Distinct cognitive and structural correlates of pain extent and central sensitization symptoms in older women and men with chronic pain

Chronic pain in later life may be accompanied by alterations in brain structure and cognition, but whether pain extent and central sensitization symptoms identify distinct brain-behavior patterns remains unclear. We examined associations of pain extent and central sensitization symptoms, assessed using the 9-item Central Sensitization Inventory (CSI-9), with regional gray matter volume and cognitive function in community-dwelling older adults. This cross-sectional study included 272 participants with chronic pain from the Bunkyo Health Study. Participants were classified as having single-site or multisite pain and by CSI-9 score as having lower or higher scores, with 12 or higher defining the higher group. Regional gray matter volume was quantified using 0.3-Tesla magnetic resonance imaging, and cognition was assessed using the Trail Making Test Part B (TMT-B), processing speed, and global and domain-specific measures. Pain extent and CSI-9 group interacted for TMT-B performance, with the longest completion time in participants with single-site pain and a higher CSI-9 score. No other cognitive outcome remained significant after correction for multiple testing. In categorical analyses, the higher CSI-9 group had smaller volumes in the right middle frontal gyrus, bilateral anterior cingulate cortex, right insula, right hippocampus, and bilateral amygdala, whereas pain extent and the interaction were not associated with regional volume. In a contextual comparison, only the single-site/higher CSI-9 group showed slower TMT-B performance than participants with no current pain. Pain extent and central sensitization symptoms may represent partly distinct dimensions of chronic pain, although the small single-site/higher CSI-9 group and attenuation in several sensitivity analyses warrant caution. Significance StatementChronic pain is often described by where it hurts, but location alone may miss important differences between patients. In older adults, pain extent and symptoms measured by the 9-item Central Sensitization Inventory captured partly different aspects of chronic pain. Participants with pain at one site and a higher CSI-9 score performed most slowly on a task requiring attention and mental flexibility, whereas differences in regional brain structure were related mainly to CSI-9 score rather than pain extent. These findings support a multidimensional approach to chronic pain and may inform future research on cognitive vulnerability and brain health across pain conditions. Graphical Abstract Text O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/742487v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@17eacb7org.highwire.dtl.DTLVardef@17d535borg.highwire.dtl.DTLVardef@ebb79forg.highwire.dtl.DTLVardef@16464b7_HPS_FORMAT_FIGEXP M_FIG C_FIG Among older adults with chronic pain, pain extent and CSI-9 score captured different aspects of vulnerability. Slower performance on a task requiring attention and cognitive flexibility was concentrated in those with single-site pain and higher CSI-9 scores, whereas regional brain-volume differences tracked CSI-9 category more broadly.