Breakthrough Blood Test Allows Detection of ALS Years Before Symptoms Manifest

Researchers at Johns Hopkins University School of Medicine, alongside the National Institutes of Health, the UK Biobank, and the University of Turin, have developed a groundbreaking blood test capable of detecting amyotrophic lateral sclerosis (ALS) long before clinical symptoms appear. ALS, also known as Lou Gehrig's disease, affects approximately 400,000 people worldwide by 2040, progressively damaging nerve cells that control voluntary muscle movement, leading to muscle weakness, atrophy, and breathing difficulties. Currently, ALS diagnosis depends on neurological assessments and symptom presentation, with no definitive early diagnostic test available.

The new study, published in Nature Medicine, identified a specific set of proteins in blood that can signal ALS with over 98% accuracy up to ten years prior to symptom onset. Using advanced proteomic analysis and machine learning, scientists examined nearly 3,000 neural and muscle-related proteins in blood samples from more than 600 participants. Their model effectively distinguished ALS patients from healthy individuals and those with other neurological disorders.

The significance of this discovery lies in the potential for early intervention, as Dr. Alexander Pantelyat from Johns Hopkins emphasizes: "With an accessible blood test, we could enroll individuals in observational studies, offering the chance for disease-modifying or even disease-stopping treatments before ALS becomes debilitating."

The study also revealed that changes in blood proteins occur well before traditional symptoms, indicating early dysfunction in skeletal muscles, nerve signaling, and energy metabolism. Notably, these protein alterations were consistent across different populations and independent of genetic mutations, suggesting a broadly applicable biomarker for ALS.

Validation trials, including a large cohort from the UK Biobank, confirmed the test's high accuracy and ability to identify at-risk individuals up to a decade before symptom onset. These findings challenge previous assumptions that ALS develops rapidly in the year or two before diagnosis, revealing a prolonged pre-symptomatic phase.

This advancement opens new avenues for earlier diagnosis, targeted monitoring of disease progression, and evaluation of treatment effectiveness. The research underscores the importance of collaboration across institutions and shares the data publicly to accelerate biomarker development for ALS and possibly other neurodegenerative diseases.

Source: https://medicalxpress.com/news/2025-08-blood-als-early-years-symptoms.html