Alzheimer’s: Can a blood test detect disease 3.5 years before diagnosis?

For the study, the researchers collected 161 blood samples over several years from 56 individuals diagnosed with MCI.

They then observed how these blood samples affected the development of human brain cells over time. Among the individuals, 36 went on to develop Alzheimer’s disease. However, 18 did not.

The researchers found that baseline data generated from the blood samples could predict progression from MCI to Alzheimer’s up to 3.5 years before a clinical diagnosis.

Blood from patients who went on to develop Alzheimer’s within 3.5 years promoted decreased cell growth and division, as well as an increase in apoptotic cell death.

“Based on the proteomic data, it appears possible that MCI patients that convert may have altered levels of secreted proteins that affect receptor signaling,” Dr. Laura J. Blair, assistant professor at the Department of Molecular Medicine at the University of South Florida, who was also not involved in the study, told MNT.

The researchers also noted that blood samples obtained closer to the time of MCI transitioning to Alzheimer’s disease were linked to an increase in neurogenesis or maturation of brain cells.

While they noted it remains unclear whether neurogenesis contributes to Alzheimer’s, they wrote that the increased neurogenesis observed may be a compensatory mechanism in response to aging and neurodegeneration.

MNT spoke with Dr. Paula C. Bickford, a distinguished professor in the Department of Molecular Pharmacology and Physiology, at the University of South Florida, who was not involved in the study, on whether these findings could provide a basis for a blood test to detect early Alzheimer’s disease.

She noted that after looking closely at the data, it is premature to say that these findings could be used to develop a new blood test.

“A caveat at this time is how specific this test is to Alzheimer’s disease versus other neurodegenerative diseases such as Parkinson’s disease or other types of dementia. [While] there is promise with this finding, more studies are needed to make conclusions on the clinical impact for diagnosing which subjects convert to Alzheimer’s,” she added.

MNT also spoke with Dr. David A. Merrill, psychiatrist and director of the Pacific Neuroscience Institute’s Pacific Brain Health Center at Providence Saint John’s Health Center in Santa Monica, California.

“The findings need to be replicated and expanded to include more diverse populations. Development and deployment of such a test could take months, if not years,” he said.

“In the meantime, it’s important that we stress to people that our behaviors matter. Striving to optimize our own health and those of our loved ones with aging can have a significant impact on delaying or preventing the onset of AD, regardless of what an early diagnosis biomarker test reveals,” he added.

The researchers concluded that their findings might pave the way for early prognosis, monitoring disease progression, and future mechanistic studies.

When asked about limitations, Dr. Swerdlow noted: “A limitation is we don’t know what caused the differences seen in the assay. For a study like this, it is important to see how well the assay works in a prospective fashion.”

Dr. Bickford added that the findings might also not translate to live models.

“There is strong evidence that serum from older individuals has a strong negative effect on neurogenesis in vivo and some data in vitro as well,” she said.

MNT also spoke with Dr. David A. Merrill, psychiatrist and director of the Pacific Neuroscience Institute’s Pacific Brain Health Center at Providence Saint John’s Health Center in Santa Monica, California.

“The findings need to be replicated and expanded to include more diverse populations. Development and deployment of such a test could take months, if not years,” said Dr. Merrill.

“In the meantime, it’s important that we stress to people that our behaviors matter. Striving to optimize our own health and those of our loved ones with aging can have a significant impact on delaying or preventing the onset of AD, regardless of what an early diagnosis biomarker test reveals,” he added.

When asked about the study’s implications, Dr. Bickford said:

“If the protein signatures indeed show consistency, these could lead to potential therapeutics targeted to prevent subjects from converting to Alzheimer’s disease. Again, this is not an imminent possibility, but could over time be beneficial.”

“To me, the biggest implication is that these findings are at least consistent with the possibility that at a molecular level, Alzheimer’s disease is a systemic event rather than a brain-limited event,” Dr. Swerdlow added.

“If we can find a basis for molecular changes that occur both within and outside of the brain, that could bring us closer to understanding what actually drives Alzheimer’s disease. Of course, the better we understand what actually drives Alzheimer’s disease, the better the chance we have of developing effective treatments.”
— Dr. Russell Swerdlow