The New Alzheimer's Blood Tests and Treatments: What Changed
Families ask us about the new Alzheimer's drugs more than they ask about anything else in the news, and the honest answer has always taken longer than they expect. Something real has changed. It is also narrower than the headlines suggest, and the part that matters most to families is usually the part that gets left out.
Two things happened. There are now approved drugs that modestly slow early Alzheimer's disease, and there are now blood tests that can confirm the disease without a PET scan or a spinal tap. The second may end up changing more lives than the first.
The blood tests, which are the bigger practical change
For most of the history of Alzheimer's diagnosis, confirming the disease meant a PET scan or a lumbar puncture. Both are expensive, both take specialists, and in much of the country neither is easy to get. So most people never got confirmation at all. They got a clinical impression, which is a doctor's careful judgment, and often a correct one, but not the same thing.
Blood tests have now cleared the FDA for this purpose. Fujirebio's Lumipulse G pTau217/beta-Amyloid 1-42 Plasma Ratio cleared in May 2025, and Roche's Elecsys Phospho-Tau (181P) Plasma test, aimed at primary care, cleared in October 2025. Both are looking for evidence of the amyloid pathology that defines Alzheimer's disease.
The reason this matters is access. A test that can be ordered by a regular doctor, from a blood draw, does not require a family to get an appointment at an academic medical center months out. For families in Troy and around Oakland County that is less of an obstacle than it is elsewhere in Michigan, since the specialists are relatively close. For a family two hours north it can be the whole obstacle.
A blood test result is not a diagnosis on its own. It is one piece of evidence a doctor weighs with the history, the cognitive testing, and the rest of the picture. But it removes a barrier that kept a lot of people from ever finding out what they actually had.
The drugs, and who they are actually for
Two anti-amyloid drugs are approved: lecanemab, sold as Leqembi, and donanemab, sold as Kisunla. Both are antibodies that clear amyloid from the brain.
Here is the part that gets lost, and it is worth stating precisely, because the loose version of it is wrong in a way that matters. Both labels say the drug is indicated for the treatment of Alzheimer's disease, and then say that treatment should be initiated in patients with mild cognitive impairment or the mild dementia stage, the population studied in the trials. Amyloid has to be confirmed by testing before the first dose.
So the restriction is on starting, not on continuing. A person who began treatment at the mild stage and has since progressed has not aged out of an approval, and a family in that position should not read a headline and conclude their parent's prescription is now off-label. What is true is the thing that decides the question for most families who ask us: if the disease is already moderate or advanced when you first go looking, these drugs were never on the table.
That single sentence decides the question for most families who ask us. By the time a person is considering a memory care setting, they are usually well past the window these drugs were built for. It is a hard thing to hear from a family who just read an article about a breakthrough, and we would rather say it plainly than let someone spend three months chasing something that was never available to them.
They also do not stop or reverse the disease. The figures usually quoted are relative ones, roughly 27 percent slowing for lecanemab and roughly 35 percent for donanemab, and relative percentages are the most flattering way to state a result. The FDA labels report the same trials in absolute terms instead, and that is the version worth seeing.
The lecanemab study that supported approval measured a difference of 0.45 points on the CDR-SB, a scale running 0 to 18, after 18 months. Donanemab's measured 2.92 points on the iADRS, a 0 to 144 scale, and 0.70 points on the CDR-SB, at 76 weeks. Both were statistically significant. Both are also small absolute movements on long scales over roughly a year and a half, which is why "27 percent" and "half a point" can describe the same finding and leave people with completely different impressions. Whether that difference is meaningful in a particular person's daily life is exactly what the field is still arguing about, and it is a fair thing to ask the prescribing doctor directly.
What treatment actually involves
These are infusions, not pills, and they come with monitoring.
The main risk is a category called ARIA, amyloid related imaging abnormalities, which means swelling or small bleeds in the brain that show up on MRI. Often it causes no symptoms. Sometimes it causes headache or confusion, and in rare cases it is serious. Patients get MRIs on a set schedule to watch for it, and the schedule is in the labels rather than left to anyone's discretion: for lecanemab, a baseline scan and then after 1, 2, 3 and 6 months of treatment; for donanemab, a baseline and then before the 2nd, 3rd, 4th and 7th infusions. That is real time, real travel and real cost, and it is worth counting before treatment starts rather than discovering it in month two.
Medicare covers both, with conditions. There has to be a diagnosis of mild cognitive impairment or mild dementia due to Alzheimer's, amyloid has to be confirmed by biomarker testing, and the prescribing doctor has to enroll the patient in an approved registry that tracks safety outcomes. That registry requirement is unusual, and it exists because these drugs were approved while questions about real world safety were still open.
Two things changed more recently. In July 2026 the FDA approved a subcutaneous starter dose of lecanemab, an injection under the skin rather than an infusion, which is the first time an anti-amyloid treatment has been available that way. And donanemab carries the possibility of stopping treatment once scans show the amyloid is cleared, rather than continuing indefinitely.
Why the diagnosis itself is worth having
Some families ask a fair question: if a person is past the window for treatment, why put them through an evaluation at all?
There are several answers, and none of them are about drugs.
The first is that a meaningful share of people evaluated for memory loss turn out to have something else. Thyroid problems, vitamin B12 deficiency, sleep apnea, depression, medication interactions, and normal pressure hydrocephalus can all look like dementia, and several of them improve with treatment. Assuming Alzheimer's and skipping the workup means never finding the version of this that had a fix.
The second is that the specific type matters for care even when nothing slows it. Alzheimer's, vascular dementia, Lewy body dementia and frontotemporal dementia progress differently, respond differently, and carry different cautions. A person with Lewy body dementia in particular can react severely to antipsychotic medications as a class, which is a fact every doctor treating them needs on the chart before anyone prescribes anything. That is not a decision a family makes, it belongs to the prescribing physician, but it is a piece of information a family can make sure travels with their parent to every appointment and every hospital admission.
The third is planning. A diagnosis on paper is what makes it possible to sort out a patient advocate designation, finances, and preferences while the person can still say what they want, rather than having those decisions made for them later by people guessing.
What we would tell a family
If you are seeing early changes in someone, the useful conclusion from all of this is not about drugs. It is about timing.
Everything described above is available only at the beginning. The people who benefit from any of it are the ones who got evaluated when the changes were still small and easy to explain away, not the ones who waited until the situation was undeniable. Most families wait. The waiting is completely understandable, and it is also the thing that closes the door.
So if a parent is repeating themselves, losing the thread of a conversation, struggling with money they used to handle, or getting lost somewhere familiar, that is a reason to see a doctor this season rather than after the holidays. Whatever the answer turns out to be, and a good number of these evaluations turn up something else entirely, some of which is treatable, the early version of the answer is worth more than the late one.
If a parent is already well into the disease, none of this changes what helps them, and it is worth saying that clearly rather than leaving families feeling they missed something. What helps at that stage has not changed: routine, familiar people, good pain and sleep management, treating infections quickly, and a setting where the day makes sense to them. That work is not in the headlines and it is most of what actually determines how someone lives.
Where to ask questions
For anything specific to a person, the prescribing doctor or a neurologist is the right place, because eligibility here turns on details no article can assess.
For the general version, the Alzheimer's Association serves Oakland County through its Michigan chapter and staffs a free helpline around the clock at 800.272.3900, answered by people who do this all day. They also run free support groups, by phone, by video, and in person. Families tell us afterward that they should have called years earlier.