Years of research have highlighted the mind-health risks of traumatic brain injury (TBI). People who lose consciousness for an hour or more following a TBI have two times the chance of developing dementia as those who have not suffered such an injury.

In more recent years, there has been greater attention paid to the cognitive and behavioral problems associated with TBI. A study published in JAMA Neurology indicates that even mild TBIs, with or without loss of consciousness, increase the risk of dementia in military personnel.

Dr. Deborah Barnes of the University of California, San Francisco, and her colleagues studied 178,779 subjects who were diagnosed with a TBI in the Veterans Health Administration healthcare system. On average, these veterans were 50 years old and did not have a diagnosis of dementia at the start of the study.

After more than a decade of follow-up, just 2.1 percent of the subjects without a TBI developed dementia, compared with 6.1 percent of subjects who had a history of TBI.

The more severe the TBI, the greater the risk of dementia. But even mild TBI without loss of consciousness can double the risk of developing dementia.