How drug addictions form and how they affect the dopaminergic pathways in the brain

Abstract

Dopamine gets a lot of attention from the public for being the pleasure neurotransmitter, but it does so much more, including regulating motivation, reward learning, cognition, memory, mood, and movement to name a few. In reward learning, if the activity is better than expected, then dopamine is released, but if the activity doesn’t meet expectations, then less dopamine is released, helping us learn what actions to focus on. Although highly adaptive, or perhaps because it is, this complex reward system can be hijacked by drugs that mimic dopamine, giving users more-than-natural amounts of pleasure. As addictive stimulants, such as cocaine enter the body and brain, they give intense feelings of euphoria, much more than anticipated, and users become addicted. As their brains and dopamine pathways adapt to the dopamine fluctuations, they become more dependent on these drugs to live and experience joy. Eventually, the brain adapts and develops tolerance, decreasing the amount of dopamine released by doing the pleasurable action. This leads to less pleasure release in other actions and more cravings for this sole source of relief. In this research paper, we will discuss how drug addictions progress and become less controllable, and the neurological changes that ensue. It will detail how and why addictions develop. I will also look at how a goal can become a habit and then an addiction, through damage to the brain areas that control motivation and habit formation.