Substance: Nature and type of substance(s); Route of administration

Individual: Psychologic predisposition; Constitutional genetic and biochemical characteristics

Environment: Family: history and emotional climate; Culture; Friends

The Addictive Process
    The length of time that passes from casual use to dependence is a function of many factors related to the host (individual), agent (drug), and environment as explained by public model. The type of drug, frequency of use, amount of drug used, route of administration, health of the user, and support for drug use (enabling) from friends or family members affect the development of an addiction. The typical progression of drug use begins with cigarettes and alcohol and moves to marijuana, cocaine, hallucinogens, and opiates. Repeated IV use of heroin or cocaine can produce addiction in a few days or weeks, although it generally takes years and heavy periods of drinking to develop an addiction to alcohol. The process of addiction may be thought of a cycle that is reinforcing. Interruptions in the cycle occur because of inaccessibility of the substance, decrease in the amount used, attempts to control drug use, or entry into treatment. These factors may precipitate withdrawal symptoms in the physically dependent individual. Substance use may be initiated to ward off withdrawal symptoms and leads to rapid reinstatement of the cycle, or relapse.