The American Society of Addiction Medicine (ASAM) defines addiction as a chronic disease of brain reward, motivation, and memory. People can become addicted to many different substances including alcohol, tobacco, prescription opioids and stimulant medications, marijuana, heroin, hallucinogens (e.g., PCP, LSD), inhalants (e.g., paint thinner, glue), cocaine, and methamphetamines.
“Addiction” is a word used to describe the behavioral manifestation of a substance use disorder, characterized by a pattern of behaviors that impair a person’s ability to function effectively. Substance use disorders can affect learning, judgment, decision-making, memory, and behavior.
People develop substance use disorders because certain types of substances affect areas of the brain associated with reward (called the “reward circuit”). These substances trigger the release of dopamine, a chemical responsible for causing pleasant feelings. This pleasant effects of substances on the brain motivates people to repeatedly seek them out (positive reinforcement). With repeated use, people can build a tolerance to specific substances as the brain adapts to them. When people build a tolerance to a substance, they need to take greater doses to experience the same benefits, and when the body needs the substance to create those sensations, not using it may cause unpleasant symptoms or withdrawal (negative reinforcement).
Treatment for substance use disorders is based on the type of substance and the severity of use, and often requires a combination of medication and behavioral therapy. Treatment works best when it is tailored to an individual person’s needs. Treatment for addiction is similar to treatment for other chronic conditions. It is common for people recovering from addiction to experience relapse, and it is important to remember that treatment and recovery are ongoing processes.
More information is available from the National Institute on Drug Abuse.