Nature's Pharmacopeia: A World of Medicinal Plants

Chapter 9



Cannabis sativa


The window of a medical marihuana clinic in Los Angeles, California. (Photograph by Neeta Lind/Flickr)

Hemp grows as an annual and can reach a height of 5 meters.1 It is highly branched and produces leaves with multiple long, thin, serrate (jagged-edged) leaflets (figure 9.1). Uncommon among plants, hemp is dioecious, having male individuals producing only pollen-bearing flowers and female individuals producing only egg-bearing flowers. Fertilization takes place on the female plants, yielding seeds that have culinary uses.2 Hemp stems produce a versatile fiber, and the leaves, leaf buds, and flower buds are most commonly harvested for their medicinal properties. Human selection and geographic isolation have distinguished C. sativa ssp. sativa, used for fiber, from the more strongly medicinal C. sativa ssp. indica.3 It grows both as a weed and in cultivation throughout the temperate and subtropical zones. In recent decades, medicinal hemp varieties have been subject to intensive breeding efforts to select characteristics allowing the plant to thrive in tropical areas and in indoor settings. Cannabis, hemp, and (particularly since the twentieth century) marihuana are all common English names for this plant and sometimes also refer to its parts prepared for fiber (hemp) and medicine (marihuana).4


FIGURE 9.1   Hemp leaves.


The hemp plant probably originated in Central Asia and may have been under human cultivation as early as 20,000 years ago.5 Stone Age peoples recognized numerous useful properties in the plant, from its nutritious seeds, to the versatile fibers that can be coaxed from its stem, and perhaps to its effects on the senses.6 Cannabis seeds have been found in archaeological sites across Europe and Asia dating as early as 5000 to 10,000 years ago, and farmers in China processed hemp stalks into ropes, cords, and fabrics at least about 5000 years ago.7 By about 1000 B.C.E., hemp was widely employed as a food and source of fiber for rope, cloth, and paper, from western Europe, through Central Asia, to South and East Asia (figure 9.2).

In addition to these uses, ancient people also noticed that the leaves, flowers, and especially buds of hemp altered the senses when ingested. Much has been written about the relationship between ancient societies and the many psychoactive plants used for ceremonial and religious communion,8 and it is likely that hemp was among those employed in shamanic rituals in Central Asia by nomadic people thousands of years before the present.9 Long ago, people recognized that the leaves and flowers, particularly of the female plants, generated the strongest mind-altering experience. They learned to prepare and eat the harvested material or inhale its smoke to achieve a numbing, exhilarated state that they might have interpreted as otherworldly. These effects are attributable to the oily resin produced on the glandular surfaces of leaves and flowers, especially concentrated in leaf and flower buds.


FIGURE 9.2   A Hmong woman teases hemp fibers into thread in Sa Pa, Vietnam.

In time, hemp consumption was taken up throughout Europe and Asia, and evidence of the use of hemp for spiritual-medical purposes comes from several sources in diverse geographic settings. As early as 1500 to 1000 B.C.E. in what is now India, a book containing healing charms called the Atharva Veda described hemp (bhang) as a “sacred grass” that “may release us from distress,” indicating its perceived role in physical and spiritual health.10 Later, the Greek historian Herodotus (484–425 B.C.E.) related a custom among the Scythians, nomadic tribes that inhabited eastern Europe and the Crimea, in which at funerals they burned the seeds or flowering tops of cannabis on red-hot stones and inhaled the smoke as part of a cleansing ritual. In their lamentations, according to the chronicler, “the Scythians howl in their joy at the vapor-bath.”11 The ancient Persians (perhaps as early as the seventh century B.C.E.) also likely used cannabis to achieve states of shamanic ecstasy in religious ceremonies, and among the Germanic tribes, hemp served as a sacred ritual aphrodisiac.12 Archaeological evidence supports the notion that Central Asians used cannabis for spiritual-medical purposes 2400 to 2700 years ago, as grave sites of nobles and shamans have been found containing hemp flowering tops and seeds placed in a fashion suggesting ritual importance.13

In ancient Egypt, cannabis is documented in stone carvings and medical papyri as useful for its fiber (to prepare bandages) and for its pharmaceutical properties. In ancient texts dating to a period about 3500 years ago, cannabis was recommended to treat the eyes and aid childbirth.14 Among the Assyrians of seventh-century B.C.E. Mesopotamia, hemp was described as “the drug which takes away the mind,” and it was used as an ointment for bruises and swellings, eaten or boiled in water, and drunk to alleviate depression, cure impotence, and protect against witchcraft hexes. Its smoke was said to relieve “poison of all limbs,” perhaps a reference to arthritis.15

Although hemp was widely used for textiles and food in China and elsewhere in East Asia dating back millennia, it is difficult to ascertain when its psychoactive properties were first noted. Interestingly, the Chinese character for hemp, 麻, can mean “fiber,” such as that obtained from hemp and flax; “pockmarked” or “spotty,” like the exterior pattern of some hemp seeds; “sesame,” a parallel to the small size of its oil-rich seeds; and “numbing” or “tingling,” in reference to the altered sensory experiences that the plant can induce.16 A single Chinese character thus evokes the ancient roles of hemp as fiber, foodstuff, and psychoactive material. Chinese medicine records the use of hemp at least 2000 years ago, and medical texts recommend hemp boiled in wine as a numbing agent before abdominal surgery, to treat diarrhea, and as a remedy for rheumatism (figure 9.3).17 In contemporary Chinese medicine, hemp seed is also valued as a laxative.18 However, an ancient Chinese text warns that cannabis seeds taken in excess can cause a person to begin “seeing devils.”19

In the Greco-Roman world, as elsewhere, hemp was known for its fiber, oil, and diverse ascribed medicinal properties, although generally writers of the era who addressed hemp warned of its ill effects on health.20 The Roman encyclopedist Pliny the Elder (23–79) described the plant in his Natural History, writing about its usefulness in rope making and in human and veterinary medicine. He suggested the “juice of this seed” to eliminate worms and other parasites from the ears, “though at the cost of producing head-ache.” He also recommended hemp infused in water to treat diarrhea in livestock.21 Pedanius Dioscorides, a Greek herbalist working in the first century C.E., wrote that the “juice extracted from it when green and instilled is appropriate for earaches.”22 These authors and the influential physician Galen (129–ca. 216) warned of hemp seed’s dangers when eaten. As a strongly warming, drying herb, they cautioned, hemp could render men impotent.23 Furthermore, Galen said the seeds are “hard to digest, disagree with the stomach, cause headaches and contain bad juices.”24 It seems that he was also aware of cannabis’s influence on the mind, as he wrote: “[Hemp seeds] are particularly heating and so affect the head, when just a few too many have been eaten, by sending up to the head a hot and medicinal vapor.”25 (Since hemp seeds themselves do not contain a psychoactive resin, it is possible that the “seeds” employed in Chinese and Mediterranean medicine included some surrounding leaves.)


FIGURE 9.3   Hemp in a Chinese herbal. (Woodcut from Li Zongzi, Origins of the Materia Medica [1612])


In South Asia, hemp assumed an important role in indigenous spiritual life, employed to transcendent, purifying, and therapeutic ends.26 Many centuries ago, people recognized that the psychoactive properties of cannabis are stronger in female plants than in male and are concentrated in the resin that exudes from specialized leaf hairs covering the leaves, stem, and flower buds. The resin glands being denser at the growing tip of the plant, ancient cultivators learned to harvest hemp and manipulate it in particular ways for ritual consumption.

In the Hindi language, bhang refers to the hemp plant and a variety of medicinal products made from it. Bhang consists of the dried leaves and flowering tops of cannabis plants (male and female, or selectively female), which can be eaten directly or prepared into small balls of chopped, flavored leaves. Alternatively, bhang can be added to dishes such as curries and dumplings; mixed with sugar, black pepper, nuts, and other additives as a confection; and blended with water and yogurt or milk as a beverage.27 Long associated with Hindu religious practice, bhang was thought to ward off evil spirits and bring good luck. As early as 1000 years ago and continuing through more recent centuries, bhang and other cannabis preparations were employed as a form of worship, an avenue to communion with the divine.28Cannabis consumption in this spiritually engaged way often took place in social settings, with ritualized behaviors established for sharing the product (figure 9.4).29

A more potent form of cannabis is ganja, consisting of the resin-rich female flowers, buds, and young leaves plucked before producing seed (figure 9.5). Some cultivators recognized they could increase the yield of ganja by limiting the amount of airborne pollen, and therefore the fertilization of female flowers, learning to remove male plants from hemp fields as early as possible. In this way, the female plants produce more numerous, denser resin-rich flowers.30 (This technique is now known as sinsemilla, from the Spanish for “seedless.”) Ganja is traditionally eaten and, after the development of smoking pipes, probably in the sixteenth century, also smoked. The practices of smoking and pipe making likely reached Asia during the early or mid-sixteenth century, borne by European merchants carrying tobacco.31


FIGURE 9.5   A resin-rich female flower bud. Glandular hairs coat the surface of the leaves. (Photograph by eggrole/Flickr)

The most strongly medicinal cannabis preparation is composed of the resin-rich glands, scraped or rubbed from the flowering tops of hemp plants and compressed into a thick paste called charas.32 (In much of the world, the resinous paste is instead called hashish, Arabic for “grass.”)33 This material can be eaten or smoked.

Those who developed the techniques to prepare potent cannabis extracts in ancient times gleaned insights into biochemistry that can now be explained in modern terms. The most strongly psychoactive chemical in cannabis resin is Δ9-tetrahydrocannabinol (THC), a fat-soluble compound produced when fresh or dried hemp is heated (figure 9.6). Interestingly, newly harvested leaves contain THC in an inactive THC carboxylic acid form, and traditional preparation techniques—such as drying in the hot sun, boiling, cooking, or heating on charcoal—convert the inactive structure to the active THC.34 Early South Asian manufacturers also recognized that the psychoactive agents in cannabis were not well carried in water alone, and they therefore used fatty and oily ingredients in their bhang preparations, such as dairy. THC’s low solubility in water also renders cannabis poorly psychoactive as an herbal tea.35


FIGURE 9.6   Δ9-tetrahydrocannabinol (THC).


FIGURE 9.4   Social-spiritual cannabis consumption in India. One woman in the hut prepares bhang while another smokes a water pipe. The gathering includes a musician, holy men, and soldiers. The men in the foreground have consumed bhang. (Painting, Pahari school [eighteenth century]; British Museum, 1940.0713-0.49)

In addition to the chemical transformation of inactive to active THC that occurs in hemp exposed to heat, the route of consumption greatly affects its physiological actions in the human body. When cannabis resin vapor is inhaled, it passes rapidly into the bloodstream and exerts an array of effects on the system, including altered mood and sensation. If cannabis products are eaten, they are slowly absorbed by the stomach and small intestine, and THC is carried to the liver, where metabolic enzymes convert it to 11-hydroxy-THC, a more potent and longer-lasting psychoactive chemical.36 Therefore, a large quantity of bhang, eaten as an oil-rich confection or mixed into a milky drink in the traditional South Asian way, might provoke rather powerful effects.


While the social, ritual, spiritual bond of cannabis remained strong in India and parts of Central Asia during much of history, in Europe, hemp cultivation was primarily directed at producing fiber for rope, cloth, and paper. Through the Middle Ages, the Renaissance, and the centuries that followed, medicinal hemp was little documented in scholarly literature, except largely for variations on the themes of Galen, Dioscorides, and Pliny. As exceptions, there are a few surviving manuscripts from England in the eleventh century and Italy in the thirteenth that recommend hemp leaves in an ointment to treat breast swelling or tenderness.37 Certainly, hemp must have also been employed in folk medicine: there are stories of medieval Germans using sprigs of hemp as charms to ease childbirth and of eastern Europeans inhaling the vapor of toasted hemp seeds to assuage toothache.38 Generally, however, a systematic knowledge of cannabis preparation and use for psychoactive ends was not well documented.



The plant Cannabis sativa and its products


The plant C. sativa, particularly when used for food or fiber; the fiber itself


The plant C. sativa, particularly when used for psychoactive purposes; its products


The leaves and flowers of cannabis; drinks, confections, and snacks produced from them


The female flowers, buds, and young leaves of cannabis


The resinous exudate of cannabis, also known as hashish


Seedless, high-potency marihuana produced from isolated female plants


Δ9-tetrahydrocannabinol, the primary active principle of cannabis

It is possible that cannabis played a role in the countercultural religious-medical practices of witchcraft and sorcery, employed, probably in concert with other psychoactive herbs, for its ability to alter the senses and evoke feelings of spiritual release and flight. In Catholic western and central Europe, people suspected of pursuing such practices would have been considered morally corrupt and persecuted by the Inquisition. In 1484, Pope Innocent VIII issued an edict that in effect declared the use of cannabis as a tool of the satanic mass, further suppressing medicinal, spiritual, and recreational hemp from the European consciousness.39 Perhaps the force of Catholic Church doctrine dissuaded experimentation with the physiological properties of hemp and its record in writing. It is also possible that the varieties of cannabis selected by generations of farmers for making textiles in Europe were poorly psychoactive and might not have yielded much in terms of mind-altering effects.40 Whatever the case, there is relatively little note of hemp’s psychoactive or other medicinal properties in the European sphere across many centuries, even after the broad revival of herbal scholarship that took hold during the sixteenth century.

In The Herball, or Generall Historie of Plants (1597), John Gerard summarized the properties of hemp relayed by Galen and Dioscorides many centuries earlier and recommended the pressed flesh of the seed for “yellow iaunders [jaundice], when the disease first appeereth,” and to treat the gall bladder and to disperse and concoct (his terms) the choler.41 A handful of decades later, John Parkinson’s Theatrum Botanicum greatly elaborated on hemp’s medicinal properties, listing first a series of ancient warnings dating to Galen—hemp seed is bad for digestion, “hurtful to the head & stomack,” “breedeth ill blood and juyce in the body,” and “dryeth up the natural seede of procreation”—and then recommending it for diarrhea and colic pain. The leaves, prepared by frying, are said to be good to staunch bleeding and to expel internal parasites; the juice of the leaf, Parkinson suggested, as had Dioscorides, for “wormes in the eares”; and the boiled root, for inflammation, gout, joint pain, and “hard tumours.”42 While the list of hemp’s medicinal applications in Europe grew longer during the seventeenth century, it did not include (with the exception of its analgesic properties) the mind-altering effects so well known in South Asia and the Muslim world.

In an era of active trade across the Middle East and South Asia, the eleventh through sixteenth centuries saw considerable exchange of technology between nations, including the methods of hashish production for spiritual or recreational purposes.43 Adherents to the mystic Sufi Muslim sect might have brought hashish eating to Egypt from Syria during the twelfth century; by the thirteenth century, hashish users were said to gather in Cairo’s Garden of Cafour.44 When European explorers reached exotic destinations in the sixteenth century, they discovered uses for cannabis unknown at home. For example, the Italian Prospero Alpini (1553–1617) visited Egypt and noted the ways local people used hashish to intoxicate themselves as Europeans did with alcohol.45 A few decades earlier, the Portuguese physician Garcia de Orta (ca. 1501–1568) had written of his medicinal plant discoveries in India, describing bangue (bhang) as an herb capable of relieving anxiety, inducing sleep, and lessening sexual inhibitions.46

It wasn’t until Napoleon’s army rampaged through North Africa during the late eighteenth and early nineteenth centuries that medicinal-recreational cannabis became established in Europe. French soldiers returning from Egypt shared their hashish eating and smoking experiences, and before too long, this exotic amusement had spread among the avant-garde of society.47 Part of the fascination and enjoyment of hashish must have been in the novel method of smoking the Europeans witnessed in North Africa.

Arabs had adopted an Indian water pipe, which came to them via the Persians and Turks, and used it to smoke hashish and other herbs (figure 9.7).48 Using this device, the smoke is drawn through water before being inhaled, which moistens the vapor and softens its harshness. The enjoyment of such a means of smoking came through the sociable atmosphere of the water pipe garden, the pleasantly flavored smoke, and the intoxicating effects of the hashish (figure 9.8). Parisian literary circles became seduced by the vivid water-pipe experience and established the Club des hachichins in the 1840s, embracing artistic masters such as the poet Charles Baudelaire (1821–1867) and the novelist and playwright Alexandre Dumas (1802–1870).49 Along with absinthe and opium, hashish inspired a generation of European intelligentsia in their exploration of the human mind and its creative outlets.

The new forms of expression emerging from the Paris artists’ colonies were revolutionary, containing rich descriptions of surreal sensations and dramatic changes in mood and insight. These effects fascinated the French psychiatrist Jacques-Joseph Moreau (1804–1884), who viewed hashish inebriation as a tool to study mental disorders. In an early expression of psychopharmacology, he wrote: “It seems there are two modes of existence. … The first one results from our communication with the external world, with the universe. … The second one is but the reflection of the first in the self, fed from its own distinct internal sources.”50 The world of dreams, mental illness, and drug-induced states of consciousness, according to the doctor, was the point of connection between the external and internal lives. More recently, neuroanatomists have located particular regions of the brain affected at a chemical level by medicinal plants such as cannabis, addressing to some degree the mysteries of Moreau’s “modes of existence.”


FIGURE 9.7   A man smoking a water pipe. (Photograph by Osgood Company [ca. 1901]; Library of Congress, Prints and Photographs Division, LC-USZ62-49951)

At about the same time that the social circles of poets and thinkers were using cannabis in the pursuit of inspiration, physicians were reassessing its medicinal values. In a series of striking trials conducted during the mid-1840s, the Irish physician William O’Shaughnessy (1809–1889), working in India, produced an alcohol-based extract of cannabis resin for administration to animals and humans.51 He documented its usefulness as an anticonvulsant for conditions such as tetanus and delirium tremens, an antidiarrheal for the treatment of cholera, and a palliative measure for rabies. As for the mental side effects, O’Shaughnessy considered them rather useful for patients facing frightening, life-threatening illnesses. “The changed state of mind it produces is truly wonderful,” he wrote. “From the appalling terror which generally predominates, the patient soon passes into a state of cheerfulness, often of boisterous mirth, and soon sinks into a happy sleep.”52


FIGURE 9.8   The Shisha Hookah Bar, Washington, D.C. The water pipe historically has been used to smoke marihuana, opium, tobacco, and other herbs.

During the second half of the nineteenth century, physicians in Britain experimented with hashish imported from the South Asian colonies, publishing their findings and gaining a place for cannabis in the national pharmacopeias and pharmaceutical recipes of Europe and the United States (figure 9.9). While cannabis was available in various medicinal preparations worldwide by the end of the nineteenth century and considered a useful drug, physicians were sometimes wary of using it, in light of its effects on the psyche. For example, The Dispensatory of the United States of America of 1892 recognized that “in morbid states of the system, it has been found to cause sleep, to allay spasm, to compose nervous disquietude, and to relieve pain” and listed it “as a decided aphrodisiac” and appetite enhancer. Yet doctors were cautioned of its “powerful narcotic” action and risk of “delirious hallucinations … drowsiness and stupor,” “alarming effects,” according to the Dispensatory.53 Furthermore, despite considerable efforts, chemists had not succeeded in isolating the chemicals responsible for cannabis’s effects, and the quality and efficacy of hemp tinctures was highly variable.54 In an era when the biochemical extraction of the active principles of medicinal plants contributed to a drug’s perceived legitimacy, many cannabis-containing concoctions came across as patent medicines, and its side effects hardly endeared it among the conservative medical set.55 As a result of these factors and others, the reception of cannabis was mixed in mainstream Western medical practice, and it never became firmly established as a therapeutic agent.56


FIGURE 9.9   “Recipe for Colds, Coughs, Consumption & Bronchitis”: a cannabis-containing medication to treat respiratory conditions, published by H. James, a doctor in New York, 1856. (Collection of George Glastris)


Hemp has a long history of cultivation in North America, dating back to colonial times, when it was grown extensively for rope, canvas, cloth, and paper.57 It diminished as a fiber crop when cotton became more plentiful in the mid-nineteenth century, demand for sailcloth and rigging declined, and other fibers replaced hemp for making rope and canvas.58 By the mid-twentieth century, hemp cultivation had essentially ended in the United States.

Toward the middle and end of the nineteenth century, the custom of smoking hashish among European artists spread to the United States, where literary types took pleasure in its effects.59 In addition to the cosmopolitan use of cannabis among the educated classes of the cities, the late nineteenth and early twentieth centuries saw the rise of marihuana smoking among the disadvantaged tier of U.S. society.

Because cannabis grows as a weed, it became an inexpensive drug of choice among poor American and new immigrant communities both in cities and in the rural and deprived southern states.60 Among these groups, it was frequently smoked not through elegant glass and decorated metal water pipes but as cigarettes rolled with inexpensive tobacco. In time, American artists and musicians gravitated toward hemp as a tool of social connection and inspiration, such that jazz performers of the 1920s considered “tea smoking” part of their revolutionary new culture.

From New Orleans to Chicago and New York, jazz music’s new rhythm and structure attracted countless devotees and gave rise to a lifestyle that embraced marihuana. In “tea pads” scattered across Harlem in New York City, smokers—some white, most black—gathered to perform and listen to music. At dance halls, patrons and musicians smoked as new cannabis-inspired tunes caught hold, ultimately entering the American songbook on Broadway and performed by A-list artists such as Cab Calloway (1907–1994), Louis Armstrong (1901–1971), and Benny Goodman (1909–1986).61

To many journalists and the conservative elements in government, the seeming rise in marihuana use, particularly among immigrants and people of color, was perceived as a threat. Late-nineteenth-century immigration from southern Europe brought large numbers of the working poor to the American seacoasts and inland metropolitan regions, and after about 1910 Mexicans began moving into the southern states in increasing numbers. A general antiforeigner sentiment and directed racism converged in the vilification of marihuana, marihuana smoking, and the people who supposedly smoked it. (Indeed, the term “marihuana” was introduced into English during the late nineteenth century, ringing of Mexican or Mexican American slang.) The commissioner of the Federal Bureau of Narcotics, the antidrug crusader Harry Anslinger (1892–1975), argued on no linguistic basis that the name marihuana drew from a Nahuatl (Aztec) root meaning a “prisoner taken captive by the plant.”62

Criminalization of Cannabis

Government officials and journalists reported in stark language the alleged risks of marihuana both to the user and to society. In 1915, for example, an American newspaper headline wondered in a sinister font whether cannabis smoking might explain the perceived character flaws in the people living south of the border: IS THE MEXICAN NATION “LOCOED” BY A PECULIAR WEED?63 Other accounts elaborated on the tendency of cannabis to incite the user to violence and give him unusual strength, a common observation, apparently, among Mexicans. For instance, a Texas police captain wrote that under the sway of marihuana, Mexicans turn “very violent, especially when they become angry and will attack an officer even if a gun is drawn on him. They seem to have no fear. I have also noted that when under the influence of this weed they have enormous strength.”64 A newspaper report from 1920 described a knife-wielding “crazed Mexican” who turned himself on a crowd, a “seemingly demented man,” who had to be “beaten into submission by police and citizens.” The accessory to the crime, according to the article, was “marihuana, or ‘loco weed.’ ”65

Public discourse over marihuana became increasingly targeted through the 1920s, and by the 1930s the plant was associated with extremes of violence, promiscuity, and ethnic contagion. The commissioner of public safety of the city of New Orleans warned of a “menace to public safety,” including “unpremeditated and premeditated crime.” One of the most troubling risks of marihuana, according to this official, was “the general lowering of morals and restraint which follows the continued use of this vicious dissipation.”66 In painting a scene of a cannabis party targeting high-school students, an antimarihuana activist warned that the drug induced young people to “the wildest sexuality” and sharpened his point by including “ordinary intercourse and several forms of perversion … girl to girl, man to man, woman to woman” among the threats to social propriety.67

The connection among marihuana, crime, and ethnicity was nearly always explicit during this era. Who was responsible for the distribution of cannabis in New Orleans during the 1910s and 1920s? “Mexicans, Italians, Spanish-Americans and drifters from ships,” according to the New Orleans official.68 “The idle and irresponsible classes of America,” wrote a professor of pharmacology.69 In newspaper and magazine articles and on film, cannabis was increasingly portrayed as a drug of foreign origin with a unique capacity to incite the user to extreme violence and to corrupt the innocence of American youth.

The federal government played an important role in the demonization of cannabis, as the Bureau of Narcotics fed stories to the press that effectively illustrated its evils.70 This agenda resulted in a proliferation during the 1930s of print pieces with titles such as “The Menace of Marihuana” (American Mercury), “Tea for a Viper” (New Yorker), and “Sex Crazing Drug Menace” (Physical Culture) and motion pictures such as Assassin of Youth and Marihuana (figure 9.10).71 In the film Reefer Madness (1936), one of the best-known examples of this genre of antimarihuana dramas, several clean-cut white suburban high-school students are seduced into a seedy, amoral underworld by drug dealers.72 Over the course of their marihuana encounters, their privileged existence quickly unravels into a morass of theft, vehicular hit-and-run, sexual promiscuity, murder, rape, and suicide.

The tactics of this era generated a public protest against hemp, which was ultimately regulated with the passage of the federal Marihuana Tax Act of 1937.73 According to this legislation, anyone possessing or dealing commercially in hemp was required to register with the government and pay a tax through the purchase of tax stamps (figure 9.11).74 The tax stamps were sold to only those individuals possessing cannabis, essentially requiring self-incrimination in any attempt to comply with the law. The Tax Act was overturned by the Supreme Court in 1969 for this reason, but Congress drafted and passed the Comprehensive Drug Abuse Prevention and Control Act of 1970, which includes the Controlled Substances Act, explicitly to criminalize marihuana as a schedule I controlled substance. The Controlled Substances Act and the earlier Marihuana Tax Act applied to all forms of cannabis extract, resin, and herb, with exceptions for only processed fiber and hemp seed, if sterilized before sale. Rarely, the cultivation for fiber production of varieties low in psychoactive potential has been permitted. For example, World War II cut off American supplies of imported fibers, and the United States funded hemp-fiber production between 1942 and the end of the war.75


FIGURE 9.10   An advertising poster for the film Marihuana (1936). (Library of Congress, Prints and Photographs Division, LC-DIG-ppmsc-04768)


FIGURE 9.11   Marihuana tax stamps. (Smithsonian Institution, National Postal Museum, 1998.2013.4555.2.1-10)

Despite the federal regulatory status, hemp remained popular as a recreational drug in illicit use throughout the twentieth century, and clandestine growers trained the plant to thrive in the underground economy. From the 1970s onward, American hemp cultivation increasingly moved indoors, with specially selected varieties that performed well in greenhouses and interior grow rooms.76 Under the pressures of directed breeding and intensive yield-centered techniques, cannabis has been manipulated to grow larger, denser buds rich in glandular leaf hairs, producing ever-increasing levels of THC. Aided by biochemical assays as well as subjective experiences, producers can select varieties that induce a range of subtle effects on mood and sensation. In the quest to produce a uniform harvest of potent material, many cultivators have preserved desirable female plants as essentially immortal vegetative specimens. Grown under particular controlled conditions, the plants do not flower and can be used to produce cuttings for plants that will flower (generate buds) in the commercial setting. In this way, the cultivator can harvest an abundant crop of sinsemilla buds several times a year.77

While breeders made advances in the production of potent marihuana in controlled, indoor settings, many users sought the herb for treating illness: to ease pain, alleviate anxiety, increase appetite, and suppress vomiting, for example. Dropped from the United States Pharmacopeia and National Formulary in 1941, strongly restricted by the federal government, and the subject of very little scientific research, marihuana’s possible utility in therapy was only rarely considered during the second half of the twentieth century.78 Recently, a number of state ballot initiatives have lifted state penalties for the possession and consumption of limited amounts of cannabis. In some cases, the new state measures permit the cultivation, manufacture, possession, and use of marihuana for what are deemed “medicinal” purposes. In other states, restrictions were lifted for “medicinal” or “recreational” uses. Despite these moves by states and the District of Columbia, the federal government maintains that marihuana remains prohibited nationally, placing cannabis in a knotty legal predicament. The federal government has discretion over which cannabis-related crimes to prosecute while holding the position that marihuana is a schedule I controlled substance, with a high potential for abuse, no accepted medical use, and no accepted safe use.

The state actions permitting the use of medical marihuana have carved an unusual exception to the standard practices of science-based pharmaceutics. Whereas drugs regulated by the Food and Drug Administration are subjected to appropriate clinical trials to demonstrate safety and efficacy, measures allowing physicians to prescribe and vendors to dispense marihuana as a pharmaceutical agent ignore the long-established role of the federal government to monitor the quality of pharmaceuticals.79 In contrast to FDA-regulated medications, medical marihuana preparations are not subjected to federal oversight of manufacturing practices and content, or reporting of effectiveness or side effects, and patients face a diverse array of products with varying levels of potency.80


The primary active principle of cannabis, THC, was isolated by the Israeli biochemist Raphael Mechoulam (b. 1930) and his co-workers in 1964. Unlike many psychoactive plant chemicals, THC and other biologically active marihuana compounds are soluble in fat rather than water. Active agents include a family of structures, of which THC is largely responsible for the psychoactive properties. Other members of this family of chemicals, called cannabinoids, include constituents such as cannabidiol (CBD) and about sixty other molecules (figure 9.12).81 Hashish contains approximately 10 to 20 percent THC by weight, the buds and small leaves around 5 to 8 percent, and other plant parts 2 to 5 percent. Recent advances in cultivation and selection have resulted in an increase in the THC content in hashish made from certain elite varieties.82

While hemp seeds have health value for their nutritive content, they are not naturally psychoactive because they contain negligible levels of THC.83 Whatever minuscule amount of THC might be present in the prepared seeds is generally thought to be the result of contact with the resin in the flower parts carried over through harvesting.84

Throughout history, the most common methods of cannabis consumption have been via the oral route and in smoke. (Intravenous injection has not been practical because hemp’s active principles are not water soluble.) It is also possible to apply cannabis-containing ointments or lotions to the skin. The route of administration influences the effects on the body.

In a marihuana cigarette containing about 30 milligrams of THC, approximately 30 percent of the active principle is destroyed by heat before inhalation, the remainder being taken up with more or less efficiency, depending on smoking habits such as depth and pace of draw and loss to side-stream smoke.85 Uptake of the fat-soluble chemical is rapid, and levels of THC peak within a few minutes of smoking. In contrast to smoked cannabis, THC that enters the body via ingestion is broken down to some degree by stomach enzymes and is more slowly absorbed, reaching peak concentration in the blood after four to six hours.86 (Unlike when taken up through the lungs, ingested THC is converted in the liver to 11-hydroxy-THC, a more potent and longer-lasting metabolite).87 The concentration of CBD and perhaps other cannabinoids is also relevant to marihuana’s pharmacological effects; these molecules are thought to prolong the effects of THC and may have specific physiological effects of their own.88 Some herbalists consider marihuana to be a “synergistic medicine” composed of dozens of active principles that together generate therapeutic effects.89 Regardless of the mode of consumption, cannabinoids become stored in fat deposits throughout the body and brain and are slowly released at a very low level over a period of days to weeks without behavioral effects.90


FIGURE 9.12   Cannabinoid-signaling molecules: the cannabis active principles THC and cannabidiol (CBD); the endocannabinoids anandamide and 2-arachidonoylglycerol.

The cell receptors that perceive THC and other cannabinoids are present in many regions of the brain as well as in cells of the immune and reproductive systems. The brain receptors are particularly densely situated in the basal ganglia, cerebral cortex, hippocampus, cerebellum, and spinal cord, which may account for THC’s effects on the sense of time; the experience of distortions in taste, color, and sound processing; and the ability to concentrate and form memories.91 Cannabinoid receptors located in regions of the limbic system likely give rise to the sense of reward associated with cannabis.92 However, cannabinoid receptors are absent in the brain stem, which may explain why THC does not affect respiration and is relatively nonlethal at high doses. THC mediates analgesia and euphoria through extensive connections to the opioid-signaling network and interferes with hunger regulation by acting as an appetite signal. It also suppresses vomiting.93

THC and related chemicals from cannabis mimic the brain’s own signaling molecules, called the endocannabinoids (for endogenous cannabinoids), a group of chemicals that bear little resemblance to THC but nonetheless activate the same receptors (see figure 9.12). Endocannabinoid receptors on presynaptic neurons recognize endo-cannabinoids released by postsynaptic neurons in response to sustained signaling by glutamate, acetylcholine, and other neurotransmitters.94 As a result, endocannabinoids modulate a wide range of excitatory and inhibitory signals affecting numerous physiological activities.




Lightening of mood

Changes in perception

Disruption of short-term memory

Reduction of nausea

Increase in appetite


Therefore, endocannabinoids play a role in regulating those processes also affected by THC consumption: the perception of pain, anxiety, and hunger, among others. The role of the endocannabinoids in sensory experiences (discernment of space and time) is less clear. In this regard, THC may have particularly strong effects because its dose in cannabis consumption is frequently higher than the endogenous molecules. Chronic marihuana users experience tolerance and a range of withdrawal symptoms on discontinuation of use, including anxiety, decreased food intake, and pain.95

With such diverse roles in memory, pain, anxiety, hunger, and other aspects of health, some cannabinoids and synthetic analogs have been developed for use as medicines in the modern era. For example, the synthetic THC drug dronabinol (sold as Marinol) and the synthetic THC analog nabilone (sold as Cesamet) are approved to be taken orally as appetite stimulants for use in patients with AIDS and antiemetics for cancer patients undergoing radiation treatment and chemotherapy.96 There is great interest in developing new preparations of cannabis, including naturally derived active principles, for oral and inhaled delivery, as some patients wish to avoid the side effects of ingested THC and believe the combination of THC with other active principles to be more effective. As one step in this direction, the drug Sativex, a combination of natural THC and CBD in a one-to-one ratio delivered to the lungs via an inhaler, has been demonstrated effective for use by multiple sclerosis patients against neuropathic pain and spasticity.97The cannabinoid CBD itself is the target of much research because it appears to exert anticonvulsive, sedative, and anti-inflammatory effects without altering the patient’s mood or sense of time and space.98

Clinical studies are addressing the efficacy and safety of THC and THC analogs for a wide array of conditions, including chronic pain and glaucoma.99 At the same time, the laws of many jurisdictions are making cannabis more readily available to those who wish to take it for “recreational” or “medical” purposes. As modern research on the use of medicinal marihuana is relatively recent, it is important to allow the scientific method to guide the development of therapies, taking sampling, placebo effects, and controlled route of administration into account.

Hemp has long been valued as a medicinal plant and a source of a versatile fiber throughout Asia and Europe. It was associated with spiritual and healing properties in ancient texts and has survived to modern times as a mystical, recreational drug. Europeans rediscovered its effects during the nineteenth century, when artists drew inspiration from its calming and mind-opening influence. Although illegal in the United States according to federal law, many states have passed measures permitting its use for medical or recreational purposes, giving hemp a complex regulatory status. Meanwhile, researchers have made strides to understand how its assortment of active principles function singly or in concert to influence the mind and body in diverse ways. Since ancient times, people have documented hemp’s social, spiritual, and therapeutic properties. As our modern society debates cannabis use, we are discussing and engaging the same physiological effects experienced by communities thousands of years ago.

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