As people get older, they likely face many health problems. Alzheimer’s disease (AD) is one of the common chronic age-related conditions that cause brain issues in older adults including memory loss and cognitive difficulties.
According to the Alzheimer’s Association, there are more than six million older adults living with Alzheimer’s, mostly at the age of 65 and above. People who have dementia might not get AD, but AD patients typically experience memory problems, one of the first signs of cognitive impairment related to Alzheimer’s. And AD is the most common type of dementia.
An Algorithm for Estimating the Risk of Disease
What is the cause of AD dementia? There are changes in the brain when people grow old, but not every person will have dementia.A study from Washington University School of Medicine in St. Louis has developed an algorithm that can estimate the risk of AD within the next five years, helping participants predict whether they may face the risk of a debilitating disorder. It is said that this five-year estimate calculator can compute the absolute risk of AD dementia.
According to principal investigator Jessica Mozersky, Ph.D., an assistant professor of medicine in the university’s Bioethics Research Center, people wanted to know how much risk of the disease they might face, rather than just receiving a report showing whether their test results were normal or not.
In the study, researchers used demographic information, such as brain imaging test results and genetic biomarkers, to constructively articulate the risk of developing early symptoms of dementia from Alzheimer’s.
Co-principal investigator Sarah M. Hartz, MD, Ph.D., an associate professor of psychiatry, said that there were thousands of volunteers participating in the study at Alzheimer’s research centers around the country.
“They come back and undergo tests year after year, including PET (positron emission tomography) and MRI (magnetic resonance imaging) scans, blood draws, cognitive tests, and lumbar punctures that measure proteins in spinal fluid. Those studies advance the overall understanding of Alzheimer’s disease, but they give participants relatively little information about their own risk,” said Hartz.
“This algorithm is a way to help illuminate that information and to let individuals know whether they have a significant risk for dementia related to Alzheimer’s disease,” she added.
The study was published Sept. 30 in the Alzheimer’s & Dementia journal, with findings from researchers with the university’s Knight Alzheimer Disease Research Center (Knight ADRC).
How Can the Risk Be Measured?
Using a survival analysis of the five-year risk of AD dementia, researchers analyzed longitudinal data from more than 10,000 cognitively unimpaired older adults. Various factors were examined to determine whether the algorithm could help the volunteers better understand what their futures held and whether researchers could also evaluate the participants’ final outcomes.As mentioned earlier, participants wanted to know the percentage of risk they might encounter in the future. Therefore, researchers developed a calculator to compute the AD dementia risk for individuals.
Mozersky said, “We’ve performed studies with people who receive results reporting elevated amyloid (the buildup of amyloid makes organs of the body not work properly), for example. They tell us, ‘You know what I really want to know? My risk.’”
Over the years, there has been much controversy regarding how much information should be revealed to people who participate in the studies. There is currently no cure or treatment that can prevent AD dementia from developing. Additionally, it has not been discovered how much biomarkers can do to help predict the problem in people who have no symptoms of the disorder.
However, researchers decided to let people better understand their future risk of this condition. The AD dementia calculator is accessible on the Knight ADRC’s website, giving users more substantial details about their risk for this disorder.
“We developed the algorithm so that we can tell participants what currently is known in a meaningful way, and so that the algorithm can be updated easily as new research or data emerges,” Hartz said.
For instance, a 69-year-old woman would have about a six percent risk in the next five years of developing the early symptoms of AD dementia if she went to college and had a parent with AD dementia. Nonetheless, the remaining 94 percent of those not developing AD symptoms is very high. If the woman had turned 85, instead of 69, her risk would rise to about 32 percent in the next five years, even without knowing any biomarker-related results.
The demographic model verifies the increased risk of AD dementia associated with a parental history of AD dementia and lower educational attainment.
Besides that, the imaging test (PET scan) of amyloid and brain hippocampal volumes (a smaller volume of the hippocampus that can seriously affect patients with AD) involved in the algorithm can tell how the risk changes when such extra information is known. If the same 69-year-old woman had elevated levels of amyloid and a reduced hippocampal volume, her risk would rise to about 33 percent.
“Still, age is the biggest demographic risk factor,” Hartz said.
Further, nearly two-thirds of Americans with Alzheimer’s are women, but the finding appears to contradict that. It shows that men have a higher risk of AD dementia than women.
Also, a gene was found to increase the risk of Alzheimer’s dementia, which is called APOE (depending on what type of APOE an individual carries). But it is said that the gene did not show anything different from imaging test results when the APOE genotype was included in the model. So it is likely that the gene plays a part in the brain-altering process.
“Researchers worry about how such information will affect study participants,” Hartz said. “We want to learn how the information might affect them and whether providing this sort of information may actually help them.”
Five million dollars was granted for Hartz and Mozersky from the National Institute on Aging to proceed with clinical trials to discover more about the impact of providing these risk assessments to volunteers and to validate the algorithm in bigger samples.
