By Lorraine L. Janeczko
ATLANTA—Head injury appears to be linked with a higher risk of long-term cognitive decline and dementia in community-dwelling adults, according to a new study.
"We looked at the associations of head injury with long-term outcomes - cognitive change and incident dementia over 20 years - and we found that having a history of head injury was associated with increased risk of dementia as well as greater decrease in cognitive function over 20 years," said Dr. Andrea L. C. Schneider of Johns Hopkins University in Baltimore, Maryland.
"We also saw evidence of a dose response, whereby more head injuries were associated with increased risk of dementia and worse cognitive decline over 20 years," she told Reuters Health in an interview.
The findings were presented in a poster October 22 at the 2018 Annual Meeting of the American Neurological Association (ANA) in Atlanta.
For their study, Dr. Schneider and her colleagues examined data on more than 13,192 participants in the ARIC (Atherosclerosis Risk in Communities) study. The study followed participants from their second (baseline) visit, between 1990 and 1992, through 2015.
Head injury information was obtained from self-reports and from ICD-9 codes from emergency-department visits and hospitalizations. About every five years, the participants underwent Delayed Word Recall, Digit Symbol Substitution and Word Fluency cognitive tests.
Dementia was assessed using neuropsychological tests, telephone interviews with participants and others familiar with their condition, and hospitalization and death certificate codes.
At the baseline visit, participants were 57 years old on average and 56% were female. During the study, 24% of patients had at least one head injury (1,492 with one or more head injuries before study baseline, 400 with head injuries prior to study baseline and during follow-up, and 1,408 with the first head injury during follow-up).
Head injury was associated with a significantly steeper drop in global cognitive Z-score over a median of 20 years (difference, -0.13) and a significantly greater risk of incident dementia (hazard ratio 1.54).
The number of head injuries ranged from one to 33, and 25% of participants had more than one head injury. More head injuries was associated with more profound cognitive decline and risk of dementia (P <0.001).
Dr. Schneider noted that, even though the observational design of the study does not allow for clinical recommendations and more related research is needed, a growing body of literature suggests that head injuries have more sequelae than previously thought, including cognitive decline and dementia.
Dr. M. Elizabeth Ross, the director of the Center for Neurogenetics at Weill Cornell Medicine in New York City, told Reuters Health by email, "In this interesting study, even after adjusting for factors of cardiovascular, genetic, and demographic risks, there was still an increased risk of incident dementia among those who sustained head injury and the rate of decline was coincident with the number of traumatic events."
"This analysis suggests that prevention of head trauma and neuroprotection against injury is vitally important for the community at large and is not the concern solely of athletes and the military," added Dr. Ross, who is the scientific program advisory committee chair of the American Neurological Association and was not involved in the study.
American Neurological Association Annual Meeting 2018.
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