Throughout history, a variety of factors have been considered in trying to explain and understand the causes of drug addiction. One thing is clear from this research, no single factor can be said to cause addiction. People become addicted due to a combination of factors.
Genetic Factors: It appears that some people may inherit a genetic vulnerability to the addictive properties of drugs. Studies have shown, for example, that the risk of substance use disorders is higher for people who have close relatives with substance use disorders. However, when one examines the causes of drug addiction, many people who have a genetic vulnerability to addiction do not become addicted and others who do not have a family history of addiction do become addicted.
How do the drugs communicate with the brain: All substances with addictive potential stimulate the release of dopamine, a chemical in the brain that is associated with reward and pleasure. Eating, drinking, and having sex are all natural activities that release dopamine. Substance use, however, brings a flood of dopamine which alters the chemistry of the brain. The brain, in turn, tries to keep things in balance by developing a tolerance. This means that more and more of the drug is needed to bring feelings of pleasure.