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Can probiotics help with Alzheimer’s?

With an aging population, more and more people know someone with Alzheimer’s. As a disease of the brain, symptoms could be helped by supporting an organ that plays directly into brain health: the gut.

Study under review: Effect of Probiotic Supplementation on Cognitive Function and Metabolic Status in Alzheimer’s Disease: A Randomized, Double-Blind and Controlled Trial

Introduction

Alzheimer’s disease[1] (AD) is the most common form of dementia. People are at higher risk for it as they age, and while some of the biological changes that occur with the disease are known, it’s still not clear what its underlying causes are. However, there are some interesting correlations. For instance, biomarkers for oxidative stress tend to be higher[2] in people with AD. In addition, inflammation[3] is higher. Insulin resistance[4] and abnormally high blood lipids[5] also tend to co-occur with AD.

While these co-occurrences could be the result of chance or confounding factors such as aging, they may share an underlying factor as well. One possible suspect is the gut microbiome, as shown in Figure 1. After all, the microbiome may be implicated, with varying quality of evidence, in affecting all the factors mentioned above: oxidative stress[6], inflammation[7], insulin resistance[8], and high lipids[9]. There is also reason to suspect[10] that the microbiome may influence cognition and AD, although the evidence is sometimes indirect and the data scarce.

Figure 1: How gut bacteria may connect to Alzheimer's

Reference: Pistollato et al. Nutr Rev. 2016 Oct.

The suggestive findings mentioned above, combined with the lack of direct evidence, led the authors of the study under review to examine directly whether probiotic supplementation could affect AD.

Alzheimer’s disease (AD) sometimes co-occurs with a host of other metabolic disorders which may be linked, at least in part, to the gut microbiome. Given the indirect evidence of microbiome influence on these co-occurring disorders as well as cognition, the authors of this study intended to directly test if probiotic supplementation could affect AD.

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