Gray matter morphology and pain-related disability in young adults with low back pain

Structural neuroplasticity in the brain may contribute to the persistence of low back pain (LBP) symptoms and the disability associated with them. It is not known if structural adaptations are evident early in the lifespan in young adults with LBP. This study compared gray matter in cortical sensorimotor regions in young adults with and without persistent LBP and identified gray matter and clinical predictors of pain-related disability. Eighty-two individuals with and without a history of LBP participated. Peak and average gray matter density in cortical sensorimotor regions of interest was quantified using voxel-based morphometry. Pain-related disability, pain intensity, pain duration, and pain-related fear were also assessed. Multiple linear regression was used to determine independent predictors of pain-related disability. We document significantly greater peak gray matter density in individuals with LBP in the primary somatosensory cortex, angular gyrus, and the midcingulate cortex. Pain-related disability positively correlated with average gray matter density in the posterior cingulate cortex. The most robust predictors of disability were average gray matter in the posterior cingulate, pain intensity, and pain-related fear. We demonstrate that in young adults, persistent LBP, and pain-related disability, are linked with structural differences in regions forming part of the brain network termed the pain matrix. In contrast with studies of LBP in older adults, our findings of increased rather than decreased gray matter in young adults with LBP suggest that gray matter may increase initially in response to nociceptive pain.