Pulse pressure and risk of Alzheimer disease in persons aged 75 years and older: a community-based, longitudinal study.

BACKGROUND AND
PURPOSE: Elevated blood pressure has been found to increase the risk of dementia, including Alzheimer disease. We sought to investigate whether pulse pressure was predictive of Alzheimer disease and dementia.
METHODS: A community-based, dementia-free cohort (n=1270) aged > or =75 years was clinically examined twice over 6 years to detect incident dementia with the use of the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition. Cox proportional hazards models were used to analyze pulse pressure in association with incident Alzheimer disease and dementia after adjustment for several potential confounders, including systolic pressure and diastolic pressure.
RESULTS: During the 5464.6 person-years (median, 4.7 years) of follow-up, 339 subjects developed dementia, including 256 Alzheimer disease cases. Pulse pressure as a continuous variable was not statistically related to the risk of Alzheimer disease and dementia. In the categorical analysis, however, in comparison with median tertile of pulse pressure (70 to 84 mm Hg), subjects with higher pulse pressure had adjusted relative risks (95% CI) of 1.4 (1.0 to 2.0; P=0.04) for Alzheimer disease and 1.3 (0.9 to 1.7) for dementia. The corresponding figures related to lower pulse pressure were 1.7 (1.2 to 2.3) for Alzheimer disease and 1.4 (1.0 to 1.9; P=0.03) for dementia. This association was particularly pronounced among women.
CONCLUSIONS: Higher pulse pressure is associated with increased risk for Alzheimer disease and dementia in old adults, which is probably due to artery stiffness and severe atherosclerosis. Poor cerebral perfusion related to decreased pulse pressure may explain the association between lower pulse pressure and increased dementia risk.