Traumatic brain injury associated with increased dementia risk in older adults

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According to a study published online by JAMA Neurology, traumatic brain injury appears to be associated with an increased risk of dementia in adults 55 years and older.

Controversy exists about whether there is a link between a single traumatic brain injury and the risk of developing dementia because of conflicting study results. The Centers for Disease Control and Prevention says that Americans 55 years and older account for more than 60% of all hospitalisations for traumatic brain injury, with the highest rates of traumatic brain injury-related emergency department visits, inpatient stays and deaths happening among those patients 75 years and older. Therefore, understanding the effects of a recent traumatic brain injury and the subsequent development of dementia among middle or older adults has important public health implications.

Researchers Raquel C Gardner, of the University of California, San Francisco, and colleagues examined the risk of dementia among adults 55 years and older with recent traumatic brain injury compared with adults with non- traumatic brain injury body trauma, which was defined as fractures but not of the head or neck. The study included 164,661 patients identified in a state-wide California administrative health database of emergency department and inpatient visits.

In the study, a total of 51,799 patients with trauma (31%) had traumatic brain injury. Of those, 4,361 patients (8.4%) developed dementia compared with 6,610 patients (5.9%) with non-traumatic brain injury body trauma. The average time from trauma to dementia diagnosis was 3.2 years and it was shorter in the traumatic brain injury group compared with the non- traumatic brain injury group (3.1 vs 3.3 years). Moderate to severe traumatic brain injury was associated with increased risk of dementia at 55 years or older, while mild traumatic brain injury at 65 years or older increased the dementia risk.

“Whether a person with traumatic brain injury recovers cognitively or develops dementia, however, is likely dependent on multiple additional risk and protective factors, ranging from genetics and medical comorbidities to environmental exposures and specific characteristics of the traumatic brain injury itself,” the authors note.

Steven T DeKosky, of the University of Pittsburgh School of Medicine, writes: “Unfortunately, there was not a non-trauma control group included, which may have answered the question of whether non-traumatic brain injury body trauma raised the risk of dementia significantly above age-equivalent controls without non-brain trauma (perhaps from inflammation or other complications).”

“Judicious use of data by skilled researchers who are familiar with the entire range of dementia research from pathobiology to healthcare needs will enable us to ask important questions, evolve new or more informed queries, and both lead and complement the translational questions that are before us. Dementia is both a global problem and a pathological conundrum; thus, the complementary use of big data and basic neuroscience analyses offers the most promise,” DeKosky concludes.