Marijuana is the most common name used in the United States for the Cannabis sativa plant, which is one variety of the cannabis or hemp plant family. Cannabis is the more appropriate scientific term and the more common term used throughout the
world to refer to the various psychoactive products derived from the Cannabis sativa plant that are used by humans to alter their state of mind. Slang terms for marijuana and other psychoactive products derived from Cannabis sativa change over time but some stable and more current terms include: weed, pot, herb, grass, reefer, Mary Jane, dagga, bhang, Aunt Mary, skunk, boom, gangster, kif, ganja, hashish, and hash oil. Cannabis remains in the early twenty-first century the most widely used illicit substance in the United States and in most other developed countries that regulate marijuana. Between the late 1960s and 2008, marijuana use has generated continued controversy regarding its addictive potential, health consequences, potential for medical use, and legal status.
THE CANNABIS PLANT
Cannabis sativa grows easily throughout the tropics, subtropics, and temperate regions. It can also grow in colder climates with a shortened growing season. As of 2008 it was grown in most states across the United States. Once established, the plant can reseed and spread. Marijuana comes from the dried flowering tops (buds or heads), leaves, and stems of the harvested plant. The primary mind-altering ingredient in cannabis is delta-9-tetrahydrocannabinol (THC). The THC concentration (strength of the marijuana) partially depends Page 5 | Top of Articleupon growing conditions and the genetics of the plant. Generally, THC concentration is greatest in the buds, then the leaves, and finally the stems and seeds. Sophisticated growing techniques and breeding of alternative genetic strains have resulted in producing more potent marijuana, with potencies of that confiscated in the first decade of the twenty-first century by legal authorities in the United States and of other samples tested in the Netherlands ranging from approximately 2 percent to more than 20 percent.
Hashish or hash is another way that Cannabis sativa is prepared for use. Hash consists of dried cannabis resin and compressed flowers. Its THC concentration is usually 2 to 8 percent, but can get as high as 10 to 15 percent. Extracting THC from hash or marijuana using filtering and purification processes produces hash oil, and its concentration of THC can range from 20 to 60 percent.
The most popular way to use cannabis and hash is by smoking (inhaling) it in pipes or rolling it in cigarette papers (joints, reefers, doobies, spliffs). Water pipes or bongs (a type of pipe) are also used because they cool the smoke and there is not as much marijuana lost through smoke that escapes when a standard pipe is used. Another method for smoking that has become common is rolling cannabis into an emptied cigar casing. This product is usually called a blunt, and has become popular because it looks like a legal substance, it can be re-lit easily, and some people report enjoying the effect of the mixture of marijuana and tobacco. Note that the term spliff also can be used to refer to a cigarette that is a mixture of marijuana and tobacco. Hash is also typically smoked in some form of a pipe, and hash oil is usually used by adding a few drops to a cigarette or to the mixture in a pipe. Also, the oil can be heated by itself and the vapors inhaled. Marijuana or hash can also be taken orally (eaten), and usually eating has involved cooking or baking it in foods (e.g., brownies). When eaten, the onset of the effects is delayed by about an hour because the drug needs to be absorbed through the stomach, but the effects can last several hours longer.
The use of cannabis as a medicine dates back to the third millennium BCE in China, and to the second and first millennia BCE in India and ancient Assyria. This drug's history offers a collage of medicinal, agricultural, industrial, religious, cultural, and political tales, each of which can be traced back over many centuries. In his 1980 book, Marihuana: The First Twelve Thousand Years, Ernest Abel notes:
Armies and navies have used it to make war, men and women to make love. Hunters and fishermen have snared the most ferocious creatures, from the tiger to the shark, in its herculean weave. Fashion designers have dressed the most elegant women in its supple knit. Hangmen have snapped the necks of thieves and murderers with its fiber. Obstetricians have eased the pain of childbirth with its leaves. Farmers have crushed its seeds and used the oil within to light their lamps. Mourners have thrown its seeds into blazing fires and have had their sorrow transformed into blissful ecstasy by the fumes that filled the air.
In the United States, approximately 30 cannabis preparations, including Chlorodyne, a concoction of morphine and cannabis, were marketed in the 1930s. Superior medications eventually became available, and the drug was removed from the U.S. Pharmacopoeia and National Formulary in 1941.
Periodically, commissions of inquiry, for example, the 1925 Panama Canal Zone Committee and the 1944 Mayor's Committee on Marihuana (The LaGuardia Committee), were formed to assess the degree of risk posed to public health by recreational cannabis use. A movement grew to prohibit cannabis possession, and by 1937, when the federal Marijuana Tax Act was passed, all states had banned the drug. The Vietnam antiwar movement saw a substantial increase in the drug's popularity, particularly among young adults in the United States. In reaction to the long prison terms being imposed for possession, the National Commission on Marihuana and Drug Abuse recommended in 1972 that cannabis possession be decriminalized. In that decade a number of states replaced prison terms with either civil penalties or misdemeanor fines. While cannabis remained classified under federal law as having high risk and no accepted medical use, the last decades of the twentieth century saw a number of states enacting laws designed to protect patients from prosecution if a physician recommended use of cannabis. In 1999 the Institute on Medicine released a comprehensive report on the status of marijuana as a recreational drug and its potential for use as a medicine.
CHEMISTRY / PHARMACOLOGY
Cannabis sativa contains over 400 chemical substances. The compounds responsible for most direct effects are called cannabinoids, and over 66 such cannabinoids have been identified. The three most abundant are cannabidiol, tetrahydrocannabinol (THC), and cannabinol. Delta-9-THC is the compound that causes the most notable effects of cannabis. Cannabidiol and cannabinol do not appear to have strong psychoactive properties, but it is thought that they may modify the effects of THC. The proportions of these cannabinoids can vary among strains and can be modified by breeding, resulting in cannabis with different effects and varying potencies.
The effects of THC result from its ability to activate receptors on the surface of specific cells in the brain and body. In the late 1980s it was discovered that humans and animals have an endogenous cannabinoid system, indicating that THC interacts with a naturally occurring system in the body. Two specific types of cannabinoid receptors have been identified (the CB1 and CB2 receptors). CB1 receptors are located primarily on nerve cells in the brain and spinal cord, as well as in some tissues outside the brain. CB2 receptors are located mostly on cells of the immune system and do not appear to be present in the brain. An endogenous cannabinoid, anandamide, has also been identified. The role of the cannabinoid system has only begun to be explored. The effects of cannabinoids known from animal and human experiments include appetite modulation, pain relief, impairment of memory and the control of movements, and reductions in body temperature and in the activity of the gut. Research on cannabinoid pharmacology continues to grow rapidly in the early twenty-first century, and promises to facilitate the understanding of the role of endogenous cannabinoids and the effects of cannabis.
DIRECT EFFECTS AND PSYCHOPHARMACOLOGY
Approximately 30 percent of the THC is delivered into the blood stream when cannabis is smoked. A lower proportion of THC is absorbed after taking cannabis by mouth because THC is metabolized in the liver, but its metabolite is also psychoactive and thus likely prolongs its effects. THC is distributed widely throughout the body via the bloodstream and is stored primarily in fatty tissues. The effects of smoking marijuana are felt within minutes, with maximal effects typically experienced thirty to ninety minutes after smoking. The effects of eating marijuana are usually not felt for about thirty to sixty minutes, and they peak 120 to 240 minutes after ingestion. The direct effects of smoked marijuana may persist for approximately four to six hours; effects following oral consumption may last six to eight hours. The slow release of THC from fatty tissues produces low levels of THC metabolites for many days but no significant effects appear to be caused by such release. Nonetheless, storage and slow release from fatty tissues result in THC being detectable in urine for long periods of time (up to a month) following its ingestion.
When THC enters the brain, it activates the release of dopamine, a neurotransmitter, which is important because dopamine release is associated with the rewarding properties of most drugs and thus may contribute to repeated use and perhaps addiction. Marijuana's actions include a wide range of fairly diverse effects. Indeed, it is difficult to classify marijuana into other common drug categories. In most classification systems, marijuana is either placed in its own category or included with the hallucinogens.
Although wide variation in the effects of marijuana is observed based on an individual's previous experience with the drug, the dose smoked or consumed, and the current smoking environment, the early effects are usually more stimulating in nature: feeling high or a mild euphoria; increased silliness, laughter, and talkativeness; having altered perceptual experiences that include a distorted sense of time and more intense experiences of hearing music, seeing colors, watching movies or television, and eating. Some of the effects might not be pleasant. The most commonly reported unpleasant effects are anxiety, panic reactions, fear of going crazy, and depression. At very high doses, the experience may seem more intense, and one may even feel a sense of depersonalization or experience delusions (beliefs not based in reality) or hallucinations (seeing or hearing things that are not there). These more extreme unpleasant psychological effects are usually felt by infrequent users who are less familiar with the effects of marijuana or by people who have eaten or smoked more marijuana than they are used to. Also, using marijuana with a higher THC concentration or that is laced with other substances can cause such effects. These experiences are typically short-lived and stop when the high obtained from marijuana ends.
Subsequent effects of use are more relaxing, and individuals may become more introspective, with thought or concentration requiring more effort, and memory and psychomotor tasks becoming more difficult. Common physiological effects include increased pulse rate, reddening of the eyes, dry mouth, thirst and hunger, and drowsiness.
With repeated and regular use, tolerance to many of marijuana's effects can develop, which means the user may take more marijuana to achieve an effect or feel less effect when using the same amount of marijuana. Different degrees of tolerance develop for different effects of marijuana. For example, tolerance to the increase in heart rate can develop rapidly. Whether substantial tolerance develops to feeling euphoric is debated.
A withdrawal syndrome can occur in many persons who have been using marijuana heavily for a substantial period of time. The symptoms of this withdrawal syndrome appear somewhat similar to that described with tobacco smokers. The most common symptoms reported are: irritability/anger, restlessness, nervousness, sleep difficulties, vivid dreams, and nausea, craving, and depressed mood. These symptoms typically appear within two to four days after stopping regular use and may last two to three weeks.
Cannabis remains the most widely used illicit substance in most developed countries that regulate its use, and its rate of use is also increasing in developing countries. In the United States, it is estimated that 98 million people (39 percent) have used the drug; 15 million (6 percent) are currently using it (i.e., at least once in the past month); and 3.1 million are using cannabis daily. Cannabis use is most prevalent among adolescents and young adults aged sixteen to twenty-five. Approximately 34 percent of high school seniors and 28 percent of sophomores have used marijuana at least once, and daily use approximates 6 percent and 4 percent among seniors and sophomores, respectively. Although illegal in the United States, marijuana is readily accessible; approximately 40 percent of eighth graders, 73 percent of tenth graders, and 86 percent of twelfth graders report that they know where to get marijuana.
As with other drugs of abuse, cannabis is used more often by males than females. Cannabis is used across all regions of the United States with minimal variance, although some states have significantly higher rates of use than others. Prevalence of use across major ethnic and racial groups is similar, though there is some indication of slightly higher rates among African Americans, American Indians, and those who claim membership in two or more races.
ADVERSE HEALTH, COGNITIVE, AND BEHAVIORAL CONSEQUENCES
Much remains unknown about cannabis. Moreover, proving that the drug's use causes specific adverse effects, rather than their simply co-occurring with those effects or perhaps being an attempt at self-medication to ameliorate those effects, is an ongoing challenge in cannabis research with humans. Alternative explanations can and should be considered viable until well-controlled research necessitates their being ruled out. This caveat notwithstanding, the findings to date warrant mention of the following potential adverse consequences.
Personal Development. The possibility that cannabis use contributes to disturbances in normal adolescent development is of considerable concern. Frequent cannabis use by adolescents is correlated with such negative psychosocial outcomes as poorer academic performance, truancy, and dropping out of school. Teens who initiate use earlier are at higher risk of developing dependence. There are mixed findings concerning the suggestion that cannabis may interfere with normal adolescent brain development.
Cognitive Function. Although the findings are mixed, some studies indicate that heavy and long-term cannabis use impairs memory and executive functioning, with these consequences persisting after cannabis use has ceased. Moreover, there is evidence that the onset of use before age sixteen or seventeen respectively predicts poorer performance in tasks requiring focused attention and lower verbal IQ in adulthood.
Affective and Psychotic Disorders. Brief psychotic episodes that mimic schizophreniform disorders can occur following cannabis consumption and are generally short-lived. Such episodes are more likely following heavy consumption. In those who are susceptible to schizophrenia, cannabis use increases the Page 8 | Top of Articlelikelihood of an acute episode, an earlier relapse, more frequent hospitalization, and poorer psychosocial functioning. There is also evidence that heavy cannabis use can be a contributing factor in the development of psychotic illness in those without such a predisposition, although conclusions concerning this relationship remain contentious.
There appears to be a small but significant risk of major depression occurring in young adults who are current cannabis users. Early onset and frequent use may increase the risk of both anxiety and depression in young adulthood.
Respiratory System. Heavy cannabis smokers have a greater risk of chronic cough, chronic sputum production, wheezing, and episodes of acute bronchitis than nonsmokers. Additionally, cannabis smokers are at an increased risk of such infectious diseases as pneumonia. Bronchial biopsies give evidence of pre-cancerous pathological changes suggestive of an elevated risk of respiratory tract cancers. One New Zealand population-based case control study in adults fifty-five years of age and younger found that the risk of lung cancer increased 8 percent for each year of cannabis smoking. In contrast, a large case control survey in California found no association between cannabis use and these types of cancer.
Cardiovascular System. For individuals with cardiovascular disease, increased stress on the heart due to the effects of cannabis on the circulatory system may increase the risk of chest pain, heart attack, or stroke.
Driving. Due to cognitive and psychomotor impairments when high, drivers who have consumed cannabis are at a modestly increased risk of accidents.
Fetal Development. Subtle disturbances of brain development may result in cognitive impairment in the offspring of women who use cannabis during pregnancy. The impairment may not appear until preschool or school age.
Although the concept of dependence or addiction in relation to cannabis has been questioned by some, diagnostic, epidemiological, laboratory, and clinical studies clearly indicate the existence, importance, and potential for harm of cannabis addiction. As with other substances, including alcohol and tobacco, a subset of individuals who try to continue to use cannabis eventually develops what is labeled as dependence or addiction. It is estimated that 9 percent of those who have used marijuana at least once meet the diagnostic criteria for cannabis dependence, which compares to approximately 15 percent for cocaine, 24 percent for heroin, and 32 percent for tobacco cigarettes. More frequent marijuana use results in greater risk for developing dependence, and in heavier users the proportion meeting dependence criteria may be as high as 50 percent. Between 1992 and 2002, the prevalence of marijuana use disorders among adults increased despite a stabilization of overall rates of marijuana use, and both the rates of use and prevalence of disorders increased among adolescents. It appears that the risk of developing cannabis dependence is elevated (one in six or seven) for users who first use the drug at a young age. Compared with adults, adolescent cannabis users qualify for a diagnosis of dependence with a lower frequency and quantity of cannabis consumption. Cannabis dependence as reported by those seeking treatment because of marijuana-related problems appears highly similar to other substance dependence disorders, although it is usually less severe than most others.
Treatment admissions in the United States for primary cannabis abuse more than doubled between 1993 and 2003, and similar trends have been observed in such other countries as Australia. There is increased recognition that cannabis is a drug that can lead to addiction and significant negative consequences in a subset of those who use it. This awareness has led to the development of cannabis-specific interventions and treatment materials paralleling those used with other substance use disorders. These advances have increased the acceptability of seeking and providing treatment for cannabis dependence, and consequently the number of individuals seeking help has increased. Types of treatments shown to be effective include: motivational enhancement therapy, cognitive-behavioral treatments, contingency management, and various behavioral family-based treatments (for adolescents). However, as with treatment for other substance use disorders, many individuals do not respond well to these interventions; hence, there is a continued need to develop more effective treatment options. Page 9 | Top of ArticleOptimistic expectations for continued enhancements to treatment approaches appear warranted given that behavioral treatments continue to demonstrate incremental gains in efficacy as innovative interventions are evaluated. Furthermore, rapid advances in understanding the neurobiology of cannabis and the cannabinoid system provide further hope for increasingly effective treatment options (e.g., medications).
Cannabis may have beneficial effects for a number of medical conditions. Oral THC has been approved by the U.S. Food and Drug Administration for use as an appetite- and food-intake stimulant in patients with AIDS wasting syndrome and as an antinausea and antiemetic agent in cancer patients receiving chemo-therapy. In 1999 the Institute of Medicine and the National Institutes of Health acknowledged the importance of initiating additional scientific study of the risks and benefits of cannabis use and, in particular, the use of smoked cannabis for specific medical conditions. The interest in the benefits of smoked cannabis in contrast to oral THC arises primarily from differences in the pharmacokinetics of these two routes of administration. Through the oral route, THC absorption is slow and variable; and as a result, clinical effects have a slower onset and longer duration than smoked cannabis. In addition, smoked cannabis delivers both delta-9-THC and other compounds (e.g., delta-8-THC and cannabidiol), which may have direct or interactive effects of therapeutic interest. As of 2008, research comparing the efficacy of oral THC and smoked cannabis for various medical conditions was needed.
By 2008 the medicinal effects of cannabis were being studied regarding a number of other conditions, including as pain relief (analgesia), for the treatment of neuromuscular symptoms (tremors, spasms, or loss of coordination associated with multiple sclerosis or other neurological disorders such as spinal cord injury), and for glaucoma (a disorder of the eye associated with increased intraocular pressure). Case studies and laboratory research suggest that cannabis can positively affect these conditions. Unfortunately, research on these conditions and those for which oral THC has been approved had yet to advance to allow (a) a clear determination of the positive and negative effects of smoked cannabis on each condition; (b) comparisons of oral THC with smoked cannabis; and (c) a comparison of smoked cannabis with other types of medications or medical treatments.
As of 2008, much more data on the effectiveness of smoked cannabis and oral THC for various medical conditions were expected to become available because a number of funding sources had initiated focused efforts to stimulate research in this area. Of additional importance, there was much optimism that additional advancements in research on the newly discovered cannabinoids and the cannabinoid system would result in the development of effective alternative medications that could accentuate the positive effects of cannabis but not produce the other potentially problematic effects of THC and smoke such as sedation, memory problems, intoxication, carcinogens, and respiratory irritation.
As of 2008, THC was a Schedule I drug (i.e., one that has a high potential for abuse, has no currently accepted medical indication, and for which there is a lack of accepted safety when used under medical supervision). Under the U.S. Controlled Substances Act, a first conviction for cannabis possession can result in a term of imprisonment of not more than one year, a minimum fine of $1,000, or both. A first conviction for trafficking in cannabis (1 to 49 plants) can result in up to five years of imprisonment and a fine of up to $250,000. However, there has been a long history of controversy concerning the drug's legal status. Signatories to the 1961 United Nations Single Convention on Narcotic Drugs agreed to “[a]dopt such measures as may be necessary to prevent the misuse of, and illicit traffic in the leaves of the cannabis plant.” Despite the subsequent enactment of prohibition legislation to comply with the Convention, in the latter half of the twentieth century cannabis became the most widely used illicit drug in the Western world.
In the United States in 1972, the National Commission on Marihuana and Drug Abuse recommended that cannabis possession be decriminalized. The Commission members reasoned that overly severe penalties risked undermining the credibility of government in educating the public about potential drug-related harms, and the rationale for decriminalization (i.e., removing criminal penalties for possession while retaining them for selling) was to avoid that consequence while continuing to discourage cannabis use. The Netherlands in 1976, Page 10 | Top of Articleseeking to distinguish among drugs according to risk level, classified cannabis as a soft drug. Possession, cultivation, and sale of small amounts, while remaining illegal, would not be prosecuted. Subsequently, other countries, most notably Canada, Australia, New Zealand, Switzerland, Germany, Spain, Austria, Belgium, Luxembourg, Portugal, Italy, and some U.S. jurisdictions, reduced emphasis on a criminalization approach to cannabis use prevention.
Some people in the United States have argued for full legalization, that is, permitting over-the-counter sale of all drugs. An alternative model that has been suggested is a regulatory system in which cannabis sale is authorized in state-licensed establishments. Proponents of retaining criminal sanctions argue that cannabis use can be harmful and that restrictive laws have effectively kept levels of cannabis use lower than they would be if the drug were to be legalized. Policy reform advocates argue that using criminal penalties to protect users from harming themselves is an unwarranted infringement of individual liberty and that criminalizing cannabis possession has failed to prevent its use.
See also Adolescents and Drug Use; Cannabis Sativa; Controls: Scheduled Drugs/Drug Schedules, U.S; Driving, Alcohol, and Drugs; Monitoring the Future.
Abel, E. L. (1980). Marihuana: The first twelve thousand years. New York: Plenum.
Budney, A. J., Moore, B. A., & Vandrey, R. (2008). Health consequences of marijuana use. In J. Brick (Ed.), Handbook of medical consequences of alcohol and drug abuse (2nd ed., pp. 251–282). New York: Haworth Press.
Budney, A. J., Roffman, R., Stephens, R. S., & Walker, D. (2007). Marijuana dependence and its treatment. Addiction Science & Clinical Practice, 4(1), 4–15.
Hall, W., & Pacula, R. L. (2003). Cannabis use and dependence: Public health and public policy. Cambridge, UK: Cambridge University Press.
Roffman, R. A., & Stephens, R. S. (Eds.) (2006). Cannabis dependence: Its nature, consequences, and treatment. Cambridge, UK: Cambridge University Press.
ALAN J. BUDNEY
ROGER A. ROFFMAN