The Neural Mechanisms of Reward and Addiction : A Review of the Role of Dopamine in Cocaine Addiction

Abstract: Cocaine is known for its severe addictive properties and still, there is no effective treatment for cocaine addiction. Cocaine is a powerful chemical substance. It enters the brain rapidly and cause abnormal high levels of dopamine. Dopamine is found to be the neural correlate for reward. Addictive drugs such as cocaine are reported to be rewarding and initially generate many dimensions of positive effects. However, repeated cocaine use are associated with both structural and functional abnormalities in several brain regions, especially in areas responsible for voluntary control. Loss of control gives way to compulsive consumption and craving for more cocaine stimulation. These neuronal changes and negative symptoms tend to occur gradually, while the tolerance increases. The addicted individual has to enhance the dose in order to obtain the desired effect, which is; becoming physically dependent of a substance. Also, dysregulation of reward circuitries causes decreased sensitivity to natural rewards leading to increased interest in cocaine-related reward stimulation. The abstinence usually last for long time, even years, after self-administration, which makes addicts highly sensitive to relapse. Up to date, effective therapeutic interventions and pharmacological treatments are limited. Neurostimulation techniques such as DBS have shown positive results in regulation of dopaminergic excitability. Though, more research in the complexity of dopamine and mesolimbic areas is well needed, in order to better understand the neural basis of cocaine addiction and be able to offer evidence-based treatments. This thesis will provide an overview of the neuronal impact of cocaine on the dopaminergic reward circuitries in the brain.