Head injury 25 years later -- Penn study finds increased risk of dementia

https://www.eurekalert.org/pub_releases/2021-03/uops-hi2030521.php

 

News Release 9-Mar-2021
Penn Medicine research reveals stronger associations between head injuries and dementia among women compared to men, and among white participants as compared to black participants
University of Pennsylvania School of Medicine

 

Head injury in the United States is common, with over 23 million adults age 40 or older reporting a history of head injury with loss of consciousness. Many head injuries can be caused by a host of different situations - from car and motorcycle accidents to sports injuries. What's more, it has become increasingly recognized that the effects from head injuries are long-lasting. New research led by the Perelman School of Medicine at the University of Pennsylvania shows that a single head injury could lead to dementia later in life. This risk further increases as the number of head injuries sustained by an individual increases. The findings also suggest stronger associations of head injury with risk of dementia among women compared to among men and among white as compared to among Black populations.


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"Head injury is a significant risk factor for dementia, but it's one that can be prevented. Our findings show that the number of head injuries matter - more head injuries are associated with greater risk for dementia," said lead investigator, Andrea L.C. Schneider, MD, PhD, an assistant professor of Neurology at Penn. "The dose-dependence of this association suggests that prevention of head injury could mitigate some risk of dementia later in life. While head injury is not the only risk factor for dementia, it is one risk factor for dementia that is modifiable by behavior changes such as wearing helmets and seat belts."

The findings show that compared to participants who never experienced a head injury, a history of a single prior head injury was associated with a 1.25 times increased risk of dementia, and a history of two or more prior head injuries was associated with over 2 times increased risk of dementia compared to individuals without a history of head injury. Overall, 9.5 percent of all dementia cases in the study population could be attributed to at least one prior head injury.

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This data from the ARIC study found evidence that females were more likely to experience dementia as a result of head injury than males. Further, the study showed that although there is increased dementia risk associated with head injury among both White and Black participants, White participants were at higher risk for dementia after head injury compared to Black participants. The authors conclude that more research is needed to better understand reasons for these observed sex and race differences in the association of head injury with dementia risk.

[Men have larger fluid-filled spaces in their brains, which act as shock absorbers, which account for at least one of the reasons that men are less affected than women.  This is probably an evolutionary adaptation due to the fact that men tend to subject themselves more often to activities that put them at risk of head injuries.]

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