Marijuana is the Nation’s most commonly used illicit drug. More than 83 million Americans (37 percent) age 12 and older have tried marijuana at least once, according to the 2001 National Household Survey on Drug Abuse (NHSDA). Use is widespread among adolescents and young adults.
What is Marijuana?
Marijuana – often called pot, grass, reefer, weed, herb, Mary Jane, or MJ – is a greenish-gray mixture of the dried, shredded leaves, stems, seeds, and flowers of Cannabis Sativa, the hemp plant. Most users smoke marijuana in hand-rolled cigarettes called joints, among other names; some use pipes or water pipes called bongs. Marijuana cigars called blunts have also become popular. To make blunts, users slice open cigars and replace the tobacco with marijuana, often combined with another drug, such as crack cocaine. Marijuana also is used to brew tea and is sometimes mixed into foods.
The major active chemical in marijuana is delta-9-tetrahydrocannabinol (THC), which causes the mind-altering effects of marijuana intoxication. The amount of THC (which is also the psychoactive ingredient in hashish) determines the potency and, therefore, the effects of marijuana. Between 1980 and 1997, the amount of THC in marijuana available in the United States rose dramatically.
What are the Effects of Marijuana Use?
Marijuana’s effects begin immediately after the drug enters the brain and last from 1 to 3 hours. If marijuana is consumed in food or drink, the short-term effects begin more slowly, usually in 1/2 to 1 hour, and last longer, for as long as 4 hours. Smoking marijuana deposits several times more THC into the blood than does eating or drinking the drug.
Within a few minutes after inhaling marijuana smoke, an individual’s heart begins beating more rapidly, the bronchial passages relax and become enlarged, and blood vessels in the eyes expand, making the eyes look red. The heart rate, normally 70 to 80 beats per minute, may increase by 20 to 50 beats per minute or, in some cases, even double. This effect can be greater if other drugs are taken with marijuana.
As THC enters the brain, it causes a user to feel euphoric – or “high” – by acting in the brain’s reward system, areas of the brain that respond to stimuli such as food and drink as well as most drugs of abuse. THC activates the reward system in the same way that nearly all drugs of abuse do, by stimulating brain cells to release the chemical dopamine.
A marijuana user may experience pleasant sensations, colors and sounds may seem more intense, and time appears to pass very slowly. The user’s mouth feels dry, and he or she may suddenly become very hungry and thirsty. His or her hands may tremble and grow cold. The euphoria passes after awhile, and then the user may feel sleepy or depressed. Occasionally, marijuana use produces anxiety, fear, distrust, or panic.
Marijuana use impairs a person’s ability to form memories, recall events (see Marijuana, Memory, and the Hippocampus), and shift attention from one thing to another. THC also disrupts coordination and balance by binding to receptors in the cerebellum and basal ganglia, parts of the brain that regulate balance, posture, coordination of movement, and reaction time. Through its effects on the brain and body, marijuana intoxication can cause accidents. Studies show that approximately 6 to 11 percent of fatal accident victims test positive for THC. In many of these cases, alcohol is detected as well.
Marijuana use has been shown to increase users’ difficulty in trying to quit smoking tobacco. This was recently reported in a study comparing smoking cessation in adults who smoked both marijuana and tobacco with those who smoked only tobacco. The relationship between marijuana use and continued smoking was particularly strong in those who smoked marijuana daily at the time of the initial interview, 13 years prior to the followup interview.
Even infrequent marijuana use can cause burning and stinging of the mouth and throat, often accompanied by a heavy cough. Someone who smokes marijuana regularly may have many of the same respiratory problems that tobacco smokers do, such as daily cough and phlegm production, more frequent acute chest illnesses, a heightened risk of lung infections, and a greater tendency toward obstructed airways.
Cancer of the respiratory tract and lungs may also be promoted by marijuana smoke. A study comparing 173 cancer patients and 176 healthy individuals produced strong evidence that smoking marijuana increases the likelihood of developing cancer of the head or neck, and that the more marijuana smoked, the greater the increase. A statistical analysis of the data suggested that marijuana smoking doubled or tripled the risk of these cancers.
Students who smoke marijuana get lower grades and are less likely to graduate from high school, compared with their nonsmoking peers. In one study, researchers compared marijuana smoking and nonsmoking 12th-graders’ scores on standardized tests of verbal and mathematical skills. Although all of the students had scored equally well in 4th grade, the smokers’ scores were significantly lower in 12th grade than the nonsmokers’ scores were.
Workers who smoke marijuana are more likely than their co-workers to have problems on the job. Several studies have associated workers’ marijuana smoking with increased absences, tardiness, accidents, workers’ compensation claims, and job turnover. A study among municipal workers found that employees who smoked marijuana on or off the job reported more “withdrawal behaviors” – such as leaving work without permission, daydreaming, spending work time on personal matters, and shirking tasks – that adversely affect productivity and morale.
Depression, anxiety, and personality disturbances are all associated with marijuana use. Research clearly demonstrates that marijuana use has the potential to cause problems in daily life or make a person’s existing problems worse. Because marijuana compromises the ability to learn and remember information, the more a person uses marijuana the more he or she is likely to fall behind in accumulating intellectual, job, or social skills. Moreover, research has shown that marijuana’s adverse impact on memory and learning can last for days or weeks after the acute effects of the drug wear off.
Is Marijuana Use Addictive?
Long-term marijuana use can lead to addiction for some people; that is, they use the drug compulsively even though it often interferes with family, school, work, and recreational activities. According to the 2001 National Household Survey on Drug Abuse, an estimated 5.6 million Americans age 12 or older reported problems with illicit drug use in the past year. Of these, 3.6 million met diagnostic criteria for dependence on an illicit drug. More than 2 million met diagnostic criteria for dependence on marijuana/hashish. In 1999, more than 220,000 people entering drug abuse treatment programs reported that marijuana was their primary drug of abuse.
Along with craving, withdrawal symptoms can make it hard for long-term marijuana smokers to stop using the drug. People trying to quit report irritability, difficulty sleeping, and anxiety. They also display increased aggression on psychological tests, peaking approximately 1 week after they last used the drug.
What Treatments Are Available For Marijuana Abusers?
Treatment programs directed at marijuana abuse are rare, partly because many who use marijuana do so in combination with other drugs, such as cocaine and alcohol. However, with more people seeking help to control marijuana abuse, research has focused on ways to overcome problems with abuse of this drug.
No medications are now available to treat marijuana abuse. However, recent discoveries about the workings of THC receptors have raised the possibility that scientists may eventually develop a medication that will block THC’s intoxicating effects. Such a medication might be used to prevent relapse to marijuana abuse by reducing or eliminating its appeal.