Serial Mediation: How Optimism Reduces and Pessimism Intensifies Chronic Low Back Pain Through Depression and Biological Aging

There is growing evidence that psychological (e.g., optimism, pessimism, depressive symptoms) and biological factors play an essential role in the experience of chronic low back pain (CLBP). This study aimed to examine the nature of the relationship between optimism or pessimism, depressive symptoms, the pace of biological aging, CLBP severity, and interference. Using mediation analysis, we tested the hypothesis that depressive symptoms and pace of biological aging measured using the Dunedin Pace of Aging from the Epigenome (DunedinPACE) serially mediate the relationship between optimism or pessimism and CLBP severity and interference. Our sample included non-Hispanic Black and non-Hispanic White adults aged 18–82 years: 74 without pain, 56 with low-impact pain, and 77 with high-impact pain. On average, individuals with high-impact pain reported lower levels of optimism, greater pessimism, and faster DunedinPACE than those in the low-impact or no-pain group (p <.05). Mediation analyses revealed indirect associations between both optimism and pessimism with pain severity and interference serially via depressive symptoms and the pace of biological aging (p <.05). These indirect effects were not statistically significant after controlling for chronological age, sex, race, and BMI. The results suggest that psychological interventions that increase optimism and reduce pessimism may slow the biological aging process, which may improve nonspecific CLBP outcomes in non-Hispanic Black and non-Hispanic White adults.