Biomarkers predict Alzheimer’s five years before onset

Canadian researchers have identified two biomarkers which were able to predict Alzheimer’s disease (AD) five years before its onset. Their discovery could revolutionise how, and at what stage of disease, patients are diagnosed.

Typically, AD is diagnosed through a series of psychometric tests assessing cognitive function, brain imaging and cerebrospinal fluid analysis. However, these tests have their limitations: “The lumbar puncture is invasive, while brain imaging is expensive and not 100 percent reliable. This complicates regular follow-up,” explained Professor Charles Ramassamy of the Institut National de la Recherche Scientifique (INRS), Canada, who directed the researchers.

Moreover, people with the disease are often diagnosed at a late stage of the disease when there is too much damage to reverse. “We need to find more and more early markers so we can act as soon as possible. When the disease is symptomatic, there is little, if any, way back,” he added.

In their study, the researchers focused on sporadic AD, the most common form of the disease, which is primarily caused by the expression of the ε4 variant of the APOE gene that encodes apolipoprotein. They analysed blood samples collected as part of the Canadian Study of Health and Aging (CSHA). The population studied consisted of patients with cognitive problems, but not suffering from dementia, only some of whom developed AD.

The scientists discovered that in patients who developed AD five years later, the ratio between pentraxin‐2 and α‐synuclein expressed in the extracellular vesicles circulating in their blood stream varied from those who did not develop the disease. As a result, they concluded that the pentraxin‐2/α‐synuclein ratio could serve as a useful early biomarker for AD susceptibility. Extracellular vesicles are pockets that are naturally released by all cells in the body and play an essential role play an essential role in the crosstalk between the brain and the periphery.

Professor Ramassamy said he now hopes to analyse a larger population with pre- and post-disease samples to determine the progression of markers after the onset of symptoms. He added that their research on the markers located in the vesicles could enable the study of other diseases, such as vascular dementia.

The study was published in Alzheimer’s & Dementia: Translational Research & Clinical Interventions (TRCI).