Serum clusterin levels are not increased in presymptomatic Alzheimer's disease

Increased plasma levels of clusterin have recently been found to be associated with severity and progression in Alzheimer's disease (AD). We have investigated clusterin levels in serum of elderly people with presymptomatic AD from a population-based prospective cohort study. During 10 years follow-up, 43 participants were diagnosed with AD after on average 4.2 years (±2.6 years SD) after the initial blood sampling. At the time of blood sampling, these participants showed normal cognitive function. For each presymptomatic AD case, a control was matched on gender and age. Furthermore, the selected controls had to remain dementia-free and still be alive at the end of follow-up. Quantitative serum clusterin levels were measured with a newly developed multiple reaction monitoring (MRM) assay. Results of the assay showed no significant difference in clusterin levels between presymptomatic AD and controls (p-value 0.54). In conclusion, serum clusterin is not an early, presymptomatic biomarker for AD.