Cannabis is an annual, dioecious, flowering herb. The leaves are palmately compound or digitate, with serrate leaflets.[9] The first pair of leaves usually have a single leaflet, the number gradually increasing up to a maximum of about thirteen leaflets per leaf (usually seven or nine), depending on variety and growing conditions. At the top of a flowering plant, this number again diminishes to a single leaflet per leaf. The lower leaf pairs usually occur in an opposite leaf arrangement and the upper leaf pairs in an alternate arrangement on the main stem of a mature plant.
Cannabis normally has imperfect flowers, with staminate "male" and pistillate "female" flowers occurring on separate plants.[10] It is not unusual, however, for individual plants to bear both male and female flowers.[11] Although monoecious plants are often referred to as "hermaphrodites," true hermaphrodites (which are less common) bear staminate and pistillate structures on individual flowers, whereas monoecious plants bear male and female flowers at different locations on the same plant. Male flowers are normally borne on loose panicles, and female flowers are borne on racemes.[12] "At a very early period the Chinese recognized the Cannabis plant as dioecious,"[13] and the (ca. 3rd century BCE) Erya dictionary defined xi 枲 "male cannabis" and fu 莩 (or ju 苴) "female cannabis".[14]
All known strains of Cannabis are wind-pollinated[15] and produce "seeds" that are technically called achenes.[16] Most strains of Cannabis are short day plants,[15] with the possible exception of C. sativa subsp. sativa var. spontanea (= C. ruderalis), which is commonly described as "auto-flowering" and may be day-neutral.
Cannabis, like many organisms, is diploid, having a chromosome complement of 2n=20, although polyploid individuals have been artificially produced.[17] The plant is believed to have originated in the mountainous regions northwest of the Himalayas. It is also known as hemp, although this term is often used to refer only to varieties of Cannabis cultivated for non-drug use. Cannabis plants produce a group of chemicals called cannabinoids, which produce mental and physical effects when consumed. Cannabinoids, terpenoids, and other compounds are secreted by glandular trichomes that occur most abundantly on the floral calyxes and bracts of female plants.[18] As a drug it usually comes in the form of dried flower buds (marijuana), resin (hashish), or various extracts collectively known as hashish oil.[3] In the early 20th century, it became illegal in most of the world to cultivate or possess Cannabis for drug purposes.
Cannabis is a popular recreational drug around the world, only behind alcohol, caffeine and tobacco. In the United States alone, it is believed that over 100 million Americans have tried Cannabis, with 25 million Americans using it within the past year.[80]
The psychoactive effects of Cannabis are known to have a biphasic nature. Primary psychoactive effects include a state of relaxation, and to a lesser degree, euphoria from its main psychoactive compound, tetrahydrocannabinol. Secondary psychoactive effects, such as a facility for philosophical thinking; introspection and metacognition have been reported, amongst cases of anxiety and paranoia.[81] Finally, the tertiary psychoactive effects of the drug cannabis, can include an increase in heart rate and hunger, believed to be caused by 11-Hydroxy-THC, a psychoactive metabolite of THC produced in the liver.
Normal cognition is restored after approximately three hours for larger doses via a smoking pipe, bong or vaporizer.[81] However, if a large amount is taken orally the effects may last much longer. After 24 hours to a few days, minuscule psychoactive effects may be felt, depending on dosage, frequency and tolerance to the drug.
Various forms of the drug cannabis exist, including extracts such as hashish and hash oil[3] which, due to appearance, are more susceptible to adulterants when left unregulated.
The plant Cannabis sativa is known to cause more of a "high" by stimulating hunger and by producing a rather more comedic, or energetic feeling. Conversely, the Cannabis indica plant is known to cause more of a "stoned" type of feeling, possibly due to a higher CBD to THC ratio.[82]
Cannabidiol (CBD), which has no psychotropic effects by itself[83] (although sometimes showing a small stimulant effect, similar to caffeine),[citation needed] attenuates, or reduces[84] the higher anxiety levels caused by THC alone.[85]
According to the UK medical journal The Lancet, Cannabis has a lower rate of dependence compared to both nicotine and alcohol.[86] However, everyday use of Cannabis can in some cases, be correlated with some psychological withdrawal symptoms such as irritability, and insomnia[81] and evidence could suggest that if a user experiences stress, the likeliness of getting a panic attack increases due to an increase of THC metabolites.[87][88] However, any Cannabis withdrawal symptoms are typically mild and are never life-threatening.[86]
A synthetic form of the main psychoactive cannabinoid in Cannabis, Δ9-tetrahydrocannabinol (THC), is used as a treatment for a wide range of medical conditions.[89]
In the United States, although the Food and Drug Administration (FDA) does acknowledge that "there has been considerable interest in its use for the treatment of a number of conditions, including glaucoma, AIDS wasting, neuropathic pain, treatment of spasticity associated with multiple sclerosis, and chemotherapy-induced nausea," the agency has not approved "medical marijuana". There are currently 2 oral forms of cannabis (cannabinoids) available by prescription in the United States for nausea and vomiting associated with cancer chemotherapy: dronabinol (Marinol) and nabilone (Cesamet). Dronabinol is also approved for the treatment of anorexia associated with AIDS.[90] The FDA does facilitate scientific investigations into the medical uses of cannabinoids.[91]
In a collection of writings on medical marijuana by 45 researchers, a literature review on the medicinal uses of Cannabis and cannabinoids concluded that established uses include easing of nausea and vomiting, anorexia, and weight loss; "well-confirmed effect" was found in the treatment of spasticity, painful conditions (i.e. neurogenic pain), movement disorders, asthma, and glaucoma. Reported but "less-confirmed" effects included treatment of allergies, inflammation, infection, epilepsy, depression, bipolar disorders, anxiety disorder, dependency and withdrawal. Basic level research was being carried out at the time on autoimmune disease, cancer, neuroprotection, fever, disorders of blood pressure.[92]
Clinical trials conducted by the American Marijuana Policy Project, have shown the efficacy of cannabis as a treatment for cancer and AIDS patients, who often suffer from clinical depression, and from nausea and resulting weight loss due to chemotherapy and other aggressive treatments.[93] A synthetic version of the cannabinoid THC named dronabinol has been shown to relieve symptoms of anorexia and reduce agitation in elderly Alzheimer's patients.[94] Dronabinol has been approved for use with anorexia in patients with HIV/AIDS and chemotherapy-related nausea. This drug, while demonstrating the effectiveness of Cannabis at combating several disorders, is more expensive and less available than whole cannabis and has not been shown to be effective or safe.[95]
Glaucoma, a condition of increased pressure within the eyeball causing gradual loss of sight, can be treated with medical marijuana to decrease this intraocular pressure. There has been debate for 25 years on the subject. Some studies have shown a reduction of IOP in glaucoma patients who smoke cannabis,[96] but the effects are generally short-lived. There exists some concern over its use since it can also decrease blood flow to the optic nerve. Marijuana lowers IOP by acting on a cannabinoid receptor on the ciliary body called the CB receptor.[97] Although Cannabis may not be the best therapeutic choice for glaucoma patients, it may lead researchers to more effective treatments. A promising study shows that agents targeted to ocular CB receptors can reduce IOP in glaucoma patients who have failed other therapies.[98]
Medical cannabis is also used for analgesia, or pain relief. It is also reported to be beneficial for treating certain neurological illnesses such as epilepsy, and bipolar disorder.[99] Case reports have found that Cannabis can relieve tics in people with obsessive compulsive disorder and Tourette syndrome. Patients treated with tetrahydrocannabinol, the main psychoactive chemical found in Cannabis, reported a significant decrease in both motor and vocal tics, some of 50% or more.[100][101][102] Some decrease in obsessive-compulsive behavior was also found.[100] A recent study has also concluded that cannabinoids found in Cannabis might have the ability to prevent Alzheimer's disease.[103] THC has been shown to reduce arterial blockages.[104]
Another potential use for medical cannabis is movement disorders. Cannabis is frequently reported to reduce the muscle spasms associated with multiple sclerosis; this has been acknowledged by the Institute of Medicine, but it noted that these abundant anecdotal reports are not well-supported by clinical data. Evidence from animal studies suggests that there is a possible role for cannabinoids in the treatment of certain types of epileptic seizures.[105] A synthetic version of the major active compound in Cannabis, THC, is available in capsule form as the prescription drug dronabinol (Marinol) in many countries. The prescription drug Sativex, an extract of cannabis administered as a sublingual spray, has been approved in Canada for the treatment of multiple sclerosis.[106]
Cannabis normally has imperfect flowers, with staminate "male" and pistillate "female" flowers occurring on separate plants.[10] It is not unusual, however, for individual plants to bear both male and female flowers.[11] Although monoecious plants are often referred to as "hermaphrodites," true hermaphrodites (which are less common) bear staminate and pistillate structures on individual flowers, whereas monoecious plants bear male and female flowers at different locations on the same plant. Male flowers are normally borne on loose panicles, and female flowers are borne on racemes.[12] "At a very early period the Chinese recognized the Cannabis plant as dioecious,"[13] and the (ca. 3rd century BCE) Erya dictionary defined xi 枲 "male cannabis" and fu 莩 (or ju 苴) "female cannabis".[14]
All known strains of Cannabis are wind-pollinated[15] and produce "seeds" that are technically called achenes.[16] Most strains of Cannabis are short day plants,[15] with the possible exception of C. sativa subsp. sativa var. spontanea (= C. ruderalis), which is commonly described as "auto-flowering" and may be day-neutral.
Cannabis, like many organisms, is diploid, having a chromosome complement of 2n=20, although polyploid individuals have been artificially produced.[17] The plant is believed to have originated in the mountainous regions northwest of the Himalayas. It is also known as hemp, although this term is often used to refer only to varieties of Cannabis cultivated for non-drug use. Cannabis plants produce a group of chemicals called cannabinoids, which produce mental and physical effects when consumed. Cannabinoids, terpenoids, and other compounds are secreted by glandular trichomes that occur most abundantly on the floral calyxes and bracts of female plants.[18] As a drug it usually comes in the form of dried flower buds (marijuana), resin (hashish), or various extracts collectively known as hashish oil.[3] In the early 20th century, it became illegal in most of the world to cultivate or possess Cannabis for drug purposes.
Cannabis is a popular recreational drug around the world, only behind alcohol, caffeine and tobacco. In the United States alone, it is believed that over 100 million Americans have tried Cannabis, with 25 million Americans using it within the past year.[80]
The psychoactive effects of Cannabis are known to have a biphasic nature. Primary psychoactive effects include a state of relaxation, and to a lesser degree, euphoria from its main psychoactive compound, tetrahydrocannabinol. Secondary psychoactive effects, such as a facility for philosophical thinking; introspection and metacognition have been reported, amongst cases of anxiety and paranoia.[81] Finally, the tertiary psychoactive effects of the drug cannabis, can include an increase in heart rate and hunger, believed to be caused by 11-Hydroxy-THC, a psychoactive metabolite of THC produced in the liver.
Normal cognition is restored after approximately three hours for larger doses via a smoking pipe, bong or vaporizer.[81] However, if a large amount is taken orally the effects may last much longer. After 24 hours to a few days, minuscule psychoactive effects may be felt, depending on dosage, frequency and tolerance to the drug.
Various forms of the drug cannabis exist, including extracts such as hashish and hash oil[3] which, due to appearance, are more susceptible to adulterants when left unregulated.
The plant Cannabis sativa is known to cause more of a "high" by stimulating hunger and by producing a rather more comedic, or energetic feeling. Conversely, the Cannabis indica plant is known to cause more of a "stoned" type of feeling, possibly due to a higher CBD to THC ratio.[82]
Cannabidiol (CBD), which has no psychotropic effects by itself[83] (although sometimes showing a small stimulant effect, similar to caffeine),[citation needed] attenuates, or reduces[84] the higher anxiety levels caused by THC alone.[85]
According to the UK medical journal The Lancet, Cannabis has a lower rate of dependence compared to both nicotine and alcohol.[86] However, everyday use of Cannabis can in some cases, be correlated with some psychological withdrawal symptoms such as irritability, and insomnia[81] and evidence could suggest that if a user experiences stress, the likeliness of getting a panic attack increases due to an increase of THC metabolites.[87][88] However, any Cannabis withdrawal symptoms are typically mild and are never life-threatening.[86]
A synthetic form of the main psychoactive cannabinoid in Cannabis, Δ9-tetrahydrocannabinol (THC), is used as a treatment for a wide range of medical conditions.[89]
In the United States, although the Food and Drug Administration (FDA) does acknowledge that "there has been considerable interest in its use for the treatment of a number of conditions, including glaucoma, AIDS wasting, neuropathic pain, treatment of spasticity associated with multiple sclerosis, and chemotherapy-induced nausea," the agency has not approved "medical marijuana". There are currently 2 oral forms of cannabis (cannabinoids) available by prescription in the United States for nausea and vomiting associated with cancer chemotherapy: dronabinol (Marinol) and nabilone (Cesamet). Dronabinol is also approved for the treatment of anorexia associated with AIDS.[90] The FDA does facilitate scientific investigations into the medical uses of cannabinoids.[91]
In a collection of writings on medical marijuana by 45 researchers, a literature review on the medicinal uses of Cannabis and cannabinoids concluded that established uses include easing of nausea and vomiting, anorexia, and weight loss; "well-confirmed effect" was found in the treatment of spasticity, painful conditions (i.e. neurogenic pain), movement disorders, asthma, and glaucoma. Reported but "less-confirmed" effects included treatment of allergies, inflammation, infection, epilepsy, depression, bipolar disorders, anxiety disorder, dependency and withdrawal. Basic level research was being carried out at the time on autoimmune disease, cancer, neuroprotection, fever, disorders of blood pressure.[92]
Clinical trials conducted by the American Marijuana Policy Project, have shown the efficacy of cannabis as a treatment for cancer and AIDS patients, who often suffer from clinical depression, and from nausea and resulting weight loss due to chemotherapy and other aggressive treatments.[93] A synthetic version of the cannabinoid THC named dronabinol has been shown to relieve symptoms of anorexia and reduce agitation in elderly Alzheimer's patients.[94] Dronabinol has been approved for use with anorexia in patients with HIV/AIDS and chemotherapy-related nausea. This drug, while demonstrating the effectiveness of Cannabis at combating several disorders, is more expensive and less available than whole cannabis and has not been shown to be effective or safe.[95]
Glaucoma, a condition of increased pressure within the eyeball causing gradual loss of sight, can be treated with medical marijuana to decrease this intraocular pressure. There has been debate for 25 years on the subject. Some studies have shown a reduction of IOP in glaucoma patients who smoke cannabis,[96] but the effects are generally short-lived. There exists some concern over its use since it can also decrease blood flow to the optic nerve. Marijuana lowers IOP by acting on a cannabinoid receptor on the ciliary body called the CB receptor.[97] Although Cannabis may not be the best therapeutic choice for glaucoma patients, it may lead researchers to more effective treatments. A promising study shows that agents targeted to ocular CB receptors can reduce IOP in glaucoma patients who have failed other therapies.[98]
Medical cannabis is also used for analgesia, or pain relief. It is also reported to be beneficial for treating certain neurological illnesses such as epilepsy, and bipolar disorder.[99] Case reports have found that Cannabis can relieve tics in people with obsessive compulsive disorder and Tourette syndrome. Patients treated with tetrahydrocannabinol, the main psychoactive chemical found in Cannabis, reported a significant decrease in both motor and vocal tics, some of 50% or more.[100][101][102] Some decrease in obsessive-compulsive behavior was also found.[100] A recent study has also concluded that cannabinoids found in Cannabis might have the ability to prevent Alzheimer's disease.[103] THC has been shown to reduce arterial blockages.[104]
Another potential use for medical cannabis is movement disorders. Cannabis is frequently reported to reduce the muscle spasms associated with multiple sclerosis; this has been acknowledged by the Institute of Medicine, but it noted that these abundant anecdotal reports are not well-supported by clinical data. Evidence from animal studies suggests that there is a possible role for cannabinoids in the treatment of certain types of epileptic seizures.[105] A synthetic version of the major active compound in Cannabis, THC, is available in capsule form as the prescription drug dronabinol (Marinol) in many countries. The prescription drug Sativex, an extract of cannabis administered as a sublingual spray, has been approved in Canada for the treatment of multiple sclerosis.[106]
