PSYCHOACTIVE SUBSTANCE USE DISORDERS:
Drug: It is derived from a French word 'drogue'. A medical substance used in the treatment of disease. (Taber's Dictionary).
'Drug dependencelsubstance dependence: A state psychic, sometimes also physical, resulting from taking a drug characterized by behavioural and other responses that always include a compulsion to take a drug on a continuous or periodic basis in order to experience its psychic effects and sometimes to avoid the discomfort of its absence. Tolerance may or may not be present.
Physical dependence: Physical dependence occurs when the drug user's body becomes so accustomed to a particular drug that slhe can fundtion normally only if the drug is present in the body chemistry.
Psychic Dependence: Psychic or psychological dependence occurs when the drug is central to a person's thought, emotions and activities. It is difficult for the person to stop thinking of the drug which causes intense craving for it and its effect. .
Tolerance: It is 'an adaptive state characterized by a diminished response to the same quantity of a drug or by the fact that a larger dose is required to produce the same degree of pharmacodynamic effect'. (WHO Bulletin, 1965)
Withdrawal: It is an organic mental disorder following cessation (stopping) or reduction in the intake of a substance such as alcohol, an opioid, amphetamines, tobacco or sedatives that have previously been used regularly to induce intoxication.