Relationship between plasma amyloid p and cognitive impairment: a cross-seciional study based on a populaiion in a rural area of Xi'an, China

Objective To explore the relationship between plasma amyloid-β (Aβ) and cognitive impairment. Methods A total of all villagers (aged 40 years and above) from two villages of Xi'an, China, were enrolled. A validated Chinese version of the Mini-Mental State Examination and neuropsychological battery were used to assess cognition. Levels of fasting plasma Aβ_1-42and Aβ_1-40were tested using commercial enzyme-linked immunosorbent assay (ELISA).Relationship between plasma Aβ and cognitive impairment was analyzed using Logistic regression analysis. Results Of the 1314 enrolled subjects, 1180 (89.80%) had normal cognition, 85 (6.47%) had suspected cognitive impairment, and 49 (3.73%) had probable cognitive impairment. Univariate analysis showed that plasma Aβ_1-42/Aβ_1-40ratio was higher in the suspected cognitive impairment group than in the probable cognitive impairment group (P＜0.05) and normal cognitive group (P＜0.05): plasma Aβ_1-42level in the suspected cognitive impairment group was higher than that in normal cognitive group (P＜0.05).The level of Aβ_1-40did not differ between the three groups. After correcting for confounding factors (including age, gender, degree of education, cognitive impairment risk factors, habits of living) in the multivariate Logistic regression analysis, the results were consistent with those in the univariate analysis. Conclusion Levels of plasma Aβ_1-42and Aβ_1-42/Aβ_1-40ratio were elevated in patients with suspected cognitive impairment, indicating that elevated plasma AAβ_1-42and Aβ1-Aβ_1-42/Aβ_1-40ratio may be more pronounced in early stage of cognitive impairment. They may be early biomarkers for cognitive impairment, which can help identify and intervene the disease earlier.