New research shows that a head injury could lead to dementia later in life. The investigation used data from the Atherosclerosis Risk in Communities (ARIC) Study, which aimed to uncover associations between head injury and dementia over 25 years.
Over 23 million adults over the age of 40 in the U.S. have reported a history of head injury with loss of consciousness. The injuries were caused by a host of different situations, including car and motorcycle accidents, sports injuries, and falls.
Previous studies have shown that the effects of head injuries are long-lasting. But until this new research, it had not been known if it could affect the risk of dementia later in life. The study published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association found that not only did it increase the risk, but it also showed that the risk further increases as the number of head injuries sustained by an individual increase.
“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, Ph.D. “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.”
For the study, the authors gathered data from a diverse cohort with a mean baseline age of 54 years. The participants were comprised of 56 percent female and 27 percent black participants from four different communities across the United States. They were followed for a median of 25 years and were required to have six in-person visits and semi-annual telephone follow-ups. Hospital records, as well as self-reporting, were used for data on head injuries.
The study found that compared to participants who never experienced a head injury, a single 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 two times increased risk of dementia. Of all dementia cases in the study population, 9.5 percent could be attributed to at least one prior head injury.
Women More at Risk
Researchers also noted that females were more likely to experience dementia as a result of head injury compared to males. The study also showed that although there is increased dementia risk associated with head injury among white and black participants, white participants were at higher risk for dementia after head injury than black participants. The reason for these differences is not understood, and the authors of the study suggest more research is needed.
Given the strong association of head injury with dementia, there is a need for prevention and intervention strategies to reduce the risk of dementia after head injury. Even one injury can be a cause for concern, and health care professionals should start to take this into consideration when assessing for dementia risk.