FDA clears blood test to aid evaluation for Alzheimer's disease
medicine.washu.edu134 points by dabinat 10 hours ago
134 points by dabinat 10 hours ago
This Alzheimer's blood test, PrecivityAD2, is based on the p-tau217 biomarker.
In one recent study, people very high p-tau217 had a 38% chance of progressing to cognitive impairment within 5 years vs 12% for those with low levels. The current tests cost about $200-300, so they're not unreasonable as a screening test. PrecivityAD2 looks to be priced around $1,400-$1,500 so at that price, this specific test likely only makes sense for people with established disease.
We can also test for PSEN1, which is 100% accurate in determining early onset alzheimer's disease, quite a it more expensive, so unreasonable as a screening tool unfortunately.
That sounds pretty expensive for me for a test with that low accuracy, especially when there's not much you can do different if it comes back high vs. coming back low.
From TFA:
> Early detection of Alzheimer’s disease is important since the first treatments capable of slowing the progression of the neurodegenerative disease recently became available to patients, and these drugs are more effective when started sooner rather than later. Other promising investigational drugs are in the pipeline.
A very good friend's wife had Alzheimer's caught early, and the medication she's on stopped its progression. It's much better for her than my family members who had no treatment options.
> the medication she's on stopped its progression
what medication is that?
Creatine supplementation is showing some promising indications of being a low cost, mild to moderate intervention https://www.psychologytoday.com/us/blog/the-modern-brain/202...
I definitely wouldn't be sharing that as evidence of anything much at all
Google scholar link for the article https://scholar.google.com/scholar?cluster=10296105574478709...
Whether this ends up being replicated or not, I love the classic gym bro supplement being studied for its potential benefits to the brain.
What a time to be alive
what? there aren't any treatments that stop alzheimers, there are some that help manage symptoms
Agreed that we can't do as much as we'd like. There are some general health things that are believed to prevent cognitive decline, such as managing cholesterol, HbA1c, blood pressure, sleep apnea, etc. One phrase I've heard is that cholesterol at age 50 predicts cognitive health at age 70.
But hopefully we'll start to have more options and wider approvals for things like anti-amyloid drugs.
> anti-amyloid drugs
Isn’t the viewpoint in the last decade that amyloid plaques are likely a finding rather than the underlying cause of Alzheimer’s Disease?
The "standard" theory is that amyloid leads to tau protein accumulation which leads to neurodegeneration: https://www.astralcodexten.com/p/in-defense-of-the-amyloid-h.... Which would explain why current treatments don't really work: by the time Alzheimer's has progressed to noticeable impairment there's already too much tau, so reducing amyloid will at best slow the rate of decline by reducing the formation of new tau.
That's the viewpoint of everyone sensible outside of Alzheimer's research.
Those in it are still throwing billions per year at the idea.
Meanwhile, back in reality, no amyloid-beta drug has had any clinical effect in humans, other than reducing the plaques. But both the shingles and RSV vaccines are proven to reduce Alzheimer's risk.
Which did not stop the FDA from approving a useless anti-amyloid drug, leading to the resignation of several experts, one of whom called it "probably the worst drug approval decision in recent U.S. history" in his resignation letter. [0]
I can't think of a good reason why this happened.
[0] https://www.npr.org/2021/06/11/1005567149/3-experts-have-res...
if cholesterol predicted future cognitive health we wouldn’t need dedicated tests, do we?
the better way to phrase that would be "is predictive"... there is an association, but it is not high accuracy.
The forecast predicts rain, I'm still going to look outside before I throw on a raincoat
I guess you can start spending your retirement money faster
I know it’s a joke but then you’ll leave your family bearing the burden of your care. As someone whose parents had dementia, finding a place that treats your parents with dignity is extremely expensive and very rare. We were spending 12k/month and even we needed to set up camera’s and my sister slept with my mom and took care of her like a nurse. When the pandemic hit my sister couldn’t enter so every morning they took my mom, clothed her and sat her facing the bathroom all day long.
The only other alternative is some sort of mental hospital which is more like a prison than anything else.
The sad fact is that some people really should. Many people find it far easier to be or become indigent and fall on Medicaid services. If you do not qualify for Medicaid, then there is a real possibility that your insurance carrier will help put you or your caregivers into massive debt for a long-term illness like this.
If you do go into long-term care, Medicaid will probably seize your assets to help pay for everything. For example, a house in your name. They'll use those to pay back what they paid for your care.
So if you're gonna get sick and you're gonna be a burden in your old age, best to plan for leaving this world the way you came in: naked and penniless.
That price difference seems like the key point. A $200 test can plausibly be used to decide who should get further workup; a $1500 test is already competing with the cost of the workup itself
From a medical perspective, what's the point of the initial test or the workup though? Is it just to check a box? If it comes back positive you will be told to exercise, eat well, take sleep seriously, and manage cholesterol. If it comes back negative you will be told to do the same things.
I've seen up close what dying with these kinds of illnesses look like. For me, a positive test would be a sign that it may be time to say my goodbyes and plan my exit.
I do think telling you to get your affairs in order and to arrange for hospice care is probably good for the doctors. They don't want a family coming in with a sudden decline case and all the information about how to pay for it lost, at minimum
epistemics asks how many different hypotheses besides p-tau217 levels were tested before arriving at the specified spread.
Are you suggesting that these research scientists don't understand basic statistics?
While I’ve nothing to say about these research scientists in particular, knowing precisely nothing about them, it wouldn’t be the first time that so-called ‘bonafide’ research scientists made a statistical boo-boo, even one structural to the research thesis than any sort of math error.
Given the widely-reported extent of p-hacking in the biomedical literature over the decades, I’m surprised anyone would float an avid ‘but how could research scientists ever be wrong’ default reflex.
do you have the reference for that one? I'd be interested in reading it.
Sure! The study is from July 2026: https://jamanetwork.com/journals/jama/fullarticle/2851720
Do we yet have any good avoidance or mitigation regimes, be they drug or otherwise for people who show positive on a test like this? The alternative is that it lets you put things in place for when you lose agency.
Good as in scientifically proven. Not speculative fantasy.
We don’t currently have any data that shows any clear way to halt or slow Alzheimer’s.
As someone with family affected by this disease, it’s a very personal choice whether you want to know or not, but I wish people understood that there are many things you can do with it, particularly for those who will be there for you if/when it hits.
Taking care of a loved one with this disease is extremely hard, and it’s even harder when they haven’t had any chance to prepare for this eventuality. Stuff like written records of your history (health, life, etc.), clear powers of attorney, and so on.
It also makes things much easier for healthcare professionals.
Just lost my aunt to Alzheimer's this last week. +1 on the hard to take care of bit. They turn into toddlers, then animals, then nothing. It's heartbreaking.
I've lost my aunt and now losing my mother to it. It's a garbage diseases and such a burden on the loved ones, mental, physical and financial.
One other piece of advice I would offer is: find a class at your local hospital or similar. I attended a once-a-week for six weeks thing and it made a huge difference in my perception of dealing with someone suffering from dementia and gave me so much more patience/ grace than I would have had otherwise.
Sometimes the majority of the suffering is had by the people around the dementia patient.
Not true!
https://www.harvardmagazine.com/2025/05/harvard-taxi-drivers...
For some reason, taxi drivers seem to have a dramatically lower risk of it.
The also have an abnormally short lifespan of something like 67 years. I wonder if the two are related?
The article doesn't explicitly say but presumably you can start taking the anti-amyloid drugs to slow down the progression immediately, there's also lifestyle changes that can be made (most of those would likely benefit most people)
https://www.nih.gov/news-events/news-releases/combination-he...
> Early detection of Alzheimer’s disease is important since the first treatments capable of slowing the progression of the neurodegenerative disease recently became available to patients, and these drugs are more effective when started sooner rather than later.
Not a doctor or medical scientist, but my understanding is a) the effectiveness of those anti-amyloid drugs as a preventative tool is unclear, and b) they have a pretty scary safety profile.
Clearly the goal is to be able to prevent the disease from progressing or slow it significantly, but are we really there yet even if we have a test?
As someone with a family member taking one of the newest drugs, I can attest that it does seem to meaningfully slow progression — from rapid decline nearly to a halt in my loved one’s case.
The risk of dangerous side effects seems to be much higher for those with APOE4 — before approving the treatment they required among other things a genetic test ruling that out. (There are several other genetic variants that predispose to Alzheimer’s, fwiw.) We were lucky and saw none of the concerning side effects.
Are we “there” yet? Where’s there?
The prognosis after this treatment is a massive improvement over what it would have been at this stage of progression if it had been reached even 5 years ago.
If you can detect the disease even earlier and halt progress at a point where you retain more cognitive function, that’s a huge win — and gives you time to wait it out a bit longer in hope that we’re able to develop a treatment that doesn’t just pause but can reverse progression.
Yeah, I doubt we’re ready yet to administer these drugs to people who are asymptomatic (not to mention how pricey they currently are). But for someone who likely has the genes for it, just _knowing_ would in some ways be a relief.
Yes, there is the FINGERS method. See e.g. https://fbhi.se For Alzheimer is particular, there are also some drugs now (e.g. Leqembi) that slow down the process, but no cure yet.
If this gets cheap enough and the predictive values hold up in ordinary clinical populations, it could change when people actually get evaluated rather than just how they get evaluated
Why is the FDA "clearing" something that is completely innocuous like a blood test?
Because tests aren't completely innocuous? Because tests lead people to make significant medical decisions?
Look at the supplements world, where grifters are shilling chemicals that cause harm and make radical claims for absurd markups. Or gas station pills. You want those companies making Alzheimer's tests? People going in to a 7-11 and buying a "all illness test card" that tells people they do or don't have degenerative diseases?
No, it's very very important to ensure tests are actually indicative and ensure they are well made. To do that, a regulating body needs to be involved.
Their doctor should be qualified to make that judgment without a government bureaucracy evaluating the efficacy of the test on their behalf, unless you want to completely destroy the rate of medical breakthroughs. If there's no potential harm from the procedure itself, the government shouldn't be involved at all.
Imagine if every new AI model had to be "cleared" by a government regulator. The role of government in healthcare evaluation needs to be simplified and streamlined. The liability needs to be shifted to doctor, and if it's a case of charlatanism, that liability should include a lengthy prison sentence.
> "If there's no potential harm from the procedure itself"
There is potential harm from the procedure itself because of https://en.wikipedia.org/wiki/Opportunity_cost and https://en.wikipedia.org/wiki/Budget_constraint and because sticking needles in people and drawing blood carries inherent medical risks.
So we should just let companies flood doctors with potential treatments and then hope they have enough time to figure out whats relevant for their patients?
Seems much better use of time and money to have people developing tests meet a pre-defined standard and after that point they're allowed to flood doctors with marketing for the tests.
What use is future medical advancements if it can't meet low bars like proving it works?
I think you need FDA clearance to be able to market a test as actually being effective for treatment/prevention etc. For exactly the same reason woo-woo supplements must disclaim that they aren't intended for that purpose
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These tests are more or less useless because there's no treatment anyway so knowing about it a long time in advance will not lead to any substantial gain. Even slowing the disease isn't within the realm of today's technology. Today's pharmaceutical companies are close to quacks as far as Alzheimer is concerned. We know next to nothing about its origins or even how the disease progresses.
The only thing you gain is giving people more time to worry and despair.
Earlier diagnosis, or at least suspected diagnosis, could make a difference in studying progression, origin, etc.
Imagine the test is 100% accurate: if you gave it to a group of people, you could then try to make interventions earlier, capture more data about lifestyle before symptoms, etc.
Patients becoming involuntary guinea-pigs for science? No thanks.
As long as there isn't a clear root cause found and some real mitigating medicines reach the market I would propose keeping people ignorant as long as we can.
I think I'd want to know.
It would affect my financial and estate planning, and how I'd like to navigate the disease's progression.
This is an infuriatingly clueless comment. It gives nothing? It allows people to set their affairs in order, and that is an invaluable thing.
Alzheimers can lead to all kinds of other issues like impulsivity, or aggressiveness. People gambling away their life savings, not knowing that they are even doing it. Doctors unable to intervene due to rights around patient autonomy. All of this has big consequences in the lives of those affected.
When the symptons set on you'll have plenty of time to wind down your affairs.
These tests are not useless, but I’d agree (from personal experience) that it’s far from clear that everyone should take one.
There’s a degenerative genetic disease that runs in my family that for various reasons we only found out about ten years ago. To get the test done in the UK for it, you have to go to mandatory genetic counselling where they try to convince you not to get it done. Of four siblings, the two of us who thought initially we’d definitely get it done, we’ve not, and the two who were sure they wouldn’t, have done.
They try and convince you not to get it done so you don’t end up confusing being tired one morning or tripping with “oh my God it’s starting”.
Everyone should get their affairs in order, regularly, without needing a test, if they care about their loved ones.