The Association of Plasma Amyloid-β and Cognitive Decline in Cognitively Unimpaired Population

PURPOSE: This study investigates the relationship between baseline plasma Aβ and cognitive decline during follow-up in cognitively unimpaired population. MATERIALS AND METHODS: Cognitively unimpaired population was selected from people who lived in the suburbs of Xi’an, China. The levels of plasma Aβ(1-42) and Aβ(1-40) were tested using commercial enzyme-linked immunosorbent assay (ELISA). The mini-mental state examination (MMSE) and neuropsychological battery were used to assess cognition. Two years later, MMSE was tested again, and significant cognitive decline was defined as a decrease in MMSE scores ≥5 points. Logistic regression analysis was performed to analyze the relationship between baseline plasma Aβ and cognitive change during the two-year follow-up. RESULTS: A total of 1144 participants completed the study, among whom 59 subjects (5.2%) presented significant cognitive decline. The high plasma Aβ(1-42) level group had more significant cognitive decline (P = 0.023). Multivariable logistic regression analysis showed that significant cognitive decline was associated with the high levels of baseline plasma Aβ(1-42) (OR = 1.043, 95% CI: 1.005–1.083, P = 0.026). However, significant cognitive decline was not associated with baseline plasma Aβ(1-40) levels and Aβ(1-42) /Aβ(1-40) ratio. CONCLUSION: Population with high level of baseline plasma Aβ(1-42) manifested significant cognitive decline over 2 years; however, further investigation on the dynamics of plasma Aβ and long-term follow-up are needed.