The presence of a distinct set of proteins in the blood can accurately identify patients who will develop the fatal nerve disease amyotrophic lateral sclerosis up to a decade before symptoms appear, researchers reported in Nature Medicine.
“We had always assumed that ALS was a rapid disease that starts 12 to 18 months before symptom onset,” study author Dr. Alexander Pantelyat from Johns Hopkins University School of Medicine said in a statement.
“But when we look at our findings, we see this has been a process that goes on for a decade or so before the patient ever steps into the doctor’s office or clinic.”
The researchers validated their test by analyzing blood samples obtained at the start of a long-term study from more than 23,000 volunteers, including 110 individuals who eventually developed ALS, also known as Lou Gehrig's disease.
Blood from those 110 had the predictive pattern of changes in 33 proteins 10 to 15 years before the disease was diagnosed, indicating early dysfunction of the muscles and nerves.
The test was 98% accurate in differentiating between blood samples taken from people with ALS, those without the disease, and those with other neurological disorders, the researchers said.
ALS causes muscle atrophy, respiratory failure and death, typically within two to four years. Patients often face a delay of 6 to 18 months before receiving a diagnosis.
“We see the light at the end of the tunnel here, and that target is an approved and available blood test for ALS,” Pantelyat said.
Treatments can slow the progression of the ALS and help manage symptoms, but there is presently no cure for the disease.
“With a test that allows for earlier detection of ALS, we have opportunities to enroll people in observational studies, and by extension, offer promising disease-modifying - and hopefully disease-stopping - medications, before ALS becomes debilitating.”