Longitudinal changes in triglyceride-glucose index and the risk of incident dementia: a prospective cohort study

BACKGROUND: The triglyceride-glucose (TyG) index, a practical and reliable indicator for insulin resistance, has been linked to an increased risk of dementia. However, the impact of its longitudinal changes on dementia risk remains unexplored. METHODS: Data were obtained from the Atherosclerosis Risk in Communities Study (ARIC). TyG index was calculated by combining triglyceride and fasting blood glucose levels. Longitudinal changes in TyG were evaluated using two indicators over two visits (median time interval: 2.9 years): the average TyG index and the difference in TyG index. Participants were stratified into tertiles based on these measures. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: A total of 12 601 participants (54.9% female, mean age: 54.2 years) were included. During 264 735.5 person-years of follow-up, 2460 (19.5%) participants developed incident dementia. Individuals in the highest tertile (T3) of the average TyG index had a 26% higher risk of dementia (HR: 1.26, 95% CI: 1.13-1.40, p-trend <.001) compared to those in the lowest tertile (T1). Furthermore, independent of baseline levels, a greater increase in TyG index between visit 1 and visit 2 was associated with an elevated dementia risk, with the HRT3 vs T1 of 1.17 (95% CI: 1.05-1.29, p-trend = .003). CONCLUSIONS: A higher level of average TyG index and increase in TyG index were both associated with a higher risk of dementia. These findings suggest that long-term monitoring of the TyG index may contribute to identifying individuals at elevated dementia risk.