The risk of concussion is three to five times higher for teenagers who use marijuana or alcohol, compared with their peers who do not smoke marijuana or drink, according to a new study.
Sports accounted for more than half of recent concussions among teens, the study of almost 9,000 Canadian teens found. Researchers report in the Journal of the American Medical Association that 20 percent of teens surveyed said they had suffered a concussion, and almost 6 percent said they had at least one in the past year.
Students who reported drinking alcohol occasionally or frequently had more than five times the risk of a concussion, while those who reported using marijuana 10 or more times over the past year had more than three times the risk, compared with students who did not use alcohol or marijuana. The researchers told HealthDay the study did not explain why teens who used alcohol or marijuana had a great risk of concussion.
The study also found concussions were more common in males, and in those with lower school grades.
According to a news release from St. Michael’s Hospital in Toronto, where the study was conducted, “There is growing evidence that people who have had one or more concussions are at greater risk of future concussions, and evidence that multiple brain injuries can result in lasting cognitive impairment, substance use, mental health and physical health harms.”