The long-term risk of suicide is three times higher for adults who have suffered from a concussion during the workweek, compared to the general population, according to a new study published in the Canadian Medical Association Journal (CMAJ).
The risk for suicide was even greater if the concussion occurred on a weekend, which may suggest people are more prone to severe concussions through recreational accidents rather than accidents at work.
“Given the quick usual resolution of symptoms, physicians may underestimate the adverse effects of concussion and its relevance in a patient’s history,” said Dr. Donald Redelmeier, senior core scientist at the Institute for Clinical Evaluative Sciences (ICES) and a physician at Sunnybrook Health Sciences Centre, Toronto, Ontario.
“Greater attention to the long-term implications of a concussion might save lives because deaths from suicide can be prevented.”
In 2010, there were 38,364 deaths from suicide in the United States and 3,951 in Canada. Concussion is the most common brain injury in adults. Each year, there are about four million cases of concussions in the United States and about 400,000 in Canada.
“The link between concussion and suicide is not confined to professional athletes or military veterans,” said Michael Fralick, a coauthor and medical trainee at the University of Toronto.
For the study, researchers looked at anonymized records for 235,110 patients with concussion over a 20-year period in Ontario, Canada, using diagnostic codes from the health insurance database.
The investigators specifically compared concussions that occurred on a weekend or a weekday to distinguish between recreational and occupational injuries. The mean age of the patients was 41 years, about half were men, and the majority lived in cities. Most had no prior suicide attempt, hospitalization or past psychiatric disorder.
After a follow-up period of nearly nine and a half years, the researchers found that there had been 667 suicides. Patients diagnosed with a concussion on weekdays accounted for 519 suicides and an absolute suicide risk three times the population norm (29 suicides per 100,000 people a year).
Patients who had suffered from a concussion on weekends accounted for 148 suicides and an absolute suicide risk four times that of the population norm (39 per 100,000 a year).
The mean time from concussion to subsequent suicide was 5.7 years. Additional concussions were linked to a greater risk of suicide. Most of the patients had visited their family physician in the month before suicide. The most common mechanism was a drug overdose, and the average age at death was 44 years.
Previous research has shown an association between concussion and suicide. However, “no past study, to our knowledge, has focused on concussions and tested the potential difference between weekends and weekdays,” write the authors.
“The increased long-term risk of suicide observed in this study persisted among those who had no psychiatric risk factors and was distinctly larger than among patients after an ankle sprain.”
The researchers hope these findings will help doctors and patients better understand the risks of concussion and prevent possible suicides.