Dorsolateral prefrontal cortex hemispheric asymmetry and chronic low back pain at 8-year follow-up in community-dwelling older adults

Chronic low back pain affects 20-30% of older adults, posing a significant public health concern. A few longitudinal neuroimaging studies have demonstrated that pre-existing brain structural features predict the acute-to-chronic pain transition; nevertheless, such evidence remains limited. Therefore, we hypothesized that the gray matter volume and asymmetry in the cortical regions involved in pain processing would be associated with chronic low back pain in older adults after 8 years of follow-up. The longitudinal cohort study included 319 community-dwelling older adults (aged 67.6 ± 5.2 years). Chronic low back pain was defined as self-reported pain in the lower back, persisting for > 3 months. Gray matter volumes were calculated using FreeSurfer 6.0, and the following pain-processing-related regions were analyzed: the dorsolateral prefrontal cortex, anterior cingulate cortex, inferior frontal gyrus, and insula. Brain volumetric asymmetry was evaluated using the following asymmetry index: (R-L) / (R + L) ×100. Logistic regression analysis was used to determine the relationship between chronic low back pain prevalence after follow-up examination and the brain asymmetry index. Adjusted logistic regression analysis demonstrated that chronic low back pain was significantly associated with the asymmetry index of the dorsolateral prefrontal cortex (odds ratio = 0.87; 95% confidence interval = 0.78-0.97; p = 0.009). We suggest that interhemispheric asymmetry of DLPFC may influence chronic low back pain prevalence after 8 years of follow-up.