Background: Cardiovascular risk factors are associated with a higher risk of developing dementia. Studies in older populations, however, have often failed to show this relationship. We assessed the association between cardiovascular risk factors measured in midlife and risk of being hospitalized with dementia and determined whether this association was modified by age and ethnicity.
Methods: We studied 11,151 participants in the population-based Atherosclerosis Risk in Communities cohort, aged 46-70 (23% African Americans) in 1990-1992, when participants underwent a physical exam and cognitive testing. Hospitalizations with dementia were ascertained through December 2004.
Results: During follow-up, 203 cases of hospitalization with dementia were identified. Smoking (hazard ratio (HR), 95% confidence interval (CI): 1.7, 1.2-2.5), hypertension (HR, 95% CI: 1.6, 1.2-2.2) and diabetes (HR, 95% CI: 2.2, 1.6-3.0) were strongly associated with dementia, both in whites and African-Americans. These associations were stronger when risk factors were measured at younger age than at older age. In analyses including updated information on risk factors during follow-up, the HR of dementia in hypertensive versus non-hypertensive participants was 1.8 at age <55 years compared to 1.0 at age 70+ years. Parallel results were observed for diabetes (HR 3.4 in <55, 2.0 in ≥70), smoking (4.8 in <55, 0.5 in ≥70), and hypercholesterolemia (HR 1.7 in <55, 0.9 in ≥70)
Conclusion: In this prospective study, smoking, hypertension, and diabetes were strongly associated with subsequent risk of hospitalization with dementia, particularly in middle aged individuals. Our results emphasize the importance of early lifestyle modification and risk factor treatment to prevent dementia.