B.C. overdoses linked to risk of lasting brain injury, researchers say

Drug overdoses can cause lasting brain injury through a lack of oxygen when breathing stops, B.C. researchers say, urging health-care systems to place greater emphasis on preventing overdoses.

A study published in Addiction using B.C. data found that within one year of a first overdose, adults had a six per cent risk of receiving a brain-injury diagnosis. The risk was 10 per cent for people younger than 19.

Dr. Daniel Vigo, B.C.’s chief scientific advisor for psychiatry, toxic drugs and concurrent disorders and a study co-author, said the data likely captures only the most severe injuries. Between 2015 and 2024, B.C. recorded 256,000 non-fatal drug overdoses.

Vigo said people with serious mental illnesses, including schizophrenia or bipolar disorder, have been disproportionately affected. He said more than half of overdose episodes and 40 per cent of overdose deaths over the past decade involved people with severe mental illness, whose access to addiction services is often inadequate.

The researchers say repeated overdoses can affect memory, decision-making and impulse control. Vigo said naloxone remains highly effective at reversing an overdose but cannot undo damage that has already occurred, and called for better integration of mental-health and addiction care as well as early prevention efforts.

B.C. declared the toxic-drug crisis a public-health emergency in April 2016. The province recorded more than 18,900 deaths from unregulated drugs between January 2016 and January 2026.