Alzheimer’s Smell Loss Linked to Early Locus Coeruleus Axon Damage
A 2025 Nature Communications study found that Alzheimer’s-like mice lost locus coeruleus noradrenergic axons in the olfactory bulb early: 14% loss by 2 months, 27% by 3 months, and 33% by 6 months, before broader forebrain axon degeneration appeared.1 Early smell loss may reflect a specific brainstem-to-olfactory circuit injury, while smell testing still needs biomarker …