Here’s a sobering statistic. In the United States, 1 of every 3 elderly people dies from Alzheimer’s. This disease is the sixth leading cause of death in this country. While deaths from heart disease fell more than 10 percent from 2000 to 2015, deaths from Alzheimer’s increased almost 125 percent.
Today, it’s estimated that 5.7 million people are living with Alzheimer’s, at a cost of $275 billion in 2018. Most of these people are 65 or older, but 200,000 have early onset Alzheimer’s. About 10 percent of Americans 65 or older have Alzheimer’s. By 2050, the number of Americans with Alzheimer’s is expected to reach almost 14 million, and their care will cost $1.1 trillion. It’s a devastating disease that robs individuals of a quality life and devastates families.
Compounding the misery is the fact that Alzheimer’s progresses slowly, and there are no inexpensive and non-invasive diagnostic tests currently available. Everyone agrees that a diagnostic test that provided early and reliable diagnostics would save medical costs.
Recently, reported research on a blood test for Alzheimer’s could be an important advance. A multi-national study headed by the German Center for Neurodegenerative Disease reported the development of a simple blood test that predicts the progression of Alzheimer’s disease at an early stage. The test centers on a protein called neurofilament light chain (NfL). Changes in the NfL protein can predict future Alzheimer’s onset more than 16 years before symptoms appear. NfL is a protein that’s found in a part of the brain cell called the axon. Axons are long thin projections of nerve cells, along which electrical impulses travel to connect the nervous system across the body.
When nerve cells become damaged, they release NfL. Many things can damage nerve cells, so the presence of NfL in the blood alone isn’t an indication of Alzheimer’s. The rate of change in NfL levels over time is the key to diagnosing Alzheimer’s.
The study utilized 243 patients with a genetic trait for early onset Alzheimer’s and 162 of their relatives who didn’t have the gene variant. Scientists got samples of cerebrospinal fluid and blood over many years, and assessed the samples for NfL levels at one-to-three-year intervals. The test used was an immunoassay, which is standard technology in a clinical diagnostic lab. NfL levels showed significant elevation an average of 6.8 years before symptom onset. After more experimentation, scientists found that they could detect illness more than 16 years before symptoms appeared. That’s astounding for a disease that has had no reliable non-invasive screening test to date. While cerebrospinal fluid samples require an invasive spinal tap, blood samples can be taken routinely during office visits.
There are more studies needed for this test to become a reality. This study addressed genetically acquired Alzheimer’s. We need to continue testing this diagnostic in older patients with Alzheimer’s. Once further validated, it’s easy to imagine this test becoming part of your regular blood work at your annual checkup.