A low blood pressure is associated with an increased risk of dementia in people over 75 years of age, according to a new report. This risk seems to pertain only to Alzheimer’s type dementia and is highest in subjects with persistently low pressures.
The findings, which are reported in the medical journal Neurology, are based on a study of 406 community-dwelling elderly subjects who were dementia-free at study entry and were followed for up to 21 years. Systolic and diastolic blood pressures, the first and second numbers, respectively, in a blood pressure measurement, were determined in all subjects.
During the study, 122 subjects developed dementia, lead author Dr. J. Verghese and colleagues, from Albert Einstein College of Medicine in New York, note.
The authors found that a diastolic blood pressure below 70 raised the risk of dementia. Specifically, for each 10-point drop in pressure, the risk of dementia increased by 20 percent. Low pressures were only linked to an increased risk of Alzheimer’s type dementia, not the type that occurs as a result of blocked blood vessels in the brain.
Compared with other subjects, people with consistently low blood pressures throughout the first two years of the study were twice as likely to develop dementia.
“Our results suggest that low blood pressure may be both the cause and the consequence of dementia,” the researchers state. “If our results are replicated, intervention studies are required to study whether maintaining blood pressure at optimal levels reduces the risk of dementia in elderly individuals.”