Srinagar, June 27 -- What is Drug Abuse and Drug Addiction ? Drug abuse is a chronic or habitual use of any chemical substance to alter states of body or mind for other than medically warranted purposes. Drug abuse is relatively an old term encompassing the use of drugs for psychotropic (affecting brain function) rather than medical purposes. Among the most common psychotropic drugs are opiates (opium, morphine, and heroin), hallucinogens (LSD, mescaline, and psilocybin), barbiturates, cocaine, amphetamines, tranquilizers, and cannabis. Alcohol and tobacco are also sometimes classified as drugs. The term 'drug abuse' is normally applied to excessive and addictive use of drugs as such drugs can have severe physiological and psychological, ...