Concussion triples adult suicide risk, with rates highest following weekend concussions: Ontario study

Adults who experience a concussion have a long-term suicide risk that is three times higher than that of the general population, and that risk increases by a further third if the concussion occurs on a weekend. These are among the findings of a new study from the Institute for Clinical Evaluative Sciences (ICES) and Sunnybrook Health Sciences Centre published today in the Canadian Medical Association Journal (CMAJ).

“Patients who experienced a concussion were at increased risk of suicide regardless of demographic factors such as age, sex, socioeconomic status or past psychiatric conditions," says the study’s lead researcher Donald Redelmeier who is a senior core scientist at ICES and a physician at Sunnybrook Health Sciences Centre. "We also found that each additional concussion was associated with a further increase in suicide risk, and that the risk was higher still when the concussion occurred on a weekend.”

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In this large study, the researchers identified 235,110 concussion patients over a 20-year period using diagnostic codes from the Ontario Health Insurance Plan database. They looked at whether concussions occurred on a weekend or a weekday, to distinguish between recreational injuries and occupational injuries. The mean age of patients was 41 years, about half were men, and the majority lived in cities. Most had no prior suicide attempt, prior hospitalization or previous psychiatric disorder. 

The researchers excluded patients hospitalized immediately or within two days of injury, as such cases tend to reflect severe brain injury, which is a known risk factor for suicide.

Over the 20-year period studied, the researchers subsequently observed an additional 470 suicide deaths in the concussion patients not accounted for by expected rates of suicide. The average time delay between concussion and suicide was six years.

Among the study's findings:

• Of the 667 people who died from suicide after a concussion, about half had visited a physician in the last week of life, typically for a diagnosis unrelated to psychiatry.
• Those injured on weekdays accounted for 519 suicides and an absolute suicide risk of 29 per 100,000 annually, which is three times the population norm of about nine per 100,000 annually.
• Those injured on weekends accounted for 148 suicides with an absolute suicide risk of 39 per 100,000 annually, or about four times the population norm.
• Of the 168,188 patients experiencing concussion who had no prior suicide attempt, psychiatric diagnosis or hospitalizations, a total of 387 completed a suicide, equal to an absolute risk of 24 per 100,000, or more than twice the population norm.
• Having multiple concussions was associated with a further increase in suicide risk, increasing the relative risk of suicide by an additional 30 per cent with each additional concussion.
• The increased risk of suicide following weekend concussions was present in all patient subgroups, regardless of demographic factors.
• Several other factors were additional independent predictors of the long term risk of suicide including male sex, low socioeconomic status, prior psychiatric diagnosis, and past attempts.

Other studies have shown a link between concussion and risk of suicide among professional athletes and military veterans. However, the researchers say that no study focused on concussions and suicide tested the potential difference between weekends and weekdays.

"We know that a concussion can cause lasting changes in the brain that can alter mood, perhaps resulting in behaviour changes including impulsivity,” says Redelmeier. “It’s possible that we’re seeing greater suicide risk linked to weekend concussions due to risk-taking associated with recreation or misadventure, whereas weekday injuries may be linked to employment hazards. We may also be seeing an effect of self-blame if the injury event was self-initiated.”

Noting that further investigation is needed, the authors say their findings suggest that a past history of a concussion may be relevant when assessing a patient’s suicide risk.

Says Redelmeier, “Understanding how a history of concussion raises the risk of suicide, and supporting patients with better screening, treatment and follow-up for recovery may be important steps in preventing these tragic and avoidable deaths.”

“Risk of suicide after a concussion” was published today in CMAJ (Canadian Medical Association Journal).

Author block: Michael Fralick, Deva Thiruchelvam, Homer Tien, Donald A Redelmeier.

The Institute for Clinical Evaluative Sciences (ICES) is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy. For the latest ICES news, follow us on Twitter: @ICESOntario

Sunnybrook Health Sciences Centre is inventing the future of healthcare for the 1.2 million patients the hospital cares for each year through the dedication of its more than 10,000 staff and volunteers. An internationally recognized leader in research and education and a full affiliation with the University of Toronto distinguishes Sunnybrook as one of Canada’s premier academic health sciences centres. Sunnybrook specializes in caring for high-risk pregnancies, critically-ill newborns and adults, offering specialized rehabilitation and treating and preventing cancer, cardiovascular disease, neurological and psychiatric disorders, orthopaedic and arthritic conditions and traumatic injuries. The Hospital also has a unique and national leading program for the care of Canada’s war veterans. For more information about how Sunnybrook is inventing the future of healthcare please visit us online at www.sunnybrook.ca

FOR FURTHER INFORMATION PLEASE CONTACT:

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• Nadia Norcia Radovini
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