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On April 4, 2023, we reported on a study published in PNAS that examined whether persons with multisite chronic pain (MCP) are at a greater risk for neurocognitive abnormalities than those with single site chronic pain or without pain.
Researchers conducted a longitudinal cross sectional study analyzing data from 354 943 persons aged 39 to 82 years in the UK Biobank cohort. They found that MCP conferred a significantly increased risk of dementia, more rapid cognitive decline, and greater atrophy in the hippocampus compared to no pain or single-site chronic pain. Specifically, the risk of dementia among participants with chronic pain at ≥5 sites was 1.59-fold higher than for participants who were pain-free, an effect, the researchers note, comparable to that of heart failure, post-traumatic stress disorder, and depression. Further, when compared with individuals with no pain or single-site pain, those with pain at multiple sites performed worse in tests of fluid intelligence, matrix pattern completion, numeric memory, paired associative learning, and symbol digit substitution.
Results also showed marked effects on hippocampal volume among participants with multisite pain. Researchers found that chronic pain at a single site was associated with a 9.795 mm³ reduction in the volume in the left hippocampus and 8.272 mm³ in the right. Pain at 3 sites was associated with a reduction in the hippocampus of 33.255 mm³ in the left and 36.042 mm³ in the right. When chronic pain was associated with ≥5 sites, hippocampal volume was reduced 100.330 mm³ in the left and 87.522mm³ in the right. The researchers found after mediation analyses that the decline in fluid intelligence was partially mediated by the observed hippocampal atrophy.
Note from authors
"Our results suggested that cognitive decline and hippocampal atrophy interact biologically and may underlie the increased risk of dementia associated with MCP."