Metabolic Syndrome Increases Risk of Young-Onset Dementia, Reveals Large Korean Study

The study, involving a large cohort of patients, revealed that both MetS as a whole and its components—such as hypertension, high blood sugar, elevated cholesterol, and abdominal obesity—were linked to a heightened risk of developing dementia at an earlier age. These findings shed light on the potential long-term effects of MetS on cognitive health.

Metabolic syndrome, a cluster of conditions that increase the risk of heart disease, stroke, and type 2 diabetes, has long been a known contributor to various health complications. However, its relationship with cognitive decline, particularly in younger individuals, has not been thoroughly explored until now. Jeong-Yoon Lee, Department of Neurology, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, Seoul, Korea, and colleagues aimed to fill that gap by determining whether MetS and its individual components increase the risk of YOD, including all-cause dementia, Alzheimer's disease (AD), and vascular dementia (VaD).

For this purpose, the researchers conducted a nationwide cohort study using data from the Korean National Insurance Service. The study included individuals aged 40–60 who underwent health check-ups in 2009 and were followed until age 65 or December 31, 2020. Metabolic syndrome (MetS) was defined based on waist circumference, blood pressure, fasting glucose, triglycerides, and HDL cholesterol. The study also considered factors like age, sex, income, smoking, alcohol use, and comorbidities.

The primary outcome was all-cause young-onset dementia, with secondary outcomes of young-onset Alzheimer's and vascular dementia. Hazard ratios (HRs) with 95% confidence intervals were calculated using multivariable Cox regression.

The study revealed the following findings:

• A total of 1,979,509 participants were included in the study, with a mean age of 49.0 years; 51.3% were men, and 50.7% had metabolic syndrome (MetS).
• Over an average follow-up period of 7.75 years, 8,921 individuals (0.45%) developed young-onset dementia.
• MetS was associated with a 24% higher risk of all-cause YOD (adjusted HR 1.24).
• MetS was linked to a 12.4% increased risk of Alzheimer's disease (AD) (HR 1.12).
• MetS was associated with a 20.9% increased risk of vascular dementia (VaD) (HR 1.21).
• Significant interactions were observed with younger age (40–49 vs 50–59), female sex, drinking status, obesity, and depression.

In this large Korean cohort study, the authors found that metabolic syndrome and its individual components were significantly associated with an increased risk of young-onset dementia.

The findings suggest that targeting MetS through early interventions may help mitigate the risk of developing YOD. However, the authors caution that the study's observational design limits the ability to draw definitive causal conclusions, and the reliance on claims data may introduce potential misclassification bias. The authors recommend further research using longitudinal designs and comprehensive data collection to validate and expand upon these associations.

Reference:

Lee J-Y et al "Association between metabolic syndrome and young-onset dementia: a nationwide population-based study" Neurology 2025; DOI: 10.1212/WNL.0000000000213599.