Reverse BP Dipping Tied To Dementia, Alzheimer's Disease In Older Men

Older men with higher systolic blood pressure at night than during the day have an increased risk of developing any dementia as well as Alzheimer's disease in particular, a Swedish study suggests.

Researchers examined data on about 1,000 older men in Sweden who were followed for up to 24 years starting when they were in their early 70s. Participants didn't have dementia, stroke, or cognitive impairment at baseline and they all underwent 24-hour ambulatory blood pressure monitoring at the start of the study.

During follow up, a total of 286 men were identified with dementia based on a review of medical records and confirmation by at least two geriatricians.

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Reverse systolic dipping was associated with a significantly higher risk of any form of dementia (adjusted hazard ratio 1.64) and Alzheimer's disease in particular (aHR 1.67). While reverse dipping also appeared to be linked to vascular dementia (aHR 1.29), this difference wasn't statistically significant.

"Reverse BP dipping might be a hallmark of undetected sleep disorders, such as sleep apnea," said lead study author Xiao Tan of Uppsala University and the Karolinska Institute in Solna, Sweden.

Individuals with untreated sleep apnea suffer from hypoxia and repeated wakefulness during their sleep, both conditions known to be associated with the development of dementia, Tan said by email.

"For example, wakefulness disrupts the normal functioning of the glymphatic system - a network transporting metabolic waste out of the brain," Tan said. "The accumulation of metabolic waste such as amyloid beta in the brain is an issue for the onset of Alzheimer's disease."

Both reduced and reversed dipping of nocturnal blood pressure are more common among certain patient populations that are already at increased risk for incident dementia including smokers as well as those with hypertension and diabetes. This makes it possible that reverse dipping might lack a causal tie to dementia, although the adjusted analysis accounted for independent dementia risk factors, the authors note in Hypertension.

Limitations of the study include the lack of data on the type of antihypertensive medications used by some participants as well as a lack of individual level data on sleep and wake cycles.

"I think doctors should pay more attention to sleep disturbances which are also associated with dipping and surges of nocturnal blood pressure and well as dementia risk," said Dr. Costantino Iadecola, director of the Feil Family Brain and Mind Research Institute at Weill Cornell Medicine in New York City.

"Reports from partners about heavy snoring, choking, abnormal movements, acting out dreams etc. may trigger a sleep study which may unveil potentially treatable sleep disorders and help preserve brain health," Dr. Iadecola, who wasn't involved in the study, said by email.

—Lisa Rapaport

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