Two studies focusing on veterans and American football players have linked an increased risk of Alzheimer’s or cognitive decline with head injury. The study findings have been reported at the Alzheimer’s Association International Conference 2011 in Paris.
By reviewing the medical records of 281,540 US veterans age 55+ who received care through the Veterans Health Administration, researchers from the University of California identified that, in those diagnosed with a traumatic brain injury, the risk of dementia was 15.3%, compared with 6.8% in those without a brain injury diagnosis.
The study group had at least one inpatient or outpatient visit during 1997-2000 and a follow-up during 2001-07, and did not have a dementia diagnosis at the start of the study. The researchers took into account demographics and other medical conditions, including psychiatric disorders.
The research team suggests that brain injury is associated with swelling of axons, which form connections between brain cells. This swelling is linked to the build up of proteins in the brain, including amyloid, one of the hallmark proteins in Alzheimer’s.
In a second study, a team from Loyola University Medical Centre in Chicago compared the likelihood of decline in cognitive function among retired American football players from the NFL, and older adults who had not played professional sports.
In 2001, 3729 retired NFL players were mailed a general health survey, with respondents aged over 50 sent a second survey in 2008 focusing on memory issues. Over 500 of the follow up surveys were returned, with 35% obtaining a score suggesting possible dementia. This compares to a 13% figure in the general American populous, according to the US Alzheimer’s Association.
Using the data to identify former players with probable mild cognitive impairment, telephone interviews screened the group further and eligible players took part in cognitive testing. The researchers found that the retired players were impaired in comparison to similar non-athletes. With the players’ professional sports background being the principal difference in the group, the team suggests this part of their history may have played a role in the impairment.
Rebecca Wood, Chief Executive of the UK’s leading dementia research charity, Alzheimer’s Research UK, said: “These are preliminary findings in groups where head trauma is more common, but they do serve as a reminder to take precautions wherever possible. Accidents can happen, but wearing a seatbelt, crash helmet or head protection in the workplace where appropriate is essential advice.
“These studies further contribute to our understanding of dementia risk, which we know is a highly complicated relationship between lifestyle, the environment and our genes. Research is the only answer to producing a holistic picture of what causes dementia and to empower people to take control of their personal risk as far as possible.”