How does addiction affect the brain?
Addiction is sometimes (misleadingly) referred to as a ‘brain disease’. This biomedical concept emerged because frequent drug use can alter brain function of the limbic system, which regulates memory, motivation, and emotions. This includes the feeling of ‘reward’ – our experience of pleasure, motivating us to engage in activities vital for human survival, such as eating and sex. These changes in turn can lead to ongoing drug use.
At a basic level, people choose to use a drug repeatedly because it makes them feel good. These feelings are produced by neurotransmitters in the brain such as dopamine, serotonin and noradrenaline. Drug use also affects the brain’s production of these chemicals and the levels that are available for normal processes, such as thinking, feeling, and relating to people. Because of these neurological changes, a person may feel compelled to continue using drugs to feel normal. Stopping may lead to withdrawal (with unpleasant physical or emotional symptoms) and drug cravings. Consequently, people may continue using a drug not just to experience those rewarding feelings, but to avoid the unpleasant symptoms of withdrawal.
Addiction is sometimes referred to as a ‘chronic relapsing condition’ because people may be susceptible to returning (relapsing) to drug use after a period of abstinence. The risk of relapse is partly due to the biological and psychological changes produced by long-term drug use, but the social environment also plays a large part. Someone exposed to a stressful event such as family breakdown, loss of work, or an accident may go back to drug use as a way to cope with stress. Alternatively, running into an old friend may provide an unexpected drug use opportunity.
Activities, places, objects, or sensations that were associated with a person’s drug use, like going to a bar or even hearing a piece of music, can serve as a cue for using the drug again. Memories that are linked to drug use can be a trigger for further use, especially if they have strong emotional content.