Addictions
When pleasure becomes pain: How substance use damages the body and brain

By Alexandra Keeler
Sustained drug use profoundly impacts brain function and physical health, leading to irreversible damage and long-term health risks
On Jan. 3, the US’s top doctor made headlines for recommending that alcoholic drinks include health warnings about their cancer risks. Alcohol consumption is a leading preventable cause of cancer, U.S. Surgeon General Dr. Vivek Murthy’s advisory notes.
Murthy’s recommendation comes amidst mounting attention to the health risks of alcohol consumption. In 2023, the World Health Organization sparked controversy when it said “no level of alcohol consumption is safe for our health.”
But all substance use affects the body, sources say, with illegal substances damaging nearly every organ in the body. Yet, the health effects of illegal substances receive relatively little attention.
“If you’ve ever looked at a population of people with substance use disorder [and] compared them to the general population, they would be worse off in terms of their cardiovascular risk,” said Dr. Christopher Labos, a Montreal-based cardiologist and host of The Body of Evidence podcast.
Several confounders
Illicit drugs like fentanyl, heroin and cocaine affect the body in all sorts of ways. But isolating their direct effects can be difficult, experts say, due to the social factors that often accompany addiction.
“People who are suffering from substance use disorder probably have poor nutrition, probably don’t exercise as much,” said Labos.
“Anybody who’s suffering from these problems is going to have several confounders that are going to increase the risk of cardiovascular disease.”
But Labos says cocaine is known to be the most damaging to the heart.
“In terms of which [illegal] substances are directly damaging to the heart, we clearly have a number one winner, and that would be cocaine,” Labos said.
“Cocaine is the one that’s very deliberately going to lead to higher rates of atherosclerosis [thickened artery walls] by increasing your heart rate, increasing your blood pressure and actually having a direct effect on thrombosis, so clogging of the arteries,” he added.
Opioids such as fentanyl and heroin also influence heart activity, Labos says. They lengthen the QT interval — a measure of heart electrical activity — which increases the risk of abnormal heart rhythms and potentially life-threatening cardiac issues.
Brain injury is another significant risk associated with illicit drug use.
Mauricio Garcia-Barrera, a psychology professor at the University of Victoria, says opioids such as fentanyl and heroin cause respiratory depression, leading to oxygen deprivation in the brain that damages brain cells.
“Between one to two minutes [after overdose, before resuscitation], the brain damage can start initiating, and between five minutes of cells in the brain not receiving oxygen, then we have the death of brain cells,” said Garcia-Barrera.
By contrast, stimulants like cocaine accelerate brain aging by damaging neurotransmitters, causing grey matter loss that leads to cognitive decline and impaired decision-making.
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Brain changes
Neuropsychologist Carolyn Lemsky is the clinical director of Community Head Injury Resource Services, a Toronto not-for-profit that runs a brain rehabilitation program.
Lemsky says many of her patients want to quit using substances. But habitual drug use alters brain structure and function, making it difficult to quit.
“In people who use opioids and who have a lot of these non-fatal overdoses, their brain changes in many ways,” said Lemsky.
The brain atrophies in critical areas like the hippocampus, the region responsible for memory, and the temporal lobes. Simultaneously, neural pathways linked to habitual behaviour “get a little fatter,” reinforcing addiction.
This rewiring “tilts the brain toward immediate gratification,” Lemsky said. Meanwhile, impairments in the hippocampus diminish the ability to recall the negative consequences of past actions, making recovery even more challenging.
But Lemsky says alcohol remains the most problematic substance for her clients, due to its widespread use.
And while it is a legal substance, alcohol also affects the brain, she says. It leads to cognitive issues like memory and executive functioning problems. Many of her clients develop alcohol-related dementia due to vitamin deficiencies caused by chronic alcohol use.
Cannabis, another legal substance, has also become “more and more problematic” for her clients over the past 15 years, Lemsky says.
“Cannabis also interferes with cognitive functioning,” she said.
According to Health Canada’s 2024 cannabis survey, 80 per cent of Canadians recognize cannabis can be habit-forming and detrimental to youth brain development. Only 71 per cent said they were aware it is linked to mental health issues such as psychosis.
‘Further research is needed’
In a statement to Canadian Affairs, Health Canada said the long-term health consequences of illegal drug use require further study.
“Further research is needed to better understand long-term impacts of opioid-related harms, including the relationship between brain injury and substance use, as well as predisposing factors and long-term effects,” said Marie-Pier Burelle, a media relations advisor for Health Canada.
Lemsky says it is problematic that the Canadian Drugs and Substances Strategy — the government’s framework for addressing substance use-related harms — does not address the known health effects of illegal drugs.
“If you look at the Canada drug strategy, it doesn’t mention brain or cognition once,” she said.
In 2022, NDP MP Alistair MacGregor introduced Bill C-277, a private member’s bill that aims to establish a national strategy on brain injuries. The bill was at the report stage when Parliament was prorogued in early January. Further work on the bill could resume in the next parliamentary session.
“They need a brain injury strategy,” says Lemsky, explaining that cognitive impairment is the leading reason people disengage from medical support services, such as getting treatment for addiction.
“The treatment has too high a cognitive load and isn’t adapted to their needs,” she said. “They can’t manage, and they leave.”
This article was produced through the Breaking Needles Fellowship Program, which provided a grant to Canadian Affairs, a digital media outlet, to fund journalism exploring addiction and crime in Canada. Articles produced through the Fellowship are co-published by Break The Needle and Canadian Affairs.
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Addictions
“Unscientific and bizarre”: Yet another Toronto addiction physician criticizes Canada’s “safer supply” experiment

By Liam Hunt
“It seems to be motivated by a very small, vocal, and well-connected group of advocates” says Dr. Michael Lester
Dr. Michael Lester, a Toronto-based addiction physician with 30 years of experience, says Canada’s “safer supply” programs are “inherently dangerous” and causing “dystopian” community harms due to widespread fraud.
These programs claim to reduce overdoses and deaths by distributing free addictive drugs—typically 8-milligram tablets of hydromorphone, an opioid as potent as heroin—to dissuade addicts from consuming riskier street substances. Yet experts across Canada say recipients regularly divert (sell or trade) their safer supply on the black market to acquire stronger illicit drugs, which then fuels addiction and organized crime.
“I have a couple dozen patients in my practice who were drug-free prior to the advent of safe supply, and they’ve gone back to using opioids in a destructive way because of the availability of diverted hydromorphone,” said Lester. “Every single day that I go to work, people tell me they’re struggling with the temptation not to take diverted safe supply. They don’t want to take it, but they take it anyway just because it’s cheap and available.”
After safer supply programs became widely accessible across Canada in 2020, Lester’s patients reported an influx of 8-milligram hydromorphone tablets on the black market, coinciding with a crash in the drug’s street price from $15–$20 per pill to just $2. He now estimates that 80 percent of his patients struggling with opioid addiction have relapsed due to diverted safer supply, leading some to abandon treatment entirely.
“Even if it’s sold at the rock-bottom price of $2 or $3 a pill, a person would make tens of thousands of dollars a year, which would have a tremendous impact on their ability to buy other drugs,” he explained. “Selling hydromorphone is too tempting not to do it, which keeps them entrenched in the whole world of dealing with opioid users and having opioids in their premises.”
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Lester said safer supply is evidently “fueling organized crime” because drug seizures in Ontario now commonly include hydromorphone, “which wasn’t happening before.” He added that some individuals who try these diverted drugs later transition to stronger opioids, such as fentanyl.
In July, for example, the London Police Service announced that seizures of hydromorphone had increased by more than 3,000 percent in the city since 2020. According to London Police Chief Thai Truong, “Diverted safer supply is being resold into our community. There’s organized drug trafficking at the highest levels of organized crime, and there’s drug trafficking at the street level. We’re seeing all of it.”
While Lester acknowledges that safer supply can be useful as a “treatment of last resort, after traditional treatments have been tried and failed,” he said it is now being offered immediately to a wide variety of patients, which has “decimated” uptake of traditional addiction therapies, such as methadone and Suboxone.
As a result, conventional addiction clinics are now at risk of shutting down, meaning some communities could lose access to gold-standard treatments (i.e., methadone and Suboxone) while highly profitable, but unscientific, safer supply programs take over instead.
Lester said the evidence supporting safer supply is biased and “misleading” because, generally speaking, these studies simply interview enrolled patients and ask them to self-report whether they benefit from the programs. He noted that many safer supply researchers are public health academics, not doctors, meaning they lack clinical experience with the communities they study.
“It seems to be motivated by a very small, vocal, and well-connected group of advocates that has completely changed the landscape in addiction medicine treatment in a very short time,” he said.
Lester argues that some safer supply researchers seem to purposefully design their study methodologies to favor the programs and disregard systemic harms. He said this flawed science is then propagated by credulous journalists who fail to adequately scrutinize agenda-driven research.
While he personally knows “a couple dozen” colleagues in addiction medicine who regularly express skepticism about safer supply, many have been reluctant to speak out, fearing backlash from activist groups that “terrorize” critics.
“The stories are common of people being harassed and insulted on social media. We’ve heard of doctors being threatened [and] dropped from committees because they spoke out.”
For example, after Lester and his colleagues published two open letters criticizing safer supply in late 2023, they were targeted by a series of articles by Drug Data Decoded, a popular Canadian harm reduction Substack, which compared the doctors to Nazis and eugenicists. The articles were then widely shared on social media by safer supply activists.
Lester recalled an incident in which harm reduction activists targeted a doctor’s daughter at her high school in retaliation for her parent’s public criticism of safer supply.
“It’s just something that seems so unscientific and so bizarre in medicine,” he said. “Physicians just aren’t used to a powerful political lobby changing a treatment protocol.”
After Lester and more than a dozen of his colleagues wrote several public letters calling for reform and requested a meeting with Ya’ara Saks, the federal Minister of Mental Health and Addictions, they found themselves “sidelined and ignored.”
After months of delays, they were able to present their clinical observations to Saks, only to have her disregard them and incorrectly claim, weeks later, that criticism of safer supply is rooted in “fear and stigma.”
“The insults aren’t a big enough consequence to keep me from speaking my mind,” he declared.
After a short reflection, he then added, “If anyone doesn’t have a stigma against this population, it’s me. I’ve dedicated my life to helping them.”
Liam Hunt is a Canadian writer and journalist with an interest in humanism, international affairs, and crime and justice. This story is produced by the Centre For Responsible Drug Policy’s “Experts Speak Up” series in partnership with the Macdonald-Laurier Institute.
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Addictions
Does America’s ‘drug czar’ hold lessons for Canada?

Harry Anslinger (center) discussing cannabis control with Canadian narcotics chief Charles Henry Ludovic Sharman and Assistant Secretary of the Treasury Stephen B. Gibbons in 1938. (Photo credit: United States Library of Congress’ Prints and Photographs division)
The US has had a drug czar for decades. Experts share how this position has shaped US drug policy—and what it could mean for Canada
Last week, Canada announced it would appoint a “fentanyl czar” to crack down on organized crime and border security.
The move is part of a suite of security measures designed to address US President Donald Trump’s concerns about fentanyl trafficking and forestall the imposition of 25 per cent tariffs on Canadian goods.
David Hammond, a health sciences professor and research chair at the University of Waterloo, says, “There is no question that Canada would benefit from greater leadership and co-ordination in substance use policy.”
But whether Canada’s fentanyl czar “meets these needs will depend entirely on the scope of their mandate,” he told Canadian Affairs in an email.
Canadian authorities have so far provided few details about the fentanyl czar’s powers and mandate.
A Feb. 4 government news release says the czar will focus on intelligence sharing and collaborating with US counterparts. Canada’s Public Safety Minister, David McGuinty, said in a Feb. 4 CNN interview that the position “will transcend any one part of the government … [It] will pull together a full Canadian national response — between our provinces, our police of local jurisdiction, and work with our American authorities.”
Canada’s approach to the position may take cues from the US, which has long had its own drug czar. Canadian Affairs spoke to several US historians of drug policy to better understand the nature and focus of this role in the US.
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The first drug czar
The term “czar” refers to high-level officials who oversee specific policy areas and have broad authority across agencies.
Today, the US drug czar’s official title is director of the Office of National Drug Control Policy. The director is appointed by the president and responsible for advising the president and coordinating a national drug strategy.
Taleed El-Sabawi, a legal scholar and public health policy expert at Wayne State University in Detroit, Mich., said the Office of National Drug Control Policy has two branches: a law enforcement branch focused on drug supply, and a public health branch focused on demand for drugs.
“Traditionally, the supply side has been the focus and the demand side has taken a side seat,” El-Sabawi said.
David Herzberg, a historian at University at Buffalo in Buffalo, N.Y., made a similar observation.
“US drug policy has historically been dominated by moral crusading — eliminating immoral use of drugs, and policing [or] punishing the immoral people (poor, minority, and foreign/traffickers) responsible for it,” Herzberg told Canadian Affairs in an email.
Harry Anslinger, who was appointed in 1930 as the first commissioner of the Federal Bureau of Narcotics, is considered the earliest iteration of the US drug czar. The bureau later merged into the Drug Enforcement Administration, the lead federal agency responsible for enforcing US drug laws.
Anslinger prioritized enforcement, and his impact was complex.
“He was part of a movement to characterize addicts as depraved and inferior individuals and he supported punitive responses not just to drug dealing but also to drug use,” said Caroline Acker, professor emerita of history at Carnegie Mellon University in Pittsburgh, Pa.
But Anslinger also cracked down on the pharmaceutical industry. He restricted opioid production, effectively making it a low-profit, tightly controlled industry, and countered pharmaceutical public relations campaigns with his own.
“The Federal Bureau of Narcotics [at the time could] in fact be seen as the most robust national consumer protection agency, with powers to regulate and constrain major corporations that the [Food and Drug Administration] could only dream of,” said Herzberg.
The punitive approach to drugs put in place by Anslinger was the dominant model until the Nixon administration. In 1971, President Richard Nixon created an office dedicated to drug abuse prevention and appointed Jerome Jaffe as drug czar.
Jaffe established a network of methadone treatment facilities across the US. Nixon initially combined public health and law enforcement to combat rising heroin use among Vietnam War soldiers, calling addiction the nation’s top health issue.
However, Nixon later reverted back to an enforcement approach when he used drug policy to target Black communities and anti-war activists.
“We knew we couldn’t make it illegal to be either against the war or Black, but by getting the public to associate the hippies with marijuana and Blacks with heroin, and then criminalizing both heavily, we could disrupt those communities,” Nixon’s top domestic policy aide, John Ehrlichman, said in a 1994 interview.
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Michael Botticelli, Acting Director of the Office of National Drug Control Policy March 7, 2014 – Jan. 20, 2017 under President Barack Obama. [Photo Credit: Executive Office of the President of the United States]
Back and forth
More recently, in 2009, President Barack Obama appointed Michael Botticelli as drug czar. Botticelli was the first person in active recovery to hold the role.
The Obama administration recognized addiction as a chronic brain disease, a view already accepted in scientific circles but newly integrated into national drug policy. It reduced drug possession sentences and emphasized prevention and treatment.
Trump, who succeeded Obama in 2016, prioritized law enforcement while rolling back harm reduction. In 2018, his administration called for the death penalty for drug traffickers, and in 2019, sued to block a supervised consumption site in Philadelphia, Pa.
Trump appointed James Carroll as drug czar in 2017. But in 2018 Trump proposed slashing the office’s budget by more than 90 per cent and transferring authority for key drug programs to other agencies. Lawmakers blocked the plan, however, and the Office of National Drug Control Policy remained intact.
In 2022, President Joe Biden appointed Dr. Rahul Gupta, the first medical doctor to serve as drug czar. Herzberg says Gupta also prioritized treatment, by, for example, expanding access to naloxone and addiction medications. But he also cracked down on drug trafficking.
In December 2024, Gupta outlined America’s international efforts to combat fentanyl trafficking, naming China, Mexico, Colombia and India as key players — but not Canada.
Gupta’s last day was Jan. 19. Trump has yet to appoint someone to the role.
Canada’s fentanyl czar
El-Sabawi says she views Canada’s appointment of a drug czar as a signal that the government will be focused on supply side, law enforcement initiatives.
Hammond, the University of Waterloo professor, says he hopes efforts to address Canada’s drug problems focus on both the supply and demand sides of the equation.
“Supply-side measures are an important component of substance use policy, but limited in their effectiveness when they are not accompanied by demand-side policies,” he said.
The Canada Border Services Agency and Health Canada redirected Canadian Affairs’ inquiries about the new fentanyl czar role to Public Safety Canada. Public Safety Canada did not respond to multiple requests for comment before publication.
El-Sabawi suggests the entire drug czar role needs rethinking.
“I think the role needs to be re-envisioned as one that is more of a coordinator [across] the administrative branch on addiction and overdose issues … as opposed to what it is now, which is really a mouthpiece — symbolic,” she said.
“Most drug czars don’t get much done.”
This article was produced through the Breaking Needles Fellowship Program, which provided a grant to Canadian Affairs, a digital media outlet, to fund journalism exploring addiction and crime in Canada. Articles produced through the Fellowship are co-published by Break The Needle and Canadian Affairs.
Subscribe to Break The Needle.
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