by Seshata on 06/01/2014 | Uncategorized

How Many Deaths are Attributable to Cannabis? Part II

Estimates of the number of deaths attributable to cannabis vary wildly, from the preposterous claim of 30,000 per year published in a largely-debunked letter to the British Medical Journal in 2003, all the way down to zero. Here, we assess the claims made by the media and the science—or lack of it—behind them.

Estimates of the number of deaths attributable to cannabis vary wildly, from the preposterous claim of 30,000 per year published in a largely-debunked letter to the British Medical Journal in 2003, all the way down to zero. Here, we assess the claims made by the media and the science—or lack of it—behind them.

Cannabis Blamed for Depression-Related Suicides

Some consider cannabis to be responsible for multiple deaths through indirect means. In 2007, 31-year-old James Taylor, a long-term cannabis user that developed depression several years after commencing regular use of the drug later committed suicide by hanging; cannabis was cited as responsible.

17-year-old Guy Summers had reportedly been smoking cannabis for six months when his behaviour irreversibly changed—from outgoing and sociable to reclusive and paranoid. He was diagnosed with cannabis psychosis by his G.P. and ceased use immediately. A year later, also in 2007, he committed suicide.

A quick internet search will reveal dozens of similar articles, all attributing suicide to cannabis use; however, the flaws in the argument are glaringly obvious. Cannabis use is at most a contributory factor for these undoubtedly tragic deaths: the link between cannabis and mental illness has not yet been established as causal, and there is no way to tell to what extent cannabis influenced the decision to commit suicide in these individuals.

Cannabis is Too Often Blamed in Suicides

Cannabis apparently occupies a unique position within public and media perception; if an alcoholic and depressed individual killed him- or herself alcohol would not be cited as the responsible factor unless alcohol poisoning was the actual cause of death; the same goes for other illegal (and commonly-abused prescription) drugs.

To imply that cannabis, above all other drugs, has the capacity to cause severe mental illness resulting in suicide is erroneous and a gross oversimplification of the highly complex factors responsible for such illnesses.

It has never been demonstrated that cannabis causes otherwise healthy individuals to become insane; there is evidence that cannabis use may precede manifestation of underlying conditions in susceptible individuals, but there is no consensus as to whether this phenomenon is causal or simply correlative.

Suicide Ideation & Cannabis Use

Several studies have suggested a relationship between suicide ideation and cannabis use—a 2004 twin study submitted to JAMA Psychology concluded that cannabis-using twins were 2.5-2.9 times more likely to experience suicidal thoughts, and that those commencing cannabis use prior to age 17 were more likely to subsequently attempt suicide.

However, a Swedish longitudinal study spanning 33 years and published in 2009 concluded that cannabis use was “unlikely to have a strong effect on risk of completed suicide, either directly or as a consequence of mental health problems secondary to its use”.

Certainly, our understanding of severe mental illness remains somewhat rudimentary, and as such, laying the blame for suicide solely on cannabis seems hugely trivial and simplistic.
If Cocktails of Drugs are Involved, Why is Only Cannabis Blamed?

An English man who drove directly into the path of an oncoming bus and was killed was found to have been taking cannabis prior to his death, and that he had been a regular user; however, the idea that cannabis caused him to become incapacitated to the point of appearing “almost comatose” does not seem entirely convincing.

A quick search for more information almost immediately yields the possibly crucial fact—omitted by the original Daily Telegraph article—that the man was in fact on a “cocktail” of ecstasy, alcohol and cannabis at the time of death, and that blood levels of ecstasy were observed to be “significant” in the coroner’s report.

Another Telegraph article (“Coroner blames death on ‘toxic cannabis’”) follows a very similar pattern: in 2008, 17-year-old Hadrian Gardner died suddenly after leaving work to meet his father. The post-mortem showed “no recent signs of drug use”; however, post-mortem examiner Dr Sally Hales concluded that Gardner had died of inflammation of the heart best explained by “a history of using cannabis, amphetamines and cocaine”.

Cannabis & Myocardial Infarction

Cannabis has been linked to myocardial infarction (MI), commonly referred to as heart attack, in various studies. In a study published in Circulation (the Journal of the American Heart Association), the authors concluded that the risk of acute MI was elevated by 4.8 times in the 60 minutes following use of cannabis.

The seven-year study documented 3882 MI survivors, of which 124 had smoked cannabis in the year prior to onset of symptoms. Although the cannabis smokers were younger on average than non-smokers, they were more likely to be obese and smoke cigarettes—two significant contributing factors to cardiovascular ill-health.


Another study found that survivors of acute MI who smoked cannabis had increased rates of mortality over an eighteen-year follow-up, but this observation was found to be statistically insignificant. Rather than cannabis being a direct cause of heart attack in otherwise healthy individuals, these studies demonstrate that people in high-risk groups may, in rare cases, be triggered by cannabis use to experience heart attacks.

Cannabis and Driving-Related Deaths

There are indications that cannabis use can cause some degree of impairment to motorists, although the research is by no means conclusive.

There are also counter-arguments to suggest that, as cannabis use becomes more prevalent and alcohol use begins to decline, particularly among the 5-34 age group (road accidents are the leading cause of death in the USA for this demographic), driving-related deaths and accident rates are actually decreasing overall.

A study conducted in Denver, Colorado in 2011 concluded that since medical cannabis laws had been implemented in various U.S. states, there had been an average 9% reduction in traffic fatalities and a 5% reduction in sales of beer, the most popular alcoholic beverage for those in the 20-29 age range.

Does Cannabis Increase Risk of Death While Driving?

But does a cannabis-using driver have an increased risk of death over a non-cannabis-using driver? The jury is still out—some studies suggest that cannabis users take fewer risks and are overall more cautious while driving; others suggest that impairment to coordination and motor skills outweighs any possible advantage and puts the driver more at risk of injury or death.

A Dutch study conducted in 2001 found that while use of alcohol and benzodiazepines increased risk of road trauma, use of cannabis did not. An Australian study found that alcohol consumption increased driver culpability, but that cannabis consumption did not. This study also found that cannabis-using drivers were less likely to be responsible for accidents compared to drug-free drivers, although the difference was not statistically significant.

However, contradictory findings have been published in various studies. One study in particular takes issue with the idea that cannabis-using drivers are less culpable than alcohol-using or drug-free drivers, stating that when THC itself is directly measured rather than its inactive metabolites (which were included in many previous studies, although they are not an indication of impairment as THC is), drivers are three to seven times more likely to be responsible for road accidents.

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Please realize that Depression significantly increases your chance of stroke/heart attacks/ and vasospasm. So even if cannabis had no vasoactive affects there would still be a large association.


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