A high resting heart rate puts you at greater risk of coronary heart disease, abnormal heart rhythm, heart failure and stroke. These same conditions are also linked to dementia.
So, does it follow that a rapid pulse leads to a greater dementia risk, too? And if it does, is it caused by these heart conditions or by something else, a factor that may have nothing to do with the cardiovascular system?
This question has never been explored in older adults. Until now.
An elevated resting heart rate (RHR) predicts future heart problems. There’s an abundance of evidence to support this. What’s more, evidence has also accumulated showing how cardiovascular diseases are linked to the development of dementia through shared damage to blood vessels.
Up until now, only a few studies have looked at the relationship between RHR and dementia, and these were conducted in middle-aged adults. The most important study was carried out by scientists at Johns Hopkins School of Medicine and published in The American Journal of Cardiology in 2019.
An Elevated Pulse is Hazardous to Your Memory
The study included 13,172 participants with no history of stroke or abnormal heart rhythm (atrial fibrillation). After 18 years of follow up, those with an RHR of 80 beats per minute (bpm) or greater had a 28 percent increased risk of dementia compared to those with an RHR of less than 60 bpm.
In addition, those with an RHR of 70 bpm or greater showed a steeper decline in cognition even after accounting for cardiovascular risk factors. This suggests RHR could be an independent risk factor for cognitive decline.
Other studies found that a high RHR was linked to an increase in small blood vessel damage in the brain, and lower scores on cognitive tests. However, because no study has been conducted in older adults, scientists from the Karolinska Institute in Sweden carried out a trial of their own.
Boosts Risk by Over Half
They enrolled 2,147 men and women aged 60 to 99 who were free from dementia when the study began, although many of these participants had preexisting heart problems. Every participant was evaluated regularly for an average of 12 years or until death.
The results showed that compared to participants with an RHR of 60 to 69 bpm, those with an RHR of 80 beats per minute or higher had a 55 percent higher risk of dementia. That’s a dramatic increase!
Even after the scientists adjusted their findings to account for those with vascular risk factors and heart disease or for those who developed heart problems during the study period, the association remained significant. It also remained significant after excluding participants with existing heart problems or those who developed them.
Notably, the research team also found that individuals with an RHR of 70 bpm or more experienced a faster decline in general cognitive function compared to those with an RHR in the 60s.
An Independent Risk Factor?
These results are in line with the Johns Hopkins study in middle aged folks and suggest that a high RHR is an independent risk factor for dementia.
This type of study, however, can only show that the two are linked, it cannot prove that one causes the other. The scientists suggest that an imbalanced nervous system is one plausible explanation for the connection, but whether it is a true causal relationship will require additional research.
The study’s lead author, Yume Imahori, explained the importance of the research, saying, “If we follow such patients’ cognitive function carefully and intervene early, the onset of dementia might be delayed, which can have a substantial impact on their quality of life.”
She and her colleagues suggest in their paper, published in the journal Alzheimer’s & Dementia in December, that interventions to lower a high resting pulse could include medications and exercise.
They wrote, “regular exercise, especially yoga and endurance training could reduce RHR.”