Blood Tests Show New Promise for ALS Diagnosis and Prognosis
Highly accurate neurofilament light chain assays may soon transform ALS testing
Topline
A new study found that four blood-based neurofilament light chain (NfL) tests are highly accurate in diagnosing and predicting the course of amyotrophic lateral sclerosis (ALS), potentially offering a non-invasive diagnostic and prognostic tool for clinicians.
Study Details
Researchers from CHU Montpellier in France examined how well blood tests measuring neurofilament light chain (NfL)—a marker of nerve damage—could identify and forecast ALS progression. ALS is a debilitating neurodegenerative disease that often requires months of clinical observation before a confident diagnosis is made. The study aims to fill that diagnostic gap with faster, more accessible testing options.
Methodology
The study enrolled 139 ALS patients (mean age 67.3, 50% women) and 70 controls without ALS (mean age 63.8, 41% women). Researchers compared four different technologies for measuring NfL in serum:
Simoa (Ultrasensitive platform)
Ella (Microfluidic platform)
Lumipulse (Clinical-grade assay)
Elecsys (Clinical-grade assay)
They also evaluated two other blood-based biomarkers—GFAP and pTau181—using the Elecsys platform. ALS patients were followed for an average of 42 months.
Key Findings
All four NfL tests demonstrated strong diagnostic performance, with correlation coefficients ranging from 0.939 to 0.963 (P < .0001).
Diagnostic accuracy (AUC values) was highest for Lumipulse (0.912), Elecsys (0.910), and Ella (0.906), all outperforming Simoa (0.889).
GFAP and pTau181 had poor diagnostic utility (AUCs of 0.546 and 0.565).
High NfL levels were strongly associated with worse prognosis. ALS patients with NfL above the proposed cutoff had near-zero survival at 50 weeks; those below had a 40%-50% chance of surviving past that point.
Implications for Practice
For healthcare providers, this research supports integrating NfL serum testing into diagnostic workflows, especially when clinical symptoms are inconclusive. These assays may offer a more objective tool for identifying ALS earlier and assessing prognosis more precisely.
For patients and families, the availability of a reliable blood test could reduce the emotional toll of diagnostic delays and help plan care more effectively.
The study also proposed diagnostic and prognostic cutoffs for NfL on all four platforms, setting the stage for broader clinical use.