Researchers led by King’s College London have found that levels of a protein known as neurofilament light chain (Nfl) in the blood can indicate whether people have neurodegenerative diseases. The research could be used to diagnose conditions inducing Down’s syndrome, dementia and motor neuron disease when clinical symptoms are inconclusive.
Currently, doctors diagnose neurodegenerative disorders from samples of cerebrospinal fluid taken from the fluid around the brain and spinal column. Extracting this fluid requires an invasive procedure called a lumbar puncture.
Blood tests offer a less invasive solution to finding biomarkers. A central and irreversible characteristic of neurodegenerative disorders is damage to the nerve fibre, leading to the release of Nfl.
To see whether levels of this protein could be detected and used to predict neurodegeneration, the researchers examined 3138 people. They included people with no cognitive impairment, some with neurodegenerative disorders, Down's syndrome and depression.
The researchers found that concentrations of Nfl were higher across all neurodegenerative disorders compared to those with no cognitive impairment. The highest levels however were detected among those with Down’s syndrome, dementia, motor neuron disease and frontotemporal dementia.
The researchers found that while the biomarker could not be used to differentiate between all the disorders, it could provide insight into subtypes of various disorders. For example, among those with Parkinson’s disorder, higher Nfl levels indicated atypical Parkinaons’s disorder. Levels of the biomarker could also be used to distinguish between neurodegenerative disorders and depression.
"This study shows that neurofilament light chain levels were particularly increased in adults with Down syndrome who have a genetic predisposition for Alzheimer’s disease. Furthermore, we showed that those individuals with a dementia diagnosis following onset of Alzheimer’s disease had higher levels than those who did not.” says Andre Strydom, co-author of the study.
“This suggests that the new marker could potentially be used to improve the diagnosis of Alzheimer’s in people with Down syndrome, as well as to be used as biomarker to show whether treatments are effective or not. It is exciting that all that could be needed is a simple blood test, which is better tolerated in Down syndrome individuals than brain scans.”