Long-Term Correlates of Mild Traumatic Brain Injury on Postconcussion Symptoms After Deployment to Iraq and Afghanistan in the UK Military.

Objectives: We assessed whether mild traumatic brain injury (mTBI) reported by UK service personnel between 2007 and 2009 was associated with postconcussion symptoms (PCS) 7 to 8 years later.

Setting: United Kingdom.

Participants: A total of 4601 service personnel all of whom had deployed to Iraq and/or Afghanistan.

Design: Longitudinal study.

Main Outcome Measures: Nine PCS reported in a survey carried out between 2014 and 2016. The main independent variable was mTBI reported between 2007 and 2009.

Results: A total of 2318 (50.4%) out of 4601 participants completed the follow-up questionnaire. Mild traumatic brain injury was associated with 2 of 9 PCS. Mild traumatic brain injury at baseline was associated with dizziness at follow-up in the fully adjusted model, in comparison with either "other injury" or "no injury" group. Mild traumatic brain injury was associated with loss of concentration in comparison with "no injury" but in comparison with the "other injury" group, it was not in the fully adjusted model. The prevalence of 7 of the 9 PCS increased over time regardless of mTBI status.

Conclusions: Mild traumatic brain injury reported in 2007-2009 was associated with dizziness and possibly with loss of concentration 7 years later but not with most PCS. The prevalence of most PCS increased over time independently of mTBI.