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| Cannabis | |
|---|---|
.jpg) Close-up of flowering cannabis plant | |
| Pronunciation |
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| Source plant(s) | Cannabis sativa, Cannabis indica, Cannabis ruderalis |
| Part(s) of plant | Flower and fruit |
| Geographic origin | Central or South Asia |
| Active ingredients | Tetrahydrocannabinol, cannabidiol, cannabinol, tetrahydrocannabivarin |
| Main producers | Afghanistan, Canada, China, Colombia, India, Jamaica, Lebanon, Mexico, Morocco, Netherlands, Pakistan, Paraguay, Spain, Thailand, Turkey, United Kingdom, United States |
| Legal status |
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| Part of a series on |
| Cannabis |
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Cannabis,[a] also known as marijuana[b] or weed among other names, is a psychoactive drug from the cannabis plant. Native to Central or South Asia, the cannabis plant has been used as a drug for both recreational and entheogenic purposes and in various traditional medicines for centuries. Tetrahydrocannabinol (THC) is the main psychoactive component of cannabis, which is one of the 483 known compounds in the plant, including at least 65 other cannabinoids, such as cannabidiol (CBD). Cannabis can be used by smoking, vaporizing, within food, or as an extract.
Cannabis has various mental and physical effects, which include euphoria, altered states of mind and sense of time, difficulty concentrating, impaired short-term memory, impaired body movement (balance and fine psychomotor control), relaxation, and an increase in appetite. Onset of effects is felt within minutes when smoked, but may take up to 90 minutes when eaten (as orally consumed drugs must be digested and absorbed). The effects last for two to six hours, depending on the amount used. At high doses, mental effects can include anxiety, delusions (including ideas of reference), hallucinations, panic, paranoia, and psychosis. There is a strong relation between cannabis use and the risk of psychosis, though the direction of causality is debated. Physical effects include increased heart rate, difficulty breathing, nausea, and behavioral problems in children whose mothers used cannabis during pregnancy; short-term side effects may also include dry mouth and red eyes. Long-term adverse effects may include addiction, decreased mental ability in those who started regular use as adolescents,[3] chronic coughing, susceptibility to respiratory infections, and cannabinoid hyperemesis syndrome.
Cannabis is mostly used recreationally or as a medicinal drug, although it may also be used for spiritual purposes. In 2013, between 128 and 232 million people used cannabis (2.7% to 4.9% of the global population between the ages of 15 and 65). It is the most commonly used largely-illegal drug in the world, with the highest use among adults in Zambia, the United States, Canada, and Nigeria. Since the 1970s, the potency of illicit cannabis has increased, with THC levels rising and CBD levels dropping.
Cannabis plants have been grown since at least the 3rd millennium BCE and there is evidence of it being smoked for its psychoactive effects around 500 BCE in the Pamir Mountains, Central Asia. Since the 14th century, cannabis has been subject to legal restrictions. The possession, use, and cultivation of cannabis has been illegal in most countries since the 20th century. In 2013, Uruguay became the first country to legalize recreational use of cannabis. Other countries to do so are Canada, Georgia, Germany, Luxembourg, Malta, Mexico, South Africa, and Thailand. In the U.S., the recreational use of cannabis is legalized in 24 states, 3 territories, and the District of Columbia, though the drug remains federally illegal. In Australia, it is legalized only in the Australian Capital Territory.
Etymology
The word is borrowed from Latin cannabis ("hemp"), from Ancient Greek κάνναβις (kánnabis).[citation needed]
The first reference to marihuana was found in 1842 in Mexican newspapers, and then the term made its way to the U.S. in the 1890s.[4]
Uses
Medical
Medical cannabis, or medical marijuana, refers to the use of cannabis to treat disease or improve symptoms; however, there is no single agreed-upon definition (e.g., cannabinoids derived from cannabis and synthetic cannabinoids are also used).[5][6][7] The rigorous scientific study of cannabis as a medicine has been hampered by production restrictions and by the fact that it is classified as an illegal drug by many governments.[8] There is some evidence suggesting cannabis can be used to reduce nausea and vomiting during chemotherapy, to improve appetite in people with HIV/AIDS, or to treat chronic pain and muscle spasms. Evidence for its use for other medical applications is insufficient for drawing conclusions about safety or efficacy.[9][10][11] There is evidence supporting the use of cannabis or its derivatives in the treatment of chemotherapy-induced nausea and vomiting, neuropathic pain, and multiple sclerosis. Lower levels of evidence support its use for AIDS wasting syndrome, epilepsy, rheumatoid arthritis, and glaucoma.[12]
The medical use of cannabis is legal only in a limited number of territories, including Canada,[13] Belgium, Australia, the Netherlands, New Zealand,[14][15] Spain, and many U.S. states. This usage generally requires a prescription, and distribution is usually done within a framework defined by local laws.[12]
Recreational
According to DEA Chief Administrative Law Judge, Francis Young, "cannabis is one of the safest therapeutically active substances known to man".[16] Being under the effects of cannabis is usually referred to as being "high".[17] Cannabis consumption has both psychoactive and physiological effects.[18] The "high" experience can vary widely, based (among other things) on the user's prior experience with cannabis, and the type of cannabis consumed.[19]: p647 When smoking cannabis, a euphoriant effect can occur within minutes of smoking.[20]: p104 Aside from a subjective change in perception and mood, the most common short-term physical and neurological effects include increased heart rate, increased appetite, impairment of short-term and working memory, and psychomotor coordination.[21][22]
Additional desired effects from consuming cannabis include relaxation, a general alteration of conscious perception, increased awareness of sensation, increased libido[23] and distortions in the perception of time and space. At higher doses, effects can include altered body image, auditory and/or visual illusions, pseudohallucinations and ataxia from selective impairment of polysynaptic reflexes.[citation needed] In some cases, cannabis can lead to dissociative states such as depersonalization[24][25] and derealization.[26]
Spiritual
Cannabis has held sacred status in several religions and has served as an entheogen – a chemical substance used in religious, shamanic, or spiritual contexts[27] – in the Indian subcontinent since the Vedic period. The earliest known reports regarding the sacred status of cannabis in the Indian subcontinent come from the Atharva Veda, estimated to have been composed sometime around 1400 BCE.[28] The Hindu god Shiva is described as a cannabis user, known as the "Lord of bhang".[29]: p19
In modern culture, the spiritual use of cannabis has been spread by the disciples of the Rastafari movement who use cannabis as a sacrament and as an aid to meditation.[28]
Consumption
Modes of consumption
Many different ways to consume cannabis involve heat to decarboxylate THCA into THC;[30][31] common modes include:
- Smoking, involves burning and inhaling cannabinoids ("smoke") from small pipes, bongs (portable versions of hookahs with a water chamber), paper-wrapped joints, tobacco-leaf-wrapped blunts, or the like.[32]
- Vaporizing, heating various forms of cannabis to 165–190 °C (329–374 °F),[33] causing the active ingredients to form vapor without combustion of the plant material (the boiling point of THC is 157 °C (315 °F) at atmospheric pressure).[34]
- Edibles, adding cannabis as an ingredient to a wide variety of foods, including butter and baked goods. In India it is commonly consumed as the beverage bhang.
- Cannabis tea, prepared with attention to the lipophilic quality of THC, which is only slightly water-soluble (2.8 mg per liter),[35] often involving cannabis in a saturated fat.[36]
- Tincture of cannabis, sometimes known as green dragon, is an alcoholic cannabis concentrate.
- Capsules, typically containing cannabis oil, and other dietary supplement products, for which some 220 were approved in Canada in 2018.[13]
Consumption by country
| Substance | Best estimate |
Low estimate |
High estimate |
|---|---|---|---|
| Amphetamine- type stimulants |
34.16 | 13.42 | 55.24 |
| Cannabis | 192.15 | 165.76 | 234.06 |
| Cocaine | 18.20 | 13.87 | 22.85 |
| Ecstasy | 20.57 | 8.99 | 32.34 |
| Opiates | 19.38 | 13.80 | 26.15 |
| Opioids | 34.26 | 27.01 | 44.54 |
In 2013, between 128 and 232 million people used cannabis (2.7% to 4.9% of the global population between the ages of 15 and 65).[38] Cannabis is by far the most widely used illicit substance,[39] with the highest use among adults (as of 2018[update]) in Zambia, the United States, Canada, and Nigeria.[40]
United States
Between 1973 and 1978, eleven states decriminalized marijuana.[41] In 2001, Nevada reduced marijuana possession to a misdemeanor and since 2012, several other states have decriminalized and even legalized marijuana.[41]
In 2018, surveys indicated that almost half of the people in the United States had tried marijuana, 16% had used it in the past year, and 11% had used it in the past month.[42] In 2014, surveys said daily marijuana use amongst US college students had reached its highest level since records began in 1980, rising from 3.5% in 2007 to 5.9% in 2014 and had surpassed daily cigarette use.[43]
In the US, men are over twice as likely to use marijuana as women, and 18–29-year-olds are six times more likely to use as over-65-year-olds.[44] In 2015, a record 44% of the US population has tried marijuana in their lifetime, an increase from 38% in 2013 and 33% in 1985.[44]
Marijuana use in the United States is three times above the global average, but in line with other Western democracies. Forty-four percent of American 12th graders have tried the drug at least once, and the typical age of first-use is 16, similar to the typical age of first-use for alcohol but lower than the first-use age for other illicit drugs.[39]
A 2022 Gallup poll concluded Americans are smoking more marijuana than cigarettes for the first time.[45]
Adverse effects
Short-term
Acute negative effects may include anxiety and panic, impaired attention and memory, an increased risk of psychotic symptoms,[c] the inability to think clearly, and an increased risk of accidents.[48][49][50] Cannabis impairs a person's driving ability, and THC was the illicit drug most frequently found in the blood of drivers who have been involved in vehicle crashes. Those with THC in their system are from three to seven times more likely to be the cause of the accident than those who had not used either cannabis or alcohol, although its role is not necessarily causal because THC stays in the bloodstream for days to weeks after intoxication.[51][52][d]
Some immediate undesired side effects include a decrease in short-term memory, dry mouth, impaired motor skills, reddening of the eyes,[55] dizziness, feeling tired and vomiting.[10] Some users may experience an episode of acute psychosis, which usually abates after six hours, but in rare instances, heavy users may find the symptoms continuing for many days.[56]
Legalization has increased the rates at which children are exposed to cannabis, particularly from edibles. While the toxicity and lethality of THC in children is not known, they are at risk for encephalopathy, hypotension, respiratory depression severe enough to require ventilation, somnolence and coma.[57][58]
Fatality
There is no clear evidence for a link between cannabis use and deaths from cardiovascular disease, but a 2019 review noted that it may be an under-reported, contributory factor or direct cause in cases of sudden death, due to the strain it can place on the cardiovascular system. Some deaths have also been attributed to cannabinoid hyperemesis syndrome.[59] There is an association between cannabis use and suicide, particularly in younger users.[60]
A 16-month survey of Oregon and Alaska emergency departments found a report of the death of an adult who had been admitted for acute cannabis toxicity.[61]
Long-term
Psychological effects
A 2015 meta-analysis found that, although a longer period of abstinence was associated with smaller magnitudes of impairment, both retrospective and prospective memory were impaired in cannabis users. The authors concluded that some, but not all, of the deficits associated with cannabis use were reversible.[63] A 2012 meta-analysis found that deficits in most domains of cognition persisted beyond the acute period of intoxication, but was not evident in studies where subjects were abstinent for more than 25 days.[64] Few high quality studies have been performed on the long-term effects of cannabis on cognition, and the results were generally inconsistent.[65] Furthermore, effect sizes of significant findings were generally small.[64] One review concluded that, although most cognitive faculties were unimpaired by cannabis use, residual deficits occurred in executive functions.[66] Impairments in executive functioning are most consistently found in older populations, which may reflect heavier cannabis exposure, or developmental effects associated with adolescent cannabis use.[67] One review found three prospective cohort studies that examined the relationship between self-reported cannabis use and intelligence quotient (IQ). The study following the largest number of heavy cannabis users reported that IQ declined between ages 7–13 and age 38. Poorer school performance and increased incidence of leaving school early were both associated with cannabis use, although a causal relationship was not established.[68] Cannabis users demonstrated increased activity in task-related brain regions, consistent with reduced processing efficiency.[69]
A reduced quality of life is associated with heavy cannabis use, although the relationship is inconsistent and weaker than for tobacco and other substances.[70] The direction of cause and effect, however, is unclear.[70]
The long-term effects of cannabis are not clear.[10] There are concerns surrounding memory and cognition problems, risk of addiction, and the risk of schizophrenia in young people.[9]
Neuroimaging
Although global abnormalities in white matter and grey matter are not consistently associated with heavy cannabis use,[71] reduced hippocampal volume is consistently found.[72] Amygdala abnormalities are sometimes reported, although findings are inconsistent.[73][74][75]
Cannabis use is associated with increased recruitment of task-related areas, such as the dorsolateral prefrontal cortex, which is thought to reflect compensatory activity due to reduced processing efficiency.[75][74][76] Cannabis use is also associated with downregulation of CB1 receptors. The magnitude of down regulation is associated with cumulative cannabis exposure, and is reversed after one month of abstinence.[68][77][78] There is limited evidence that chronic cannabis use can reduce levels of glutamate metabolites in the human brain.[79]
Cannabis dependence
About 9% of those who experiment with marijuana eventually become dependent according to DSM-IV (1994) criteria.[12] A 2013 review estimates daily use is associated with a 10–20% rate of dependence.[9] The highest risk of cannabis dependence is found in those with a history of poor academic achievement, deviant behavior in childhood and adolescence, rebelliousness, poor parental relationships, or a parental history of drug and alcohol problems.[80] Of daily users, about 50% experience withdrawal upon cessation of use (i.e. are dependent), characterized by sleep problems, irritability, dysphoria, and craving.[68] Cannabis withdrawal is less severe than withdrawal from alcohol.[81]
According to DSM-V criteria, 9% of those who are exposed to cannabis develop cannabis use disorder, compared to 20% for cocaine, 23% for alcohol and 68% for nicotine. Cannabis use disorder in the DSM-V involves a combination of DSM-IV criteria for cannabis abuse and dependence, plus the addition of craving, without the criterion related to legal troubles.[68]
Psychiatric
At an epidemiological level, a dose–response relationship exists between cannabis use and increased risk of psychosis[82][83][84][85] and earlier onset of psychosis.[86] Although the epidemiological association is robust, evidence to prove a causal relationship is lacking.[87]
Cannabis may also increase the risk of depression, but insufficient research has been performed to draw a conclusion.[88][84] Cannabis use is associated with increased risk of anxiety disorders, although causality has not been established.[89]
A review in 2019 found that research was insufficient to determine the safety and efficacy of using cannabis to treat schizophrenia, psychosis, or other mental disorders.[90][91] Another found that cannabis during adolescence was associated with an increased risk of developing depression and suicidal behavior later in life, while finding no effect on anxiety.[92]
Physical
Heavy, long-term exposure to marijuana may have physical, mental, behavioral and social health consequences. It may be "associated with diseases of the liver (particularly with co-existing hepatitis C), lungs, heart, and vasculature".[93] A 2014 review found that while cannabis use may be less harmful than alcohol use, the recommendation to substitute it for problematic drinking was premature without further study.[94] Various surveys conducted between 2015 and 2019 found that many users of cannabis substitute it for prescription drugs (including opioids), alcohol, and tobacco; most of those who used it in place of alcohol or tobacco either reduced or stopped their intake of the latter substances.[95]
Cannabinoid hyperemesis syndrome (CHS) is a severe condition seen in some chronic cannabis users where they have repeated bouts of uncontrollable vomiting for 24–48 hours. Four cases of death have been reported as a result of CHS.[96][97]
A limited number of studies have examined the effects of cannabis smoking on the respiratory system.[98] Chronic heavy marijuana smoking is associated with respiratory infections,[99] coughing, production of sputum, wheezing, and other symptoms of chronic bronchitis.[48] The available evidence does not support a causal relationship between cannabis use and chronic obstructive pulmonary disease.[100] Short-term use of cannabis is associated with bronchodilation.[101] Other side effects of cannabis use include cannabinoid hyperemesis syndrome (CHS), a condition which involves recurrent nausea, cramping abdominal pain, and vomiting.[102]
Cannabis smoke contains thousands of organic and inorganic chemical compounds. This tar is chemically similar to that found in tobacco smoke,[103] and over fifty known carcinogens have been identified in cannabis smoke,[104] including; nitrosamines, reactive aldehydes, and polycylic hydrocarbons, including benzpyrene.[105] Cannabis smoke is also inhaled more deeply than tobacco smoke.[106] As of 2015[update], there is no consensus regarding whether cannabis smoking is associated with an increased risk of cancer.[107] Light and moderate use of cannabis is not believed to increase risk of lung or upper airway cancer. Evidence for causing these cancers is mixed concerning heavy, long-term use. In general there are far lower risks of pulmonary complications for regular cannabis smokers when compared with those of tobacco.[108] A 2015 review found an association between cannabis use and the development of testicular germ cell tumors (TGCTs), particularly non-seminoma TGCTs.[109] Another 2015 meta-analysis found no association between lifetime cannabis use and risk of head or neck cancer.[110] Combustion products are not present when using a vaporizer, consuming THC in pill form, or consuming cannabis foods.[111]
There is concern that cannabis may contribute to cardiovascular disease,[112] but as of 2018[update], evidence of this relationship was unclear.[113] Research in these events is complicated because cannabis is often used in conjunction with tobacco, and drugs such as alcohol and cocaine that are known to have cardiovascular risk factors.[114] Smoking cannabis has also been shown to increase the risk of myocardial infarction by 4.8 times for the 60 minutes after consumption.[115]
There is preliminary evidence that cannabis interferes with the anticoagulant properties of prescription drugs used for treating blood clots.[116] As of 2019[update], the mechanisms for the anti-inflammatory and possible pain relieving effects of cannabis were not defined, and there were no governmental regulatory approvals or clinical practices for use of cannabis as a drug.[91]
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