Peter van Ruitenbeek, assistant professor at our Department, gave a talk about what addiction actually entails beyond the conventional narrative focused on the acute increase in dopamine levels that substances of abuse cause.
Here is a summary of his interesting presentation hosted by the 2022 edition of the Pleasure, Art and Science Festival 2022.
In popular media, the stereotypical addicted person is portrayed as someone who can only get pleasure from that to which he or she is addicted, for example to drugs. This state is usually explained by the idea that drugs cause pleasure by enormously increasing dopamine in the reward system of the brain (e.g. nucleus accumbens as pleasure centre). When the drug is absent there is a shortage of dopamine, which reduces the pleasure in everyday life. The continuous use of the drugs is then explained by trying to avoid these reductions in pleasure (withdrawal symptoms).
I argue that dopamine is not strongly related to pleasure, neither is the brain reward system (nucleus accumbens). For example, increasing levels of dopamine does not seem to induce any pleasure. Conversely, blocking the functioning of the dopamine system does not prevent cocaine from inducing euphoria. Second, I show that withdrawal symptoms cannot be a main motivator for drug use. For a long time, studies have shown that going through withdrawal by means of institutionalisation alone is overwhelmingly insufficient to stop the addiction. Consequently, any theory explaining addiction in terms of pleasure has very little basis.
However, dopamine and the reward system do play a very prominent role in developing and maintaining addiction. How can we explain this? Results from a large number of studies now point in the direction of dopamine playing a role in learning about what things or behaviours result in pleasure such that can be sought out in the future. For example, dopamine enables you to learn that a certain candy tastes sweet, but dopamine is not the enjoyment of the sweet taste itself. Second, dopamine and the reward system play a very important role in motivation to seek out the things or behaviour that will bring pleasure. It is why you get up out of your chair to walk to the cupboard to get that piece of candy.
These findings bring about a different way of thinking about addiction. Instead of considering malfunctioning pleasure systems as the core problem of addiction, we should focus on motivation and the learning mechanisms in the brain.