Many people do not understand how or why people become addicted to drugs. It is often incorrectly assumed that substance use abusers lack morals or willpower and that they can stop using drugs simply by choosing to change their behavior. Drug addiction is a complex disease that requires more than good intentions or a strong will to defeat.
Addiction is a chronic, often relapsing brain disease that causes compulsive drug seeking and use, despite harmful consequences to the addicted individual and to those around him or her. Although the initial decision to take drugs is voluntary for most people, the brain changes that occur over time challenge an addicted person’s self-control and hamper his or her ability to resist intense impulses to take drugs.
Similar to other chronic, relapsing diseases, such as diabetes, asthma, or heart disease, drug addiction can be managed successfully. And, as with other chronic diseases, it is not uncommon for a person to relapse and begin abusing drugs again. Relapse, however, does not signal treatment failure—rather, it indicates that treatment should be reinstated or adjusted or an alternative treatment is needed to help the individual regain control and recover. - (Source: National Council on Alcoholism and Drug Dependence)
People with substance abuse issues may act differently than they are normally accustomed. Behaviors include:
(Source: National Institute on Drug Abuse (NIH))