Abstract
A blood-based biomarker of Alzheimer's disease (AD) progression could be instrumental in targeting asymptomatic individuals for treatment early in the disease process. Given the direct connection between sphingomyelins (SM), ceramides, and apoptosis, these lipids may be indicators of neurodegeneration and AD progression. Baseline serum SM and ceramides from 100 women enrolled in a longitudinal population-based study were examined as predictors of cognitive impairment. Participants were followed up to six visits over 9 years. Baseline lipids, in tertiles, were examined in relation to cross-sectional and incident impairment (<1.5 S.D. below standard norms) on HVLT-immediate and -delayed memory recall and Trails A and B. SM and ceramides varied in relation to the timing of HVLT-delayed impairment: low levels were associated with cross-sectional impairment; high levels predicted incident impairment in asymptomatic individuals. Lipids were not associated with loss-to-follow-up. Results suggest serum SM and ceramides vary according to the timing of the onset of memory impairment and may be good pre-clinical predictors, or biomarkers, of memory impairment: a deficit observed early in AD pathogenesis.