Do Concussions Increase the Risk of Suicide?

Even mild traumatic brain injuries may increase the risk of suicide.

Posted Nov 13, 2018

Previous studies have suggested that people who suffer traumatic brain injury (TBI) have an increased risk for suicide. Many of these studies had methodological limitations, however, including small sample sizes. Trine Madsen, Michael Benros, and their colleagues took advantage of the comprehensive medical registries in Denmark to address the relationship between traumatic brain injury and suicide in a very large sample of individuals. Because the data in these registries are gathered longitudinally, the research team was able to examine relationships between pre-existing conditions and outcomes. The results of their study were published recently in the Journal of the American Medical Association.

Madsen and colleagues analyzed data for 7,418,391 individuals who were 10 years old or older from January 1, 1980 until they died, left Denmark, or December 31, 2014, whichever came first. This represented a total of 164,265,624 person-years of observations. The number of people who died as a result of suicide totaled 34,529. Of the 567,823 individuals who had been diagnosed with one or more TBIs, 3,536 died as a result of suicide. Overall, the rates of suicide were 19.9 suicides per 100,000 person-years for individuals with no evidence of TBI in their medical records and 40.6 suicides per 100,000 person-years for those who had experienced at least one TBI. In other words, the rate of suicide was two times higher for those who had experienced TBI. This difference remained even after the investigators controlled for several concurrent and pre-existing factors that might have contributed to an increased suicide rate, including age, education, cohabitation status, socioeconomic status, marital status, fractures not involving the skull or spine, epilepsy, medical comorbidities, pre-existing psychiatric conditions, and pre-injury history of self-harm. It is thus likely that the increased rate of suicide was related to head trauma.

The investigators examined the relationship between suicide rates and severity of the TBI. Three levels of severity were ascertained: mild (concussion), skull fracture without documented TBI, and severe TBI involving head injury with evidence of structural brain damage. The rates of suicide increased with severity of the injury, but even those with mild TBI had almost double the rate (38.6 per 100,000 person-years) when compared to those without TBI (19.9 per 100,000 person-years).

Rates of suicide were higher in individuals with psychiatric disorders. In those who had no pre-existing psychiatric disorders before they experienced TBI, the rate of suicide was 32.8 per 100,000 person-years compared to 13.7 per 100,000 person-years for individuals with no pre-existing psychiatric disorder and no TBI. In those with pre-existing psychiatric disorders, the rates increased from 129 (for those with no documented TBI) to 169 per 100,000 person-years (for those with TBI). Also, those individuals who had no pre-existing psychiatric disorders but developed a psychiatric disorder following TBI had a suicide rate almost 7-fold higher than individuals with TBI who had no evidence of a psychiatric disorder either before or after TBI.

The investigators examined the relationship between risk for suicide and time since the TBI occurred. They found that the rates of suicide were highest during the 6-month interval following the TBI; however, the rates remained elevated for the entire duration of the study.

What does this mean? The data suggest that even mild TBI, i.e., a concussion, can result in changes in the brain that increase the risk of suicide. The mechanisms underlying these TBI-associated behavioral changes are not known.

Friends and family of an individual with even mild TBI should be aware of the increased risk of suicide, especially during the six months following the accident. If a person develops depressive symptoms, increased impulsivity, or other significant behavioral changes, it is probably a good idea to have them evaluated by a physician or a mental health professional.

This column was written by Eugene Rubin MD, Ph.D. and Charles Zorumski MD.

References

Madsen, T., Erlangsen, A., Orlovska, S., Mofaddy, R., Nordentoft, M., Benros, M.E. (2018). Association between traumatic brain injury and risk of suicide. JAMA. 320(6): 580-588.

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