TyG index and mild cognitive impairment and dementia: a review of current evidence.

This narrative review aimed to synthesize current epidemiological, mechanistic, and clinical evidence on the association between the triglyceride-glucose (TyG) index and cognitive impairment, and to discuss its potential role in metabolic-neurocognitive risk assessment. Current evidence from cohort studies, cross-sectional analyses, and meta-analyses suggests that higher TyG index levels are generally associated with an increased likelihood of mild cognitive impairment, dementia, and related cognitive decline across different populations. TyG-derived indices that combine the TyG index with anthropometric measures may provide additional information on the combined burden of insulin resistance and adiposity-related metabolic dysfunction. Mechanistically, TyG-related insulin resistance and metabolic dysregulation may be linked to cognitive impairment through multiple interconnected pathways, including impaired cerebral energy metabolism, mitochondrial dysfunction, vascular endothelial dysfunction, blood-brain barrier disruption, abnormal amyloid-β metabolism, tau pathology, and neuroinflammatory responses. From a clinical perspective, the TyG index may be regarded as a simple and accessible metabolic risk-stratification marker, rather than an established diagnostic or predictive biomarker for cognitive impairment. Its potential value may lie in identifying individuals with metabolic dysfunction who may benefit from closer cognitive monitoring and integrated vascular-metabolic risk management. However, because current evidence remains predominantly observational, further prospective, mechanistic, and interventional studies are needed to clarify the causal relevance, incremental predictive value, and clinical utility of the TyG index in cognitive impairment and dementia.