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Metabolic Syndrome and Stroke Risk

Metabolic syndrome is gaining recognition as an important independent risk factor for vascular disease and stroke.

The authors of these two studies attempted to characterize the complex relations among metabolic syndrome, type 2 diabetes mellitus, silent brain infarction, and clinical stroke. Metabolic syndrome is defined by the presence of three or more of the following criteria: fasting blood glucose 110 mg/dL; systolic blood pressure (BP) 130 mm Hg or diastolic BP 85 mm Hg; triglyceride level 150 mg/dL; HDL cholesterol level 40 mg/dL in men or 50 mg/dL in women; and abdominal obesity (normally, waist circumference 102 cm in men or 88 cm in women).

Najarian and colleagues examined the risk for stroke in 2097 participants from the Framingham Offspring Study, of whom 22% had metabolic syndrome alone, 5% had type 2 diabetes alone, and 5% had both; all were stroke-free at baseline. Follow-up lasted up to 14 years. After adjustments for typical risk factors, the relative risk for stroke during follow-up was 3.28 for individuals with both metabolic syndrome and diabetes, and 2.10 and 2.47, respectively, for those with metabolic syndrome alone and diabetes alone. The authors conclude that metabolic syndrome and type 2 diabetes are independent risk factors for stroke. Furthermore, they concluded that metabolic syndrome is more prevalent than type 2 diabetes and, therefore, has a greater population-attributable risk.

Silent brain infarctions (i.e., strokes with no associated clinical signs or symptoms) are associated with future clinical strokes and reduced cognitive function. Kwon and colleagues examined whether metabolic syndrome is a risk factor for silent infarctions. (They defined abdominal obesity as waist circumference 90 cm in men and 80 cm in women.) "Healthy" individuals presenting to a facility in Korea over a 14-month period for a routine check-up underwent a brain MRI. After adjustments for age, sex, history of coronary artery disease, and C-reactive protein level, individuals with metabolic syndrome were more than twice as likely as those without it to show evidence of silent brain infarctions on MRI (27% vs. 13%). Age and history of coronary artery disease also strongly predicted silent brain infarctions.

Comment: The association of metabolic syndrome — a prediabetic state with treatable components — with stroke is an extremely important health issue. More than 22% of American men and 24% of American women over age 20 are estimated to have metabolic syndrome. Recognition and treatment of this syndrome may lead to decreased stroke risk, improved cognitive function, and better quality of life as the population continues to age.

— Richard T. Benson, MD, PhD

Dr. Benson is Program Director for the Office of Minority Health and Research at the National Institute of Neurological Disorders and Stroke, Bethesda, MD.

Published in Journal Watch Neurology May 4, 2006

Citation(s):

Najarian RM et al. Metabolic syndrome compared with type 2 diabetes mellitus as a risk factor for stroke: The Framingham Offspring Study. Arch Intern Med 2006 Jan 9; 166:106-11.

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Kwon H-M et al. Metabolic syndrome as an independent risk factor of silent brain infarction in healthy people. Stroke 2006 Feb; 37:466-70.

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• Medline abstract (Free)