Certain types of bacteria in the nose can trigger the development of olfactory dysfunction and cognitive decline in older adults, a new study has demonstrated.
Researchers from Fudan University in China have found that olfactory dysfunction was associated with a higher richness of nasal bacteria.
Prior studies have discovered that older adults affected by olfactory function are at greater risk of experiencing cognitive complications.
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The authors said: “Emerging evidence has highlighted that olfactory dysfunction, a common feature of aging, is increasingly linked to cognitive decline in older adults. However, research on the underlying mechanism, particularly the role of nasal microbiome, remains limited.
“In this study, we investigated the associations between olfactory function, the nasal microbiome, and cognition among 510 older adults with an average age of 77.9 years.”
Throughout the trial, the team of researchers used the Chinese smell identification test to analyse the participant’s olfactory function.
Participants also outlined their cognitive abilities by undergoing tests based on two psychometric measures.
The authors explained: “We observed that olfactory dysfunction was associated with a higher richness of nasal bacteria, and such observation was replicated in an external dataset.
“A total of 18 nasal bacterial genera were identified to be associated with olfactory function with eight genera such as Acidovorax and Morganella being enriched in the hyposmic group.”
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They added: “A composite microbial index of nasal olfactory function significantly improved the reclassification accuracy of the traditional risk model in distinguishing hyposmic from normosmic participants.
“Furthermore, participants with a nasal biotype dominated by Corynebacterium had a lower prevalence of mild cognitive impairment compared to those dominated by Dolosigranulum or Moraxella.”
The study has been published in the journal Translational Psychiatry.
