The Study
The study looked at 2,322 emergency room visits for cannabis poisoning among people 65 and older in Ontario. The visits spanned 2015 through 2022, allowing researchers to see what happened before and after October 2018, when Canada legalized the sale of dried cannabis, and January 2020, when the sale of edibles was legalized.
In 2015, there were 55 emergency room visits caused by cannabis poisoning. That figure rose steadily to 462 by 2021, and then fell off slightly to 404 in 2022.
Dr. Stall said he was motivated to undertake the study after being called into the emergency room to consult on an octogenarian who was experiencing severe confusion. The patient was barely conscious and showed strokelike symptoms. Multiple tests revealed no clear cause, until Dr. Stall ordered a toxicology test and found cannabis in the patient’s urine.
When Dr. Stall disclosed the finding, he said, a family member of the patient who was present at the bedside “went beet red and realized that the older adult had got into their edible cannabis product and mistaken it for food.”
Dr. Stall said that the patient was hospitalized and given supportive care, and that there was not a specific treatment or antidote for such poisonings.
Why the Increase?
The study did not look at why seniors overdosed, but Dr. Stall said that he and other doctors were seeing poisonings caused by accidental ingestion as well as intentional use of edibles for recreation or medicinal reasons.
There are several reasons seniors might be prone to overdose, Dr. Stall said. Many cannabis strains are far more potent than in past decades, and seniors who used the drug earlier in life may underestimate the concentrations of THC they are inhaling or ingesting. Particularly with edibles, Dr. Stall said, the high can take about three hours to unfold, which might prompt users to ingest too much in the buildup.
Older adults also metabolize cannabis differently from younger people, Dr. Stall said, and their bodies eliminate the drug more slowly. Seniors also are more likely than younger people to take other medications, including psychoactive drugs for sleep, that can have problematic interactions with cannabis. And, Dr. Stall said, some seniors might already be prone to confusion or falling, which the use of cannabis could worsen.
“The question is What do we do about it?” Dr. Stall said.
What Can Be Done
Dr. Stall noted the importance of ensuring edibles were kept in locked locations and in clearly identified packaging, to prevent unintentional exposure.
Also, he said, policymakers should encourage senior-specific dosing information for cannabis, along with public-education campaigns about the kinds of conditions and circumstances that put older adults at risk when using the drug. He added that seniors who are experimenting with cannabis for the first time might want to draw from a mantra used in geriatric medicine: “Start low and go slow.”
“That would mean starting lower and going lower than a younger population who is trying cannabis for a first time,” Dr. Stall said.