Drug overdoses can cause irreversible brain injury, B.C. research shows
Within one year of a first overdose, adults have a 6 percent risk of acquiring a brain injury, and people under 19 face a 10 percent risk, according to a study published in Addiction.
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Research conducted in British Columbia has documented that drug overdoses can cause permanent brain damage, prompting experts to call for urgent changes in how the province responds to overdose risk.
A study published in the journal Addiction, based on B.C. data, found that within one year of a first overdose, adults have a six percent risk of being diagnosed with a brain injury. People under the age of 19 face a 10 percent risk.
The injury occurs because when someone overdoses, they stop breathing. "The minute a person stops breathing, brain cells start to die," said Dr. Daniel Vigo, chief scientific advisor for psychiatry, toxic drugs, and concurrent disorders for B.C. "Depending on how long that anoxia—the lack of oxygen in the brain—happens, that is the extent of the acquired injury the person will have."
Vigo and co-author Dr. Nathaniel Day, chief scientific officer at the Canadian Centre for Recovery Excellence (CoRE), argue in a letter to the journal that overdose prevention must become a clinical priority. Day noted that overdoses can create long-term problems in memory, decision-making, and impulse control—damages comparable to cumulative concussions in contact sports.
Between 2015 and 2024, there were 256,000 non-lethal drug overdoses in B.C. Vigo's analysis of provincial health data confirms that people with severe mental illness—including schizophrenia and bipolar disorder—suffer disproportionately from exposure to toxic drugs. Over the past decade, more than half of overdose episodes and 40 percent of overdose deaths have affected people with severe mental illness, "for whom most addiction services are woefully inadequate," Vigo said.
Drugs have become increasingly toxic since 2013, when synthetic opioids like fentanyl began to dominate the illicit supply. These drugs are significantly more potent than older opioids and are manufactured without safety standards. "The person cutting those powders in a back shed somewhere, with no knowledge about how to do it safely, is exposing people to an opiate that immediately produces respiratory depression," Vigo said.
Vigo noted that while the most severe brain injuries are diagnosed and reflected in B.C.'s medical records, a much larger group of people have acquired brain injury that is not registered in their medical records.
What specific policy or clinical changes are Dr. Vigo recommending to prevent first overdoses?
How many people with acquired brain injury from overdoses are currently in B.C.'s addiction services, and what support do they receive?
We'll update this story as answers emerge.
The facts
What's the risk of brain injury within a year of a first overdose?
Adults have a 6 percent risk of being diagnosed with a brain injury within one year of a first overdose, while people under 19 face a 10 percent risk, according to a study published in the journal Addiction based on B.C. data.
How many non-lethal drug overdoses occurred in B.C. between 2015 and 2024?
There were 256,000 non-lethal drug overdoses in British Columbia between 2015 and 2024.
What percentage of overdose episodes in B.C. have affected people with severe mental illness?
More than half of overdose episodes in B.C. over the past decade have affected people with severe mental illness, along with 40 percent of overdose deaths.
Why does brain injury occur during an overdose?
When someone overdoses, they stop breathing, which causes brain cells to die from anoxia—the lack of oxygen in the brain. The extent of the injury depends on how long the oxygen deprivation lasts.
