Association between modified a body shape index and incident cognitive impairment in middle-aged and older adults: a prospective cohort study

Abstract Background Central obesity contributes significantly to cognitive decline. Traditional indices like BMI inadequately capture visceral adiposity and exhibit the obesity paradox in elderly populations.This study looked into the connection between a modified A Body Shape Index (ABSI) and the development of cognitive impairment in middle-aged and older adults. Methods Longitudinal data from 4,353 eligible participants in the 2011–2020 CHARLS cohort were analyzed. Modified ABSI was calculated based on waist circumference, BMI, and height and categorized into quartiles. Cox proportional hazards regression models were used to evaluate the association between modified ABSI and incident cognitive impairment. The fully adjusted model included age, sex, residence, education, marital status, smoking, drinking, hypertension, diabetes mellitus, dyslipidemia, stroke, heart disease, systolic and diastolic blood pressure, triglycerides, LDL-C, HDL-C, HbA1c, CRP, serum creatinine, and uric acid. Restricted cubic spline, subgroup, and sensitivity analyses were also performed. Results Over the follow-up period, cognitive impairment occurred in 1,822 participants, corresponding to 41.9% of the study population. In the Cox model that was fully adjusted, individuals in the highest ABSI quartile (Q4) exhibited a markedly elevated hazard of cognitive impairment relative to those in the lowest quartile (Q1) (HR = 1.22, P = 0.024). A pronounced dose–response pattern was evident, which persisted as statistically significant and linear following comprehensive covariate adjustment ( P = 0.037). Subgroup analyses indicated more pronounced associations among female participants and individuals aged 70 years or older ( P < 0.05). Conclusion High ABSI levels are significantly associated with an increased long-term risk of cognitive impairment in middle-aged and older adults. The findings suggest that ABSI could serve as an effective surrogate marker for central adiposity, facilitating the early recognition of individuals at heightened risk for cognitive decline.