The impact of combat injury on the development of chronic pain and mental health concerns in combat-exposed populations is unknown. This study examined associations of combat injury and injury–related pain with pain-related factors and mental health outcomes, and potential mediation of the relation between combat injury and mental health outcomes by pain-related factors.

Pain interference, pain catastrophizing, pain intensity, post-traumatic stress disorder (PTSD), and major depressive episode (MDE) were assessed in (1) a probability sample of US Army soldiers and veterans cross-sectionally and (2) US Army soldiers before and 1, 3, and 9 months after deployment to Afghanistan. Associations among these variables were modeled using logistic regression and multiple mediation analyses.

Among 5003 service members with cross-sectional data, combat injury–related pain was associated with increased odds of clinically significant pain intensity (OR=2.69), pain interference (OR=3.69), MDE (OR=2.17), and PTSD (OR=3.96) relative to pain from other injuries and conditions. Among 4645 service members assessed pre- and post-deployment, combat injury was associated with increased odds of new-onset pain interference (OR=2.78), pain catastrophizing (OR=2.75), PTSD (OR=4.06), and MDE (OR=2.56) 3 months post-deployment, and PTSD (OR=2.86) and MDE (OR=1.74) 9 months post-deployment. Pain-related factors mediated the relations of combat injury with post-deployment PTSD and MDE.

Combat injury is associated with greater odds of pain interference, pain catastrophizing, PTSD, and MDE compared to other sources of pain in a cohort of US service members. Efforts to address pain-related factors following combat injury may mitigate the risk of subsequent chronic pain and mental health disorders.

The impact of chronic pain and opioid use on cognitive decline and mild cognitive impairment (MCI) is unclear. We investigated these associations in early older adulthood, considering different definitions of chronic pain.

Men in the Vietnam Era Twin Study of Aging (VETSA; n = 1,042) underwent cognitive testing and medical history interviews at average ages 56, 62, and 68. Chronic pain was defined using pain intensity and interference ratings from the SF-36 over 2 or 3 waves (categorized as mild versus moderate-to-severe). Opioid use was determined by self-reported medication use. Amnestic and non-amnestic MCI were assessed using the Jak-Bondi approach. Mixed models and Cox proportional hazards models were used to assess associations of pain and opioid use with cognitive decline and risk for MCI.

Moderate-to-severe, but not mild, chronic pain intensity (β = −.10) and interference (β = −.23) were associated with greater declines in executive function. Moderate-to-severe chronic pain intensity (HR = 1.75) and interference (HR = 3.31) were associated with a higher risk of non-amnestic MCI. Opioid use was associated with a faster decline in verbal fluency (β = −.18) and a higher risk of amnestic MCI (HR = 1.99). There were no significant interactions between chronic pain and opioid use on cognitive decline or MCI risk (all p-values > .05).

Moderate-to-severe chronic pain intensity and interference related to executive function decline and greater risk of non-amnestic MCI; while opioid use related to verbal fluency decline and greater risk of amnestic MCI. Lowering chronic pain severity while reducing opioid exposure may help clinicians mitigate later cognitive decline and dementia risk.