Should You Get a P-Tau217 Biomarker Test?

[00:00:03] Are you caring for a loved one with dementia? You don't have to figure this out all on your own. Welcome to Truth, Lies & Alzheimer's, the show that helps you reimagine a new relationship with your loved one. A relationship a little more free of stress and anxiety. Join host Lisa Skinner and her 30 plus years of experience as she guides you on a new path to a better relationship with those you care for.

[00:00:33] Here's Lisa. Welcome everybody to the Truth, Lies, and Alzheimer's show. I'm Lisa Skinner, your host. Last week, I ran across an article that was published by a neurologist and it really caught my attention.

[00:00:55] Her name is Dr. Jennifer Buxner and she is with the Atria Institute that has a focus on preventive neurology. And the reason why it caught my attention is because she was discussing this fairly new biomarker test that is now available. It's called the P-Tau217 Biomarker Test.

[00:01:25] And I'm going to read to you what she tells us about it. But then I did some further research because I think that, you know, should we or shouldn't we get this biomarker test is the real question.

[00:01:47] And I wanted to lay out the pros and cons for all of you so you can make an informed decision if and when you ever have that conversation with your physician as to whether or not you should have the biomarker test or if you even feel comfortable having it. So that's what this episode is all about today.

[00:02:10] So let me start off by telling you what Dr. Jennifer Buxner has shared with us about this new P-Tau217 biomarker test. And what she says is that it's a question she's been hearing more and more from her patients.

[00:02:37] And increasingly from primary care offices that have started ordering the test. Now, she says that the P-Tau217, she tells us is a biomarker that tracks closely with Alzheimer's disease biology,

[00:03:04] particularly amyloid accumulation and tau pathology in our brains. It's a blood biomarker, and this is not a weak association.

[00:03:20] Across studies, an elevated plasma P-Tau217 has shown a high correlation with amyloid PET scan positivity.

[00:03:34] In one large analysis of cognitively unimpaired adults, a positive P-Tau217 predicted underlying amyloid pathology with roughly 79% to 86% positive predictive value. And that was depending on the assay and the threshold that was used.

[00:03:59] This information, she says, makes it incredibly useful, but this is the part that gets us lost. And I completely agree with her. A positive P-Tau217 test does not mean that someone has dementia.

[00:04:20] What it means is if you receive an elevated result, that may strongly suggest an underlying pathology of Alzheimer's disease, but it in no way, shape or form does not tell us exactly when or even if someone will develop symptoms.

[00:04:46] And the number is not interpreted in a vacuum. Kidney disease can raise our P-Tau217 levels. Acute systemic infection or significant illness can affect the levels. Age matters. Genetics matter. The clinical history matters.

[00:05:06] And the specific assay and cutoff matter because results from different platforms are not directly interchangeable. And what makes this even more interesting is the new prognostic data. At AAIC of 2026, nearly 2,700 cognitively unimpaired adults were studied.

[00:05:32] Those with very high P-Tau217 levels had an estimated 78% chance of developing cognitive impairment within 10 years. And roughly a 1 in 3 chance within 5 years. This is really powerful information, but it still doesn't mean that everyone should run out and get tested. Why?

[00:05:59] The better question is, what will I be trying to learn from this test? And what will I do once I have the answer? Now for the right patients, P-Tau217 can help identify Alzheimer's biology earlier, guide additional testing, sharpen risk assessment, and potentially lead to earlier intervention.

[00:06:29] But the thing is, without thoughtful interpretation, for all those reasons that she states in her article, an abnormal result can certainly create more anxiety than clarity.

[00:06:47] And even though this biomarker test is relatively simple for a physician to order, the nuanced interpretation is not. So, y'all remember the Sheriff Andy Taylor of Mayberry on the Andy Griffith Show and he used to say, I studied on this for a while. I think I need to study about that for a while.

[00:07:16] Well, that's exactly what I did. And I do that for pretty much everything. I wanted to learn more about this test so I could share it with all of you from a very objective lens. And this is what I discovered.

[00:07:38] So if you notice changes in memory or thinking, the hardest part is not just the fear. It's the uncertainty. It is normal aging. Or is it normal aging? Or is it something like Alzheimer's disease?

[00:07:59] So we now know that there is this test called the P-Tau217 that can give biological information earlier than even when the symptoms start showing up. But today I want to answer the question people are asking again and again. Because this is the question that came into my mind after reading her article.

[00:08:28] What is the point of testing if knowing is just going to cause and create an imaginable anxiety? So that's what I'm covering today. I'm going to tell you what I found out. What P-Tau217 biomarker test actually is. Why it matters.

[00:08:55] Why you should not treat results as your destiny. And how the test is actually performed. So what exactly is P-Tau217 in plain language? It's referred to as a biomarker test. Now Tau is a protein involved in Alzheimer's related brain changes.

[00:09:22] The P stands for phosphorylated, which means that Tau has phosphate groups attached. The 217 is a specific mark that scientists track because it tends to relate closely to Alzheimer's related Tau biology. So an important takeaway right here is this is not a crystal ball.

[00:09:50] It's not meant to be a crystal ball. It's a signal about likelihood. Well, the reason why that matters and what it can help us do if we get the test is because it can help clinicians and patients move from guesswork to a clearer plan. It can help with clarifying diagnosis support when symptoms overlap with other causes.

[00:10:19] It can provide earlier evaluation with symptoms alone are ambiguous like you're, you know, not sure if what your experience is normal aging forgetfulness or something more serious developing in your brain like Alzheimer's disease. It'll help understand risk in earlier cognitive stages.

[00:10:42] Again, not guarantees, but meaningful probability shifts better research matching for trials that depend on biological pathways. But the value depends on interpretation and what happens next.

[00:11:04] And interpretation is really the million dollar consideration because not all interpretations are going to be equal across the board. So why you should not take results at face value. This is what I've learned. Why you should be careful.

[00:11:31] Here are some of the reasons biomarkers shift our likelihood of developing Alzheimer's disease. They do not promise outcomes. Also, the meaning depends on the test and the lab platform. The cutoffs vary. Context matters. Symptoms, stage and often other biomarkers, especially amyloid.

[00:12:00] And biology overlaps. Tau related signals can appear in more than one clinical context. So the right mindset to have about this is interpretation first. Certainty never. Here's one hypothetical scenario for you to hopefully relate everything I've shared so far. So let's meet Margaret.

[00:12:28] Margaret is 66 years old. Over the last year, she started forgetting appointments and repeating questions. Nothing catastrophic yet. She still functions well and still lives alone.

[00:12:46] But it's noticeable enough that she discloses her concerns to her family and they tell her that yes, they've been noticing the signs too. So her first thought is, oh, is this Alzheimer's disease?

[00:13:08] Her second thought is, if I test and it's positive, am I going to spend the rest of my life panicking? So Margaret did what many people do. She debates the decision for a long period of time. She worries about both outcomes, but she finally decides to go ahead and have the test because her goal is not to panic.

[00:13:37] It's to get clarity and next steps. So next she has the pretest conversation with her physician where the point, this is the point where her testing will start. So instead of testing blindly, she meets with her doctor who explains something crucial.

[00:14:03] So, how P-Tau-217 results are not about likelihood explains. Not they are about likelihood, sorry, not certainty. They need context, symptoms, the stage she's in and often other biomarkers.

[00:14:25] And most importantly, there should be a plan after the result, whether your results turn out to be high or low, he says. However, in the moment, I understand it's still very frightening and worrisome to you because many people, once they hear the word Alzheimer's disease, they're going to think doom, right?

[00:14:53] But her doctor reframes it and brings the honest outcome back to reality for her. However, he tells her that an elevated P-Tau-217 test suggests Alzheimer's related tau biology is more likely to be involved, but it's does not guarantee the exact course of our futures. We still need to understand the full picture.

[00:15:23] What happens next that turned her anxiety into action? In Margaret's case, she went ahead and also got an amyloid assessment and a more complete clinical evaluation. Now here comes the twist in Margaret's story. Her amyloid result came back that it was mixed or unclear.

[00:15:47] So instead of one frightening label, now Margaret gets a structured approach, a more careful clinical evaluation to look for other contributors, a follow up and monitoring. If amyloid is also positive, then the interpretation strengthens.

[00:16:12] Alzheimer's biology is much more likely to be the driver of what's happening. But if amyloid is negative, the clinician can consider other explanations and different trajectories because tau signals can appear in multiple contexts, other underlying medical conditions. So either way, the outcome is the same emotionally.

[00:16:39] Margaret is not going to be left alone with a frightening number. She's left with a clearer next step. And how did this change her life? Well, over the following months, she did five practical things. She got a structured cognitive evaluation.

[00:17:00] She discussed sleep, mood, medications and vascular risk with her physician because those can worsen cognition regardless of its underlying cause. She planned for the future with her family, taking care of financial and caregiving considerations and concerns while she has time and clarity.

[00:17:28] She learns what symptoms to watch for and when to follow up. She connected with support resources. So anxiety did not become isolation for her. So here's the key message of Margaret's story. Testing helped not because it predicted her fate.

[00:17:52] It helped because it reduced her uncertainty and enabled her to have a plan. But what if instead Margaret's p-tau-217 turned out to be low? Well, she still doesn't want to ignore her symptoms. But now her clinician has evidence that makes Alzheimer's tau biology less likely at that time.

[00:18:23] And they can now focus on other causes like a sleep disorder, depression, medication side effects, thyroid issues or vascular contributors while continuing appropriate monitoring. Again, I want to emphasize that Margaret's story. Her results were not a verdict. They are a direction for her.

[00:18:51] And that's the core lesson. The point of p-tau-217 isn't just learning a result. The point is using it carefully, contextually, and with support to decide what will come next. So one more hypothetical scenario, but this time our gentleman gets a negative result. So let's imagine a different person. I'm going to call him Daniel. Daniel.

[00:19:20] He's 70 years old and he's been noticing word finding trouble and a bit of mild forgetfulness, but he's still worried sick. Not just about Alzheimer's disease, but about what a test might prove. So he's in that pretest moment. Daniel asks about the same fear that many, many, many patients have.

[00:19:47] Again, if I test positive, will I live with dread? His clinician responds with the responsible framing of Daniel. The test cannot predict everything. The result should be interpreted with the rest of the clinical picture.

[00:20:10] And you only get testing value if there's a plan in place for what will happen next, no matter what your result is. So Daniel decided to proceed because he wants an evidence based direction, not endless guessing. His P-Tau217 biomarker result was negative. It came back low.

[00:20:41] Negative or elevated, not detected, depending on the lab's wording. Now, many people hear negative and instantly think, oh my gosh, I'm fine. I'm okay. But the better clinical takeaway is more careful than just that.

[00:21:02] A negative P tau 217 result makes Alzheimer's related tau biology less likely at that time. The time that you actually get the test results. And also given the test context. It does not erase symptoms or guarantee that nothing could ever happen.

[00:21:28] Now, it shifts the probability landscape and opens the door to other explanations. So what happens next? We're going to shift the focus. Instead of treating the result as a dead end, Daniel's clinician uses it as a redirection tool. They broaden the differential diagnosis.

[00:21:51] They evaluate other common treatable factors that can also cause cognitive symptoms. So in practical terms, Daniel's follow up might include a review of his medications and possible side effects. Screening for sleep issues, especially sleep apnea. Doing an assessment of mood and stress.

[00:22:18] And an evaluation of vascular risk factors. And cognitive testing to characterize the pattern of symptoms. And that includes monitoring over time so changes are not missed. And the emotional outcome for Daniel in his situation was that he feels he can move forward now with less dread.

[00:22:46] More agency. And here are the key emotional differences from a positive result. Daniel now feels less certainty of developing Alzheimer's disease, which often reduces catastrophic thinking. But he also keeps a responsible stance. He still takes his symptoms seriously, just with a different biological emphasis.

[00:23:17] At the end of the day, Daniel did not get a guarantee of the future. But he got something just as valuable. He got clarity about what's less likely. And a practical plan for what he needs to address now moving forward. So, I hope you found this as interesting as I have. But I wanted it to be very informational.

[00:23:46] And, you know, just spell out for you the pros and the cons of taking this test if that situation arises for you. Because I want you to understand both sides of the possibilities of what you could go through and what you might avoid going through. And make an informed decision.

[00:24:11] If you are put in a position where your doctor says, I recommend that you get a P-Tau 217 biomarker test. Now you have questions to ask and things to really take into serious consideration before making your final decision. So, I really hope that this will end up being very informative and very helpful for you.

[00:24:42] And I'll be back next week, as always, with a new episode of the Truth, Lies and Alzheimer's show. I'm Lisa Skinner, your host. And I hope you all have a great rest of your week. And you stay happy and healthy. And I'll see you back next week. Thanks. Bye-bye. Thank you for listening to Truth, Lies and Alzheimer's. We hope you found something in today's episode that helps.

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