A team of researchers from the US and Germany has developed a new, simple blood test to detect Alzheimer’s disease even before symptoms appear.
The team involved Washington University School of Medicine in St. Louis, US and the German Center for Neurodegenerative Diseases in Germany.
The researchers designed the Alzheimer’s test to identify blood levels of neurofilament light chain, a structural protein that leaks into the cerebrospinal fluid when brain neurons are damaged or dying.
Testing of cerebrospinal fluid for high neurofilament levels is known to indicate that damage to brain cells has occurred. However, patients are usually reluctant to undergo a spinal tap that is required to obtain the fluid.
To address this challenge, the team investigated the link between the protein levels in blood and neurological damage. They analysed more than 400 participants from the Dominantly Inherited Alzheimer’s Network (DIAN) study on Alzheimer’s.
Of the total participants, 247 carried an early-onset genetic variant and 162 were unaffected relatives.
The protein levels were observed to be higher at baseline and increased over time in people with the faulty gene variant, while the levels were low and remained largely steady in those with a healthy gene.
According to the researchers, this difference in protein levels was detectable nearly 16 years before cognitive symptoms were expected to appear.
Washington University graduate student Stephanie Schultz said: “16 years before symptoms arise is really quite early in the disease process, but we were able to see differences even then.
“This could be a good preclinical biomarker to identify those who will go on to develop clinical symptoms.”
The team further assessed data from 39 people with disease-causing variants after two years from their last visit to a clinic.
It was observed that people whose blood protein levels had previously increased were most likely to display signs of brain atrophy and diminished cognitive abilities when they revisited the clinic.
While additional research is required to validate the findings and determine the number of neurofilament changes for clinical predictability, the researchers hope that the new test can be used to detect Alzheimer’s, as well as other conditions related to neurological damage.
High levels of the protein are known to occur in Lewy body dementia, Huntington’s disease, multiple sclerosis, traumatic brain injury and stroke.
An estimated 5.7 million people in the US are living with Alzheimer’s disease. The Alzheimer’s Association expects this figure to grow to 14 million by 2050. Currently, Alzheimer’s kills more people in the US than breast cancer and prostate cancer combined.
Additional reporting by Charlotte Edwards.