Poor mid-life heart health linked to dementia in later years
A compelling new study, led by a team of Spanish researchers, is suggesting cardiovascular disease in mid-life is linked to neurodegeneration and cognitive decline in senior years. The research found subjects in their 50s with mild hypertension displayed evidence of impaired brain metabolism in areas associated with Alzheimer’s and dementia.
Atherosclerosis is a common cause of cardiovascular disease, involving the slow build-up of cholesterol and fats on artery walls. Atherosclerosis can remain asymptomatic for significant periods of time, progressively narrowing one’s arteries over the course of years before any clinical signs appear.
In this regard, atherosclerosis is similar to Alzheimer’s and other neurodegenerative conditions, where it can be years before dementia-like symptoms appear.
For some time researchers have detected a consistent association between heart disease and cognitive decline in senior citizens but this new research is the first to investigate the earliest stages of both conditions. Juan Domingo Gispert, joint first author on the new study, says his goal is to better understand how these two seemingly disparate conditions may be linked.
“…there is abundant evidence linking cardiovascular risk factors and Alzheimer's disease,” says Gisbert. “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 new study, published in the Journal of the American College of Cardiology, looked at PET scans from 547 subjects. The average age of subjects in the cohort was 50, and all subjects were 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 particular brain areas showing lower levels of metabolism are the same ones known to be affected by neurodegenerative diseases such as Alzheimer’s. Valentin Fuster, a lead author on the study, hypothesizes a possible causal link 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," suggests Fuster.
It is important to note, this new study offers no longitudinal data. All this research can suggest is a link between subclinical atherosclerosis and impaired metabolism in certain brain areas.
So it is impossible at this stage to know whether this association plays a role in any subsequent onset of Alzheimer’s disease. Cortés Canteli suggests this particular question is one they hope to answer, albeit in quite a few years time.
"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.
In the short-term, the researchers suggest because these cardiovascular disease risk factors are modifiable, the new findings affirm the broad value of strong heart health strategies in middle age.
“…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 concludes.
The new study was published in the Journal of the American College of Cardiology.