Nasal Microbiota, Olfactory Health, Neurological Disorders and Aging—A Review - PMC
/PMC/2026
Why It Matters
This caught my attention because smell loss often precedes cognitive decline by years, and if nasal bacteria are part of that connection, it opens a potential early intervention window. The nose is a direct pathway to the brain, so what's living up there might matter more than we thought. That said, this is a review synthesizing existing research—not new experimental data.
Key Findings
- Altered nasal microbiota composition has been observed in patients with Alzheimer's disease, Parkinson's disease, and other neurodegenerative conditions compared to healthy controls
- Olfactory dysfunction (loss of smell) is an early symptom in many neurological disorders and correlates with changes in nasal microbial communities
- The nasal cavity provides a direct anatomical route for microbes and their metabolites to reach the brain via the olfactory nerve, bypassing the blood-brain barrier
- Aging itself is associated with shifts in nasal microbiota diversity and composition, which may contribute to age-related smell decline
- Specific bacterial taxa like Corynebacterium and Staphylococcus show different abundances in diseased versus healthy nasal environments
Read the Paper↗PMC9320618