Marijuana is extracted from the hemp plant Cannabis sativa, the resin of which contains the psychoactive constituents. The drug is most commonly smoked either in a pipe or in cigarette called a joint. The drug can also be ingested in drinks or in foods, such. The dose of active drug a person receives varies considerably because of the variability in potency of preparations from the hemp plant.

Preparations of the drug come in three grades, identified by Indian names. The cheapest and least potent grade, called bhang, is derived from the cut tops of uncultivated plants and has low resin content. Much of the marijuana smoked is of this grade. Ganja, the second grade is obtained from the flowering tops and leaves of carefully selected cultivated plants, and it has a higher quality and quantity of resin than bhang. More cannabis of this strength is now available. The third and highest grade, called charas, is made largely from the resin itself, obtained from the tops of mature plants, only this version is properly called hashish. Many derivatives of cannabinol have been prepared. The active constituents of the resin are various isomers of tetrahydrocannabinol the most important as an intoxicant is THC. Recently, a specific receptor for the cannabinoids has been identified, and its gene has been cloned.

The psychological effects of cannabis include euphoria, oneiroid states, calmness, and drowsiness. Intoxication occurs almost immediately after smoking marijuana, peaks within 30 minutes, and lasts for two to four hours. The effects from ingestion continue for 5 to12 hours. The intoxication heightens sensitivity to external stimuli, reveals details that would ordinarily be overlooked, makes colors seem brighter and richer, and subjectively enhances the appreciation of art and music. Time seems to slow dawn, and more seems to happen in each moment. There is an increase in appetite, redness of eyes, increased pulse rate, and dry mouth.

Curiously, there is often a splitting of consciousness, while smokers are experiencing the high; they are objective observers of their own intoxication. They may have paranoid thoughts and, at the same time, laugh at them.

If very high blood levels of the active ingredients of marijuana are attained, the person may experience some strange sensations. These effects can include distorted perception of body parts, spatial and temporal distortions, increased sensitivity to sound, heightened suggestibility, and deep sense of awareness. Although marijuana can also cause anxiety and paranoid reactions.

There are some indications of tolerance and a mild withdrawal reaction on stopping its consumption after frequent use of high doses. However, there is no clinical evidence that withdrawal symptoms or a need to increase the dose presents any serious problem to users. Craving or difficulty in withdrawal can occur as part of a pattern of pathological use. An abstinence syndrome of sleep disturbances, nausea, vomiting, tremors, and sweating has been observed.

Amotivational syndrome: Chronic heavy use has been said to cause an amotivational syndrome characterized by the person�s unwillingness to persist at a task, be it school, work or any activity that requires prolonged attention the person becomes apathetic and anergic, usually gains weight, and has been described as slothful. Long term users of the potent versions of cannabis are passive, unproductive, and lacking in ambition. This finding suggests that chronic use of the drug in its strong forms may have debilitating effects, as does prolonged heavy drinking.

Chronic marijuana use may cause various syndromes, which are described below.

Psychosis: Hemp insanity or cannabis psychosis has been reported mainly in India. It is described as a prolonged psychosis caused mainly by chronic heavy use of the drug. This phenomenon, however, has not been reported among marijuana smokers in the United States. Several studies of large sample populations of marijuana users have found no evidence of a cannabis psychosis produced Renovo in well-integrated, stable persons.

It is characterized by false belief developing shortly after use. Associated features are listed as marked anxiety, emotional lability, depersonalization, and possible loss of memory for the episode. This is rare and remits within a day but may persist for a few days.

Delirium: A syndrome of delirium can result when marijuana is taken in large enough doses. The delirium is characterized by disturbed consciousness, restlessness, confusion, disorientation, apprehension, illusions, and hallucinations. Cannabis-induced delirium is rare although it may be becoming more common with the availability of increasingly potent forms of the drug.

Anxiety: Cannabis users may also suffer short-lived, acute anxiety states, sometimes accompained by paranoid thoughts. The anxiety may become so intense as to be called panic. Although uncommon, panic is probably the most frequent adverse reaction to the moderate use of smoked marijuana. The sufferer may believe that body-image distortions mean illness or possible death or may interpret psychological changes induced by the drug as an indication of loss of sanity. Rarely does the panic become incapacitating when it does, it usually lasts for a relatively short time. The likelihood of panic varies directly with the dose and inversely with the user�s experience, thus the most vulnerable persons are the inexperienced users who inadvertently, because they lack familiarity with the drug, take a large dose that produces sensory and bodily changes for which they are unprepared. Simple reassurance is the best treatment.

Flashback: One rather rare reaction to cannabis is the flashback, a spontaneous recurrence of drug symptoms when not intoxicated. Some reports suggest that this effect may occur in marijuana users even without prior use of any other drug.

Physical Effects: The main physical effects are reddening of the eyes a dose-related increase in heart rate. The ratio of lethal effective dose is estimated to be in the range of 20,000 to 40,000 to 1.There is no adequately documented case3 of fatality in the human being.

Chronic marijuana use has adverse effects on the lungs, partly because it contains the same carcinogenic hydrocarbons as tobacco smoke does. Chronic users are at increased risk of respiratory disease & lung cancer. Other adverse physical effects of marijuana, however, are much less well documented.

There have been studies of cerebral atrophy, fits, hormonal defects, brain damage, impairment of immune system, effect on testosterone & the menstrual cycle.

There is no specific treatment for cannabis abuse. Treatment program should include education; behavioral modification; individual; family & group psychotherapy, pharmacological interventions. If the person uses the substance for anxiety reduction or for alleviation of depression, an antianxiety agent or an antidepressant should bee considered as a substitution therapy. For an acute anxiety reaction to the drug, diazepam is useful. Accidental ingestion by children is treated with gastric emptying & activated charcoal.

Education people about the motivational syndrome & the possible complications may dissuade some from using the drug in the first place.