September 6, 2022 | Recently published findings and emerging studies are taking a closer look at the relationship between cognitive and vascular health, adding to our collective understanding of dementia and Alzheimer’s disease in the process.
Boston University researchers have revealed that early adulthood lipid and glucose levels are related to Alzheimer’s disease in later life, for example, and an international group of Australian and American researchers has shown that plaque build-up in the abdominal aorta may be a marker for late-life dementia.
Similar to the way we know that high cholesterol can elevate the risk of heart disease or high blood pressure can raise the risk of stroke, research led by UC Davis Health and the University of Texas Health Science Center at Houston is pursuing the development of a risk predictor for dementia and Alzheimer’s disease.
Findings Highlight Importance of Managing Cardiovascular Health Early On
Although the association between vascular and metabolic risk factors with cognitive decline and Alzheimer’s disease has been widely reported over the years, a group of Boston University researchers indicated that it has not been clear whether these factors measured earlier in life are a useful predictor of this disease down the road.
Previous research has found associations between cardiovascular risk factors and the subsequent development of Alzheimer’s disease, explained Lindsay Farrer, a medical geneticist at Boston University. But prior studies generally followed people who were in their 50s or beyond when they enrolled, so findings were based on observations of individuals who were already older.
“We had an opportunity, given the unique Framingham Heart Study population and the data that have been collected from the participants over generations, to pose the question of whether measures of cardiovascular health and metabolic health at a much earlier point in life are predictive of future Alzheimer’s,” Farrer told Diagnostics World.
A paper published in Alzheimer’s & Dementia (DOI: 10.1002/alz.12641) by Farrer and colleagues revealed elevated glucose levels and low HDL cholesterol levels measured in early to middle adulthood to be significant predictors of Alzheimer’s disease later in life. (When these same measurements were taken after age 50, the associations were not as significant, Farrer noted.)
The association they found between lipid and glucose levels and the development of Alzheimer’s disease supports the notion of intervening earlier in life to help lower risk. The main takeaway message, he said, is that it is a good idea to have regular check-ups of cardiovascular health starting at an age when many aren’t necessarily having that done on a regular basis.
Looking ahead, Farrer said there are all sorts of studies that could be carried out using the data already on hand to examine the relationships they’re finding with greater precision or to pose slightly different questions. “We continue to mine the resource to make new discoveries” about factors—cardiovascular or otherwise—that are involved in the development of Alzheimer’s disease, he said.
Lateral Spine Scan Warns of Vascular Calcification, Dementia Risk
Plaques can accumulate in the abdominal aorta—the largest artery in the body that supplies oxygenated blood to abdominal organs and lower limbs. This build-up, called abdominal aortic calcification (AAC), can be a helpful way of predicting the risk of cardiovascular disease. But new findings from an international group of researchers reveals that it could also be a marker for late-life dementia.
A long-term study published in The Lancet Regional Health - Western Pacific (DOI: 10.1016/j.lanwpc.2022.100502) showed that a common scan can reveal calcified plaque build-up in the abdominal aorta. This technology could help warn individuals of a heightened risk of developing late-life dementia, which may aid efforts to intervene proactively.
The researchers noted that although there is an association between vascular disease and dementia risk, there is a lack of data on whether vascular calcification could be a marker of later-life dementia risk. Prior studies have found a link between AAC and a decline in cognitive function, but research has not yet determined whether there is a link between AAC and dementia risk.
To address this gap, the researchers looked at AAC results in nearly 1,000 women and followed their health for more than 15 years. They found that women with medium to high levels of AAC were twice as likely to be hospitalized or die from late-life dementia compared to women with low AAC.
Considering the widespread use of bone density testing, the researchers noted that gathering AAC information via lateral spine imaging at the same time bone density testing is conducted has the potential to become a simple, cost-effective, non-invasive, and scalable screening method for finding women at risk of developing late-life dementia.
“Early identification may provide a window of opportunity to enable dietary, lifestyle and cardiovascular risk management modifications to prevent disease progression,” they noted.
The group includes researchers affiliated with Edith Cowan University’s Nutrition and Health Innovation Institute and Centre for Precision Health, the University of Western Australia, the University of Minnesota, Sir Charles Gairdner Hospital and the Marcus Institute for Aging Research, Hebrew SeniorLife, and Harvard Medical School.
“There’s an adage in dementia research that what’s good for your heart is good for your brain,” Professor Simon Laws, director of Edith Cowan University’s Centre for Precision Health, said in a news release. “This study reaffirms this link and further adds to our understanding of late-onset dementia risk and potential preventative strategies.”
When individuals undergo a bone density test, those same machines can be used for a lateral spine scan, which can help detect AAC. According to Joshua Lewis, an associate professor at Edith Cowan University and Future Leader Fellow with the National Heart Foundation, these scans tend to be less expensive and invasive than CT scans or X-rays and involve less radiation exposure as well.
Ultimately, the researchers view these scans as a tool that could be useful for screening a large number of older adults. It could also help weave the topic of dementia risk into cardiovascular health discussions.
Marc Sim, a senior research fellow at Edith Cowan University’s Nutrition & Health Innovation Research Institute, indicated there are plans to build upon this study. “We have a National Health and Medical Research Council Ideas Grant automating the process of assessment,” he told Diagnostics World. So when a bone density machine takes these images, people can be informed of the results.
In addition, they are now exploring whether telling older individuals and their general practitioners that they have moderate to extensive AAC and are at an increased risk of developing late-life dementia could help “prompt healthy diet and lifestyle change and improve long-term monitoring of cognitive function,” he added.
Study Aims to Understand White Matter Hyperintensities, Create Risk Predictor
A new study called Diverse Vascular Contributions to Cognitive Impairment and Dementia (Diverse VCID) aims to better understand how brain changes, genetics, and other factors contribute to dementia and Alzheimer’s disease. Led by UC Davis Health and the University of Texas Health Science Center at Houston, the researchers hope to create a “scorecard” that can help predict who is at risk.
According to a news release, the study is being conducted at 13 locations across 10 states and is expected to last for six years. The research is supported by a $53.6 million award from the National Institutes of Health National Institute on Aging.
“We’re going to take all the information we get from this study and come up with a predictor,” Principal Investigator Charles DeCarli, professor of neurology and director of the UC Davis Alzheimer’s Disease Research Center, told Diagnostics World. The goal is to give everyone around five or six questions, or markers.
Together, these will provide a scale that can predict risk, he explained. The underlying thought is that it could eventually help with efforts to mitigate, delay, or prevent disease. “We’re here to understand this disease and eventually come up with this risk profile, and then the ultimate goal is to identify people who are at higher risk to treat them and prevent this,” DeCarli added.
In addition to factoring in genetics and other markers that can indicate whether an individual’s risk is lower or higher, this research will look to factor in what is learned about brain changes called white matter hyperintensities (WMHs).
According to DeCarli, these are essentially abnormalities observed on MRI that indicate some loosening of white matter and an increase in fluid. WMHs have many different causes, but in the older population at risk for cognitive impairment, the most common are vascular disease and Alzheimer’s disease.
Almost everyone over the age of 65 has at least some small bits of these lesions in their brain. For the time being, however, it isn’t well-understood how WMHs wind up contributing to mental decline. “When someone walks through the door, we’re not certain what to say to them if they have them on their brain,” DeCarli explained.
He and colleagues hope to determine how much is enough to be considered problematic. They also want to determine whether the location of these lesions makes a difference. From there, the aim is to be able to predict growth over time and predict how that growth will impact a person’s thinking.
It is known that dementia and Alzheimer’s disease disproportionately impact women and people of color. As such, the study intends to look at diverse populations, with plans to enroll over 2,000 participants between the ages of 65 and 90.
In the United States, it is known that people who are considered Black/African American by their self-described heritage or ancestry are more likely to have hypertension, DeCarli explained, and those with hypertension are more likely to have these white matter spots.
Similarly, people who self-identify as Latino or Hispanic are more likely to have diabetes, and diabetes is associated with an increased likelihood of having these spots. “So by getting groups that represent people at higher risk, we can then assess whether it’s the risk, or the group, or both,” he said.
DeCarli’s hunch is that the real difference-maker will not be a person’s racial or ethnic background but rather health issues like hypertension, diabetes, or high cholesterol. “Whether you’re black, white, green, or blue, it’s those features that we really need to focus on—not the color of your skin,” he added.
Paul Nicolaus is a freelance writer specializing in science, nature, and health. Learn more at www.nicolauswriting.com.