Two research projects now underway could lead to a breakthrough in the early diagnosis and early treatment of Alzheimer’s disease.
Researchers are developing a test that uses a single drop of blood to predict Alzheimer’s, which could lead to treatment decades before symptoms of the disease show up.
Because early-onset Alzheimer’s is exceptionally common in people with Down syndrome, the research is a collaboration between experts in both conditions. The Alzheimer’s Association, the Linda Crnic Institute for Down syndrome, and the Global Down Syndrome Foundation are funding two projects to speed up the development of early-detection blood tests. To accomplish that, researchers have begun to examine Alzheimer’s among individuals with Down syndrome.
Nearly all adults with Down syndrome begin developing the brain changes of Alzheimer’s by their 30s. By age 55 or 60, upward of 70 percent will develop dementia.
Attacking Alzheimer’s Early
Medical evidence suggests that the brain changes of Alzheimer’s, a progressive and fatal disease, begin many years before thought and memory problems appear. Medical science wants to develop drug therapies to administer to people with high risk for the disease, years before symptoms emerge.
One study is evaluating whether changes in ribonucleic acid (RNA) discovered in a single-drop blood test can accurately identify people who will develop Alzheimer’s among a group of Down syndrome test subjects that are at high risk.
Dr. Marwan Sabbagh, director of the Alzheimer’s and Memory Disorders Division at the Barrow Neurological Institute in Arizona, is leading the study, along with Matt Huentelman, Ph.D., associate professor in the Neurogenomics Division Unit at the Translational Genomics Research Institute (TGRI) in Arizona.
Another major study, also involving individuals with Down syndrome, will examine whether the risk of Alzheimer’s can be detected among research subjects by testing a specific set of blood proteins.
Leading that project is Nicole Schupf, Ph.D., M.P.H., DrPH, professor of epidemiology at Columbia University Medical Center in New York, and Sid O’Bryant, Ph.D., director of the Center for Alzheimer’s and Neurodegenerative Disease Research at the University of North Texas Health Science Center in Texas.
As more women have children later in life, Sabbagh said, it raises the risk for Down syndrome.
“With maternal age rising, Down syndrome occurs in one of every 700 live births,” he told Healthline. “Coupled with that is the fact that people with Down syndrome live now well into later life, from the 30s a generation ago to their 60s and 70s. Most will develop Alzheimer’s dementia after age 50.”
So what makes Sabbagh’s Alzheimer’s research unique?
“People with Down syndrome represent the single largest group of people with pre-senile onset Alzheimer’s dementia,” he said. “It could be an important group with which to test prevention strategies that would benefit the population at large.”
Sabbagh and his colleagues have discovered a method that allows them to identify every strand of genetic material from a single drop of blood. In particular, they are looking for markers associated with Alzheimer’s.
“By age 40, the majority of people with Down syndrome have a build-up of amyloid plaques and tau tangles in their brains, the two main hallmarks of Alzheimer’s disease,” Sabbagh wrote in his research summary. Amyloid plaques are hardened protein fragments that accumulate between nerve cells; tau tangles are twisted fibers of abnormal protein found inside brain cells.
A Closer Look at Blood Proteins
While Sabbagh’s research focuses on genetic material, Schupf and O’Bryant are exploring the role of blood proteins.
“Recognizing early Alzheimer’s-related changes is especially difficult in adults with Down syndrome,” Schupf told Healthline, “because they have variable levels of pre-existing cognitive impairments.”
In their testing, Schupf and O’Bryant are using biomarkers – changes in the state of a protein that correlate with the risk or progression of a disease.
Identifying blood-based biomarkers of risk and determining which individuals with Down syndrome are at the highest risk can provide insights into the way Alzheimer’s develops in adults with Down syndrome, according to Schupf.
“Biomarkers are critical to the early diagnosis of dementia and can guide the development of effective early intervention and prevention approaches,” she said.
David Charmatz, senior vice president of the Global Down Syndrome Foundation (GDSF), said Down syndrome is the most frequently occurring chromosomal disorder and the leading cause of intellectual and developmental delay in the world. The disorder is caused by abnormal cell division that results in extra genetic material from chromosome 21.
“People with DS have a significantly different disease spectrum,” Charmatz told Healthline. “They are naturally protected from heart disease, cancer, and stroke, yet at the same time are highly predisposed to develop Alzheimer’s disease, diabetes, and more than 20 other medical conditions.
The intensive study of this population represents a unique opportunity for scientific breakthroughs that will stand to benefit millions of Americans, with enormous societal and economic impact.”