Crosstalk between Gut Microbiota and Central Nervous System: A Focus on Alzheimer's Disease.

The role of diet and gut microbiota in the pathophysiology of neurodegenerative diseases, such as Alzheimer's, has recently come under intense investigation. Studies suggest that human gut microbiota may contribute to the modulation of several neurochemical and neurometabolic pathways, through complex systems that interact and interconnect with the central nervous system. The brain and intestine form a bidirectional communication axis, or vice versa, they form an axis through bi-directional communication between endocrine and complex immune systems, involving neurotransmitters and hormones. Above all, studies suggest that dysbiotic and poorly diversified microbiota may interfere with the synthesis and secretion of neurotrophic factors, such as brain-derived neurotrophic factor, gammaaminobutyric acid and N-methyl D-Aspartate receptors, widely associated with cognitive decline and dementia. In this context, the present article provides a review of the literature on the role of the gutbrain axis in Alzheimer's disease.

Inflammation, Oxidation, Caloric Expenditure and Cognitive Impairment in Brazilian Elderly Assisted at Primary Care.

Cognitive impairment (CI) has a multifactorial etiology. Some studies have suggested that inflammatory, oxidative and antioxidant status and physical activity are associated with CI. However, the evidence on this subject is still controversial. The goal of this study was to verify the association of caloric expenditure by physical activity, oxidative, antioxidant power and inflammatory biomarkers with CI in older adults. We performed a cross-sectional study of 424 elderly (224 with normal cognitive function and 200 with CI) patients from the Family Health Strategy in Porto Alegre, Rio Grande do Sul, Brazil. The variables investigated were sociodemographic, biochemical, inflammatory (hs-CRP, IL-6), oxidative (TBARS, AOPP), antioxidant power (FRAP) biomarkers, energy expenditure, and cognitive function. The instruments used were the Minnesota Leisure Time Physical Activity Questionnaire + Compendium of Physical Activities, classification of energy costs of human physical activities (for physical activity evaluation and measurement of energy expenditure in METs), and a battery of neuropsychiatric instruments (for cognitive ability assessment). We found statistically significant differences only with respect to HDL-c and age (higher averages in the CI group; P<0.05). We observed no differences between the groups with respect to biochemical, inflammatory, oxidative and FRAP biomarkers or caloric expenditure. Logistic regression showed that HDL-c (OR=1.02 [IC=95%; 1.01-1.04]; P=0.011), and age (OR=1.05 [IC=95%; 1.02-1.08]; P=0.004) are independent factors associated with CI. Our results suggest that the biochemical (except HDL-c), inflammatory, oxidative, and FRAP biomarkers investigated and caloric expenditure are not associated with CI in the elderly assisted at primary care.