Exploring the threshold association between cardiometabolic index and cognitive function in U.S. adults aged ≥ 60 years

Cardiometabolic index (CMI) reflects visceral fat accumulation and lipid metabolism and has been linked to metabolic and cardiovascular diseases. Its association with cognitive function in older adults remains unclear. This study aimed to assess the relationship between CMI and global cognitive performance in a nationally representative sample of United States adults aged 60 years and older. We conducted a cross-sectional analysis of National Health and Nutrition Examination Survey 2011 to 2014 data (n = 1326). CMI was analyzed both as a continuous variable and by quartiles (Q1-Q4). Survey-weighted linear regression models examined associations with global cognitive function (GCF), adjusting sequentially for demographics (ModelI) and full covariates (ModelII). Threshold effects and smoothing curves explored nonlinear links. Interaction tests and subgroup analyses evaluated effect modification by diabetes status. In the minimally adjusted model, higher continuous CMI was associated with lower GCF (β = -2.46, 95% confidence interval [CI]: 4.58--0.35; P = .0318), but this association was not significant after full adjustment (β = -0.56, 95% CI: 2.49-1.36; P = .5807). When using quartiles, a negative trend was observed in the crude (P for trend = .0392) and minimally adjusted models (P for trend = .0166) but not in the fully adjusted model (P for trend = .4825). Nonlinear analysis identified an inflection at CMI = 0.16 for digit symbol substitution test (β = 142.74, 95% CI: 70.18-215.30; P < .001) and GCF (β = 173.67, 95% CI: 77.01-270.32; P < .001). Diabetes status significantly modified the CMI-GCF relationship (P for interaction = .035). CMI is negatively associated with cognitive function in older adults. These findings suggest that higher CMI may indicate a greater risk of cognitive decline.