A new study published in the Journal of the American College of Cardiology suggests that cardiovascular disease in mid-life is linked to Alzheimer’s Disease decline in senior years.
New Atlas’ recent article entitled “Poor mid-life heart health linked to dementia in later years” reports that the research found subjects in their 50s with mild hypertension displayed evidence of impaired brain metabolism in areas associated with Alzheimer’s and dementia. The research was led by a team of Spanish researchers.
The article explains that atherosclerosis is a common cause of cardiovascular disease, involving the slow build-up of cholesterol and fats on artery walls. It can remain asymptomatic for a long time, progressively narrowing a person’s arteries over the course of years, before any clinical signs show up. Atherosclerosis is, therefore, similar to Alzheimer’s disease and other neurodegenerative conditions, where it takes many years before dementia-like symptoms appear.
Scientists have seen a consistent association between heart disease and cognitive decline in senior citizens for several years. However, the new study is the first to consider the earliest stages of both conditions. Juan Domingo Gispert, joint first author on the study, said his goal is to better understand how these two seemingly disparate conditions may be connected.
“…there is abundant evidence linking cardiovascular risk factors and Alzheimer's disease,” says Gispert. “If we can gain a more precise understanding of this relationship at asymptomatic disease stages, we will be in a position of design new strategies to prevent Alzheimer's, matching the success of current strategies to prevent cardiovascular disease."
The study reviewed PET scans from 547 subjects. The average age of subjects in the cohort was 50, and everyone in the group was diagnosed with subclinical signs of atherosclerosis.
"We found that a higher cardiovascular risk in apparently healthy middle-aged individuals was associated with lower brain metabolism in parietotemporal regions involved in spatial and semantic memory and various types of learning," explains Marta Cortés Canteli, joint first author on the study.
These specific brain areas that exhibit lower levels of metabolism are the same ones known to be impacted by neurodegenerative diseases, such as Alzheimer’s. A lead author on the study, Valentin Fuster, believes that a possible causal link exists between this early stage of heart disease and dementia in later life.
"We think that cardiovascular risk factors the affect the large vessels carrying blood from the heart to the brain also affect the small vessels in the brain," says Fuster.
Critics note that the new study doesn’t provide any longitudinal data—it merely suggests is a link between subclinical atherosclerosis and impaired metabolism in certain brain areas. As a result, it’s impossible at this point to determine if this association plays a part in any subsequent onset of Alzheimer’s disease. Cortés Canteli suggests this particular question is one they hope to answer, but it will take years of work.
"The next step will be to determine whether individuals with subclinical atherosclerosis in the carotid arteries and low brain metabolism at the age of 50 go on to experience cognitive decline 10 years later," says Cortés Canteli.
“…although everybody knows about the importance of caring for ourselves and controlling cardiovascular risk factors in order to avoid a heart attack, the association of these same risk factors with cognitive decline may increase awareness of the need to acquire healthy habits from the earliest stages of life,” Fuster noted.
Reference: New Atlas (Feb. 15, 2021) “Poor mid-life heart health linked to dementia in later years”
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