May 28, 2025, 6:32 pm | Read time: 4 minutes
Many people fear cognitive decline—which often leads to dementia—in old age. This makes it all the more important to take preventive measures and identify risk factors early. Researchers have now discovered a link between heart rate during sleep and cognitive decline.
Cognitive decline is discussed when mental performance decreases. This manifests as increasing forgetfulness, reduced attention, concentration problems, language disorders, orientation issues, and memory loss.1 These are also typical symptoms of dementia diseases such as Alzheimer’s. Older people, in particular, struggle with the decline in cognitive performance. Researchers have now discovered that the heart rate during sleep provides insight into whether one has a higher risk of dementia.
Overview
The study Examines Over 500 Participants with an Average Age of 82 Years
Cardiovascular diseases are linked to cognitive health, as previous studies have shown.2 It is all the more important to understand the mechanisms behind this, specifically which factors influence mental fitness in old age. Therefore, researchers in a recent study examined how pulse or heart rate is related to dementia in older adults.3
For this purpose, an international research team selected 503 participants with an average age of 82 years. Seventy-six percent of the study participants were female. They all came from the longitudinal study “Rush MAP” (Memory and Aging Project) on aging and dementia, which has been ongoing since 1997. However, it was not until 2018 that nighttime pulse measurement was included in the study protocol. This involves determining the heart rate during sleep. Additionally, participants had to perform a series of cognitive tests. All participants had at least one follow-up examination.
Overall, for the current study, participants were observed over a period of up to 4.5 years and completed annual neurocognitive tests.
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Connection Between Heart Rate During Sleep and Dementia
The data analysis showed that a higher complexity of heart rate is associated with a slower cognitive decline in older adults. But what does that mean exactly? By complexity, the researchers mean slight or minimal fluctuations in heart rate. These are so small that they can only be determined with a special measuring device (pulse oximeter). Conversely, it also means that lower complexity (i.e., hardly any fluctuations) in heart rate is associated with faster cognitive decline or dementia in older people.
According to the researchers, this type of pulse measurement would be a practical test to detect cognitive problems and signs of dementia in older people.
Why Is a Complex Heart Rate Good for Us?
But why does a complex rate with minimal fluctuations positively affect cognitive performance? The researchers also provide an explanation for this. Their hypothesis is that a more adaptable heart is a healthier heart. When the heart responds to body functions with a more complex series of changes, it works as more agile. It results in a fit cardiovascular system. You can think of it like an athlete who can quickly adapt speed and changes in direction.
Previous conventional measurements of heart rate have not captured this complexity. The new method, called permutation entropy, uses a pulse oximeter. It primarily measures arterial oxygen saturation but also serves to monitor heart rate. The study authors believe this measurement method is more sensitive to health changes in the body.
Further Studies Must Confirm the Results
Although the study authors emphasize this measurement method as a practical test to detect cognitive problems and signs of dementia in older people, they also state that further studies are needed to confirm these findings. The results underscore the usefulness of our approach as a non-invasive measure of how flexibly the heart responds to nervous system signals. This could help better understand the relationship between heart health and cognitive aging.
However, it must be noted that this study’s participants were predominantly women. No conclusion was reached on whether pulse measurement is equally reliable as an indicator of cognitive decline in both women and men.