Possible link between faster heart rates, increasing age, and dementia
Globally, the number of people living with dementia is expected to increase from 55 million in 2020 to 139 million by 2050, according to Alzheimer’s Disease International.
Having an elevated resting heart rate (RHR) in individuals 60 years or older may be a risk factor for dementia. RHR can be lowered through exercise and medical treatment and is easy to measure. Researchers, therefore, believe it may be possible to identify people at higher risk for dementia and begin early intervention.
Currently, there is no cure for dementia. Still, growing evidence suggests that maintaining cardiovascular health and a lifestyle of proper diet and exercise may help to delay the onset of dementia and ease its symptoms.
The study
A recent study conducted at Karolinska Institutet in Sweden suggests that individuals 60 years or older with an elevated RHR of 80 beats per minute or higher could have a cognitive decline independent of the risk factors associated with cardiovascular disease.
The research study, published in the journal Alzheimer’s & Dementia, followed 2,147 participants living in Stockholm for up to 12 years. Their mean age was 70.6, and 62% were women.
Resting heart rates were measured using a standard 12-lead EKG, and global cognitive function was assessed using a mini-mental status examination or MMSE. Other factors considered were age, sex, education, physical activity, and smoking status. The researchers also measured participants’ BMI and cholesterol levels.
The examining physicians diagnosed dementia based on criteria from the Diagnostic and Statistical Manual of Mental Disorders, or DSM-IV.
The study findings
Individuals whose RHR was 80 beats per minute (BPM) or higher had, on average, a 55% higher risk for dementia than those with an RHR of 60-69 BPM.
The study examined the effects of other cardiovascular diseases and conditions on dementia and found the association between elevated RHR and cognitive decline to remain significant.
Although this study could not establish a causal relationship, it did offer a plausible explanation for the link between elevated RHR and cognitive decline.
The leading author of the study, Dr. Yume Imahori, states, “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.”
Dr. Ian Neel, Associate Clinical Professor of Medicine at UCSD, spoke with MNT, stating, “There is a strong link between heart health and brain health. The Alzheimer’s Association has acknowledged this concept through their recommendation for physical activity with cardiovascular exercise in an effort to reduce the risk of cognitive decline. This study helps add strength to this recommendation, using heart rate as a marker for heart health.“
Dr. Neel went on to say, “It is important not to assume that a low heart rate will reduce risk of dementia, but rather take away from this study that good heart health is associated with a lower risk of cognitive difficulties.”
Other interesting possibilities
Other possible links to increased cognitive decline in individuals 60 years of age or more include underlying cardiovascular diseases such as atherosclerosis, imbalances in the sympathetic and parasympathetic nervous systems, tiny circulating blood clots, and lack of good circulation.
It is important to note that whether an elevated RHR is independently associated with cognitive decline, or is explained merely by underlying CVDs, has yet to be investigated.
These findings are also significant because an elevated RHR is associated with an increased risk of several CVDs such as IHD, atrial fibrillation (AF), heart failure (HF), and stroke (CVA), and these CVDs are known risk factors for dementia.
A limited number of studies show an association between a high RHR and dementia or cognitive decline in the general population of middle-aged adults and patients with ischemic heart disease (IHD). However, researchers have not studied this association in the general population of older adults.
Take Away
Medical News Today contacted Dr. Karen Harrison Dening, Dementia UK’s Head of Research and Publications, who corroborated the study’s findings, stating, "This study reiterates the link between cardiovascular health and brain health; what is good for the heart is good for the brain. Increasing supplies of oxygen to the brain through physical exercise and giving the brain enough nutrients by eating health foods, including fruits and vegetables, and reducing alcohol intake, are ways to mitigate the risk of dementia, particularly vascular dementia. It's important that these lifestyle factors are started as early as possible in order to receive the most benefits.”
