New Biomarker Discovery Aids Early Alzheimer’s Diagnosis

Kevin Brooks

Written by Kevin Brooks

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Alzheimer’s disease, the most prevalent form of dementia, affects an estimated 40 million people worldwide. The challenge of diagnosing dementia lies in the similarity of symptoms across various forms. However, advancements in the identification of biomarkers in cerebrospinal fluid (CSF) and blood plasma are paving the way for early diagnosis.

The Rise of Dementia: A Global Health Concern

According to the World Health Organization, about 55 million people are living with dementia, a number projected to escalate quickly. By 2050, a Lancet report anticipates that over 150 million individuals may be affected by this condition. Alzheimer’s disease represents 60-80% of these cases and is characterized by the accumulation of beta-amyloid and tau proteins in the brain. While current treatments focus on symptom management, they do not halt the progression of Alzheimer’s, making early diagnosis a critical goal.

Insights from a Longitudinal Biomarker Study

A groundbreaking long-term study in China has uncovered differences in biomarkers between individuals who later developed Alzheimer’s and those who did not. This research is significant because it enriches the data pool with information from the Asian population, which has been underrepresented in previous studies.

The China Organized Alzheimer’s (COAST) study engaged participants between ages 45 and 65 with no initial cognitive impairment or family history of Alzheimer’s. Over the course of the study, spanning more than two decades, participants underwent clinical evaluations, CSF and blood sample analyses, neuropsychological testing, and brain imaging at intervals of two to three years, concluding in 2020.

At the end of the study, 648 participants diagnosed with Alzheimer’s were compared with an equal number of individuals without the disease. The research team employed enzyme-linked immunosorbent assay kits for biomarker analysis and MRI scans to monitor changes in brain volume.

Decoding Biomarkers and Their Timeline

Key biomarkers, including beta-amyloid-42, beta-amyloid-40, phosphorylated tau 181, and total tau concentration, were meticulously measured. Beta-amyloid-42 levels were observed to decrease as early as 18 years before an Alzheimer’s diagnosis. A notable change in the ratio between beta-amyloid-42 and beta-amyloid-40 was detected 14 years before a diagnosis was made.

Tau protein alterations appeared 11 years prior to diagnosis, with significant increases in phosphorylated tau 181 and total tau observed 10 years before diagnosis. Additional indicators included elevated levels of NfL, signaling neuroaxonal damage, 9 years before diagnosis, and a reduction in hippocampal volume 8 years before diagnosis.

The changes in these biomarkers offer a window into the preclinical stage of Alzheimer’s, presenting opportunities for early detection and the development of targeted therapies.

From Research to Clinical Practice

As the medical community seeks to improve Alzheimer’s diagnosis, blood tests and other diagnostic tools are currently in development. Early intervention with disease-modifying treatments, such as lecanemab and donanemab, is on the horizon. These potential therapies are undergoing phase 3 trials to evaluate their effectiveness in altering the course of the disease.

While the Chinese study marks a significant stride in Alzheimer’s research, it is important to note its limitations. The participant pool consisted mainly of the homogenous Han Chinese population, and potential selection bias may limit the application of findings to other ethnic groups.

Looking Ahead: The Future of Alzheimer’s Diagnosis

The discoveries regarding biomarkers and their timelines before the onset of Alzheimer’s symptoms could be a game-changer in the fight against dementia. These insights are instrumental in developing diagnostic tools that could lead to timely and personalized interventions, potentially transforming the lives of millions around the world. As research progresses, the hope is to turn these scientific advancements into accessible and effective tools that will change the future of Alzheimer’s diagnosis and treatment.