Considerable confusion exists regarding the nature of addiction. The most common misunderstanding is that addiction refers to a state of physical dependence on a drug whereby discontinuing drug intake produces a withdrawal syndrome consisting of various somatic disturbances. Addiction is better defined as a behavioral syndrome where drug procurement and use seem to dominate the individual s motivation and where the normal constraints on behavior are largely ineffective. This condition may or may not be accompanied by the development of physical dependence on the drug. The distinguishing feature of the condition commonly referred to as addiction is the ability of the drug to dominate the individual s behavior, regardless of whether physical dependence is also produced by the drug.
Many factors influence a person s initial drug use.
Personality characteristics, peer pressure, and psychological stress can all contribute to the early stage of drug abuse. These factors are less important as drug use continues and the person repeatedly experiences the potent pharmacological effects of the drug. This chemical action, which stimulates certain brain systems, produces the addiction, while other psychological and social factors become less and less important in influencing the individual s behavior. When the pharmacological action of a drug dominates the individual s behavior and the normal psychological and social control of behavior is no longer effective, the addiction is fully developed. Specialized brain systems have evolved to ensure survival of the species.