SUBSTANCE-RELATED AND ADDICTIVE DISORDERS
The core feature of a substance use disorder is a cluster of cognitive, behavioural and physical symptoms indicating that a person continues to use a specific substance despite having significant substance-related problems. Research shows that individuals with these disorders have underlying changes in brain circuits, leading to behavioural effects such as intense cravings for the substance and repeated relapses of substance use. All substances of abuse taken in excess directly activate the brain's reward system, which is involved in the reinforcement of these behaviours. These substances produce such an intense activation of the reward system that normal activities necessary for everyday functioning may be neglected.
In addition to substance-related disorders, these conditions also include behavioural addictions such as gambling. These behaviours activate the brain’s reward circuitry in a way similar to the effects of substances of abuse.