Background Military personnel are at increased risk for traumatic brain injury (TBI) from combat and non-combat exposures. Sequelae of moderate-to-severe TBI are well described, but the literature remains conflicted regarding whether mild TBI (mTBI) results in lasting brain injury and functional impairments. This study assessed risk for a range of neuropsychiatric disorders presenting after mTBI while adjusting for the potential confounds of depression and post-traumatic stress disorder (PTSD).

Methods A historical prospective association study was conducted utilising electronic demographic, medical and military-specific data for over 49 000 active duty US Air Force service members (Airmen). This study utilised diagnostic codes considered by an expert panel to be indicative of mTBI to identify cases. Cox proportional hazards modelling calculated HRs for neuropsychiatric outcomes while controlling for varying lengths of follow-up and potentially confounding variables.

Results Airmen with mTBI were at increased risk for specific neuropsychiatric disorders compared with a similarly injured non-mTBI control group. HRs for memory loss/amnesia, cognitive disorders, schizophrenia, PTSD, and depression were significantly elevated and remained so for at least 6 months post-mTBI, even after eliminating those with previous neuropsychiatric diagnoses.

Conclusions mTBI was positively associated with neuropsychiatric disorders in this population of primarily young adult males; with increased HRs 6 months post-mTBI. The results support that mTBI is distinguished from moderate-to-severe TBI in terms of risk for developing neuropsychiatric disorders. Further, these findings suggest the importance of screening for psychiatric and cognitive disorders post-mTBI in general medical practice.