Biology of addiction

It is unknown why an individual becomes addicted to drugs. Substance abuse is typified by a wide variety of use patterns and variation in individual responses. Behavioral psychology teaches that if something either increases the individual's sense of pleasure or decreases his or her discomfort, then the individual is likely to repeat the behavior. Evidence has suggested that abusers report a sense of pleasure when they use substances because of the ability of the substance to stimulate the release of neurotransmitters known to be used by the brain's pleasure system. This article provides an overview of the substance-related disorders, including their definition in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).