Table 3.
The impacts of probiotic/prebiotic/symbiotic supplementation on cognitive functions in patients with mild cognitive impairment.
| Study | Design | Mean Follow-Up | Country | Sample Size | Average Age (Year) | Sex Male/Female (%) |
Intervention | Main Results |
|---|---|---|---|---|---|---|---|---|
| Aljumaah MR et al. [31] | RCT | 3 months | USA | 169 | 64.4 ± 5.5 | 38/48 | The LGG supplementation consisted of two capsules of Culturelle Vegetarian Capsules comprising a blend of 10 billion CFUs of Lactobacillus rhamnosus GG and 200 mg of prebiotic inulin derived from chicory root extract. | The reduction in the relative abundance of the Prevotella and Dehalobacterium genera following LGG supplementation in the MCI group showed a correlation with an enhanced cognitive score. |
| Asaoka D et al. [32] | RCT | 24 weeks | Japan | 130 | 77.2 ± 5.8 | 26/29 | The patients received a daily dosage of a probiotic (B. breve MCC1274, 2 × 1010 CFU/day). | The ADAS-Jcog subscale “orientation” showed significant improvement; MMSE subscales “orientation in time” and “writing” demonstrated significant improvement, specifically in the subgroup with lower baseline MMSE scores (p < 0.05). |
| Xiao J et al. [33] | RCT | 16 weeks | Japan | 79 | 61.3 ± 7.7 | 100% male | The patients received a daily dosage of a probiotic (B. breve A1, 2 × 1010 CFU/day). | The probiotic group exhibited a significant improvement in RBANS total score (p < 0.0001). Notably, there was a substantial enhancement in domain scores, including immediate memory, visuospatial/constructional, and delayed memory (p < 0.0001), observed in both intention-to-treat (ITT) analysis and per-protocol (PP) analysis. |
| Fei Y et al. [34] |
RCT | 12 weeks | China | 42 | 76.4 ± 9.6 | 90/10 | The group receiving the probiotic received a daily dosage of 2 g of a probiotic blend. | The probiotic group exhibited a notably higher MMSE score (24.75 ± 2.47), and there were significant improvements in attention and calculation (0.90 ± 0.79 vs. 0.65 ± 0.74, p < 0.001) and recall scores (1.95 ± 0.76 vs. 0.70 ± 0.47, p < 0.001) in comparison to the control group. |
| Kobayashi Y et al. [35] | RCT | 8 weeks | Japan | 19 | 82.5 ± 5.3 | 2/98 | The patients received B. breve A1 capsules, each containing more than 1 × 1010 CFU (2 × 1010 CFU/day). | MMSE scores showed a significant increase during the intervention (+1.7, p < 0.01). POMS2 and GSRS scores exhibited significant improvement during the intervention. |
| Hwang YH et al. [36] | RCT | 12 weeks | Korea | 100 | 69.2 ± 7.0 | 28/72 | Lactobacillus plantarum C29-fermented soybean (DW2009) 800 mg per day (1 × 1010 CFU/day). | The group receiving DW2009 exhibited more significant enhancements in overall cognitive functions (z = 2.36, p = 0.02), particularly in the attention domain (z = 2.34, p = 0.02). |
ADAS-Jcog: Japanese version of Alzheimer’s Disease Assessment Scale; CFU: colony-forming unit; DW2009: Lactobacillus plantarum C29-fermented soybean; GSRS: Gastrointestinal Symptom Rating Scale; ITT: intention-to-treat; LGG: Lactobacillus rhamnosus GG; MCI: mild cognitive impairment; MMSE: Mini-Mental State Examination; POMS2: Profile of Mood States 2nd Edition; RCT: randomized controlled trial; RBANS: Repeatable Battery for the Assessment of Neuropsychological Status.