Effects of probiotics on cognitive function across the human lifespan: a meta-analysis

In recent years, probiotics have become one of the research hotspots in the scientific community, and its potential role in intestinal health, immune regulation, and the relationship with the brain has attracted much attention. However, the improvement of cognitive function by probiotics shows different effects in different stages of the human life cycle.

Therefore, we conducted a meta-analysis of randomized controlled trials to examine the specific effects of probiotics on cognitive function in different age groups.

We searched four databases from creation to December 2023. A meta-analysis of 21 randomized controlled clinical trials was conducted, using random effect Meta analysis combined with standardized mean difference (SMD) (95% confidence interval [CI]).

Our meta-analysis found that the effects of probiotics on cognitive performance were primarily seen in older age groups, with significant effects on overall cognitive performance, processing speed, memory, and spatial ability (SMD = 0.40, 95% CI [0.13, 0.67], P = 0.004), (SMD = 0.37, 95% CI [0.11, 0.63], P = 0.006), (SMD = 0. 51, 95% CI [0.25, 0.78], P = 0.0002), (SMD = 0.35, 95% CI [0.09, 0.62], P = 0.008). In addition, probiotics improved executive function in infants and children (SMD = 0.30, 95% CI [0.04, 0.56], P = 0.03). In young adults, the effects of probiotics were mainly seen in verbal ability (SMD = 0.43, 95% CI [0.15, 0.71], p = 0.003).

Probiotic supplements primarily improve overall cognitive function, information processing speed, memory, and spatial ability in older adults, with the best results observed after 12 weeks of daily intake of approximately 2 × 10¹⁰ CFU.