Association of metabolic syndrome with incident dementia: role of number and age at measurement of components in a 28-year follow-up of the Whitehall II cohort study

<p>  </p> <p><strong>Objective,</strong> Previous research suggests an inconsistent association between Metabolic syndrome (MetS) and incident dementia. We examined the role of number of MetS components and age at their assessment for incident dementia. </p> <p><strong>Research design and methods,</strong> MetS components (fasting glucose, triglycerides, waist circumference, blood pressure, and HDL cholesterol) on 7265, 6660, and 3608 participants at age <60, 60 to <70, and ≥70 years were used to examine associations with incident dementia using cause-specific Cox regression. </p> <p><strong>Results</strong>, Analyses of MetS measured <60, 60 to <70, and ≥70 years involved 393 (5.4%), 497 (7.5%), and 284 (7.9%) dementia cases over a median follow-up of 20.8, 10.4, and 4.2 years respectively. Every additional MetS component before 60 (HR 1.13, 95%CI 1.05-1.23) and 60 to <70 (HR 1.08, 95%CI 1.00-1.16) but not ≥70 years (HR 1.04, 95%CI 0.96-1.13) was associated with higher dementia risk. MetS defined conventionally (≥3 components) before 60 years (HR 1.23, 95%CI 0.96-1.57), between 60-70 years (HR 1.14, 95%CI 0.91, 1.42), or after 70 years (HR 1.10, 95%CI 0.86, 1.40) was not associated with incident dementia. Multi-state models showed higher risk of dementia in those with with ≥1 (HR 1.99, 95%CI 1.08-3.66) and ≥2 MetS components (HR 1.69, 95%CI 1.12, 2.56) before age 60, even when they remained free of cardiovascular disease over the follow-up. </p> <p><strong>Conclusions,</strong> Risk of incident dementia increases with every additional MetS component present in midlife rather than after accumulation of 3 components; only part of this risk is mediated by cardiovascular disease.</p> <p><br></p>