Understanding Today’s Alzheimer’s Diagnostic Tools

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Welcome back, everybody. You've tuned in to The Truth Lies and Alzheimer's Show. Lisa Skinner, your host. And if you tuned in last week, I brought you the most current and accurate information regarding the use of PET scans to definitively diagnose Alzheimer's disease. This week, as promised, I'm going to share the most current information about the other diagnostic tools that physicians currently use in conjunction with PET scans to help them diagnose Alzheimer's disease as accurately as they can with these tools that are currently available. So I talked about last week, we learned that an absolute diagnosis of Alzheimer's disease can still only be made at autopsy. However, physicians at specialized centers can diagnose Alzheimer's disease with up to to 90% certainty based on clinical information. To make the diagnosis as accurate as they possibly can, the following may need to be conducted: a medical history and neurological exam, neuropsychological testing that involves a careful analysis of a person's memory, problem-solving abilities, language, attention, and their visuospatial abilities. Basic blood tests. Blood tests may be used to help exclude other causes of memory difficulties. For example, a person with a thyroid disorder or a vitamin deficiency may have problems with his or her memory that mimics dementia, but the cause is not due to a brain disease and may be reversed if treated properly. Then there are brain scans, which— such as an MRI or CT or CAT scan, as it's also known as— that may need to be done in certain patients to detect brain tumors or strokes. These disorders can also cause memory problems. Now, according to Dr. Barry Rovner, who is a professor in the departments of both psychiatry and neurology at Jefferson Hospital for Neuroscience in Philadelphia, Pennsylvania, he states that, quote, Although no diagnostic tests are currently available that have 100% accuracy for Alzheimer's disease, experienced physicians can correctly diagnose Alzheimer's disease about 90% of the time. This happens when the physician obtains a history of gradual cognitive decline wherein family members also report that a person's functional abilities have declined, for example, in managing their finances, preparing meals, and taking medications competently, that they are able to demonstrate with objective evidence their cognitive deficits particularly in the short-term memory department. They find no neurological signs that suggest another condition like Parkinson's disease, a stroke, and sees no abnormalities on brain imaging studies like the CAT or CT scan or an MRI scan and laboratory tests that would indicate an alternative condition. He also says that an exciting new development are biomarkers that indicate the presence of underlying Alzheimer's disease pathology. These tests are now used to increase diagnostic accuracy in research projects but are not generally used to diagnose individuals in the community. These tests rely on the analysis of spinal fluid to measure levels of beta amyloid and the tau protein, which accumulate in the brain with Alzheimer's disease. New PET scans that reveal the presence of amyloid in the brain suggest that someday We will have tests that indicate disease pathology possibly before someone has developed symptoms. End quote. So how do these biomarkers help diagnose dementia? Well, biomarkers are measurable indicators of what's happening in our bodies. These can be found in blood, other body fluids, organs, and in tissues. Some can even be measured digitally. Biomarkers help doctors and researchers track healthy processes, diagnose diseases and other health conditions, monitor responses to medications, and identify health risks in individual persons. For example, an increased level of cholesterol in the blood is a biomarker for heart attack risk. The following are the different types of biomarkers for dementia detection and diagnosis, and when combined with other tests, these biomarkers can help doctors determine whether a person might have or be at risk of developing Alzheimer's or a related brain disease that causes dementia. But I do want to emphasize what I uncovered, and that is that no single test can diagnose these conditions. Biomarkers are only part of a complex and complete assessment. In some cases, these biomarker tests are only available through a specialty clinic or medical research facility. Physicians with expertise in this area include neurologists, geriatric psychiatrists, neuropsychologists, and geriatricians. So these are the different types of biomarkers and tests that we have available to use. There's brain imaging. Several types of brain scans enable doctors and scientists to see different factors that may help diagnose Alzheimer's or a related dementia. Di— doctors also use brain scans to find evidence of other sources of damage in the brain, such as tumors or strokes, that may aid in diagnosis. Brain scans used to help diagnose dementia include the PET scan, the CAT or CT scan, and the MRI. So this is the definition of what a CT, or computerized tomography scan, is. It's a type of X-ray that uses radiation to produce images of the brain and other parts of the body. A head CT scan can show shrinkage or atrophy of brain regions that may occur in dementia, as well as signs of other possible sources of the disease, such as an infection or even a blood clot. Then we have the magnetic resonance imaging, or MRI. Now, the MRI uses magnetic fields and radio waves to produce detailed images of body structures, including the size and shape of the brain and the brain regions. And similar to a CAT scan, MRI show whether areas of the brain have atrophied or shrunk, and repeat scans can show how a person's brain changes over time. So the first one would set a baseline to measure the changes in future scans. Evidence of shrinkage may support a diagnosis of Alzheimer's or another one of the neurodegenerative diseases that cause dementia, but cannot indicate a specific diagnosis. MRI also provides a detailed picture of our blood vessels in the brain. So before making a dementia diagnosis, doctors We often view MRI results to rule out other causes of memory changes, such as bleeding or a buildup of fluid in the brain. PET scans use small amounts of radioactive substance called a tracer to measure specific activity, such as energy use, or a specific molecule in different brain regions. PET scans take pictures of our brains, revealing regions of normal and abnormal chemical activity. There are several types of PET scans that can help doctors diagnose dementia. There is the cerebrospinal fluid biomarker, aka CSF. CSF is a clear fluid that surrounds the brain and spinal cord, and it provides protection and insulation. Doctors perform a lumbar puncture, also called a spinal tap, to get this fluid. The most widely used CSF biomarkers for Alzheimer's disease measure beta amyloid 42, which is the major component of amyloid plaques in our brains. Also tau and phosphotau, which are the major components of tau tangles in our brains, which happens to be another hallmark of Alzheimer's disease. We use blood tests. These blood biomarkers have historically been less accurate than the spinal fluid biomarkers for identifying Alzheimer's and related dementia. However, thanks to more research advances, improved methods to measure these brain-derived proteins are actually now available. There's genetic testing. Our genes are structures in a body's cells that are passed down from a person's birth parents. They carry information that determine a person's traits and keep the body's cells healthy. Now, mutations in genes can lead to diseases such as Alzheimer's. So, a genetic test is a type of medical test that analyzes our DNA from blood or saliva to determine a person's genetic makeup. Makeup. A number of genetic combinations may change the risk of developing a disease that causes dementia. Advances in biomarkers during the past decade have led to exciting new findings. Researchers can now see Alzheimer's-related changes in our brains while people are alive. Track the disease's onset and progression, and test the effectiveness of promising drugs and other potential treatments. There are two main categories of Alzheimer's disease. One is called familial, and the other is called sporadic. Familial Alzheimer's disease refers to the genetic form of the disease that is transmitted from one generation to the next. Only 5% of all cases of Alzheimer's disease have been associated with a genetic component. We've heard this as early onset Alzheimer's disease. Now, these individuals come from families in which as many as half of the members eventually develop Alzheimer's disease. Fortunately, this form of the disease— the disorder and the disease— are a much rarer form of Alzheimer's. The remaining 95% of Alzheimer's disease cases fall into the sporadic category, or randomly occurring. In the population. So what if a physician could diagnose Alzheimer's before major symptoms appear? Guess what? That's actually possible now with an FDA-approved test now being offered just recently, this in the latter part of 2025, for people experiencing mild cognitive issues. The test helps their neurologist learn if the symptoms are related to Alzheimer's disease. So a negative test can help rule out Alzheimer's disease with a 96.2% accuracy rate. A positive test can allow patients to receive a diagnosis and potentially have access to new drugs to slow the disease's progression while in a very early stage of the disease. So it was May of 2025 when the FDA approved the first blood test as a tool to help diagnose Alzheimer's disease. And this test is called LUMI Pulse. These blood tests offer a less expensive and less invasive option for helping to diagnose Alzheimer's disease. So how does this newly approved blood test by the FDA test for Alzheimer's disease work? I'll tell you, I'm not going to keep it a secret. The LUMI Pulse test uses a blood sample drawn at your doctor's office, and the test measures certain proteins including a specific form of the tau protein, and that can indicate the presence of amyloid plaques in our brains. An amyloid plaque is a buildup of protein that is considered the hallmark sign of Alzheimer's. This blood test, along with other diagnostic tools such as PET scan, can help diagnose Alzheimer's. While the blood test can detect changes even before memory problems begin, it is recommended to only be used clinically in people who are showing symptoms of Alzheimer's disease. Usually you'll get the results from the test within about 2 to 5 days. So why is this new blood test for Alzheimer's disease an important finding. Previously, the only test to detect amyloid plaques were through a PET scan and a lumbar puncture. In a lumbar puncture, a sample of the cerebrospinal fluid, or CSF, was taken from the spinal column. These tests can be expensive and a lumbar puncture is invasive. How accurate is this new test? Some studies are showing that the LUMI-Pulse test is over 90% accurate in detecting Alzheimer's-related changes. However, the test is still being refined and cannot diagnose Alzheimer's disease on its own. The LUMI Pulse Test is meant to be part of an evaluation for Alzheimer's disease, including an extensive and complex physical and medical history and imaging scans of the brain. The accuracy rate is different between LUMI Pulse and other blood tests used to help diagnose Alzheimer's disease. So you should discuss with your healthcare professional which test is going to be most appropriate for your specific situation. Who should even consider taking this test? Well, the test is approved for adults age 50 or older who have early memory or thinking problems such as forgetting names, misplacing things, or even repeating questions in the same conversation. It's not yet recommended for general screening in people who are showing no symptoms. You and your healthcare professional can decide if this test is appropriate for you. What are the results going to mean? A positive result means there are changes in your brain that may suggest Alzheimer's, but the results alone do not mean that you have the disease. So your healthcare professional may recommend more tests, such as imaging scans or tests of your memory and thinking, or he could suggest— he or she could suggest lifestyle changes to support your brain health. He can also— he or she can also help you plan your next steps, including treatment options or even a clinical trial that you can participate in. If you and your healthcare professional decide that a blood test is appropriate for you, it can be ordered right in your doctor's office. Talking with your healthcare professional can help you understand what the test can and cannot tell you. Decide if it's the right time for testing, make a plan for what to do with your results. You can mention it during your annual checkup or make a separate appointment if you're really, really concerned about the symptoms that you feel you are displaying. So what questions should you ask your healthcare professional? Ask him if he thinks this test is right for you. Why or why not? What are the risks or downsides of getting this test? What will we do if the test shows signs of Alzheimer's disease? Is this test covered by insurance, or is it going to be an out-of-pocket expense for me? Are there other tests that we should be considering instead or along with this blood test. So in conclusion, yes, a brain autopsy is still the only way to definitively confirm Alzheimer's disease by examining brain tissue for plaques and tangles because it does involve microscopic evaluation of brain tissue to find the definitive signs of Alzheimer's. In other words, the plaques and tangles. Modern techniques like biomarker tests that I went over with you, including blood and spinal fluid, and PET scans, now allow doctors to diagnose with high accuracy, up to 90%, while a person is living. Ruling out other causes. While not 100% certain without an autopsy, these advanced tests alongside clinical evaluations do provide strong evidence for a probable diagnosis, guiding treatment and research. So there you have it, the most updated and current information that was available. And I went to about 10 different resources that were all scientific resources that you will be able to see in the show notes, including NIH and The Lancet review. And these are all— they all pretty much said exactly the same thing. So I hope this has been really helpful for you, and you'll know how to approach a conversation with your doctor if you are displaying mild or moderate symptomology for cognitive decline. So thanks again for being here with me today. I'll be back next week with another episode of The Truth Lies in Alzheimer's Show. And if you have a chance, please go to our website. It's actually a new website, just completely redesigned. It's called mindingdementia.com. You can subscribe to our free weekly newsletter by hitting the subscribe button, and that goes out every Monday, and it provides you with other currently researched information on Alzheimer's disease and other related dementia, and we have also uploaded other tips, tools, and strategies that could help you in your Alzheimer's journey. So don't forget to check that out, mindingdementia.com. I hope you all have beautiful, healthy, and happy rest of your week, and I'll be back again next week with another new episode of the Truth, Lies Alzheimer's Show. I'm Lisa Skinner, your host. Take care for now. Bye-bye.

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