A population-based study on blood pressure and brain atrophy in 85-year-olds.

In the general population, mean systolic and diastolic blood pressure increases up to age 75 years but decreases thereafter. The brain has a role in blood pressure regulation; it is not clear whether the cerebral changes that occur with aging contribute to the decline in blood pressure in the very elderly. We examined a population-based sample of 484 85-year-old persons (344 nondemented and 140 demented, 61 with Alzheimer's disease, 65 with vascular dementia, and 14 with other types of dementia) with a neuropsychiatric examination and blood pressure measurements. Dementia was diagnosed according to the criteria proposed in the Diagnostic and Statistical Manual of Mental Disorders, edition 3, revised. Brain atrophy was measured by CT of the brain. In the nondemented group, frontal (r=-0.18, P=0.037) and parietal (r=-0.23, P=0.008) cortical atrophy and bifrontal ratio (r=-0.20, P=0.013) were associated with lower systolic blood pressure, and frontal (r=-0.23, P=0.010) and parietal (r=-0.24, P=0.008) cortical atrophy and bifrontal ratio (r=-0.23, P=0.006) with lower diastolic blood pressure. Systolic blood pressure was lower in subjects with Alzheimer's disease and vascular dementia, and diastolic blood pressure was lower in those with vascular dementia compared with the nondemented. Systolic (r=-0.27, P<0.0001) and diastolic (r=-0.10, P=0.020) blood pressure was negatively correlated to dementia severity. In the demented subjects, frontal cortical atrophy was correlated to lower diastolic blood pressure (r=-0.21, P=0.043). Our findings suggest that age-related changes in brain structure may contribute to the decrease in blood pressure in the very elderly and that low blood pressure in dementia disorders is mainly a secondary phenomenon.