Researchers say they have discovered a blood test that can predict with 90% accuracy if a healthy person age 70 or older will develop mild cognitive impairment or Alzheimer's disease
over a three-year period. The federally funded study of just over 500 patients
was published Sunday in the journal Nature Medicine. Although the findings are intriguing, experts say the results are still very preliminary.
“We were thrilled and surprised (about the findings),” said study co-author, Mark Mapstone, an associate professor of neurology at the University of Rochester Medical Center. “We're very excited about what this might represent for early detection of patients.”
Investigators enrolled seniors age 70 and older who were at high risk of developing Alzheimer's. Patients were in the preclinical stage of the disease, meaning that certain biological changes could be noticed in the body, but the disease had not led to noticeable clinical symptoms, like memory loss. Blood samples were taken from each patient at the time they enrolled, and run through a test which looked for lipids, or fats, hypothesized to be predictors of disease onset. The patients were followed for five years; 28 developed cognitive problems within that time frame.
“We knew that we wanted to look at lipids but we didn't have an idea about what we wanted to find. That opened us up to find things that people weren't expecting,” Mapstone said.
The study found that in the patients who had developed Alzheimer's disease or mild cognitive impairment, 10 lipids were consistently present in a subsequent blood test, and that patients could be characterized based solely on the presence of these fats. These particular lipids comprise the walls of cells, Mapstone explained, and the study suggests that when the cells broke down concentrations of these lipids increased in the body.
“We consider our results a major step toward the commercialization of a preclinical disease biomarker test that could be useful for large-scale screening to identify at-risk individuals," said corresponding author Dr. Howard Federoff, professor of neurology at Georgetown University Medical Center.
Alzheimer's disease is currently the sixth leading cause of death in the United States, though recent studies suggest that the condition may cause up to six times as many deaths as what is commonly reported
. There is no cure, and efforts to delay onset or even prevent the devastating brain disorder have been a national priority. The recent findings are promising, but more research is needed, experts say.
“The results, while intriguing, are preliminary,” said Maria Carrillo, Ph.D., Alzheimer's Association vice president of medical and scientific relations about the study. “They require replication and validation by other scientists in larger and more diverse populations to give them credibility, before further development for clinical use is warranted.”
Current biological markers for early disease are limited by their inability to specifically diagnose the disease, or because they are invasive and can be expensive, said Carillo. Still, she says, research into blood-based biomarkers is an exciting and potentially useful area of research.
Mapstone agrees that the next step would be to validate the findings with other studies, but in the meantime, he said he's hopeful about the potential impact these findings can have.
“Currently we can only treat people once they have the memory trouble, but by then the disease is far too advanced and treatments are not, or are only minimally, effective,” Mapstone said. “It's critical to identify people before the memory symptoms start. This line of work will hopefully reinvigorate the approach to therapy.” Follow Sabriya Rice on Twitter: @MHSrice