Association of triglyceride glucose index combined with obesity indicators with cognitive impairment

Abstract

Background: The association of a combination of the TyG index and obesity markers, specifically waist circumference (WC), with cognitive function is unknown. This research investigated the relationship between TyG-WC measurements and cognitive impairment in a low-income population in China; moreover, this study evaluated the role of diabetes mellitus and body mass index (BMI) in modulating this relationship.

Methods: 1125 eligible individuals aged ≥ 60 years participated in this study. The TyG index and obesity indicators (BMI, WC, and waist-to-height ratio) were calculated for individual participants and categorized into quartiles. Multivariate logistic regression analysis was used to evaluate the correlation between TyG-WC values and cognitive impairment; the possibility of a nonlinear relationship was explored using constrained cubic spline analysis. The participants were divided into different groups according to their diabetes status and BMI category for subgroup analyses. Linear regression was used to investigate the correlation between TyG-WC values and MMSE scores.

Results: The prevalence of cognitive impairment in the study participants was 47.3%, with a significant negative association between TyG-WC values and cognitive impairment, (odds ratio [OR] = 0.999; 95% confidence interval [CI], 0.997-1.00, P = 0.009). A U-shaped correlation was observed between the TyG-WC values and cognitive impairment (P = 0.008). Subgroup analyses showed that the inverse association between TyG-WC values and cognitive impairment was stronger in non-diabetic individuals (OR = 0.998; 95% CI, 0.997-0.999; P = 0.002) and in those with a lower BMI (< 24 kg/m²; OR = 0.996; 95% CI, 0.994-0.998; P = 0.001). A positive correlation was found between TyG-WC values and MMSE scores, particularly in men and non-diabetic individuals (β = 0.003; 95% CI, 0.0002-0.005; P = 0.031).

Conclusion: This study demonstrates a nonlinear U-shaped relationship between TyG-WC values and cognitive function. The stronger inverse association between TyG-WC values and cognitive decline in the non-diabetic and low-BMI subgroups suggests that these populations may benefit the most from targeted interventions. These findings are important for clinical practice and formulating disease-prevention policies, emphasizing the need for metabolic health management to prevent cognitive decline, particularly in low-income populations.

Keywords: BMI; Cognitive impairment; Diabetes mellitus; Metabolic health; TyG-WC.

Fig. 1

Restricted cubic spline analysis to evaluate the potential non-linear relationship between TyG-WC and cognitive impairment. This figure shows the non-linear relationship between TyG-WC and cognitive impairment

Fig. 2

Association between the TyG-WC and cognitive impairment in sex, age, diabetes mellitus, and BMI subgroups in logistic models. This figure shows that after adjusting for covariates, in the subgroup without diabetes, the risk of cognitive impairment decreased by 0.2% for each higher value of TyG-WC. In participants with a BMI < 24, the risk decreased by 0.4% per unit increase in TyG-WC. No significant association was found between TyG-WC and cognitive impairment in men, participants with diabetes, or those with a BMI ≥ 24

Fig. 3

Association between the TyG-WC and MMSE Scores in sex, age, diabetes mellitus, and BMI subgroups in linear models. This figure shows that after adjusting for covariates, in the male subgroup, for each unit increase in TyG-WC, MMSE scores increased by 0.005. In the non-diabetic subgroup, for each unit increase in TyG-WC, MMSE scores increased by 0.004. No significant association was found in other subgroups

Fig. 4

Restricted cubic spline analysis to evaluate the potential non-linear relationship between TyG-WC and MMSE Scores This figure shows that there was no nonlinear association between TyG-WC and MMSE Scores