Dementia risk increased among older vets with traumatic brain injury

Older veterans who experienced a traumatic brain injury have a 60% increased risk of developing dementia compared with veterans without traumatic brain injury, according to recent study findings published in Neurology.

Deborah E. Barnes, PhD, MPH, of the University of California, San Francisco, and the San Francisco Veterans Affairs Medical Center, and colleagues evaluated 188,764 veterans (mean age, 68 years) with at least one inpatient or outpatient visit at baseline (2000-2003) and follow-up (2003-2012) to determine the effect of traumatic brain injury (TBI) on dementia. No participants were diagnosed with dementia at baseline.

At baseline, 0.65% of participants had a current TBI diagnosis. Intracranial injury without skull fracture was the most common type of TBI (43%), followed by skull fracture (21%), late effects of TBI (14%) and post-concussion syndrome (4%). Twenty-seven percent of TBIs were unspecified and 57% were open wounds. Overall, 9% of veterans had more than one diagnosis of TBI.

Compared with participants without TBI, those with TBI were slightly younger (P<.001). However, comorbid conditions were more common among participants with TBI, including diabetes (P=.01), hypertension (P<.001), myocardial infarction (P<.001) and cerebrovascular disease (P<.001). Mental health conditions were also more common among participants with TBI, including depression (P<.001) and posttraumatic stress disorder (P<.001).

Dementia developed among 16% of participants with TBI during the study period vs. 10% without TBI (P<.001).

Overall, participants with TBI developed dementia earlier compared with those without TBI (P<.001). Without a diagnosis of dementia, death occurred earlier among participants with TBI compared with those without TBI (P<.001).

The risk for dementia was also increased among participants with TBI who had depression, PTSD or cerebrovascular disease compared with participants without TBI or the conditions alone.

“These findings suggest that a history of TBI contributes risk for dementia in later life in veterans,” Barnes said in a press release. “If we assume that this relationship is causal, it seems likely that the same increased risk probably occurs with TBI in the civilian population as well.”

In an accompanying editorial, Rodolfo Savica, MD, MSc, of the University of Utah School of Medicine in Salt Lake City, wrote that the study suggests the association between head trauma and dementia is complex.

“This study convincingly shows that mild trauma has a role in increasing the risk of dementia and sheds light on the more complex relationship between medical and psychiatric diseases with TBI in the development of the future risk of dementias,” Savica said in the release. “Neuroscientists must take a careful and comprehensive approach to avoid oversimplified claims of causality.”

For more information:

Barnes DE. Neurology. 2014;83:1-8.

Savica R. Neurology. 2014;83:1-2.

Disclosure: See the study for a full list of researchers’ financial disclosures.