In Vietnam-era veterans assessed on average eight years after injury, mTBI was associated with subtle but measurable long-term problems in complex attention and working memory despite largely normal standard test batteries. This underscores that long-term effects can be specific and may not appear on broad screening tests.

Adults with prior mild traumatic brain injury (mTBI) had more cognitive symptoms and lower community participation four years later compared with matched controls. Outcomes were measured with the Rivermead Post-Concussion Symptoms Questionnaire (RPSQ), Hospital Anxiety and Depression Scale (HADS), Pittsburgh Sleep Quality Index (PSQI), and a participation tool.

In a cohort of more than 350,000 U.S. veterans, even mTBI without loss of consciousness (LOC) was associated with a greater than twofold increase in dementia diagnosis risk; hazard ratios rose with injury severity. LOC means a brief period of being unresponsive and it is a standard marker used to grade concussion severity.

A systematic review and meta-analysis reported about a twofold higher relative risk (RR) of suicide among people with a history of concussion or mTBI compared with those without concussion. The elevated risk also extended to suicide attempts and suicidal ideation across military and civilian studies.