Socioeconomic Status, Knee Pain, and Epigenetic Aging in Community-Dwelling Middle-to-Older Age Adults

Chronic musculoskeletal pain is often associated with lower socioeconomic status (SES). SES correlates with psychological and environmental conditions that could contribute to the disproportionate burden of chronic stress. Chronic stress can induce changes in global DNA methylation and gene expression, which increases risk of chronic pain. We aimed to explore the association of epigenetic aging and SES in middle-to-older age individuals with varying degrees of knee pain. Participants completed self-reported pain, a blood draw, and answered demographic questions pertaining to SES. We used an epigenetic clock previously associated with knee pain (DNAmGrimAge) and the subsequent difference of predicted epigenetic age (DNAmGrimAge-Diff). Overall, the mean DNAmGrimAge was 60.3 (±7.6), and the average DNAmGrimAge-diff was 2.4 years (±5.6 years). Those experiencing high-impact pain earned less income and had lower education levels compared to both low-impact and no pain groups. Differences in DNAmGrimAge-diff across pain groups were found, whereby individuals with high-impact pain had accelerated epigenetic aging (∼5 years) compared to low-impact pain and no pain control groups (both ∼1 year). Our main finding was that epigenetic aging mediated the associations of income and education with pain impact, as such the relationship between SES and pain outcomes may occur through potential interactions with the epigenome reflective of accelerated cellular aging. PERSPECTIVE: Socioeconomic status (SES) has previously been implicated in the pain experience. The present manuscript aims to present a potential social-biological link between SES and pain via accelerated epigenetic aging.