The MCI-AD comparison (Figure ) revealed two significant clusters -disaccharides (decreased in AD) and hydroxybutyrates (increased in AD, with key metabolite BHBA, discussed above). This last cluster was also statistically altered comparing ND-AD (Figure ). Umbelliferones (increased in AD), monosaccharides and sugar acids were also significant in ND-AD. While the total number of chemical clusters identified was almost the same in the three cases (Figure ), only one significant cluster (hydroxybutyrates) overlapped between MCI-AD and ND-AD.