Salivary Dysbiosis Aligns with an Olfactory–Cognitive Phenotype in Aging
This study evaluated whether combining olfactory testing, cognitive screening, and salivary microbiome profiling can identify non-invasive markers of cognitive-decline risk. A total of 113 memory clinic patients and community controls completed same-day MMSE and UPSIT assessments and provided saliva for 16S rRNA sequencing and cytokine analysis. Unsupervised clustering of cognition and smell scores defined two phenotypes: cognitively normal with normosmia (CNN) and cognitively impaired with hyposmia (CIH). Overall salivary microbial community structure was similar between groups, but CIH participants showed enrichment of periodontal anaerobes, including Porphyromonas, Treponema, and Prevotella, while CNN participants retained nitrate-reducing commensals such as Neisseria subflava and Aggregatibacter aphrophilus. Functional predictions revealed selective agreement with prior literature, while most salivary cytokines did not differ between groups. These findings suggest a targeted, potentially modifiable salivary dysbiosis associated with an olfactory–cognitive phenotype, supporting future non-invasive screening along the oral–brain axis pending longitudinal validation.
This study evaluated whether combining olfactory testing, cognitive screening, and salivary microbiome profiling can identify non-invasive markers of cognitive-decline risk. A total of 113 memory clinic patients and community controls completed same-day MMSE and UPSIT assessments and provided saliva for 16S rRNA sequencing and cytokine analysis. Unsupervised clustering of cognition and smell scores defined two phenotypes: cognitively normal with normosmia (CNN) and cognitively impaired with hyposmia (CIH). Overall salivary microbial community structure was similar between groups, but CIH participants showed enrichment of periodontal anaerobes, including Porphyromonas, Treponema, and Prevotella, while CNN participants retained nitrate-reducing commensals such as Neisseria subflava and Aggregatibacter aphrophilus. Functional predictions revealed selective agreement with prior literature, while most salivary cytokines did not differ between groups. These findings suggest a targeted, potentially modifiable salivary dysbiosis associated with an olfactory–cognitive phenotype, supporting future non-invasive screening along the oral–brain axis pending longitudinal validation.
University Hospital Center and University of Lausanne