Addiction is a state of dependence caused by the habitual use of drugs, alcohol, or other substances. It is characterised by uncontrolled craving, tolerance, and symptoms of withdrawal when access is denied. Habitual use produces changes in body chemistry and treatment must be geared to a gradual reduction in dosage. Initially, only opium and its derivatives (morphine, heroin, codeine) were recognised as addictive, but many other drugs, whether therapeutic (such as tranquillisers) or recreational (such as cocaine and alcohol), are now known to be addictive. Research points to a genetic predisposition to addiction; environment and psychological make-up are other factors. Although physical addiction always has a psychological element, not all psychological dependence is accompanied by physical dependence. A carefully controlled withdrawal programme can reverse the chemical changes of habituation. A cure is difficult because of the many other factors contributing to addiction. Research Addiction