Researchers exploring dementia-related proteins in the brain identified Apolipoprotein E (ApoE) as a key misfolded protein. About 25% of individuals, and 50% of individuals with Alzheimer disease, have a genetic mutation, the APOE ε4 allele—a known risk factor for the disease. The researchers were surprised to find that even in the brains of patients without the disease-driving APOE ε4 allele, ApoE proteins were strongly enriched in dementia. Their findings appear in The American Journal of Pathology.