Summary: Older men who have higher blood pressure at night than during the day may face an increased risk of developing Alzheimer’s disease.
Source: Uppsala University
Nocturnal high blood pressure — when nighttime blood pressure exceeds daytime levels — could be a risk factor for Alzheimer’s disease in older men.
This conclusion comes from a longitudinal study conducted by researchers at Uppsala University and published in the journal Hypertension. The research examined whether abnormal 24-hour blood pressure patterns in elderly men are linked to a greater likelihood of being diagnosed with dementia, and in particular Alzheimer’s disease.
Dementia is a collective term for conditions characterized by progressive declines in memory, thinking and social abilities. Many factors influence dementia risk, with high blood pressure (hypertension) being one of the better-established cardiovascular contributors. Under typical healthy conditions, blood pressure varies across the day and night, reaching its lowest point during sleep — a pattern clinicians refer to as “dipping.” In some individuals, however, this nightly dip is blunted or absent, and a minority display a reversed pattern in which nocturnal blood pressure is higher than daytime values; this pattern is called “reverse dipping.”
“Nighttime is a critical period for brain maintenance,” says Christian Benedict, Associate Professor at Uppsala University’s Department of Neuroscience and senior author of the study. He notes that animal research has shown the brain clears metabolic waste during sleep and that this clearance can be disrupted by abnormal blood pressure patterns. Given the importance of nocturnal physiology for human brain health, the team investigated whether elevated nighttime blood pressure is linked to dementia risk in older men.
The research used observational data from a Swedish cohort of nearly one thousand older men monitored for up to 24 years. Participants were in their early seventies at baseline and underwent 24-hour ambulatory blood pressure monitoring to determine their night-to-day systolic blood pressure ratio. The investigators classified men as normal dippers, reduced dippers, or reverse dippers, and tracked dementia diagnoses by reviewing medical records; diagnoses were independently confirmed by at least two experienced geriatricians.
Key findings include a significantly elevated dementia risk among men with reverse systolic blood pressure dipping. Men exhibiting this reversed night-to-day pattern had a 1.64-fold higher risk of receiving any dementia diagnosis compared with those who showed normal nocturnal dipping. The association appeared strongest for Alzheimer’s disease specifically, with a similar increase in risk observed for Alzheimer’s but not for vascular dementia. In contrast, simply having a reduced dip (but not reverse dipping) was not associated with a statistically significant rise in dementia risk in this sample.
“The risk of getting a dementia diagnosis was 1.64 times higher among men with reverse dipping compared to those with normal dipping,” explains Xiao Tan, postdoctoral fellow and first author of the study. The authors emphasize that their sample consisted solely of older men, and therefore the results should be replicated in cohorts that include women and more diverse populations before broader conclusions are drawn.
Beyond confirming an association between nighttime hypertension patterns and dementia risk, the study raises clinically relevant questions. An important next step, according to the researchers, is to test whether targeted treatments that reduce nighttime blood pressure — for example, taking antihypertensive medication at night — can lower the risk of dementia or slow its progression. Because the study is observational, it cannot prove causation; randomized clinical trials would be needed to establish whether altering nocturnal blood pressure patterns directly influences dementia outcomes.
About this research
Source: Uppsala University
Contact: Xiao Tan – Uppsala University
Image: The image is in the public domain
Original research: Closed access. “Reverse Dipping of Systolic Blood Pressure Is Associated With Increased Dementia Risk in Older Men: A Longitudinal Study Over 24 Years” by Christian Benedict et al., Hypertension.
Abstract (summary)
A lower day-to-night systolic blood pressure dip has previously been associated with poorer brain health and cognitive performance. This longitudinal study assessed whether reduced (nighttime/daytime systolic BP ratio >0.9 and ≤1) or reverse (nighttime/daytime systolic BP ratio >1) dipping is linked to later dementia diagnoses in Swedish older men. Twenty-four-hour ambulatory blood pressure monitoring was used at mean ages 71 and 77.6 years in cohorts of 997 and 611 men, respectively, with a proportion taking antihypertensive medication. Over up to 24 years of follow-up, 286 participants were diagnosed with dementia. Time-updated Cox regression analyses indicated that reverse systolic BP dipping was associated with a higher risk of any dementia (adjusted hazard ratio 1.64) and Alzheimer’s disease (adjusted hazard ratio 1.67), while reduced (but not reversed) dipping was not associated with increased dementia risk. These findings suggest reverse systolic BP dipping may be an independent risk factor for dementia and Alzheimer’s disease in older men and warrant further study to determine whether lowering nocturnal systolic BP through timed antihypertensive therapy can reduce dementia development.