By Christine Barba | May 24th, 2019
Could an Alzheimer’s blood test be in our near future? Short answer: possibly, yes.
Many researchers emphasize that early detection and treatment could stop Alzheimer’s in its tracks. While Alzheimer’s can be diagnosed with a PET scan or lumbar puncture that draws cerebrospinal fluid through a needle placed in your back, these options can be invasive and are often not covered by insurance. Researchers use these methods to look for a build-up of beta-amyloid plaques or tau, toxic proteins that are often found in Alzheimer’s patients’ brains. However, scientists are looking for easier and less expensive tests that could catch Alzheimer’s early on, including an Alzheimer’s blood test.
Can I Get an Alzheimer’s Blood Test?
Not yet. However, there is mounting evidence a simple blood test could be used to detect Alzheimer’s. Most recently, researchers discovered that participants with more beta-amyloid in their brain also had more fatty amides in their blood. These molecules are meant to protect the brain and help us sleep. Researchers think beta-amyloid increases with sleep deprivation. The findings suggest that the fatty amides increase in an effort to ward off the toxic beta-amyloid plaques that scientists think eventually lead to Alzheimer’s. Measuring how much beta-amyloid and fatty amides patients have in their blood could be a useful diagnostic approach.
Researchers are developing various tests that can detect Alzheimer’s biomarkers in the blood
What Other Blood Tests Could Diagnose Alzheimer’s?
Earlier this year, researchers from St. Louis and Germany found they could use a blood test to detect neuron death. The scientists compared participants who have a gene that greatly increases Alzheimer’s risk to relatives without the gene. They looked for a protein that often appears in the blood after brain cell death. The team noticed that levels of this protein increased in participants with the gene up to 16 years before Alzheimer’s symptoms appeared. Seven years before symptoms appeared, the differing protein levels became even more apparent.
Last year, scientists from Australia and Japan detected beta-amyloid through a blood test with a 90 percent accuracy rate. However, with drugs targeting beta-amyloid increasingly failing, some researchers think looking for other Alzheimer’s disease biomarkers in the blood could be beneficial.
Scientists from Brigham and Women’s Hospital also created a blood test that focuses on tau levels. They found tau fragments in the blood and cerebrospinal fluid that helped them accurately predict Alzheimer’s disease.
What Is the Link Between Insulin Resistance in the Blood and Alzheimer’s?
In 2014, researchers from the National Institute on Aging (NIA) looked at insulin resistance in the brain. They looked at frozen blood samples that patients gave 1–10 years before an Alzheimer’s diagnosis and their current blood samples. Then, they measured an insulin receptor know as IRS-1.
When they compared the samples to participants without Alzheimer’s, they found that they could determine what participants had Alzheimer’s up to 10 years before their diagnosis. The findings suggest insulin resistance could lead to cell damage. Many researchers focus on the connection between elevated glucose levels, diabetes and Alzheimer’s.
This year, at the Society for Neuroscience conference in Washington, D.C, NIH researchers presented their latest findings. Participants with Alzheimer’s had higher levels of an inactive type of IRS-1 and lower amounts of the active version that appeared in participants without Alzheimer’s. Those with diabetes had medium IRS-1 levels. The good news? Researchers could predict whether someone was healthy or had Alzheimer’s with a 100 percent accuracy rate 10 years before symptoms appeared using this blood test.
Why Do Scientists Want to Develop an Alzheimer’s Blood Test?
Many patients do not receive an Alzheimer’s diagnosis until they develop the disease. By this time, beta-amyloid and tau plaques and tangles accumulate in the brain, eventually leading to cell death. Early diagnostic tools could lead to more effective treatment options.
Many leading brain health experts chimed in after Biogen’s recent drug failure. Researchers initially believed aducanumab could effectively halt Alzheimer’s by targeting beta-amyloid. However, the company announced they would be stopping the drug’s Stage 3 clinical trials. Leading brain health researcher and discoverer of Alzheimer’s genes Rudy Tanzi thinks pharmaceutical companies are targeting beta-amyloid too late.
“Genetics shows amyloid can cause Alzheimer’s, but we most stop it well before onset of symptoms—before neuroinflammation sets in. When will pharma learn this?” Rudy Tanzi wrote in a tweet.
Currently, Tanzi said he has been working on another drug known as a gamma secretase modulator (GSM) that targets beta-amyloid.
“Maybe someday, that drug will become the statin of Alzheimer’s. You keep your cholesterol down with those medications, but if you want to keep your amyloid down 20 years before symptoms occur, you could get a brain scan at age 50, see that your amyloid is higher than it should be and take this drug to get your amyloid down, just like for cholesterol medication,” he said. “I think that’s how we’re going to nip this disease in the bud.”
Yet blood tests that can detect Alzheimer’s biomarkers would be easier and cheaper than a brain scan. A simple method that helps doctors discover Alzheimer’s biomarkers in patients when they are young could help them prescribe more targeted treatment plans.
When Would the Blood Test Become Available to the Public?
Researchers said they are hopeful the public can access these tests in a few years. However, the tests are currently only being used for research purposes. Most researchers said they need to conduct more studies before the tests become widespread.
What Other Diagnostic Tools Are Researchers Working On?
Last year, researchers at Duke University studied the eyes of participants with Alzheimer’s, mild cognitive impairment and healthy individuals. They discovered that a certain part of the retina was thinner in those with Alzheimer’s. The team detected who had Alzheimer’s within seconds. They believe someday, we may be able to diagnose Alzheimer’s with an eye exam. Researchers are also looking at whether artificial intelligence could catch what doctors miss by building on precision medicine. Researchers like Rhoda Au, the director of neuropsychology at the Framingham Heart Study (FHS), are examining whether the way we speak and write could predict our Alzheimer’s risk. In the future, many researchers hope that easy approaches to measuring beta-amyloid levels will become commonplace during yearly physical exams at the doctor’s office.