Incentive Salience Can Motivate Destructive Behavior
There is a lot of debate about what exactly motivates people to act in certain ways. In particular, why is it that people sometimes engage in self-destructive behaviors such as addiction. Addicts may lose family, friends, and possessions, yet still they continue to abuse whatever substance they are addicted to. They may claim that they want to stop but feel powerless in the face of their addictive behavior. Even those individuals who manage to escape the abuse and build a good life in recovery may later relapse back to their destructive habits. How can this happen?
Incentive salience is a type of motivation created in the brain because it has developed an association between a certain stimuli and reward. In the case of addiction this stimuli will be whatever drug the individual is using. Incentive salience is a far greater incentive than merely liking something. In fact it can happen that the individual no longer likes the drug but feels compelled to take it due to incentive salience. This compulsion to use is driven by unconscious forces. This association between the drug and reward can last even though the individual has been in recovery for many years.
If susceptible individuals are repeatedly exposed to addictive substances it can change the way their brain operates. These individual become hypersensitive to the drug and this means that the substance can now stimulate neurobehavioral systems significantly more than before. The outcome of this change is that people start to receive increasing amounts of pleasure when they use alcohol or drugs. This leads to incentive salience and an increasing preconscious desire for the substance. As the individual takes more of the substance it only leads to more sensitization. The preconscious desire becomes a conscious obsession. This sounds like what Dr. William Silkworth described as the "phenomenon of craving" in the chapter titled The Doctor's Opinion in the AA Big Book.
Simply stated, our natural reward system becomes compromised and requires the continued use of drugs to experience pleasure. Increased and extended drug use causes damage to our brain's frontal lobes, allowing environmental cues (people, places, things, thoughts, feelings, behaviors) to override our pre-frontal cortex and sets up
this incentive salience. The adolescent brain is particularly susceptible because it is not yet fully developed.
These brain changes persist long after the stop of substance use. I have heard it said that addiction progresses on Interstate 5, while recovery progresses on side streets. The more damage done to our frontal lobes can make us more likely to relapse and more quickly to relapse. I am continually impressed by how modern science actually validates the simple explanations in the AA Big Book, which was published in 1939.