filled syringe. When the animal performs an operant response such as pressing a lever, a pump is briefly activated that slightly depresses the plunger of the syringe and delivers a small dose of the drug directly into the subject’s bloodstream.
• This is directly analogous to a drug addict giving himself an intravenous drug injection. The ability of animals to learn and maintain the lever-pressing response or for addicts to learn and maintain drug-seeking and drug-using behaviors means that the drug is acting as a reinforcer, just as food is a reinforcer for those who are hungry.
• At the neurobiologjcal level, researchers have discovered that drugs of abuse engage (and in a sense “hijack”) a system within the brain that’s intimately involved in natural rewards. This certainly helps us understand why such drugs can be so powerfully reinforcing. At the subjective level, drugs of abuse are often reported to cause euphoria, which means a feeling of well-being or elevated mood.
• In this model, the euphoria produced by initial drug use serves as reinforcement for further use. When the user attempts to abstain from taking the drug, she suffers from a craving that can be conceptualized as an overwhelming desire to re-experience drug-induced euphoria. This craving then leads to relapse.