Among these, factors closely related to brain macrophages, such as TREM2 or APOE-positive macrophages, have been highlighted.848,849 These macrophage-related risk factors underscore the critical role of brain-associated macrophages/microglia in the pathogenesis of neurodegenerative diseases.850 This is particularly evident in Alzheimer’s Disease (AD) and Parkinson’s Disease (PD), the two most common neurodegenerative disorders. The gene discussed is APOE; the disease is Parkinson disease.