Association between the atherogenic index of plasma and cognitive impairment

The Atherogenic Index of Plasma (AIP), a burgeoning composite lipid marker that reflects overall lipid balance, has an incompletely understood longitudinal relationship with cognitive impairment. This study conducted a systematic investigation into the long-term, nonlinear association between AIP and the risk of cognitive impairment among middle-aged and older adults, utilizing longitudinal data from the China Health and Retirement Longitudinal Study (CHARLS) spanning from 2011 to 2020. The study encompassed 2971 participants who were free from cognitive impairment at baseline and were followed for a period of up to 10 years. The cumulative incidence of new-onset cognitive impairment was found to be 40.46% in men and 54.45% in women. A multivariable-adjusted Cox regression analysis revealed that an elevated AIP, particularly within the 25th to 75th percentile range, was an independent risk factor for cognitive impairment (P < 0.05). Further analysis employing restricted cubic splines (RCS) uncovered a significant inverted U-shaped nonlinear association between AIP and cognitive impairment risk (P-nonlinear < 0.001), with a notably increased risk within the AIP range of 0.205 to 0.423. Subgroup analyses, stratified by sex, age, educational level, and BMI, showed consistent trends across various demographic groups. This study suggests that AIP, as a straightforward composite lipid marker, exhibits a significant nonlinear association with the risk of cognitive impairment in middle-aged and older adults. Monitoring AIP levels could assist in the early identification of individuals at high risk, and targeted interventions within specific AIP ranges, such as 0.205–0.423, could have significant public health implications, offering a new potential target for preventive strategies against cognitive decline.