MahmoudianDehkordi S, et al. - In Alzheimer's disease (AD), experts assessed the correlation between bile acids (BAs), products of cholesterol metabolism and clearance produced in the liver and further metabolized by gut bacteria, and cognitive impairment. They measured the serum levels of 15 primary and secondary BAs and their conjugated forms in subjects, including 370 cognitively normal older adults, 284 with early mild cognitive impairment, 505 with late mild cognitive impairment, and 305 AD cases enrolled in the AD Neuroimaging Initiative. A correlation between altered BA profile, genetic variants implicated in AD, and cognitive changes in disease were suggested for the first time in these findings. Compared to cognitively normal older adults, significantly lower serum concentrations of a primary BA (cholic acid) and increased levels of the bacterially produced, secondary BA, deoxycholic acid, and its glycine and taurine conjugated forms were noted in AD.