MAPT and early-onset autosomal dominant Alzheimer disease: For instance, a mouse study demonstrated that inducing chronic pain through spared nerve injury increased tau protein expression in the hippocampus, along with hippocampal atrophy.11 A Mendelian randomization study in the UK Biobank established a causal link between chronic pain, memory decline and the risk of developing Alzheimer’s disease.12 Notably, this last study focused on MCP, suggesting the need to further investigate this chronic pain phenotype.