Higher nighttime blood pressure may increase risk for Alzheimer's, study finds

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Changes in blood pressure throughout the day are normal, but there are health concerns when readings are higher at night

Blood pressure readings are always changing. Recent studies have found that different parts of the body -- like our arms -- can come back with very different numbers. While these changes are often normal and expected, a new study is exploring how certain blood pressure fluctuations could be a sign of more serious health concerns. 

According to researchers from Uppsala University, consumers with higher blood pressure at night could be at an increased risk of Alzheimer’s disease

“The night is a critical period for brain health,” said researcher Christian Benedict. “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.” 

Normal versus abnormal blood pressure changes

To better understand how changes in blood pressure could affect Alzheimer's risk, the researchers had 1,000 men in their early seventies participate in the study. For more than two decades, the researchers observed the men’s health records and paid particular attention to fluctuations in blood pressure readings and cognitive health outcomes.

The researchers learned that the risk of Alzheimer’s was higher for participants who experienced higher blood pressure at night. While it’s normal for blood pressure to ebb and flow throughout the day, nighttime hours are typically when blood pressure is the lowest. In a healthy body, blood pressure can be as much as 20 percent lower at night than it is during the day. 

However, the opposite trend was observed in this study. Many of the men experienced spikes in their blood pressure at night, which experts refer to as “reverse dipping.” This trend was then linked with an increased risk of Alzheimer’s disease. 

“The risk of getting a dementia diagnosis was 1.64 times higher among men with reverse dipping compared to those with normal dipping,” said researcher Xiao Tan. “Reverse dipping mainly increased the risk of Alzheimer’s disease, the most common form of dementia.” 

The researchers plan to do more work based on these findings, including examining whether taking blood pressure medication at night can alleviate some concerns about cognitive decline. They also want to see whether older women are at a similar risk of Alzheimer’s based on changes in blood pressure.

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