Gut microbiome predicts cognitive function and depressive symptoms in late life

Area of Science:

• Neuroscience
• Microbiology
• Gerontology

Background:

• Depression in older adults with cognitive impairment is linked to dementia progression.
• The gut microbiome's association with current mood and cognition is known, but its predictive power for future symptoms is unclear.

Purpose of the Study:

• To identify microbial features that reflect current cognitive and depressive symptoms.
• To discover microbial markers that predict future cognitive decline and increased depressive symptoms in older adults.

Main Methods:

• Collected clinical assessments and stool samples from 268 participants with varying cognitive/depressive symptoms.
• Utilized high-resolution 16S rRNA sequencing to analyze microbiome diversity, structure, and composition.
• Employed linear and elastic net regression to identify associations between microbiome features and current/future symptoms.

Main Results:

• Greater microbial diversity correlated with lower current cognition and higher depression (in non-antidepressant users).
• Lower abundance of Bifidobacterium was associated with poor current cognition; higher GABA degradation linked to greater depression severity.
• Future cognitive decline predicted by lower Intestinibacter, lower glutamate degradation, and higher histamine synthesis; future depressive symptoms by lower Bacteroidota and lower glutamate degradation.

Conclusions:

• Cognitive dysfunction and depression exhibit distinct biological effects detectable via the gut microbiota.
• The gut microbiome may serve as a noninvasive tool for assessing and predicting cognitive and psychiatric states in older adults.