Injuries to the brain, whether from a concussion or a mild traumatic brain injury (TBI), have been linked to suicide by both anecdotal evidence and clinical studies. And the evidence continues to accumulate. A meta-analysis published online in JAMA Neurology on November 12 showed that patients diagnosed with concussion or mild TBI have double the long-term risk of suicide.
For about 80 percent of people who sustain a concussion—the most common type of TBI—neurologic symptoms resolve within seven days of the injury. The other 25 percent experience chronic neuropsychiatric symptoms, such as anxiety and depression.
To find out if the risk of suicide increases after a concussion, researchers from the University of Toronto in Canada conducted a systematic review and meta-analysis of 17 relevant studies, conducted between 1963 and 2017, involving 713,706 concussion patients, including children and military personnel, and 6,236,010 people unaffected by concussion or TBI.
Based on their review, the researchers noted that people diagnosed with at least one concussion and/or mild TBI, had twice the risk of suicide compared to the unaffected population.
In two studies that provided estimates with an average follow-up of about four years, 0.50 percent and 0.59 percent of patients diagnosed with concussion or mild TBI died by suicide.
In studies that included longer follow-ups, 0.28 percent of patients died by suicide over an average of 9.3 years. Of people who sustained a concussion as a child, 0.49 percent died by suicide over an average of 12.3 years.
Among military personnel with a history of concussion or mild TBI, the risk of suicide was lower than the estimated risk among nonmilitary participants, a finding considered significant by the researchers.
However, the researchers acknowledged it's unknown whether the lower risk for suicide among military personnel was due to the low number of participants in these studies compared to others.
Despite the heightened risk, they emphasized that nearly all patients diagnosed with concussion and/or mild TBI did not die by suicide.
The correlation between suicide risk and concussion does not prove causality, the researchers noted, and it’s not clear if certain factors may make some individuals more vulnerable to suicide risk after a concussion and/or mild TBI since suicides are rare and can occur years after a concussion.
Currently, there's an ongoing prospective registry in the United States for college athletes with concussion and mild TBI. However, information from this registry is at least a decade away, the researchers noted.
"In the meantime, future studies are required to develop strategies to prevent concussions and/or mild TBI and to identify patients at highest risk of suicide after incurring such injuries," they wrote.