The relationship between plasma oxidized low-density lipoprotein and all-cause cognitive impairment: A population-based cross-sectional study in a rural area of Xi’an, China

Background: Oxidized low-density lipoprotein (ox-LDL) contributes to atherosclerosis and triggers cardiovascular and cerebrovascular events. However, its role in cognitive impairment (CogI) has not been fully elucidated. Objective: To examine the relationship between plasma ox-LDL and all-cause CogI in middle-aged and older Chinese adults. Methods: In this population-based cross-sectional study using cluster sampling, cognitive function was assessed with the Mini-Mental State Examination (MMSE) and neuropsychological tests. CogI was diagnosed based on criteria for mild cognitive impairment (MCI) and dementia. Plasma ox-LDL was measured by ELISA and analyzed as restricted cubic spline (RCS), continuous, and binary variables. Logistic regression, subgroup, and interaction analyses were performed. Results: Among 1406 subjects, 112 (8.0%) had CogI. RCS analysis showed a significant association between ox-LDL and CogI (p_overall < 0.001), with no non-linear relationship (p_non−linear = 0.327). Individuals with ox-LDL >1002.88 ng/mL had a higher risk of CogI than those with ox-LDL ≤1002.88 ng/mL (10.7% versus 6.6%, p = 0.008; OR = 1.749, 95% CI: 1.134–2.697, p = 0.012). The association remained significant among participants with normal TC (TC < 5.18 mmol/L, p < 0.001), but was not observed in those with elevated TC (p = 0.817). Interaction analysis confirmed a modifying effect of TC (p_interaction = 0.005), and a similar effect was observed for LDL-C (p_interaction = 0.028). Conclusions: Elevated ox-LDL levels (>1002.88 ng/mL) were associated with an increased risk of all-cause CogI, particularly among individuals with normal TC or LDL-C. Longitudinal studies with larger sample sizes are needed to clarify the causal relationship.