Amyotrophic lateral sclerosis, better known as ALS, is a serious disease that slowly destroys the nerve cells controlling muscle movement.
As these nerve cells die, people gradually lose the ability to walk, speak, swallow, and eventually breathe. There is currently no cure, and treatments work best when started as early as possible.
One of the biggest challenges is that doctors usually diagnose ALS only after symptoms appear. By then, many motor neurons have already been permanently damaged. Scientists have therefore been searching for warning signs that appear before symptoms begin, giving doctors a chance to act earlier.
A research team led by the University of Miami has now taken an important step toward that goal. Their study suggests that changes in certain blood proteins may predict when ALS symptoms are likely to begin, even months or years before a person notices anything is wrong.
The work used information from the long-running Pre-symptomatic Familial ALS, or Pre-fALS, study. For almost 20 years, this project has followed people who carry inherited gene changes that greatly increase their risk of developing ALS but who have not yet developed the disease.
Because these volunteers were monitored over many years, researchers were able to study what happened before symptoms appeared. This rare opportunity allowed them to look for biological changes that could not normally be seen in newly diagnosed patients.
Earlier research had already shown that a protein called neurofilament light chain, or NfL, rises in the blood shortly before symptoms develop. In the new study, the scientists expanded their search by measuring more than 5,000 different proteins in blood samples from 137 participants.
Thirty-three participants eventually developed ALS or the related brain disease frontotemporal dementia. The researchers found 92 proteins that changed before symptoms appeared. They then used machine learning to identify the smallest group of proteins that gave the most accurate predictions.
The final model included 19 blood proteins, including NfL. Using this panel, the researchers could estimate when symptoms would begin with an average error of about 18 months. They also tested the approach using information from the UK Biobank and found similar results.
Lead researcher Professor Michael Benatar said these findings could help doctors answer one of the hardest questions asked by people who know they carry an ALS-related gene: when symptoms are likely to begin. Until now, giving a reliable estimate has been extremely difficult.
The timing is especially important because new gene-targeting treatments are beginning to emerge. One example is tofersen, a medicine already approved for some people with ALS. Researchers are now testing whether giving the drug before symptoms appear could delay or even prevent the disease.
The findings do not mean the blood test is ready for everyday medical use. More research is needed to confirm the results in larger and more diverse groups of people. Scientists also need to learn whether acting on these protein changes truly changes the course of the disease.
This study is an exciting step toward preventing ALS instead of simply treating it after damage has occurred.
The research is strengthened by its long-term follow-up and advanced analysis of thousands of proteins, but it mainly involved people with inherited forms of ALS, so further studies are essential before the approach can be widely used. If future research confirms these results, blood tests could become an important tool for identifying the best time to begin preventive treatment.
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Source: University of Miami.
