Blood biomarker detects whether depression is due to neurodegeneration
A new study published in the journal Nature Communications is reporting a single blood-based biomarker can detect the presence of 13 neurodegenerative disorders, from frontotemporal dementia to motor neuron disease. The test cannot specifically distinguish each disorder but instead is proposed as a way to determine whether patients with memory problems are suffering from the early stages of neurodegenerative disease.
Neurofilament light chain (NfL) is a protein released into cerebrospinal fluid when brain cells are damaged. It can be detected in blood, and researchers have long investigated this biomarker as a way of easily diagnosing neurodegenerative diseases such as Alzheimer’s.
This new study investigated over 3,000 blood samples from a diverse cohort of subjects with the goal of finding out whether NfL blood levels could differentiate cognitively healthy subjects from those with neurodegenerative diseases.
The research found NfL levels could effectively detect subjects with one of 13 different neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS), frontotemporal dementia, and Alzheimer’s disease. Plus, even more significantly, NfL levels could be used to identify whether patients with moderate to severe depression were suffering from the early stages of neurodegeneration.
Abdul Hye, joint senior author on the study, says this particular finding means NfL levels could be used in clinical contexts to help doctors determine if a patient’s cognitive symptoms are an early sign of neurodegeneration or another kind of psychiatric problem.
“For the first time we have shown across a number of disorders that a single biomarker can indicate the presence of underlying neurodegeneration with excellent accuracy,” says Hye. “Though it is not specific for any one disorder, it could help in services such as memory clinics as a rapid screening tool to identify whether memory, thinking or psychiatric problems are a result of neurodegeneration.”
Although the study found NfL blood levels could not diagnose specific neurodegenerative conditions, the researchers note the biomarker does have value in tracking nuances within certain groups of patients. High blood NfL levels in Parkinson’s disease patients, for example, were found to signal atypical cases of the disorder. In subjects with Down syndrome high NfL levels were found to correlate with dementia.
“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 a biomarker to show whether treatments are effective or not,” explains study co-author Andre Strydom. “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.”
As NfL levels naturally rise with age, the new study also offers age-related cut-offs separating normal from abnormal NfL levels. This will help clinicians determine whether NfL blood levels are a sign of neurodegeneration or simply a natural accumulation that comes with aging.
“Blood-based NfL offers a scalable and widely accessible alternative to invasive and expensive tests for dementia,” adds Hye. “It is already used as a routine assessment in some European countries such as Sweden or Netherlands, and our age-related cut-offs can provide a benchmark and quick accessible test for clinicians, to indicate neurodegeneration in people who are exhibiting problems in thinking and memory.”
The new study was published in the journal Nature Communications.
Source: King’s College London