Fischer says there are three key contributors to cannabis dependence, with length and intensity of use being the primary predictor.
“This is almost commonsensical,” he says.
“It’s like if you drink alcohol excessively every day for 25 years, the likelihood of dependence is … much higher than if you have the occasional glass of beer.”
The second causal factor is the potency of the pot being used, says Fischer, with products containing high levels of the psychoactive compound Tetrahydrocannabinol (THC) being more addictive than milder versions.
“And then there are personality factors (that are) partly genetic, partly individual vulnerabilities, which differ quite a bit between people,” he says.
“So you could do the same thing I’m doing, same use pattern, use the same stuff and you could develop much more severe dependence than I do.”
The reasons for these different vulnerabilities, which almost certainly involve both genetic and psychological elements, are poorly understood at this time, Fischer says.
“These are sort of the three factors and they don’t necessarily act independently, there’s sort of an interplay between them as well,” he says.
“But from all the literature and scientific data … that we use and that we base our recommendations on in terms of how to reduce risks related to cannabis use, these are the things that most strongly predict whether someone becomes dependent or not.”
And while there is no “magic line” in terms of age of commencement, Fischer says teenagers who take up pot are far more likely to develop dependencies and a host of other physical and psychological problems.
It’s estimated 25 to 30 per cent of users will encounter some kind of cannabis-related problem in their lives, whether it be dependence, impaired driving charges or accidents or the exacerbation of existing or latent mental health conditions.
And severely dependent users may well encounter catastrophic problems in terms of their educational prospects, careers, marriages and other relationships, Fischer says.
Having said that, however, he maintains the physical, psychological and social ills cannabis may cause are far less severe than those related to alcohol and tobacco, both of which have long enjoyed legal sanction in Canada.
“The public health burden (of cannabis) is significantly lower than for alcohol and tobacco, which we fully accept as legal and social drugs,” he says.
For one thing, cannabis is nowhere near as lethal as either product.
“Severe cannabis dependence … can do quite a bit of harm in your life and key arenas of it,” Fischer says. “What it will not do is it will … not kill you like, for example, alcohol (and tobacco) can.”
As well, cannabis users don’t face the overdose risks that opioid, methamphetamine or even alcohol users do, Fischer says.
“From opioid dependence or even alcohol dependence you can kill yourself if you just in one sitting take too much,” he says.
“You can’t do that from cannabis and you’re also not going to incur other serious illnesses,” he says, referring to the injection disease risks that accompany heroin use.
Fischer dismisses as hidebound the theory cannabis can be a gateway drug to more dangerous narcotics.
“There’s research coming out of (the) research towers’ yin-yang … cannabis is not a gateway drug,” he says.
Indeed, Fischer says, a legalized cannabis market could lessen the use of more dangerous narcotics by luring buyers out of the black markets where those harsher drugs exist.
“That’s one of the incentives or objectives for legalization, to reduce those illicit exposures … to illegal drugs,” he says
Khalsa, who has studied cannabis for three decades, holds far less sanguine views on its dangers than many public health experts espouse.
For one thing, Khalsa says, the THC levels in modern marijuana products has been jacked up beyond anything that previous generations of users would recognize.
“Remember those good old days back in the ’60s … at that time cannabis had a THC content (that) was about 2.5 per cent to 3 per cent,” he says.
“So people, when they smoked marijuana, said ‘I smoked marijuana and nothing happened to me’.”
Now, however, some cannabis strains offer THC levels of 30 per cent or greater — levels that can quicken and cement addictions and cause a host of health problems for many people, Khalsa says.
“You see the cognitive impairment, you see dependence on cannabis and a lot of other CNS (central nervous system) complications,” he says. “From the brain to the rest of the body you find the effects on literally every organ system. So the consequences of cannabis are very significant.”
As well, Khalsa says, many users often mix cannabis with drinking — a practice that’s unlikely to abate after legalization. And alcohol and THC in combination elevate the risk of dying from car accidents 11.5 times, he says.
“So what you’re going to do … in the near future (with legalization), you’re going to see increased health consequences of cannabis use,” Khalsa says. “Auto accidents, psychological problems, health care costs, those are going to increase.”
Khalsa says cannabis use in the U.S. costs that country billions of dollars a year in health costs. And far from the revenue boon it’s being touted as, cannabis sales in a nationally legalized market would only recoup about $9 billion of that in tax revenues, he says.
Khalsa says those users who become cannabis dependent face the same problems of social loss and economic ruin that plague many alcoholics.
The THC in cannabis produces its highs by binding with a receptor in the brain known as CB1 or Cannabinoid receptor type 1. That binding prompts the release of a neurochemical known as an endocannabinoid, which produces euphoric feelings like those experienced during sex and other pleasurable activities, Khalsa says.
But persistent use of potent THC products can cause addictions and damage to the brain and other parts of the central nervous system, he says.
And he says weaning yourself from a marijuana dependence can indeed cause the same levels of physical turmoil that withdrawal from tobacco and other addictive drugs produce.
“Marijuana (also) consists of about 50 per cent more carcinogens than tobacco … and many people who smoke marijuana also smoke tobacco,” he says. “So you combine tobacco and cannabis smoking you will have, potentially, (increased) cancer and … respiratory problems.”
Fischer, who advocated for legalization, freely admits cannabis dangers warrant increased, government-sponsored monitoring now that Ottawa has given its blessing to — and will profit from — sales of the product.
“We need to assess in a few years (how) the overall public health and social harms … stack against what happened under prohibition,” he says. “And if they are greater and if it’s empirically proven that they are greater, you can call me as the first person and I will tell you that legalization … has not worked as an experiment.”
But that very legality will take away an excuse often trotted out for not monitoring cannabis-related problems and initiating public health responses to them, Fischer says.
“You could always hide behind the excuse that it’s an illegal drug … and no one should use it, end of story,” he says. Once it is legal, “we have a mandate to do everything to reduce the harms.”
Harm reduction can only be achieved, however, by having a rigorous and comprehensive monitoring system in place, Fischer says.
“We have to do a public health inventory around key outcomes … like, are there more dependent people, more people who need treatment, more people who are getting into cannabis-related accidents.”
That type of rigorous monitoring is something that did not happen in Colorado, where cannabis has been sold legally since 2014, says Andrew Freedman, who served for three year’s as the state’s Director of Marijuana Co-ordination.
Freedman says jurisdictions intent on legalizing cannabis should determine what the baseline usage and abuse levels are prior to the laws going into effect. That way, he says, they can better monitor and deal with any changes in problem usage as they are revealed going forward.
The state, however, did track treatment admissions to medical facilities for cannabis-caused problems, Freedman says.
Such admissions did not rise discernibly during the first three years of legal sales, he says.
Fischer says cannabis-related problems are unlikely to rise in Canada after Oct. 17 because usage here will not increase markedly under the new law.
About one in nine adults and one in three younger people use cannabis now — a ratio that is liable to change little with legalization, Fischer says.
“There may be a straw buyer effect,” he says. “But my reading is, overall, that in Canada at this point … pretty much everyone who chooses or desires to use cannabis uses cannabis.”
Joseph Hall is a Toronto-based reporter covering cannabis. Reach him on email: email@example.com
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