Gut microbiome modulation can improve cognitive function in older adults: a systematic review and meta-analysis

Age-related cognitive decline and dementia exert increasing pressure on healthcare systems. Gut microbiome modulation may offer a novel approach to improving cognitive health.

To establish the effect of gut microbiome modulation on cognitive function in older adults.

A systematic search was conducted of PubMed, Cochrane Library, Medline and Embase (OVID) to identify randomised controlled trials (RCTs) and observational studies assessing cognitive outcomes in adults aged ≥60. Interventions aimed at modifying the gut microbiome (prebiotics, probiotics, synbiotics) were included. Studies involving faecal transplants or comparing modifiers to one another instead of to placebo were excluded. Changes in cognitive function were measured by neuropsychological assessments and standardised cognitive tests (e.g. MMSE, MoCA).

Fourteen studies met inclusion criteria (13 RCTs, 1 interventional study), consisting of 10 probiotic, 2 prebiotic and 2 synbiotic trials. Participants included both healthy older adults and those with cognitive impairment. Nine studies reported statistically significant improvements in at least one cognitive domain, particularly global cognition, memory, attention and executive function. Meta-analysis of a sub-group resulted in a statistically significant (MD = 1.28; 95% CI = 0.15-2.40; P < 0.05) improvement in global cognition scores after supplementation.

Gut microbiome modulation through probiotic, prebiotic and synbiotic supplementation can improve cognition in older adults. Whilst heterogeneity and paucity of high-quality literature exists, the overall evidence is positive. Gut microbiome modulation therefore holds huge promise as a viable strategy to support cognitive health in older people, particularly considering the interventions are mostly already commercially available and low-risk.