Table 4.
Impacts of probiotic/prebiotic/symbiotic supplementation on cognitive functions in patients with Alzheimer’s disease.
| Study | Design | Mean Follow-Up | Country | Sample Size | Average Age (Year) | Sex Male/Female (%) |
Intervention | Main Results |
|---|---|---|---|---|---|---|---|---|
| Ton AMM et al. [37] | Clinical Trial | 90 days | Brazil | 13 | 78.7 ± 3 | 15/85 | The participants received a probiotic fermented milk (4% kefir) supplement at a dosage of 2 mL/kg/day 1. | Most patients exhibited a notable improvement in memory, visual–spatial/abstraction abilities, and executive/language functions (p < 0.05). |
| Akhgarjand et al. [38] | RCT | 12 weeks | Iran | 90 | 67.9 ± 7.9 | 33/67 | They received probiotic capsules containing L. rhamnosus HA (each capsule with 1015 CFU probiotics) or probiotic capsules containing B. longum R0175 (1015 CFU probiotics per capsule) twice daily. | Cognition showed a significant improvement with MMSE (p < 0.0001). Post hoc comparisons revealed a notably greater enhancement in the B. longum intervention group (4.86, 95% CI: 3.91–5.81; p < 0.0001) compared to both the placebo and L. rhamnosus intervention groups (4.06, 95% CI: 3.11–5.01; p < 0.0001). |
| Kobayashi Y et al. [39] | RCT | 12 weeks | Japan | 117 | 61.5 ± 6.8 | 49/51 | The individuals took two capsules every day, each containing around more than 2.0 × 1010 CFU of B. breve A1. | In a stratified analysis, a notable distinction emerged between the B. breve A1 and placebo groups concerning the ‘immediate memory’ subscale of RBANS and the total MMSE score in participants with a low RBANS total score at the baseline. The scores on the ‘language’ and ‘attention’ subscales showed a significant increase. |
| Tamtaji et al. [40] | RCT | 12 weeks | Iran | 79 | 76.2 ± 8.1 | 50/50 | The patients received selenium (200 μg/day) plus a probiotic containing Lactobacillus acidophilus, Bifidobacterium bifidum, and Bifidobacterium longum (each at 2 × 109 CFU/day). | The combined use of the probiotic and selenium resulted in a significant improvement in the MMSE test (p < 0.001). Cognitive functions significantly improved. |
RCT: randomized controlled trial; CFU: colony-forming unit; MMSE: Mini-Mental State Examination; RBANS: Repeatable Battery for the Assessment of Neuropsychological Status; 1 Probiotic fermented milk containing Acetobacter aceti, Acetobacter spp., L. kefiranofaciens, L. delbrueckii, L. fructivorans, L. fermentum, Enterococcus faecium, Leuconostoc spp., Candida famata, and krusei.