biostudies-literatureShoubridge APMRFFAustralian Medical Research Future FundNHMRC Investigator GrantNIHMatthew Flinders Professorial FellowshipAustralian Department of HealthEMBL Australia Group Leader AwardNIDDK NIH HHSNHMRC Emerging LeadershipNational Health and Medical Research CouncilCommon Fund Data EcosystemNIH HHSThe Hospital Research Foundation Mid-Career Fellowshipglaf053https://www.ebi.ac.uk/biostudies/studies/S-EPMC12168445biostudies-literatureUnknown80(7)Aging-associated cognitive decline affects more than half of those in long-term residential aged care. Emerging evidence suggests that gut microbiome-host interactions influence the effects of modifiable risk factors. We investigated the relationship between gut microbiome characteristics and severity of cognitive impairment (CI) in 159 residents of long-term aged care. Severe CI was associated with a significantly increased abundance of proinflammatory bacterial species, including Methanobrevibacter smithii and Alistipes finegoldii, and decreased relative abundance of beneficial bacterial clades. Severe CI was associated with increased microbial capacity for methanogenesis, and reduced capacity for synthesis of short-chain fatty acids, neurotransmitters glutamate and gamma-aminobutyric acThe journals of gerontology. Series A, Biological sciences and medical sciencesSevere Cognitive Decline in Long-term Care Is Related to Gut Microbiome Production of Metabolites Involved in Neurotransmission, Immunomodulation, and Autophagy.PMC12168445MCF-27-2019GNT119378OT2 OD030544U2C DK119886GNT11522683OT2OD030544GNT1155179GNT2008625U2C-DK119886Carpenter LInacio MCTaylor SLFlynn ECations MLeong LEXWesselingh SLDe Souza DPIvey KLynn DJShoubridge APChoo JMPapanicolas LENarayana VKGordon DRogers GBWhitehead CCrotty MCollins JfalseSevere Cognitive Decline in Long-term Care Is Related to Gut Microbiome Production of Metabolites Involved in Neurotransmission, Immunomodulation, and Autophagy.Aging-associated cognitive decline affects more than half of those in long-term residential aged care. Emerging evidence suggests that gut microbiome-host interactions influence the effects of modifiable risk factors. We investigated the relationship between gut microbiome characteristics and severity of cognitive impairment (CI) in 159 residents of long-term aged care. Severe CI was associated with a significantly increased abundance of proinflammatory bacterial species, including Methanobrevibacter smithii and Alistipes finegoldii, and decreased relative abundance of beneficial bacterial clades. Severe CI was associated with increased microbial capacity for methanogenesis, and reduced capacity for synthesis of short-chain fatty acids, neurotransmitters glutamate and gamma-aminobutyric ac2025-01-01T00:00:00Z2025 Jun2026-06-01T15:51:21.827Z2026-04-08T13:53:25.267ZS-EPMC121684454016686610.1093/gerona/glaf053