Clonal hematopoiesis in Alzheimer's brain: Protective, pathogenic, and context-dependent?

Clonal hematopoiesis is emerging as a surprising modifier of Alzheimer's disease. Recent findings suggest that mutant myeloid cells may enter or expand within the brain, adopting either inflammatory or reparative states. We propose that their effects depend on the mutation, timing, clone size, brain niche, and disease stage.