Higher blood pressure at night than in daytime may be a risk factor for Alzheimer’s disease in older men, new research has revealed.
Under healthy conditions, blood pressure varies over 24 hours, with lowest values reached at night. Doctors call this nocturnal blood pressure fall ‘dipping’.
However, in some people, this pattern is reversed and their nocturnal blood pressure is higher than in daytime. This blood pressure profile is known as ‘reverse dipping’.
Research from Uppsala University now suggests this could be significant in older males.
“The risk of getting a dementia diagnosis was 1.64 times higher among men with reverse dipping compared to those with normal dipping,” says Xiao Tan, postdoctoral fellow at Uppsala University and first author of this research.
“Reverse dipping mainly increased the risk of Alzheimer’s disease, the most common form of dementia.”
In the study, researchers used observational data from 1,000 Swedish older men, who were followed for a maximum of 24 years.
The included men were in their early seventies at the beginning of the study.
“The night is a critical period for brain health,” says Christian Benedict, Associate Professor at Uppsala University’s Department of Neuroscience, and senior author of the study.
“For example, in animals, it has previously been shown that the brain clears out waste products during sleep, and that this clearance is compromised by abnormal blood pressure patterns.
“Since the night also represents a critical time window for human brain health, we examined whether too high blood pressure at night, as seen in reverse dipping, is associated with a higher dementia risk in older men.”
According to the researchers, an interesting next step would be to investigate whether the intake of antihypertensive, blood pressure lowering drugs at night can reduce older men’s risk of developing Alzheimer’s disease.
Professor Benedict adds: “Our cohort consisted only of older men. Thus, our results need to be replicated in older women.”
