Understanding the science of addiction begins with a look at the reward pathway in the brain. The reward pathway evolved to encourage behaviors that enhance personal, societal and species survival. Therefore, this pathway rewards activities like eating, forming social groups, pair bonding and raising children.
Chemicals such as dopamine and serotonin surge along nerve pathways in the brain, making people feel relaxed and happy. These rewards make people feel good when they are doing things that are likely to enhance their well-being and that of the people around them.
However, drugs such as amphetamines and cocaine subvert the reward system. They give users incentives for self-destructive behaviors and encourage bad choices. Over time, continued drug use prompted by these immediate rewards changes the structure of the brain, resulting in a tenacious addiction.
Dopamine is a feel-good chemical. Its release rewards people when they spend time with loved ones, when they achieve a goal or when they are rested and well-fed. Drugs, however, promote the presence of dopamine, releasing it when users get high. Instead of being encouraged through constructive behavior, users are intensely rewarded for buying drugs.
In spite of the crushing power of drugs, not everyone who tries them becomes addicted. Nevertheless, as much as half of someone's risk of becoming an addict may be inherited, according to the National Institute on Drug Abuse. Many studies have investigated the roles of genetics and environment in determining who becomes addicted and how they should be treated.
A tendency toward addiction does run in some families. However, not everyone who has parents or grandparents with substance abuse problems becomes an addict or even has addictive tendencies. The inheritance of addiction is complex. Some people might inherit a tendency toward taking risks. Others might inherit a tendency to break down certain chemicals at atypical speeds. Attention deficit hyperactivity disorder is believed to be heritable, and people with ADHD are at higher risk of becoming addicts.
Each person lives in many environments. Within the family, conflict and discord may promote addiction. Divorce itself does not. Instead, it may reduce the chance of addiction if it reduces the amount of disruption a child must experience.
Disorganized communities seem to promote addiction, while communities with cohesion and a strong sense of place do not.
Academic failure is associated with drug use. So is belonging to a peer group that uses drugs. In fact, having friends who use illicit drugs is one of the strongest risk factors for addiction.
On the other hand, belonging and identity are protective against drug addiction, assuming that the groups a person belongs to do not contain drug users. People who feel rewarded for friendships, successes, achievements and spending pleasant time with loved ones are much less likely to become addicted to drugs.