Table 1.
Selected Clinical Trials Investigating Modulation of the Microbiota-Gut-Brain Axis in Health and Neurodegenerative Diseases With Prebiotic Isolates and Probiotics.
| Disease state | N | Treatment | Duration | Assessment | Effects compared to placebo | Ref. |
|---|---|---|---|---|---|---|
| Prebiotic Isolates | ||||||
| Healthy subjects | 45 | 5.5 g B-GOS, FOS, placebo | 3 weeks | Emotional appraisal and the psychophysiological effects | Prebiotic treatment with B-GOS had a significantly improved cortisol awakening response and reduced vigilance | 100 |
| Healthy subjects | 47 | 5 g oligofructose-enriched inulin or placebo | single dose | Acute effects on mood and cognition | Prebiotic treatment improved mood, recognition memory, and recall | 101 |
| Probiotics | ||||||
| Healthy subjects | 55 | Combination of L. helveticus R0052 and B. longum R0175 or placebo | 4 weeks | Measures on mood and distress | Probiotic treated group self-reported reduced negative mood and distress and decreased urinary cortisol | 103 |
| Healthy subjects | 25 | Combination of L. helveticus R0052 and B. longum R0175 or placebo | 4 weeks | Follow-up to above study on subset of subjects with lowest cortisol | Probiotic treatment improves the same mood scores as in the general population (i.e. same benefits compared to those with higher cortisol concentrations) | 121 |
| Healthy subjects | 20 | Multistrain probiotic (Bifidobacterium bifidum W23, Bifidobacterium lactis W52, Lactobacillus acidophilus W37, Lactobacillus brevis W63, Lactobacillus casei W56, Lactobacillus salivarius W24, and Lactococcus lactis (W19 and W58) or placebo | 5 weeks | Cognitive reactivity in non-depressed individuals | Probiotic treatment reduced cognitive reactivity to sad mood, rumination and aggressive thoughts | 124 |
| Healthy females | 36 | Multistrain probiotic (Bifidobacterium animalis, Streptococcus thermophiles, Lactobacillus bulgaricus, and Lactococcus lactis), placebo, or passive control (no treatment) | 4 weeks | Attention and vigilance to negative emotional stimuli via fMRI | Probiotic treatment group displayed decreased activity in a functional network associated with emotional, somatosensory, and interoceptive processing associated with the insula and other cortical structures | 115 |
| Parkinson’s Disease | 120 | Fermented milk, containing multistrain probiotic and prebiotic fiber, or placebo | 4 weeks | Bowel movements in patients with constipation | Probiotic and prebiotic treatment combination significantly increased the number of complete bowel movements | 125 |
| Parkinson’s Disease | 50 | Multistrain probiotic containing Lactobacillus acidophilus, Bifidobacterium bifidum, L. reuteri, and Lactobacillus fermentum or placebo | 12 weeks | Inflammation, insulin and lipid profiles | Downregulation of inflammatory IL-1, IL-8 and TNF-α and upregulated TGF-β and PPAR-γ in PBMCs | 126 |
| Parkinson’s Disease | 60 | Multistrain probiotic containing Lactobacillus acidophilus, Bifidobacterium bifidum, Lactobacillus reuteri, and Lactobacillus fermentum | 12 weeks | Movement and metabolic parameters | Probiotic treatment decreased high-sensitivity CRP and malondialdehyde and increased glutathione levels; Reduced MDS-UPDRS, insulin and insulin resistance | 127 |
| Alzheimer’s Disease | 30 | Multistrain probiotic containing L. acidophilus, L. casei, B. bifidum, and L. fermentum or no treatment in disease matched subjects | 12 weeks | Cognition and metabolic parameters | Probiotic treatment increased MMSE scores and beta cell function; decreased malondialdehyde levels, CRP, insulin resistance, and triglycerides | 157 |
| Alzheimer’s Disease | 79 | Multistrain probiotic (Lactobacillus acidophilus, Bifidobacterium bifidum, and Bifidobacterium longum) with 200 ug selenium, 200 ug selenium only, or placebo | 12 weeks | Cognition and metabolic parameters | Probiotic with selenium treatment significantly increased MMSE scores, total antioxidant capacity and glutathione and reduced hs-CRP, serum triglycerides, LDL and total cholesterol, and insulin levels compared with selenium alone and placebo treatment | 158 |
| Alzheimer’s Disease | 13 | Fermented milk containing Acetobacter aceti, Acetobacter sp., Lactobacillus delbrueckii delbrueckii, Lactobacillus fermentum, Lactobacillus fructivorans, Enterococcus faecium, Leuconostoc spp., Lactobacillus kefiranofaciens, Candida famata, and Candida krusei | 12 weeks | Cognition, inflammation, and oxidative stress | Probiotic treatment improved cognitive scores and markers of systemic inflammation, oxidative stress, and blood cell damage | 160 |