P3‐258: DETECTION OF PLASMA BIOMARKER CANDIDATES FOR ALZHEIMER'S DISEASE AND AMNESTIC MILD COGNITIVE IMPAIRMENT

We tested for differences in serum oxysterol concentrations between converters and non-converters using logistic regression. We tested for associations between serum oxysterol concentrations and rates of brain atrophy using linear mixed effects models. Results:Baseline serum concentration of 4ß -hydroxycholesterol was higher in males who later developed AD compared to controls (p1⁄40.043), and at follow-up, 4ß –hydroxycholesterol (p1⁄40.039) and 5a,6a-epoxycholesterol were (p1⁄40.031) were higher in male converters compared to controls. In BLSA-NI, lower serum desmosterol concentration in males was associated with faster rates of global brain atrophy (ventricular volume; p<0.001) as well as accelerated atrophy in the temporal lobe (p1⁄40.043), parietal white matter (p1⁄40.011), and total white matter (p1⁄40.034). A lower ratio of 27-hydroxycholesterol / 24S-hydroxycholesterol was associated with faster global atrophy (ventricular volume; p1⁄40.030) in males. In females, higher serum 7a-hydroxycholesterol concentration was associated with faster rates of atrophy in total white matter (p1⁄40.023), as well as parietal (p1⁄40.041), frontal (p1⁄40.015), and temporal (p1⁄40.042) white matter. Lower ratio of 27-hydroxycholesterol / 24S-hydroxycholesterol was associated with faster global atrophy (ventricular volume; p<0.001) in females but with slower rate of hippocampal atrophy (p1⁄40.001). Conclusions: Serum concentrations of oxysterols are associated with risk of incident AD