Table 1_Can live microbial interventions support healthy aging? A systematic review and meta-analysis of cognitive and muscle outcomes in aging adults.docx

Eleven unique studies contributed to at least one meta-analysis. For Mini-Mental State Examination scores, the overall pooled estimate was positive (g = 1.02; 95% CI: 0.36–1.68; I² = 90.84%). In exploratory post hoc subgroup analyses, the estimate was positive in Alzheimer’s disease (g = 1.46; 95% CI: 1.14–1.79) but not statistically significant in broader cognitive impairment (g = 0.49; 95% CI: −0.78 to 1.77); the subgroup difference was not significant (p = 0.15).

Excluding both Akhgarjand et al. intervention arms yielded a positive estimate in Alzheimer’s disease (g = 1.63; 95% CI: 1.21–2.06), although only two studies remained. The pooled Repeatable Battery for the Assessment of Neuropsychological Status result was not statistically significant (g = 0.46; 95% CI: −0.50 to 1.41). Handgrip strength showed a modest positive estimate (g = 0.46; 95% CI: 0.06–0.85), but exclusion of Qaisar et al. attenuated it to non-significance (g = 0.23; 95% CI: −0.27 to 0.73).</p>Discussion<p>Live microorganism-based interventions showed preliminary short-term functional signals, but the small evidence base, high cognitive heterogeneity, short follow-up, and sensitivity to individual studies preclude firm efficacy conclusions.

Subgroup and two-study sensitivity findings are exploratory. No eligible fecal microbiota transplantation trial was identified, so the evidence derives exclusively from probiotic and synbiotic studies.</p>Systematic review registration<p>crd.york.ac.uk/PROSPERO/view/CRD420251065993, unique identifier: CRD420251065993.</p>