Blood pressure and risk of dementia: Results from the Rotterdam study and the Gothenburg H-70 study

The association between blood pressure and dementia is debated. Results fro m population-based studies on blood pressure and dementia are inconclusive, and most are performed in subjects younger than 80 years of age. We examin ed the relation between blood pressure and dementia and the possible effect modification of this relation by age in a pooled dataset based on two pros pective population-based studies. Subjects came from the Rotterdam study (n = 6,668), a longitudinal population-based study among subjects aged 55 yea rs and over, and from the Gothenburg H-70 Study (n = 317), a study on subje cts aged 85 years at baseline. Screening and diagnostic procedures for asse ssment of dementia were similar at baseline and follow-up and comparable be tween studies. We estimated relative risks of dementia using Cox proportion al hazards regression analysis, adjusted for age, gender and study location . The average follow-up was 2.1 years. During this period, 196 subjects dev eloped dementia. The risk of dementia decreased with increasing blood press ure level (per 10 mm tig systolic blood pressure: RR = 0.93, 95% CI = 0.88- 0.99; per 10 mm Hg diastolic blood pressure: RR = 0.89, 95% CI = 0.79-1.00) . This association was confined to subjects who used anthypertensive medica tion. Persons who were demented at baseline had a stronger blood pressure d ecline during follow-up than those who were nondemented. This study suggest s an inverse association between blood pressure and dementia risk in elderl y persons on antihypertensive medication. Possibly, they may need higher bl ood pressure levels to maintain an adequate cerebral perfusion. Alternative ly, lower blood pressure may be secondary to brain lesions in preclinical s tages of dementia. Copyright,2001 S. Karger AG, Basel.