Review papers debunk side effects, danger of marijuana usage
A reader commented that all the junkies he knows started as recreational marijuana users. While I don’t subscribe to the gateway drug theory, I believe the topic warrants healthy discussions. We have a responsibility to understand the medical boundaries of marijuana in the face of a plurality of claims that marijuana is innocuous or a gateway drug. The problem is that we’ve been comparing apples and oranges.
Anecdotal evidence (source) suggests marijuana is the third most popular recreational drug in America (behind only alcohol and tobacco), and has been used by nearly 100 million Americans. According to government surveys, some 25 million Americans have smoked marijuana in the past year, and more than 14 million do so regularly despite harsh laws against its use.
Marijuana enthusiasts claim that marijuana is far less dangerous than alcohol or tobacco. Around 50,000 people die each year from alcohol poisoning. Similarly, more than 400,000 deaths each year are attributed to tobacco smoking. By comparison, marijuana is claimed as nontoxic and cannot cause death by overdose.
What do we really know?
The British peer-reviewed journal Lancet published a study titled “Drug Harms in the UK: A Multicriteria Decision Analysis” on Nov. 1, 2010 which calculated the harm factors of 20 drugs from alcohol to marijuana to tobacco based on harm (click here). The study calculated harm caused to individuals as for example dependence, mortality, and impairment of mental functioning which were lumped under “harm to users,” as well as “harm to others” as for example crime, environmental damage, and international damage. What makes this experimental approach useful is that these factors were quantitatively consolidated into life cycle measurements.
The study concluded that alcohol was the most harmful drug overall (72 out of 100 points), followed by heroin (55 out of a maximum of 100 points), and crack cocaine (54 out of 100 points). The most harmful drugs to users were crack cocaine, heroin, and methamphetamine (scores of 37, 34, and 32, respectively), whereas alcohol, heroin, and crack cocaine were the most harmful to others (scores of 46, 21, and 17, respectively). Marijuana had an overall harm score of 20 points, putting it in eighth place behind amphetamines and before liquid ecstasy.
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But other peer-reviewed studies shows that marijuana is not innocuous.
MacLeod et al. 2004. [The Lancet 363 (9421): 1579 – 1588] concluded that the contemporaneously available evidence did not particularly support an important causal relationship between marijuana use by young people and psychosocial harm, but cannot exclude the possibility that such a relation exists. The authors concluded that better evidence was needed.
Wang et al. 2008 [CMAJ. 178(13):1669-1678] investigated the adverse effects of cannabinoids. The authors performed a systematic review of 321 safety studies of cannabinoids published over 40 years to create an evidence base for marijuana-related adverse events and to facilitate future cannabis research initiatives. They critically evaluated the quality of published with a view to identifying ways to improve future studies. Excluding those studies that focused on recreational marijuana use the authors included 31 studies (23 randomized controlled trials and 8 observational studies) of medical marijuana. In the 23 randomized controlled trials, the median duration of cannabinoid exposure was 2 weeks (range 8 hours to 12 months). A total of 4779 adverse events were reported among participants assigned to the intervention. Most (4615 [96.6%]) were not serious. Of the 164 serious adverse events, the most common was relapse of multiple sclerosis (21 events [12.8%]), vomiting (16 events [9.8%]) and urinary tract infection (15 events [9.1%]). The rate of non-serious adverse events was higher among participants assigned to medical cannabinoids than among controls (rate ratio [RR] 1.86, 95% confidence interval [CI] 1.57-2.21); the rates of serious adverse events did not differ significantly between these 2 groups (RR 1.04, 95% CI 0.78-1.39) which suggests that serious adverse effects are non existent or extremely rare at the statistical detection level of the study. Dizziness was the most commonly reported non-serious adverse event (714 events [15.5%]) among study participants exposed to cannabinoids. The authors concluded that short-term use of existing medical cannabinoids appeared to increase the risk of non-serious adverse events. Let me paraphrase the results: if you smoke too much marijuana there is a chance you’ll get dizzy.
However, the risks associated with long-term use were poorly characterized in published clinical trials and observational studies. High-quality trials of long-term exposure are required to further characterize safety issues related to the use of medical cannabinoids.
MacLeod et al. (2007) [The Lancet 370 (9584): 319 – 328] conducted a systematic review of general population longitudinal studies reporting associations between illicit drug use by young people and psychosocial harm. They identified 48 relevant studies, of which 16 were of higher quality and provided the most robust evidence. Fairly consistent associations were noted between marijuana use and both lower educational attainment and increased reported use of other illicit drugs. But these are correlations not causal relationships as the authors pointed out.
Less consistent associations were noted between marijuana use and both psychological health problems and problematic behavior. But I don’t agree: I have interviewed people who claimed marijuana makes them paranoid.
In short, marijuana use is far more benign than the use of alcohol and tobacco and other drugs. But marijuana users and medical practitioners (where recreational marijuana is permitted or where medical marijuana is permitted by law) need education and monitoring to detect the emergence of psychotic illnesses, which may develop directly from the use of marijuana. However, the evidence of marijuana being a gateway drug is poor at best. Recently, a team of investigators from the University of Pennsylvania, the Albert Einstein College of Medicine in New York City, and the Johns Hopkins Bloomberg School of Public Health in Baltimore conducted a time-series analysis of medical cannabis laws and state-level death certificate data in the United States from 1999 to 2010 – a period during which 13 states instituted laws allowing for cannabis therapy. The results showed that jurisdictions with medical cannabis laws had a 24.8 percent lower mean annual opioid overdose mortality rate compared with jurisdictions without medical cannabis laws. More particularly, overdose deaths from opioids decreased by an average of 20 percent one year after the law’s implementation, 25 percent by two years, and up to 33 percent by years five and six (source).
More fundamentally, how could so many studies lead to such complicated results? My explanation is that we don’t actually know what we call marijuana. The plurality of the number of strains each with different cannabinoid profiles confuses the issue significantly. I suspect the variance in cannabinoid content between the multitudes of marijuana strains is the reason why we can’t seem to find studies with black and white answers.
Dr. Luc C. Duchesne is a Speaker and Author with a PhD in Biochemistry. With three decades of scientific and business experience, he has published ... <Read more about Dr. Luc Duchesne>