On the Role of Intestinal Microbiota in Patients with Cognitive Decline

Objective: The association between gut microbiota composition and biomarkers of immune activation and inflammation was assessed in the elderly. Patients: Serum inflammation markers of fifty-five outpatients (29 females, 26 males, aged 78 ± 8.5 years) were analyzed. Stool specimens and thus data on gut microbiota were available from a subgroup of 23 individuals (9 females and 14 males). Results: Global cerebral atrophy was found in all magnet resonance tomography scans. Mean mini-mental-score examination in Alzheimer's disease patients was 18.8 ± 7.1, in patients with mild cognitive impairment 27.8 ± 1.5. Serum neopterin concentrations correlated with concentrations of fecal S100A12 (p < 0.001) and α1-antitrypsin (p < 0.05). Faecalibacterium prausnitzii correlated with MMSE (p < 0.05), with Akkermansia muciniphila (p < 0.01) and with serum neopterin (p < 0.05). Fecal zonulin correlated inversely with Clostridium cluster I (p < 0.02). Conclusions: Our results underline earlier in vitro and animal studies that cognitive decline associates with age-related changes in the intestinal microbiota and neuroinflammation. However, only correlational evidence can be reported, and a causative relationship still has to be demonstrated.