Gut Bacteria and Lipid Metabolism May Influence Alzheimer’s Disease and Dementia


Several studies at the Alzheimer’s Association International Conference (AAIC) 2018 showed that lipid, cholesterol, and bile acid metabolism correlate with biomarkers for and clinical findings of mild cognitive impairment (MCI) and Alzheimer’s disease (AD).

Researchers of the Alzheimer’s Disease Metabolics Consortium (ADMC), led by RimaKaddurah-Daouk and Mitchel A. Kling found that reduced levels of cell-membrane lipids, plasmalogens—including omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), correlate with an increased risk of AD. They also found differences in plasmalogen levels between patients with AD and healthy control subjects, which correlated with levels of tau in the cerebrospinal fluid (CSF) of subjects.

Other ADMC researchers reported that they measured serum levels of 15 bile acid metabolites in older adults with early stage AD. They found that bile acids are increased in people with AD and correlate with functional and structural brain changes including cognitive decline, reduced brain glucose metabolism, and greater brain atrophy. These same bile acids were also associated with increased CSF amyloid and tau levels and accumulation. Of interest because of previous studies correlating diet, gut microbiome, and AD, higher levels of 2 bacterially-produced bile acids correlated with higher levels of tau in the CSF, decreased hippocampal volume, and decreased brain glucose metabolism.

Another study presented evaluated whether individuals with specific AD-related genes correlated with levels of cholesterol, bile acids, and other serum metabolites. This study showed that variations in AD risk genes APOE-e4 and SORL1 correlated with decreased levels of some of the cholesterol components of brain cell membranes (P < .0001).

“While still in its infancy, gut microbiome research is very exciting since it may give us a new window into why diet and nutrition are so important for brain health,” said Maria Carrillo, PhD, Alzheimer’s Association Chief Science Officer. “For example, this work may tell us more about how and why ‘good fats’ help keep the brain healthy and help guide brain-healthy dietary choices.”


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