Metabolic Syndrome and the Brain: Neurological Sequelae of Insulin Resistance and Dyslipidemia

Abstract

Metabolic syndrome is a complex clinical entity defined by a cluster of interconnected metabolic abnormalities, including central obesity, insulin resistance, hyperglycemia, hypertension, and dyslipidemia. Metabolic syndrome, characterised by the clustering of central obesity, insulin resistance, dyslipidemia, and hypertension, is increasingly recognised as a systemic disorder with profound implications beyond cardiovascular health. The review aimed to highlight convergent evidence linking insulin resistance and dyslipidemia to cognitive decline, neurodegenerative disease, and cerebrovascular pathology, while also identifying areas of uncertainty and future research directions. Emerging evidence highlights the brain as a vulnerable target organ, where metabolic derangements can precipitate structural and functional abnormalities with significant neurological consequences. Insulin resistance, a hallmark of metabolic syndrome, impairs cerebral glucose utilisation, disrupts synaptic plasticity, and promotes neuroinflammation, thereby contributing to cognitive decline, mood disturbances, and heightened risk of neurodegenerative diseases such as Alzheimer’s disease. Concurrently, dyslipidemia alters blood–brain barrier integrity, promotes oxidative stress, and facilitates the deposition of atherogenic lipids in cerebral vessels, thereby exacerbating small vessel disease and increasing the risk of stroke. Neuroimaging studies have demonstrated that individuals with metabolic syndrome exhibit reduced hippocampal volume, altered white matter microstructure, and decreased functional connectivity in networks associated with memory and executive function. In summary, the interplay between metabolic syndrome and brain health represents a critical frontier in clinical neuroscience, with implications for understanding the pathophysiology of cognitive impairment, mood disorders, and neurodegeneration. Recognising and addressing the neurological sequelae of insulin resistance and dyslipidemia may inform more comprehensive patient care, while advancing translational strategies to preserve cognitive and neurovascular integrity in populations at risk. In conclusion, the evidence reviewed here demonstrates that metabolic syndrome, through the dual pathways of insulin resistance and dyslipidemia, exerts profound and multifaceted effects on the brain.