The cerebral cortex contains about 9 million nerve cells, and is responsible for consciousness and co-ordination of external and internal stimuli. The highly organized cerebrum delineates humans from all other living organisms. Removal of the entire cerebrum in the frog produces no behavioral changes. Whereas, the human being becomes totally blind, extensively paralyzed, and soon dies. Concerning human behavior, the most important regions of the brain involved are the limbic system and the reticular formation. The limbic system controls emotions involving both mental and physical elements. The memory process, learning, and motivational aspects of behavior are all governed by the limbic system. The reticular formation is the "bridge" portion of the CNS which controls the inflow and out flow of impulses, and is responsible for alertness, arousal, sleep and attention, maintaining a state of consciousness in man. The activity and function of the nervous system can be modified by a  wide range of chemicals or drugs having either a direct effect on nerve cells, or by producing changes in the levels of chemical transmitters (neurotransmitters) in the system.

In ancient times agents given to patients with mental disorders were limited to herbal potions that consisted mostly of inactive ingredients. Major advances were made in the early 1950s with the introduction of reserpine and chlorpromazine. These two compounds provided a chemical basis for the treatment of psychosis, a major mental disorder. Later, a number of drugs followed which altered behavior, and today the most effective tool available to control mental disorders is appropriate drug therapy. This has reduced the period of hospitalization for the mentally ill.

Drugs which modify behavior are termed as psychopharmacological agents and include: (a) antipsychotics; (b) antidepressants; (c) antimanics; and (d) anti-anxiety agents. Lastly the psychotomimetics or hallucinogens, which have no medical uses, but are dangerous drugs of abuse.

Schizophrenia is a major mental disorder, which ruins the most useful years of one's life. "Cures" are rare. The antipsychotics have a profound effect on the ANS, hypothalamus, and the reticular formation. These drugs have a wide margin of safety, but adverse reactions include lethargy, involuntary muscle movements, endocrinal disorders, and depression of the bone marrow.

The antidepressants (psychic energizers) have been an outstanding success in modern psychopharmacology. They are used to treat depression, which is an affective disorder afflicting many individuals. Depression is the most frequently unrecognized emotional disorder, which can be effectively controlled by appropriate therapy.

The anti anxiety agents, which include the benzodizepines, are used to treat anxiety neuroses by producing calmness and muscle relaxation. In addition they produce euphoria, i.e., a false feeling of well being. These drugs produce tolerance, psychological and physical dependence. Thus, they are dangerous addictive drugs, very likely to be misused, particularly by the youth, more so in this modern competitive and stressful world, with a hectic lifestyle.

Many drugs today are taken by man for the pleasant effects they produce.

Such drug use leads to serious socioeconomic problems like drug abuse or drug dependence. The long list includes alcohol, tobacco, morphine, opium, codeine, heroin, brown sugar, smack, barbiturates, methaqualone, diazepam, alprazolam, amphetamine, cocaine, and hallucinogens like LSD, mescaline and cannabis.

Classically drug addiction (dependence) is characterized by: (i) an overpowering desire to continue taking the drug, and to obtain it by any means, i.e., habituation; (ii) a tendency to increase the amount taken, i.e., tolerance; and (iii) a psychic, and at times physical dependence on the effects of the drug. In physical dependence there is a biochemical and physiological adaptation of the tissues to the new chemical environment following the repeated use of the drug. Thus, upon withdrawal of the drug a serious abnormal cellular  response is produced known as the withdrawal syndrome, which is different for each drug, and may be life threatening.

Let us consider how drug abuse begins?

Usually a person tries a drug, likes what happens, and continues to use it a few more times, and ultimately becomes addicted to it. Later, their continuous use produces harmful effects, a.go., alcoholism produces progressive deterioration of physical and mental health, internal bleeding, liver and brain damage and psychosis.

Alcohol contaminated with methyl alcohol causes blindness; LSD can lead to psychosis, and dreadful thought disorders; Cannabis alters the thought process, and can lead to birth defects when consumed by pregnant women; Chronic use of tobacco is linked to coronary heart disease and lung cancer; and so on. De-addiction of the patient is difficult, and needs hospitalization, psychotherapy, supportive treatment, and rehabilitation. All these measures are time consuming, tedious, and expensive to afford.

In conclusion, today many potent and effective drugs are available, and can be effectively employed in the treatment of the mentally ill. But some of them may be misused by man to enjoy the pleasant effects they produce, leading to drug addiction. Control of addiction warrants serious attention of the medical profession, social welfare organizations, and the government which must clamp a stricter drug control in the country.