In a cohort study of >350,000 veterans, even mild traumatic brain injury (TBI) without loss of consciousness (LOC) was associated with a >2-fold increase in the risk of dementia diagnosis. Researchers included all patients diagnosed with a TBI in the Veterans Health Administration (VHA) health care system from October 1, 2001, to September 30, 2014, and a propensity-matched comparison group. Patients with dementia at baseline were excluded. Included were 178,779 patients diagnosed with a TBI in the VHA health care system and 178,779 patients in a propensity-matched comparison group. Veterans had a mean (SD) age of nearly 49.5 (18.2) years at baseline; 33,250 (9.3%) were women, and 259,136 (72.5%) were non-Hispanic white individuals. They found:

• Differences between veterans with and without TBI were small.
• A total of 4,698 veterans (2.6%) without TBI developed dementia compared with 10,835 (6.1%) of those with TBI.
• After adjustment for demographics and medical and psychiatric comorbidities, adjusted hazard ratios for dementia were 2.36 for mild TBI without LOC, 2.51 for mild TBI with LOC, 3.19 for mild TBI with LOC status unknown, and 3.77 for moderate to severe TBI.