Drug dependence occurs when you need one or more drugs to function. The American Psychiatric Association (APA) used to distinguish between dependence and abuse. Abuse was considered the mild or early phase of inappropriate drug use that led to dependence. People viewed dependence as a more severe problem than abuse.
Drug dependence differs from drug abuse in three ways. First, drug dependence consists of clearly measurable periods of tolerance and withdrawal, whereas drug abuse sets the occasion for tolerance and withdrawal. Abuse means there exist early warning signs of life impairment predictive of physical and psychological dependence. Adults arrested for driving under the influence of alcohol, for instance, often face fears that their uncontrolled drinking may result in fatal vehicular accidents. Second, drug-dependent users show marked cognitive, behavioral, and psychomotor retardation in their daily activities. Drug abusers, however, may or may not suffer apparent cognitive, behavioral, or psychomotor malfunctioning; they may mask intoxication symptoms by performing their jobs and vehicular operations adequately and interacting normally with their families. Third, the phenomenon of withdrawal syndrome applies only to drug dependence. Drug abusers are episodic and not routine users, and their consumptive rates are variable; intermittent and lesser quantity users build resistance to adverse cognitive and visceral repercussions and only suffer mild or no side effects after abrupt cessation of desired substances