Marijuana (or weed, herb, ganja, reefer, and pot, among a dizzying list of current nicknames) has been around throughout human history -- some reports cite its use in Chinese medicine as early as 2727 B.C. It became prominent in U.S. culture in the 1960s, when San Francisco's "Summer of Love" movement brought the drug to the public eye. According to the National Institute on Drug Abuse (NIDA), it's the most commonly used illegal drug in the United States today. In 2005, more than 25 million people used marijuana.

Marijuana comes from the Cannabis sativa plant, which harvesters have put to an array of uses over its 4,700-year history. These include making clothing and paper from the plant's fibers, oils such as varnish, and medicine for a laundry list of ailments. When used as a drug (for illegal or medical purposes), the chemical delta-9-tetrahydrocannabinol, or THC, is marijuana's key ingredient. In its most common form, marijuana for recreational use is a mixture of flowers, stems, and seeds, greenish in color, resembling oregano or other chopped herbs. In its more dense and resinous form, the substance is called hashish.

Most commonly, the dried leaves are rolled up into a cigarette, or joint, and smoked. Users also smoke it using special vaporizers, small pipes, or more elaborate water pipes (known as bongs), or in the form of "blunts" -- hollowed-out cigars stuffed with marijuana. Sometimes marijuana is baked into food such as brownies, or drunk as a tea.

Once ingested, THC enters the bloodstream and is carried to different parts of the body, including the brain, where it binds to cannabinoid receptors on specific nerve cells and triggers the release of dopamine, the brain's "pleasure chemical." This is what creates the drug's intoxicating effect. Smoking marijuana can bring about an altered mental state within seconds; when consumed as food, it may take up to an hour. Marijuana's hallmark sign is its dreamy euphoria. The "stoned" user is typically relaxed, or "laid back," and may become giggly or experience heightened auditory and visual sensations. (Popular culture has certified entire genres of films and music as "stoner movies" and "stoner bands" for their appeal to people using marijuana.) Other effects can include short-term memory problems ("What was I saying again?") and an inability to concentrate.

Physically, the drug hinders your reaction time, hampers your coordination, and distorts your perception, all of which make driving a very bad idea. Marijuana often induces serious hunger cravings (popularly known as "the munchies"). It dries out your mouth ("cotton mouth"), accelerates your heart rate, and expands the blood vessels in your eyes (producing the telltale bloodshot look). The strength and concentration of the drug and whether it's mixed with another substance can intensify some or all of these effects.

A "bad trip"

If a user becomes too high, he may grow anxious or paranoid, or even hallucinate, especially if he has ingested hashish in food. He may also experience abnormal heart rhythms; cold, trembling hands; nausea and vomiting; and/or a general sense of uneasiness. Some claim that the marijuana on the market these days is stronger than its predecessors (John Walters, director of the Office of National Drug Control Policy, labels today's marijuana "Pot 2.0") which could make adverse reactions more likely.

Dangerous driving

Driving under the influence of marijuana can be treacherous -- due to its effect on reaction time, concentration, and coordination, driving "high" can cause accidents. In the United States, about six to 11 percent of fatal accident victims test positive for THC. (In many of these cases, alcohol was also detected.)

Respiratory problems

Smoking marijuana may cause some of the same respiratory problems that smoking cigarettes does, such as coughing, increased phlegm production, and a greater likelihood of lung infections. It's unclear whether there is a link between smoking marijuana and the development of lung cancer. However, many of the chemicals that are found in cigarette smoke are also found in marijuana smoke, so it is likely that marijuana may have many toxic effects similar to those of cigarettes. The use of vaporizers -- which deliver a fine mist to the airways rather than smoke -- may reduce the risk of respiratory problems.

Social problems

As with any drug, frequent use may cause people to withdraw from friends and family. Prolonged use can also have a negative impact on schoolwork and job performance, according to a report by the National Institute on Drug Abuse (NIDA).

Mental and emotional problems

Marijuana use and abuse has been linked with mental disorders such as depression, schizophrenia, and thoughts of suicide. However, it is unclear whether a predisposition for mental illness influences marijuana (and other drug) use, or if it's the other way around. A study done by the New Hampshire-Dartmouth Psychiatric Research Center found that people with antisocial personality disorder may be more likely to have problems with substance abuse. A study published in the March 6, 2002, edition of the Journal of the American Medical Association found that longtime heavy users of marijuana were likely to have problems with memory and attention that could interfere with their daily life functioning.

Some studies have linked marijuana use with the development of psychosis in some users. The reasons are not clear, though the risk seems to increase with long-term, heavy consumption of the drug.

NIDA director Alan Leshner defines the "essence" of addiction as "uncontrollable, compulsive drug seeking and use, even in the face of negative health and social consequences." By these criteria, some heavy, habitual marijuana users may qualify as addicted. In 2006, 5 percent of U.S. 12th-graders reported daily use, which seems to interfere with social and academic responsibilities. According to a 2004 report by the Substance Abuse and Mental Health Services Administration (SAMHSA), out of 3.1 million daily marijuana users, 39 percent were "dependent on or abused" the drug. Overall, 4.2 million Americans abuse or are dependent on marijuana.

There is more debate over whether marijuana itself causes physical dependence -- that is, causes physical withdrawal symptoms when stopped. Some people trying to quit have become irritable, experienced anxiety, and had trouble sleeping. While these symptoms seem tame compared to those involved in withdrawal from drugs like heroin, their existence suggests it may be possible for marijuana to cause physical dependence in some people.

An emphatic yes or no is hard to come by. The gateway argument purports that marijuana use opens the door to harder drugs, such as cocaine and heroin. Scientifically, this is hard to prove, and the trick is determining whether a marijuana user is already predisposed to trying other drugs -- much the same way that someone who drinks beer might want to try wine or hard liquor. In other words (as with the emotional illness connection), it's hard to establish an "if-then" link. An Australian study came out in support of the gateway theory, but a University of Pittsburgh study of marijuana users between the ages of 10 and 22 found that they were not more likely to abuse other drugs or alcohol.

According to a SAMHSA report, close to 300,000 people entered some kind of treatment program for their marijuana abuse in 2004. Currently, there is no medication approved for the treatment of marijuana abuse but methods like cognitive-behavioral therapy -- which helps people change negative behavior and ways of thinking -- have proven effective. By identifying what triggers their abuse of the drug, users can learn new behaviors to help them cope.

A thorny issue, medical marijuana has been the subject of several recent court cases. A 2002 U.S. Department of Health and Human Services report concluded that "so far, there has been little scientific evidence that smoked marijuana can serve as a therapeutically useful drug." In April 2006, the Food & Drug Administration also issued a report dismissing marijuana as a medical option, flying in the face of conclusions reached by a panel of Institute of Medicine scientists in 1999. The Institute of Medicine report said THC might help control pain, nausea, and vomiting, and may act as an appetite stimulant -- something particularly valuable to AIDS patients suffering from "wasting" syndrome.

Based on some studies, marijuana has been found to have potential to ease glaucoma, multiple sclerosis, and AIDS-related chronic pain.The same effect that induces "the munchies" can help patients undergoing chemotherapy who are suffering from a loss of appetite. Dronabinol, which contains a synthetic form of THC, is approved for increasing appetite in AIDS patients and for nausea relief in chemotherapy patients. Animal studies also suggest that marijuana may help in treating epilepsy and slowing the progression of Alzheimer's disease.

For now, despite some research suggesting its therapeutic potential, the federal government classifies marijuana as a Schedule I drug (high potential for abuse, no accepted medical value), alongside heroin, Ecstasy, LSD, and others. Although some states, including California, have legalized the use of medicinal marijuana, a 2005 Supreme Court ruling gave the federal government the authority to arrest and prosecute medical marijuana users even in states allowing such prescriptions. However, medical marijuana supporters have not given up the cause: An April 2007 bill in New Mexico made that state the 12th to allow marijuana to be prescribed for medical use, and an AARP survey of 1,706 U.S. residents over age 45 found that 72 percent believed patients should have access to marijuana as a medicine if a doctor recommends it. Whatever its final outcome, the legal and political controversy surrounding medical marijuana has kept the drug where it was 40 years ago during the "Summer of Love": directly in the public eye.

-- Benj Vardigan is a contributing editor at Consumer Health Interactive.

References

American Journal of Respiratory Cell and Molecular Biology. "Induction and Regulation of the Carcinogen-Metabolizing Enzyme CYP1A1 by Marijuana Smoke and ⁹-Tetrahydrocannabinol." March 2001. http://ajrcmb.atsjournals.org/cgi/content/full/24/3/339

First published August 28, 2007
Copyright © 2007 Consumer Health Interactive

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