According to the National Council on Alcoholism and Drug Dependence (NCADD), most drugs overstimulate the brain’s neurotransmitter called dopamine, a chemical that nerve cells release so that the brain can send signals. The brain has multiple dopamine pathways. One of those pathways is known to have a distinct effect on the brain’s reward and pleasure centers. By taking drugs, this system becomes overstimulated.
According to the National Institute on Drug Abuse (NIDA), drugs tap into the brain’s communication system. Drug use and abuse can impede the brain’s ability to send, receive, and process information normally.
Over time, the brain adapts to an overstimulated dopamine system by producing less dopamine or lower the number of overall receptors, making it more difficult to function normally without the drugs. The NCADD also states that long-term drug use can affect regions of the brain used for judgment, learning, memory, and behavior.
Perhaps NIDA summarized the long-term effects of drugs on the brain best, “Drug addiction erodes a person’s self-control and ability to make sound decisions, while producing intense impulses to take drugs.”