Investigating Theories of Addiction: Part 1

Investigating Theories of Addiction

In this article series, we will investigate many theories of what addiction is and why it affects certain people. For our purposes, addiction is substance use disorder, and I will generally refer to it as such except to clarify and when quoting from the work of others. For well over a century, people have been developing theories around the causes of addictive behavior. In the first half of the 20th century, the argument was largely fought over whether addictions to alcohol and drugs were a moral failing or moral disease. In the modern context, different theories of addiction are more focused on the science of the brain, the body, and metabolic processes. I will try to discuss a different theory in each article of this series, and today I want to look at incentive-sensitization theory or IST. Incentive-sensitization theory (IST) concerns the connection between the phenomenon of “wanting” and the related phenomenon of “liking”. We can all understand what it means to want or to like something, but in the context of a substance use disorder, these two ideas take on added significance, particularly “wanting”. For this article, I used research that was published by The Royal Society London. 

The Incentive-sensitization theory (IST) posits that drug and alcohol use can cause hypersensitivity, as they call it, and if rendered hypersensitive, systems in the brain cause pathological incentive motivation (‘wanting’) for drugs. This theory was developed using mice and other animals, but many scientists believe that the theory could explain similar processes in humans. The theory is only tested for potentially addictive drugs, which would be drugs that are already understood to be problematic for some people, i.e. alcohol, cocaine, and fentanyl. I have discussed on this blog before how the brain is changed, sometimes for a long period of time, by substance use disorder and behaviors that follow from substance use disorder. Over the last 20 years, science has worked to better understand the mechanisms of those changes. We know that the reward system is highly affected by substance use disorder, and IST seems to account for those changes. As the researchers explain, the “sensitization” in IST is sensitization or hypersensitivity to the incentive motivational effects of drugs and drug-associated stimuli (Robinson & Berridge 1993). This hypersensitivity eventually causes major changes in behavior and priorities in the subject. We can understand that idea in this way: a person would not lie or steal to get drugs before they have become addicted to them, the drug use must come first to some extent, in order to reorder the priorities of the person. Any person who has suffered from these types of behavior changes will almost certainly need medical intervention to recover. One of the best drug rehabs in Florida can be reached at the phone number on this website, and anyone who calls will be connected with a counselor to discuss treatment options. 

As stated in the article, “The central thesis of the incentive sensitization theory (IST) of addiction is that repeated exposure to potentially addictive drugs can, in susceptible individuals and under particular circumstances, persistently change brain cells and circuits that normally regulate the attribution of incentive salience to stimuli, a psychological process involved in motivated behaviour.” That is the scientific explanation for the reordering of priorities seen in addicts, as understood through IST, the theory we have been discussing today. The journal article I researched goes on to explain that in the context of IST, the extreme focus on drugs and alcohol that happens to people with substance use disorder happens through a process called “learning”. In this context, learning is the hypersensitivity that happens over time, and focuses undue attention on drugs and alcohol, rather than things like family or work and home life. One can imagine that the effects of this refocusing are terrible, and that is in line with the immense damage we see in the lives of people with substance use disorder. If you or a loved one is suffering from substance use disorder, and this intense focus on drugs or alcohol sounds familiar to you, please call us at Florida Springs Wellness and Recovery Center for more information about the best drug rehab in Florida or anywhere else. We are available in some form 24 hours a day and 7 days a week, and Florida Springs has many different treatment levels, including inpatient, outpatient, and telemedicine. 

By T.A. Cannon (Contact me at



Robinson, T. E., & Berridge, K. C. (2008). Review. The incentive sensitization theory of addiction: some current issues. Philosophical transactions of the Royal Society of London. Series B, Biological Sciences, 363(1507), 3137–3146.