Head injuries linked to double death rate in long run: Research

WASHINGTON: Adults who sustained any form of brain injury during a 30-year study period had double the rate of mortality as those who did not, according to new research, while mortality rates among those with moderate or severe head injuries were nearly three times higher. The findings of the study were published in JAMA Neurology.

In the United States, over 23 million adults age 40 or older report a history of head injury with loss of consciousness. Head injury can be attributed to a number of causes, from motor vehicle crashes, unintentional falls, or sports injuries. What's more, head injury has been linked with a number of long-term health conditions, including disability, late-onset epilepsy, dementia, and stroke. Studies have previously shown increased short-term mortality associated with head injuries primarily among hospitalized patients.

This longitudinal study evaluated 30 years of data from over 13,000 community-dwelling participants (those not hospitalized or living in nursing home facilities) to determine if a head injury has an impact on mortality rates in adults over the long term. Investigators found that 18.4 per cent of the participants reported one or more head injuries during the study period, and of those who suffered a head injury, 12.4 per cent were recorded as moderate or severe. The median period of time between a head injury and death was 4.7 years.

Death from all causes was recorded in 64.6 per cent of those individuals who suffered a head injury, and in 54.6 per cent of those without any head injury. Accounting for participant characteristics, investigators found that the mortality rate from all causes among participants with a head injury was 2.21 times the mortality rate among those with no head injury. Further, the mortality rate among those with more severe head injuries was 2.87 times the mortality rate among those with no head injury.

"Our data reveals that head injury is associated with increased mortality rates even long-term. This is particularly the case for individuals with multiple or severe head injuries," explained the study's lead author, Holly Elser, MD, PhD, MPH a Neurology resident at Penn. "This highlights the importance of safety measures, like wearing helmets and seatbelts, to prevent head injuries."

Investigators also evaluated the data for specific causes of death among all participants. Overall, the most common causes of death were cancers, cardiovascular disease, and neurologic disorders (which include dementia, epilepsy, and stroke).

Among individuals with head injuries, deaths caused by neurologic disorders and unintentional injury or trauma (like falls) occurred more frequently. When investigators evaluated specific neurologic causes of death among participants with head injury, they found that nearly two-thirds of neurologic causes of death were attributed to neurodegenerative diseases, like Alzheimer's and Parkinson's disease. These diseases composed a greater proportion of overall deaths among individuals with head injury (14.2 per cent) versus those without (6.6 per cent).

"Study data doesn't explain why the cause of death in individuals with head injuries is more likely to be from neurodegenerative diseases, which underscores the need for further research into the relationship between these disorders, head injury, and death," said Andrea L.C. Schneider, MD, PhD, an assistant professor of Neurology at Penn.