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Mild TBI increases dementia risk

Veterans who had a mild traumatic brain injury and did not lose consciousness were at increased risk for dementia, according to findings recently published in JAMA Neurology.

“The association between mild TBI and dementia remains controversial and few studies have specifically examined the effects of mild TBI without loss of consciousness,” Deborah E. Barnes, PhD, MPH, of the San Francisco Veterans Affairs Health Care System, and colleagues wrote.

Researchers also stated there is “a growing awareness that mild, repeated TBIs are closely associated with chronic traumatic encephalopathy,” the same disorder other studies have found can be caused by concussions.

Barnes and colleagues analyzed 178,779 Veterans Health Administration health care system patients diagnosed with a TBI (mean age, nearly 49.5 years). These patients were matched in a 1:1 ratio with patients from a propensity-matched comparison group.

Researchers found that 6.1% of veterans with TBI developed dementia vs. 2.6% of the veterans who did not have a TBI. Hazard ratios for dementia were 2.36 (95% CI, 2.1-2.66) for mild TBI without loss of consciousness; 2.51 (95% CI, 2.29-2.76) for mild TBI with loss of consciousness; 3.19 (95% CI, 3.05-3.33) for mild TBI with loss of consciousness status unknown; and 3.77 (95% CI, 3.63-3.91) for moderate-to-severe TBI after adjustment for age at index date, race, place of residence and sex. The data were also adjusted to account for anxiety, cerebrovascular disease, diabetes mellitus, hypertension, mood disorder, myocardial infarction, peripheral vascular disease, PTSD, sleep disorder, substance abuse disorder and tobacco use.

“These results confirm prior studies, including a 2008 Institute of Medicine report, that have found an association between moderate-to-severe TBI and risk of dementia,” Barnes and colleagues wrote. “In addition, although prior studies of the association between mild TBI and dementia have been mixed, our study adds to the weight of evidence suggesting that mild TBI is also associated with increased dementia diagnosis risk.”

Veterans who had a mild traumatic brain injury and did not lose consciousness were at increased risk for dementia, according to findings recently published in JAMA Neurology.

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Researchers concluded that studies that ascertain the mechanisms, prevention and treatment of dementia linked to TBI are “urgently needed” in veterans.

In a related editorial, Kimbra Kenney, MD, of the department of neurology at the Uniformed Services University of the Health Sciences, and Ramon Diaz-Arrastia, MD, PhD, of the department of neurology at the University of Pennsylvania Perelman School of Medicine wrote Barnes and colleagues’ findings “provide the best information to date that military veterans [are] at increased risk for dementia as a consequence” of their military service.

Kenney and Diaz-Arrastia added that the young age of the veterans of the study suggests that the problem of TBI-related dementia will be compounded in the future.

“The implications for the military health system, VA health care, and society are profound. Substantial investments in clinical care and neuroscience research will be needed in the next decades to fulfill society’s obligations to those who have served our country,” they concluded. – by Janel Miller

Disclosure: No relevant financial disclosures were reported.