To explore whether the observed dysregulation of conjugated BAs in AD is linked to enzymatic differences in taurine and glycine conjugation, the ratios GDCA:DCA, TDCA:DCA, GCA:CA and TCA:CA were calculated (Figure ) as previously described . A significant decrease in GDCA:DCA was found in AD compared to MCI, suggesting a change in the processes involving glycine conjugation in the liver. This is in contrast with a previous study in blood where no significant changes were observed .