Alzheimer's detection in a simple blood test
Swedish scientists have shown how a blood test can reveal whether there is accelerating nerve cell damage in the brain. Published in the journal JAMA Neurology, their study should be useful for detecting Alzheimer’s disease, which is gradual in its development and currently difficult to diagnose.
Very sensitive methods have been developed in recent years to measure the presence of certain substances in blood that can indicate damage in the brain and neurological diseases such as Parkinson’s, multiple sclerosis (MS) and Alzheimer’s. Neurofilament light protein (NFL), a marker for nerve cell damage, is one such substance.
“Standard methods for indicating nerve cell damage involve measuring the patient’s level of certain substances using a lumbar puncture, or examining a brain MRI,” said study leader Niklas Mattsson, a researcher at Lund University and physician at Skåne University Hospital. “These methods are complicated, take time and are costly. Measuring NFL in the blood can be cheaper and is also easier for the patient.”
When nerve cells in the brain are damaged or die, NFL protein leaks into the cerebrospinal fluid and onwards into the blood. It was previously known that the levels of NFL are elevated among people with neurodegenerative diseases, but there has been a lack of long-term studies.
With this in mind, researchers analysed a large number of blood samples collected over several years from a total of 1583 subjects: 1182 patients with different degrees of sporadic Alzheimer’s disease — the most common form of the disease — and 401 healthy subjects in a control group.
“We discovered that the NFL concentration increases over time in Alzheimer’s disease and that these elevated levels also are in line with the accumulated brain damage, which we can measure using lumbar punctures or magnetic resonance imaging,” said Mattsson.
At present, there is no treatment that can reduce the loss of nerve cells in the brain that occurs as a result of Alzheimer’s — and while drugs are available to mitigate cognitive disorders, they do not slow the course of the disease. Measurements of NFL concentration in the blood could indicate if a medicine is actually affecting the loss of nerve cells, when an optimal dosage of the drug has been reached or if another drug should be tried.
“Within drug development it can be valuable to detect the effects of the trialled drug at an early stage and to be able to test on people who do not yet have full-blown Alzheimer’s,” explained Mattsson.
“Measuring the NFL concentration in the blood could make things easier for future drug development, both through following the effects of the drug and by including test subjects who display markers of nerve cell deterioration. This approach will enable more reliable conclusions to be drawn from the results.”
Mattsson said it is important that scientists continue to examine how sensitive the measurement of NFL in the blood is as a marker for Alzheimer’s disease and what can be expected from longitudinal changes. He also believes that the method is not far from becoming a standard clinical procedure.
“Preparatory work is ongoing at Sahlgrenska University Hospital in Gothenburg to make this method available as a clinical procedure in the near future,” he said. “Physicians can then use the method to measure damage to nerve cells in Alzheimer’s disease and other brain disorders through a simple blood test.”
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