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Donate In the last 50 years, marijuana has gone from menace to medicine. Which is it?  

by Alison Hudson

Filed under Alternative Medicine, Health

Skeptoid Podcast #470
June 9, 2015
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Once branded as a social menace, marijuana is enjoying a new push for legitimacy. Advocates herald marijuana as a medicinal herb capable of treating everything from nausea to cancer, and they push to classify it as a legal vice. And yet, anti-drug advocates continue to argue against marijuana, calling it a dangerous gateway to drug abuse and pushing lawmakers to resist legalization. So, which is it – a miracle cure or a dangerous vice? Let's consider both sides of the marijuana debate.

Marijuana is the most common name for modern preparations of Cannabis sativa, a plant closely related to hops and a relative of roses. The common preparation consists of dried and crushed cannabis leaves and buds that users smoke to "get high." A "high," which includes feelings of euphoria, altered sensations, and a temporary impairment of cognitive functions, lasts about an hour and is a result of the high levels of delta-9-tetrahydrocannabino, or THC, in the plant.

Currently, marijuana is largely illegal around the world, a result of international treaties signed in the last fifty years. In the United States, it is a Schedule I drug, meaning it is considered to have a high potential for abuse and is illegal on the federal level for any reason. Several states in the U.S. are currently challenging that status, however, and the result is a patchwork of state and local ordinances of varying levels of legality.

Marijuana first picked up its reputation as a social menace in the 1920s, when the drug's popularity began to rise amongst students and others in the United States. One article that many writers point to as a key publication in the move against marijuana is simply titled "Marihuana," written by M. H. Hayes and L. E. Bowery and appearing in the Journal of Criminal Law and Criminology in 1933. Hayes and Bowery's primary focus is promoting anti-marijuana legislation. To achieve that, they claim that a marijuana high can drive users to all sorts of depraved and illegal acts, including rape and murder. They also stoke prejudiced fears over "the Mexicans," whom they finger as the source of the problem, saying the drug is found "wherever Mexicans are located" and noting that marijuana,

so long as it was confined to Mexicans themselves, was not generally noticed. As an issue of importance, it was first called to public attention about 1925, when it spread to native whites.

Views on marijuana in the twenty-first century have largely lost this sort of extremism and racist overtone, but anti-drug advocates still argue the dangers of marijuana. The U.S. National Institute on Drug Abuse, or NIDA, is a typical voice against marijuana. In their various publications, NIDA cites the danger of addiction that marijuana carries, warns of marijuana's potentially damaging effects on the brain, especially the developing brains of young people, and labels marijuana a "gateway drug" that drives users to abuse harder substances.

It is true that, in the short term, marijuana use effects the brain. That's the whole point of getting high. But can getting high damage the brain in the long run?

That depends in part on usage. Marijuana certainly isn't a healthy vice, but studies over the years have shown that it isn't nearly as terrible as was once believed. Earlier this year, for example, the Journal of Neuroscience published a study which found that regular moderate marijuana use had no statistically significant effect on the volume or shape of several important regions of the brain. Several other studies over the years have also shown marijuana to be relatively low-impact on the human brain in casual to moderate usage patterns.

There is a chance that using marijuana in abusive amounts can have long-term mental effects, including development of dependency — addiction rates for marijuana are estimated at about 9 or 10 percent — and damage to memory and motor skills. Addiction and mental damage from substance abuse isn't unique to marijuana though. Long-term alcohol abusers, for example, can develop not only dependency — rates of true alcoholism run about 7% in the U.S., with overall addiction placed at about 12% to 15% — but also Wernicke-Korsakoff syndrome, a condition that produces mental confusion, memory lapses, and learning problems. And any former smoker is aware of the long-term mental addiction issues that regular tobacco use brings about; upwards of a third of users become addicted to nicotine, and the habit is notoriously hard to quit.

Please note that these statements apply to adult users. The impact that marijuana or any recreational drug could have on the developing brains of children is a completely different topic, and there is science to back up concerns over teenagers who begin to abuse marijuana, nicotine, alcohol, and even caffeine at a young age. It's one of the stated reasons why current laws in the United States place age limits on the legal use of many substances.

Teenagers are also viewed as being more susceptible to marijuana's alleged role as a "gateway drug." In general, there is a correlation between the use of marijuana and the use of harder drugs such as cocaine; and several studies have shown that THC can "prime" brains for other drugs, an effect known as cross-sensitization. But even NIDA acknowledges that

alcohol and nicotine also prime the brain for a heightened response to other drugs and are, like marijuana, also typically used before a person progresses to other, more harmful substances.

And the effects don't stop with nicotine or alcohol; Jennifer Temple, writing in Neuroscience and Biobehavioral Reviews in 2009, noted that even caffeine, much beloved by Starbucks customers and Mountain Dew addicts, has been shown to cross-sensitize users to other addictive drugs.

It's also worth noting that the correlation may have less to do with any direct effect of marijuana and more to do with the environment surrounding the use. Even NIDA admits that "poverty, mental illness, and friend groups are all much stronger predictors of drug use" than marijuana use. And given marijuana's legal status, those wanting marijuana must often seek out underground dealers with a vested interest in exposing users to other substances.

Another concern about marijuana cited by both NIDA and the American Lung Association is the danger of marijuana smoke, which contains many of the same carcinogens as tobacco smoke. The ALA argues that "marijuana smokers tend to inhale more deeply and hold their breath longer than cigarette smokers, which leads to a greater exposure per breath to tar." And while it's true that marijuana joints, being generally hand rolled and unfiltered, expose users to more tar puff-to-puff than cigarette users, that's not the whole picture.

In the United States, the typical smoker goes through 15-20 cigarettes a day. In contrast, a 2013 study by the State of Washington estimated that the average marijuana user in that state smoked a paltry 123 joints per year. A Colorado State University study conducted that same year estimated that the average user would smoke around 3.5 oz a year, which could be anywhere from 175-300 individual joints, depending upon the person rolling them. Obviously, the numbers aren't concrete, as marijuana is only now becoming legal and ease of availability could increase usage. But even doubling the high estimate and saying that the average user would smoke 600 joints a year, it's still nowhere near the almost 7,000 cigarettes an average adult smoker will consume in the same year. Four times the tar means little when one is smoking ten times the substance.

Incidentally, the fear of legalization increasing usage may be legitimate. However, in Amsterdam, the globetrotting pot-smoker's Mecca where marijuana is easily available, typical lifetime usage rates run at about 60% of rates in the United States. And while we're on the subject of Amsterdam, let's bust a myth right here: marijuana is not legal in Holland. Marijuana possession is only a misdemeanor offense, except in large quantities; and misdemeanor offenses are generally not prosecuted under the country's tolerance policy. Basically so long as users behave themselves and keep it discrete, the law is happy to look the other way and reap the benefits of increased tourist dollars.

Now, let's look at the other side of marijuana's reputation. In recent decades, advocates have pushed marijuana's role as a medicinal herb with a variety of medical uses. This push has seen medicinal marijuana become legal in 23 states in the U.S., as well as in other places around the world.

The strongest evidence for medicinal marijuana comes in the form of its ability to treat certain symptoms common to many conditions: pain, anxiety, nausea, and weight loss. In states where medicinal marijuana has been legalized, these are usually the treatments that have been approved for medical use. And in terms of treating these symptoms, marijuana does have some appreciable therapeutic power.

Many marijuana advocates don't stop there, however, and they commonly promote a laundry list curative benefits for marijuana that stretches credulity. Last year, for example, the website Business Insider published a list of "23 Health Benefits of Marijuana," including benefits to sufferers of cancer, Alzheimer's, glaucoma, arthritis, hepatitis c, irritable bowel syndrome, Lupus, Chron's disease, Parkinson's disease, multiple sclerosis, and epilepsy. Now be honest: if I told you that such a diverse list of health benefits was being attributed to acai berries or St. John's Wort, your woo detector would be going crazy. Yet that is only a partial list of the potential health benefits legalization supporters sometimes attribute to marijuana.

So many of these claims are based on preliminary hypotheses supported by the evidence of a scant number of studies, some decades old; or else they are stretching minor scientific findings to exaggerated lengths. For example, one of BI's listed claims, the effects on a rare form of epilepsy called Dravet's syndrome, isn't actually based on any studies at all, but instead on the anecdotal evidence of patients using cannabis to treat their symptoms. Another, that marijuana could help in delaying the onset of glaucoma by lowering the eye's intraocular pressure (IOP), is backed up by a source citing studies done in the 1970s; and the source even admits that "none of these studies demonstrated that marijuana (...) could lower IOP as effectively as drugs already on the market." Further, the Glaucoma Research Foundation notes that

marijuana's effect on eye pressure only lasts 3-4 hours, meaning that to lower the eye pressure around the clock it would have to be smoked 6-8 times a day.

That's a lot of puffing for what appears to be only a minor benefit.

But what if we could isolate, extract, or even synthesize the compounds in cannabis that offer therapeutic value, so that such benefits could be, say, made more potent and formulated into an extended release pill? If there truly are therapeutic benefits for some of these conditions, then pharmaceutical formulation is the path that will lead to the most efficacious use of that benefit. For example, some of marijuana's medicinal properties are attributed to cannabidiols, or CBDs, present within the plant. CBD is not like THC; it has little recreational effect. Growers in Colorado and elsewhere have already started breeding strains of the plant for medicinal use that are high in CBD while low in THC, meaning that users won't experience a recreational high while using it. Taking the next step of extracting and formulating CBD is logical.

In fact, even the pain-killing effects of THC may be better delivered in a pill than in a puff. A 2013 study in the journal Neuropsychopharmacology compared the analgesic effects of smoked marijuana with that of dronabinol, an already-existing pharmaceutical formulation of THC used in treating both pain and nausea. Their results found that while smoked marijuana had a quicker onset of pain relief, relief from dronabinol was longer lasting. Here we don't even have a hypothetical: science has already synthesized the active ingredient in medicinal marijuana and produced a form of it that offers comparable, possibly even better, therapeutic effects, while avoiding some of the potential drawbacks of smoking a joint.

In the end, like so many things in the world today, the truth about marijuana is neither as impressive nor as scary as its adherents and detractors would have us believe. As to what this says about whether or not marijuana should be legalized? That's not for science to decide, but instead for politicians and communities to debate … just so long as both sides come to the debate armed with facts, not hyperbole.

By Alison Hudson

Please contact us with any corrections or feedback.


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Cite this article:
Hudson, A. "Marijuana." Skeptoid Podcast. Skeptoid Media, 9 Jun 2015. Web. 24 Apr 2024. <>


References & Further Reading

Holland, J. The Pot Book: A Complete Guide to Cannabis—Its Role in Medicine, Politics, Science, and Culture. Rochester: Park Street Press, 2010.

Melamede, Robert. "Cannabis and tobacco smoke are not equally carcinogenic." Harm Reduction Journal . 18 Oct. 2005, Vol. 2: 21+.

National Eye Institute. "Glaucoma and Marijuana Use." National Eye Institute (NEI). U.S. Dept. of Health and Human Services, 2 May 2005. Web. 8 Jun. 2015. <>

National Institute on Drug Abuse. "DrugFacts: Marijuana." National Institute on Drug Abuse home page. U.S. Dept. of Health and Human Services, 1 Apr. 2015. Web. 17 May. 2015. <>

Volkow, Nora D., Ruben D. Baler, Wilson M. Compton, and Susan R.B. Weiss. "Adverse Health Effects of Marijuana Use." The New England Journal of Medicine. 14 Jun. 2014, 370.23: 2219-2227.

WHO. "Cannabis." Management of Substance Abuse. World Health Organization, 20 Jun. 2004. Web. 15 Aug. 2015. <>


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