EFFECTS OF MARIJUANA

Chemical compounds in the Cannabis plant, including 400 different cannabinoids such as tetrahydrocannabinol (THC),[1] allow its drug to have various psychological and physiological effects on the human body. Different plants of the genus Cannabis contain different and often unpredictable concentrations of THC and other cannabinoids and hundreds of other molecules that have a pharmacological effect,[2][3] so that the final net effect cannot reliably be foreseen. Acute effects while under the influence can include euphoria and anxiety.[4][5] Although some assert that Cannabidiol (CBD), another cannabinoid found in cannabis in varying amounts, may alleviate the adverse effects of THC that some users experience,[6] little is known about CBD's effects on humans. The well-controlled studies with humans have a hard time showing that CBD can be distinguished from a placebo, or that it has any systematic effect on the adverse effects of cannabis.[7][8] When ingested orally, THC can produce stronger psychotropic effects than when inhaled. At doses exceeding the psychotropic threshold, users may experience adverse side effects such as anxiety and panic attacks that can result in increased heart rate and changes in blood pressure. In the United States research about medical cannabis has been hindered by federal law.[9] Smoking any substance could possibly carry similar risks as smoking tobacco due to carcinogens in all smoke,[10][11][12] and the ultimate conclusions on these factors are disputed.[13][14][15][16] Cannabis use disorder is defined as a medical diagnosis in the fifth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).[17]

Peak levels of cannabis-associated intoxication occur approximately 30 minutes after smoking it and last for several hours.[56] Smoked ✒ Edit The total short-term duration of cannabis use when smoked depends on the potency, method of smoking – e.g. whether pure or in conjunction with tobacco – and how much is smoked. Peak levels of intoxication typically last an average of three to four hours.[56] Oral ✒ Edit When taken orally (in the form of capsules, food or drink), the psychoactive effects take longer to manifest and generally last longer, typically lasting for an average of four to six hours after consumption.[57][unreliable medical source?] Very high doses may last even longer. Oral ingestion use eliminates the need to inhale toxic combustion products created by smoking and therefore negates the risk of respiratory harm associated with cannabis smoking. Neurological effects ✒ Edit The areas of the brain where cannabinoid receptors are most prevalent are consistent with the behavioral effects produced by cannabinoids. Brain regions in which cannabinoid receptors are very abundant are the basal ganglia, associated with movement control; the cerebellum, associated with body movement coordination; the hippocampus, associated with learning, memory, and stress control; the cerebral cortex, associated with higher cognitive functions; and the nucleus accumbens, regarded as the reward center of the brain. Other regions where cannabinoid receptors are moderately concentrated are the hypothalamus, which regulates homeostatic functions; the amygdala, associated with emotional responses and fears; the spinal cord, associated with peripheral sensations like pain; the brain stem, associated with sleep, arousal, and motor control; and the nucleus of the solitary tract, associated with visceral sensations like nausea and vomiting.[58] Experiments on animal and human tissue have demonstrated a disruption of short-term memory formation,[20] which is consistent with the abundance of C receptors on the hippocampus, the region of the brain most closely associated with memory. Cannabinoids inhibit the release of several neurotransmitters in the hippocampus such as acetylcholine, norepinephrine, and glutamate, resulting in a decrease in neuronal activity in that area. In in-vitro experiments THC at extremely high concentrations, which could not be reached with commonly consumed doses, caused competitive inhibition of the AChE enzyme and inhibition of β-amyloid peptide aggregation, implicated in the development of Alzheimer's disease. Compared to currently approved drugs prescribed for the treatment of Alzheimer's disease, THC is a considerably superior inhibitor of A aggregation, and this study provides a previously unrecognized molecular mechanism through which cannabinoid molecules may impact the progression of this debilitating disease.[59] Effects on driving ✒ Edit Main article: Cannabis and impaired driving While several studies have shown increased risk associated with cannabis use by drivers, other studies have not found increased risk.[60] Cannabis usage has been shown in some studies to have a negative effect on driving ability.[61] The British Medical Journal indicated that "drivers who consume cannabis within three hours of driving are nearly twice as likely to cause a vehicle collision as those who are not under the influence of drugs or alcohol".[62] In Cannabis and driving: a review of the literature and commentary, the United Kingdom's Department for Transport reviewed data on cannabis and driving, finding although impaired, "subjects under cannabis treatment appear to perceive that they are indeed impaired. Where they can compensate, they do...".[63] In a review of driving simulator studies, researchers note that "even in those who learn to compensate for a drug's impairing effects, substantial impairment in performance can still be observed under conditions of general task performance (i.e. when no contingencies are present to maintain compensated performance)."[64] A 2012 meta-analysis found that acute cannabis use increased the risk of an automobile crash.[65] An extensive 2013 review of 66 studies regarding crash risk and drug use found that cannabis was associated with minor, but not statistically significant increased odds of injury or fatal accident.[66] In the largest and most precisely controlled study of its kind carried out by the U.S. Department of Transportation’s National Highway Traffic Safety Administration, it was found that other "studies that measure the presence of THC in the drivers' blood or oral fluid, rather than relying on self-report tend to have much lower (or no) elevated crash risk estimates. Likewise better controlled studies have found lower (or no) elevated crash risk estimates".[60] The study found that "after adjusting for age, gender, race and alcohol use, drivers who tested positive for marijuana were no more likely to crash than those who had not used any drugs or alcohol prior to driving".[67] On the other hand, a recent study of Journal of Transport & Health indicated that the numbers of fatal crashes involving marijuana after the recreational marijuana legalization or decriminalization have significantly increased in Colorado, Washington, and Massachusetts.[68] Cardiovascular effects ✒ Edit Short-term (one to two hours) effects on the cardiovascular system can include increased heart rate, dilation of blood vessels, and fluctuations in blood pressure.[69][70][71] There are medical reports of occasional heart attacks or myocardial infarction, stroke and other cardiovascular side effects.[72] Marijuana's cardiovascular effects are not associated with serious health problems for most young, healthy users.[72] Researchers reported in the International Journal of Cardiology, "Marijuana use by older people, particularly those with some degree of coronary artery or cerebrovascular disease, poses greater risks due to the resulting increase in catecholamines, cardiac workload, and carboxyhemoglobin levels, and concurrent episodes of profound postural hypotension. Indeed, marijuana may be a much more common cause of myocardial infarction than is generally recognized. In day-to-day practice, a history of marijuana use is often not sought by many practitioners, and even when sought, the patient's response is not always truthful".[73] A 2013 analysis of 3,886 myocardial infarction survivors over an 18-year period showed "no statistically significant association between marijuana use and mortality".[74] A 2008 study by the National Institutes of Health Biomedical Research Centre in Baltimore found that heavy, chronic smoking of marijuana (138 joints per week) changed blood proteins associated with heart disease and stroke.[75] A 2000 study by researchers at Boston's Beth Israel Deaconess Medical Center, Massachusetts General Hospital and Harvard School of Public Health found that a middle-age person's risk of heart attack rises nearly fivefold in the first hour after smoking marijuana, "roughly the same risk seen within an hour of sexual activity".[76][77] Cannabis arteritis is a very rare peripheral vascular disease similar to Buerger's disease. There were about 50 confirmed cases from 1960 to 2008, all of which occurred in Europe.[78] Combination with other drugs ✒ Edit A confounding factor in cannabis research is the prevalent usage of other recreational drugs, especially alcohol and nicotine.[79] Such complications demonstrate the need for studies on cannabis that have stronger controls, and investigations into alleged symptoms of cannabis use that may also be caused by tobacco. Some critics question whether agencies doing the research make an honest effort to present an accurate, unbiased summary of the evidence, or whether they "cherry-pick" their data to please funding sources which may include the tobacco industry or governments dependent on cigarette tax revenue; others caution that the raw data, and not the final conclusions, are what should be examined.[80] The Australian National Household Survey of 2001[81] showed that cannabis in Australia is rarely used without other drugs. 95% of cannabis users also drank alcohol; 26% took amphetamines; 19% took ecstasy and only 2.7% reported not having used any other drug with cannabis.[82] While research has been undertaken on the combined effects of alcohol and cannabis on performing certain tasks, little research has been conducted on the reasons why this combination is so popular. Evidence from a controlled experimental study undertaken by Lukas and Orozco[83] suggests that alcohol causes THC to be absorbed more rapidly into the blood plasma of the user. Data from the Australian National Survey of Mental Health and Wellbeing[84] found that three-quarters of recent cannabis users reported using alcohol when cannabis was not available, this suggests that the two are substitutes.[85] Memory and learning ✒ Edit Main article: Cannabis and memory Studies on cannabis and memory are hindered by small sample sizes, confounding drug use, and other factors.[86] The strongest evidence regarding cannabis and memory focuses on its temporary negative effects on short-term and working memory.[86] In a 2001 study looking at neuropsychological performance in long-term cannabis users, researchers found "some cognitive deficits appear detectable at least 7 days after heavy cannabis use but appear reversible and related to recent cannabis exposure rather than irreversible and related to cumulative lifetime use".[87] On his studies regarding cannabis use, lead researcher and Harvard professor Harrison Pope said he found marijuana is not dangerous over the long term, but there are short-term effects. From neuropsychological tests, Pope found that chronic cannabis users showed difficulties, with verbal memory in particular, for "at least a week or two" after they stopped smoking. Within 28 days, memory problems vanished and the subjects "were no longer distinguishable from the comparison group".[88] Researchers from the University of California, San Diego School of Medicine failed to show substantial, systemic neurological effects from long-term recreational use of cannabis. Their findings were published in the July 2003 issue of the Journal of the International Neuropsychological Society.[89] The research team, headed by Dr Igor Grant, found that cannabis use did affect perception, but did not cause permanent brain damage. Researchers looked at data from 15 previously published controlled studies involving 704 long-term cannabis users and 484 nonusers. The results showed long-term cannabis use was only marginally harmful on the memory and learning. Other functions such as reaction time, attention, language, reasoning ability, perceptual and motor skills were unaffected. The observed effects on memory and learning, they said, showed long-term cannabis use caused "selective memory defects", but that the impact was "of a very small magnitude".[90] A study at Johns Hopkins University School of Medicine showed that very heavy use of marijuana is associated with decrements in neurocognitive performance even after 28 days of abstinence.[91] Appetite ✒ Edit The feeling of increased appetite following the use of cannabis has been documented for hundreds of years,[92] and is known colloquially as "the munchies" in the English-speaking world. Clinical studies and survey data have found that cannabis increases food enjoyment and interest in food.[93][94] A 2015 study suggests that cannabis triggers uncharacteristic behaviour in POMC neurons, which are usually associated with decreasing hunger.[95][96] Rarely, chronic users experience a severe vomiting disorder, cannabinoid hyperemesis syndrome, after smoking and find relief by taking hot baths.[97] Endogenous cannabinoids ("endocannabinoids") were discovered in cow's milk and soft cheeses.[98][99] Endocannabinoids are also found in human breast milk.[100][101][102][103][104] It is widely accepted that the neonatal survival of many species "is largely dependent upon their suckling behavior, or appetite for breast milk"[105] and recent research has identified the endogenous cannabinoid system to be the first neural system to display complete control over milk ingestion and neonatal survival.[104] It is possible that "cannabinoid receptors in our body interact with the cannabinoids in milk to stimulate a suckling response in newborns so as to prevent growth failure".[105] Pathogens and microtoxins ✒ Edit Most microorganisms found in cannabis only affect plants and not humans, but some microorganisms, especially those that proliferate when the herb is not correctly dried and stored, can be harmful to humans. Some users may store marijuana in an airtight bag or jar in a refrigerator to prevent fungal and bacterial growth