Association of TyG index and obesity indicators with cognitive function: a cross - sectional study from Chinese health check-up centers

BACKGROUND: Whether the triglyceride-glucose index (TyG) and its derived indices [TyG-body mass index (TyG-BMI), TyG-waist circumference (TyG-WC), TyG-waist-to-height ratio (TyG-WHtR), TyG-weight-adjusted waist index (TyG-WWI), TyG-a body shape index (TyG-ABSI)] are associated with cognitive function remains unclear, particularly in middle-aged populations. METHODS: A total of 876 participants (mean age 49.4 ± 13.3 years) were recruited. The TyG and its related indices were computed and divided into quartiles (Q1-Q4). Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA), Digit Symbol Substitution Test (DSST), and Auditory Verbal Learning Test (AVLT, including immediate recall [AVLT-3] and delayed recall [AVLT-5]). Multivariable linear regression models adjusted for demographic, lifestyle, and clinical covariates (Model 2) were used to assess associations. Restricted cubic spline (RCS) models were applied to explore non-linear relationships. RESULT: Higher TyG index quartiles were generally associated with lower cognitive scores, although associations were attenuated compared to models adjusted for age and sex only. Specifically, participants in the highest quartile (Q4) of TyG-WHtR had a 0.97 point lower MoCA score (95% CI: -1.89, -0.06) and a 1.53 point lower DSST score (95% CI: -2.97, -0.10) compared to Q1. Among the TyG-obesity indices, TyG-WHtR and TyG-WC showed consistent and significant associations with MoCA and DSST scores, while TyG-WWI and TyG-ABSI showed weaker or non-significant associations across cognitive domains. These associations were generally more pronounced in females and participants aged < 60 years. RCS analyses indicated approximately linear inverse associations for most indices, with a threshold effect observed for TyG-WWI. CONCLUSIONS: Elevated TyG and its obesity-related indices, particularly TyG-WHtR, are associated with poorer cognitive function in healthy middle-aged Chinese adults. These findings highlight the potential utility of integrating metabolic and anthropometric indicators into early risk assessment for cognitive decline. CLINICAL TRIAL NUMBER: Not applicable. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12902-026-02280-4.