A recent meta-analysis published in the Journal of Affective Disorders revealed that individuals with a higher triglyceride glucose (TyG) index face an increased risk of cognitive decline.
Cognitive decline, a precursor to conditions such as dementia, affects millions worldwide, with its prevalence rising, particularly among older populations. Previous research has linked insulin resistance (IR) to cognitive impairment, but the mechanisms and surrogate markers remain under exploration.
The TyG index, a simpler and cost-effective surrogate for measuring insulin resistance compared to the homeostasis model assessment (HOMA-IR), has been examined for its association with various health outcomes. In light of the mixed findings regarding its connection with cognitive decline, Yuqin Liu and colleagues clarified this relationship through a comprehensive meta-analysis.
The researchers conducted a systematic search of several major databases, including PubMed, EMBASE, the Cochrane Library, Web of Science, and Medline, for studies published up until October 2023. They specifically sought out studies that reported on the relationship between the TyG index and cognitive decline in humans.
Inclusion criteria required that studies used a validated method to calculate the TyG index from fasting triglycerides and blood glucose levels, measured cognitive decline using reliable neuropsychological assessments, and presented statistical data on this association. Studies were limited to those written in English, and those involving human subjects. Studies that did not meet these criteria, such as duplicates, reviews, or conference abstracts, were excluded from the analysis.
The final meta-analysis included 12 studies, consisting of 3 cohort studies and 9 case-control or cross-sectional studies. The cohort studies involved over 5.5 million individuals, while the case-control and cross-sectional studies included approximately 13,358 participants. The studies spanned various populations, ages, and regions, allowing for a comprehensive analysis of the TyG index’s role in cognitive health.
The meta-analysis revealed a strong association between higher TyG index levels and an increased risk of cognitive decline. Individuals with elevated TyG levels were 14% more likely to experience cognitive decline in cohort studies, while in case-control and cross-sectional studies, this risk increased by 75%. Additionally, a dose-response relationship was observed, with a 42% higher risk of cognitive decline for each unit increase in the TyG index, emphasizing the cumulative impact of insulin resistance on cognitive health.
Subgroup analyses showed that men were more affected by elevated TyG levels, facing a 13% higher risk of cognitive decline compared to women. In Asian populations, the risk was even greater, with an 88% higher likelihood of cognitive decline among individuals with elevated TyG levels. Younger individuals, particularly those under 60, showed a 43% higher risk, while the association was less clear in older adults, likely due to other age-related factors.
These findings suggest that the TyG index is a valuable marker for predicting cognitive impairment, especially in younger adults and certain sub-group populations.
The presence of heterogeneity across studies, likely due to varying participant demographics and study designs, was a limitation to this work.
The study, “Association between Triglyceride Glucose Index and Cognitive Decline: A Meta-Analysis”, was authored by Yuqin Liu, Xingxiang Yang, Jie Gao, Chenqi Xie, Chunyan Tian, and Tianlin Gao.