Marijuana: A user’s guide to the good, the bad and the ugly
Part 2: The Bad
By: Katherine Hill
Edited By: Sienna Schaeffer
Note: This is Part Two in a three-part series. Click here for Part 1
Thirty years ago marijuana was the boogeyman of polite society. Nancy Reagan and parents across the United States warned children to “Just Say No.” Since then, marijuana’s image has undergone a remarkable rehabilitation.Today many Americans consider marijuana relatively benign at worst, or at best a possible cure for everything from cancer to glaucoma.
The whiplash in public opinion and deluge of conflicting media coverage has understandably left many people with more questions than answers when it comes to marijuana: Is it safe? Should I use it? Will it help my anxiety? Will it cause me to vomit uncontrollably for hours or days at a time?
Unfortunately, because marijuana is one of the most strictly regulated drugs in the country, very little high-quality research has been performed on most claims related to pot, be they good or bad. Research is likely to increase now that both laws and public opinion are beginning to thaw, but it will be years before results from any large studies will be available.
For those of you who have plans for the next weekend rather than the next decade, this three part series will answer these questions and others by taking an unbiased look at what current scientific evidence says about the good, the bad and the just plain ugly of marijuana use.
The Bad
Last month we examined some of the possible benefits of marijuana. This month we will be diving into the dark side of marijuana use. The Nancy Reagans of the world have spent years arguing that weed is an insidious killer that should be avoided at all costs. On the other side of the aisle, many weed advocates are happy to tell anyone who will listen that marijuana poses little or no real danger. The truth probably lies somewhere between these two extremes.
Overdose
First, the good news: it is impossible to overdose on marijuana. An overdose occurs when someone takes so much of a drug that they stop breathing and, unless they are really lucky, die. Scientists think that the reason it is impossible to overdose on marijuana may be the fact that there are no cannabinoid receptors in the part of the brain that controls breathing. Cannabinoid receptors are a fancy kind of brain cell that are triggered by marijuana and other similar compounds. Marijuana cannot affect parts of the brain without cannabinoid receptors, so your breathing keeps chugging along unimpeded no matter how much you smoke.
A word of warning; pot itself might not kill you, but flying through a windshield because you got in accident while driving high can be, as you might expect, quite deadly. While it’s still not clear exactly how dangerous driving while stoned is, it is extremely well established that marijuana impairs cognition, motor function, reaction time and other functions that are, you know, important for controlling a 4,000 pound vehicle hurtling down the highway at high speeds. Always remember, friends don’t let friends drive high.
Cancer
If you went to public school, you may remember your teacher telling you that marijuana is twenty times more carcinogenic (or twenty times more likely to cause cancer) than cigarettes. The good news is that that probably isn’t true. The bad new is that smoking cannabis is probably at least somewhat carcinogenic.
The even worse news is that we’re really not sure how carcinogenic. Although studies have shown that smoking marijuana decreases lung function, almost no studies have examined lung cancer in pot smokers. In the absence of direct evidence, scientists can make educated guesses.
Marijuana smoke and cigarette smoke are actually pretty similar. The smoke from a joint contains most of the same chemicals and toxins that are found in cigarette smoke, so it might seem that the two should be about equally carcinogenic.
Unfortunately, it’s not exactly a one to one comparison because of differences in the way the two are used in the real world. Marijuana smoke is usually inhaled more deeply into the lungs than cigarette smoke, which could mean that an individual joint does more damage than an individual cigarette. On the flipside, very few people chainsmoke joints the way nicotine addicts chainsmoke cigarettes, so the overall number of joints per marijuana user is generally way less than the number of cigarettes per tobacco user.
Hopefully in twenty years or so, after scientists have had time to track the current generation of marijuana users, we will have a better idea of exactly how carcinogenic pot is. Until then, it may be best to play it safe. Occasional use (hopefully) should not drastically affect your risk of developing lung cancer. Daily use though might be a different story.
Psychosis
One of the more frightening possible consequences of marijuana use is psychosis, which is a fancy way of saying the loss of contact with reality. Psychotic episodes can be one-offs or part of an ongoing disorder like schizophrenia.
To be clear, psychotic disorders are quite rare in both the general public and in marijuana users. However, they can be incredibly debilitating so even if marijuana carries only a small risk of causing psychosis, it is still worth investigating.
Scientists have known decades that people with schizophrenia are more likely to use cannabis than the general public. It was not clear though, whether cannabis actually caused schizophrenia. It could be, for example, that something about schizophrenia predisposes people to use more marijuana.
More recent research has led researchers to believe that in some small portion of the population, marijuana use contributes to the development of psychosis. To be clear, the vast majority of people who use marijuana will not develop psychosis. However, for a small percentage of the population that is already biologically predisposed to have the potential of developing a psychotic disorder, cannabis may act as a switch that turns potential into reality. Cannabis use during adolescence, which is thought to be a critical time for developing psychotic disorders, appears to be especially dangerous for people who are predisposed to developing these disorders.
As rare as psychotic disorders are, they can be devastating. For that reason, experts recommend that people with a strong family history of schizophrenia or other psychotic disorders, or who have a heightened risk of developing a psychotic disorder for other reasons, avoid smoking marijuana.
Addiction
Whether or not marijuana is addictive is both complicated and controversial. Part of the problem is that there is much disagreement over addiction itself and what it entails. Traditionally, addiction has mainly been defined based on physical symptoms like tolerance or dependence. More recent research has begun to expand the previously narrow clinical definition of addiction. For the sake of this article though, we will focus on the symptoms most traditionally associated with addiction.
Frequent marijuana users do develop a tolerance, which means that they require more of the drug to become high then when they first started using. Some users may also develop a psychological dependence. Psychological dependence means that a user feels anxious, uneasy, or unable to feel pleasure for a period of time after they stop taking the drug.
Some users may even develop mild physical symptoms after they stop taking cannabis, such as irritability and restlessness, decreased appetite, or trouble sleeping. Despite these symptoms, there is no evidence that cannabis users experience the serious physical dependence that is associated with drugs like alcohol or heroin. When a dependent user stops taking these drugs, they can experience a range of severe symptoms including sickness, hallucinations, and even seizures.
Brain Damage
One of the 1980’s most enduring legacies is the “This is Your Brain on Drugs” commercials. The commercials featured an egg frying a pan that was supposed to demonstrate the serious damage that drugs like cannabis could do to a person’s brain. Today, the accuracy of the commercial’s message is still one of the most hotly debated issues related to marijuana in both scientific circles and for the public.
For the record, there is absolutely no doubt that pot does not do great things for a person’s mental acuity while they are actively high. While high, a marijuana user experiences many cognitive problems, including decreased mental flexibility and memory. What many people do not realize is that marijuana actually stays in the bloodstream for 48 hours. That means that if you use marijuana multiple times a week, you are in effect constantly cognitively impaired, whether or not that impairment is technically permanent.
Temporary cognitive impairment caused by marijuana is not only bad news for frequent pot users, but also for researchers trying to determine whether marijuana causes brain damage. Most studies that scientists perform on pot and brain damage examine heavy users because they are most likely to be affected if marijuana causes cognitive problems. Unfortunately, most of the time these users have used cannabis in the 48 hours before coming into the lab. This recent marijuana use makes it difficult to determine whether any cognitive impairment that is observed was caused by long-term damage or just by the most recent hit.
Despite this caveat, several studies have been performed with mixed results. One study found that long-term heavy users (defined as people with an average age in their forties who smoked an average of five joints a day for 34 years) showed permanent cognitive deficits. In contrast, “light” smokers (average age of 28, four joints per day for eight years) showed no cognitive deficits.
I’m going to pause here because outside of that study’s authors, basically no one considers someone who smokes four joints a day for almost a decade to be a “light” user. It is possible that the extra 26 years and one more joint per day were enough to tip the high group into cognitive decline that did not affect the “light” users. There may be a more plausible explanation, though: age. The heavy users almost universally began smoking (and smoking heavily) during adolescence, while most of the light users started using cannabis seriously relatively later in life.
Adolescence has long been known to be a particularly sensitive time for brain development and damage. Rather than the overall length of time spent smoking, the cognitive damage seen in the high use group may have been caused by the fact that they began smoking during a critical window in their adolescence.
This explanation would be in line with a second study, which found that using marijuana weekly before the age of 18 can cause a permanent decline in IQ and in cognitive functions like thinking abstractly and processing information quickly. The effects on cognition that the study noted were not trivial. The cognitive problems the subjects experienced were big enough that friends and family members noticed their decline and reported it to researchers.
Although no research has yet definitively “proved”* that marijuana causes cancer, enough evidence has accumulated to be very wary of marijuana use, and especially heavy marijuana use, during adolescence. You should also probably avoid regularly smoking multiple joints a day at any point in your life, not just because of the (as of yet unproven) risk of permanent cognitive damage, but because you will never be completely free of the known “temporary” cognitive impairment caused by each individual joint.
So What?
So you’ve just read a long article on some of the downsides of using cannabis. But when it’s all said and done, where does that leave you? Even though research on the impact of marijuana on health is in many ways still in its infancy, enough research does exist to draw some broad conclusions.
First, marijuana almost certainly does not rank up there with drugs like cocaine or heroin when it comes to addiction, death and general mayhem. It is much more in the realm of drugs like tobacco and alcohol that are currently legal. In fact, some may argue with cause that cannabis is even less harmful than tobacco or alcohol. Even so, marijuana definitely is NOT harmless, and anyone who tells you so is either lying to you or lying to themselves. That does not mean you should never smoke marijuana, but it does mean you should be aware of potential consequences and be willing to take the time to weigh the risks of using cannabis with the rewards.
Second, when it comes to marijuana use, less really is more. Heavy marijuana users have a much higher risk of developing most of the consequences associated with pot than are relatively light users. Someone who smokes once a month in a social setting is unlikely to develop cancer and will regain normal cognitive function after 48 hours. The same cannot be said for someone who smokes five joints every day.
Finally, adolescents should be especially cautious. Adolescence is a critical period for the developing brain and it’s not surprise that both psychosis and, more tentatively, cognitive damage are most heavily associated with marijuana use during this critical window.
Now, go forth into the world armed with your newfound knowledge and be the best you you can be. At the very least, take heart in the fact that no matter what you do your brain probably won’t come out of it looking like a fried egg.
Stay tuned for the next article in this series on the ugly side of marijuana use. This third and final article will focus exclusively on cyclic vomiting syndrome, which is exactly as disgusting as it sounds.
*In the world of science nothing can ever truly be “proven”, but for the purposes of creating public policy and health recommendations, a fact can usually be considered “proved” once enough evidence has piled up to put it within the range of “without a reasonable doubt.” In the case of marijuana causing brain damage, most scientists would say that standard has not yet been reached.
References
Kuhn, C., Swartzwelder, S. & Wilson, W. Buzzed: The Straight Facts about the Most Used and Abused Drugs from Alcohol to Ecstasy. (W. W. Norton & Company, 2014).
