Specific changes of sulfatide levels in individuals with pre-clinical Alzheimer's disease: an early event in disease pathogenesis.

To explore the hypothesis that alterations in cellular membrane lipids are present at the stage of pre-clinical Alzheimer's disease (AD) (i.e., cognitively normal at death, but with AD neuropathology), we performed targeted shotgun lipidomics of lipid extracts from post-mortem brains of subjects with pre-clinical AD. We found sulfatide levels were significantly lower in subjects with pre-clinical AD compared to those without AD neuropathology. We also found that the level of ethanolamine glycerophospholipid was marginally lower at this stage of AD, whereas changes of the ceramide levels were undetectable with the available samples. These results indicate that cellular membrane defects are present at the earliest stages of AD pathogenesis and also suggest that sulfatide loss is among the earliest events of AD development, while alterations in the levels of ethanolamine glycerophospholipid and ceramide occur relatively later in disease.