For generations, a dementia diagnosis often meant little more than a label — a word that named the fog without illuminating its source. Now, three FDA-cleared blood biomarkers are offering clinicians something rarer in medicine: biological precision where there was once only uncertainty. Presented at the 2026 Jersey City Psychiatry Conference, the case for these tests is compelling, but so is the caution surrounding them — for a tool that clarifies must first be wielded with care, reserved for those who have already undergone the full, deliberate work of ruling out what can be healed.
Blood Biomarkers Sharpen Dementia Diagnosis, But Full Workup Must Come First
Once you know what you're dealing with more specifically, you can target appropriate therapy.
Mark
So these blood tests can tell you what type of dementia someone has. That sounds like a breakthrough. Why would you ever not use them?
Mimi
Because they're not magic. They only work if you already know something is wrong. If you use them on someone with no actual cognitive problems, you're just creating worry and false positives.
Luke
How do we define "objective cognitive impairment"? Is that a clinical exam, a test score, or something else?
Mimi
That's the clinician's job to establish first. That's why the full workup comes before the blood test.
Mark
What does that full workup actually catch that the blood test wouldn't?
Mimi
Thyroid problems, depression, strokes, tumors, bleeding in the brain. Things that look like dementia but aren't. You have to rule those out first.
Luke
And if you skip the workup and just do the blood test, what's the real harm? You get a positive result for Alzheimer markers—isn't that still useful information?
Mimi
You might treat someone for Alzheimer disease when they actually have a treatable thyroid condition. Or you might tell someone they have Alzheimer disease when they have depression. The blood test doesn't know the difference.
Mark
So the tests are good, but they're being used in the wrong order?
Mimi
Exactly. They're the last piece, not the first. That's the whole point.
Luke
How many clinicians are actually following that order right now?
Mimi
That's the real question. The guidelines say to do it this way, but we don't know yet how well people are following them in practice.
El Pulso
- Decades of vague 'wastebasket' dementia diagnoses have left patients and families without the specific answers needed to pursue targeted treatment.
- Three FDA-cleared blood biomarkers, the first approved in May 2025, now make it possible to distinguish Alzheimer disease from other forms of cognitive decline with biological specificity.
- Experts are sounding a clear warning: these tests are not for the worried well — they apply only to patients with documented, objective cognitive impairment, not subjective concern.
- A mandatory full workup — thyroid labs, depression screening, and neuroimaging — must precede any blood biomarker order to eliminate reversible causes first.
- The field is moving toward a future where dementia diagnosis shifts from educated guesswork to actionable science, but only if clinical discipline holds the line on proper use.
For generations, a dementia diagnosis often meant little more than a label — a word that named the fog without illuminating its source. Now, three FDA-cleared blood biomarkers are offering clinicians something rarer in medicine: biological precision where there was once only uncertainty. Presented at the 2026 Jersey City Psychiatry Conference, the case for these tests is compelling, but so is the caution surrounding them — for a tool that clarifies must first be wielded with care, reserved for those who have already undergone the full, deliberate work of ruling out what can be healed.
A man in his mid-50s asked his doctor for the same blood test his father had received after an Alzheimer diagnosis. His doctor declined — not out of indifference, but because the science, properly understood, does not yet support that use. That small exchange reflects a much larger tension reshaping dementia care.
Blood-based biomarkers have arrived with genuine promise. Rather than filing a patient's symptoms under a catch-all category, clinicians can now point to specific biological markers and name what is actually happening in the brain. George Grossberg, a geriatric psychiatry professor at Saint Louis University School of Medicine, made this case at the 2026 Jersey City Psychiatry Conference, arguing that the gap between what dementia science can do and what happens in everyday practice has been real and costly. Three FDA-cleared tests have begun to close it, with the first approved in May 2025 and others following within the year.
But Grossberg was emphatic about the limits. These tests are not screening tools for anyone anxious about memory. Guidelines restrict them to patients with measurable, documented cognitive impairment — and even then, only after a full clinical workup. That means standard blood work to rule out thyroid dysfunction, screening for depression which can mimic memory loss, and neuroimaging to check for strokes or structural causes. The biomarker comes last, not first.
The discipline matters because a positive result tells you something real — but not everything. It does not replace clinical judgment, and it does not substitute for the careful elimination of reversible causes. The hope is that as clinicians learn to use these tools properly, the fog surrounding dementia diagnosis will lift — replaced not by shortcuts, but by something more solid: a diagnosis that is specific, actionable, and earned.
A man in his mid-50s, worried about his memory, asked his doctor for the same blood test his father had taken after an Alzheimer disease diagnosis. It seemed like a reasonable request—a simple way to know his own risk. His doctor said no. Not yet. The science isn't there.
This small moment captures a larger tension in modern dementia care. Blood-based biomarkers have arrived with genuine promise, offering clinicians a way to move past the vague labels that have long clouded diagnosis. Instead of telling a patient she has "dementia" or "senile dementia," doctors can now point to specific biological markers and say: this is Alzheimer disease, or this is another type of cognitive decline. That precision matters. Once you know what you're actually treating, you can choose therapy with intention rather than guesswork.
George Grossberg, a geriatric psychiatry professor at Saint Louis University School of Medicine, laid out this case at the 2026 Jersey City Psychiatry Conference. The gap between what dementia science can do and what happens in everyday clinical practice has been real and costly. Patients arrive at clinics with fuzzy diagnoses, their symptoms filed away under catch-all categories. Families don't know what they're dealing with. Treatment becomes a matter of trial and error.
Three FDA-cleared blood biomarkers have begun to close that gap. The first cleared in May 2025, and others followed within a little more than a year. These tests can identify the biological signature of Alzheimer disease and distinguish it from other forms of cognitive decline. As clinicians learn to use them properly, Grossberg expects the old "wastebasket" diagnoses to fade. More patients will receive specific, actionable classifications instead.
But there is a crucial caveat, and Grossberg was emphatic about it: these tests are not for everyone who worries about memory. They are not screening tools for the worried well. Guidelines restrict them to people who already show objective cognitive impairment—measurable decline that a clinician can document, not just subjective concern.
Before ordering a blood biomarker, a full workup must come first. That means standard blood work to check thyroid function and rule out reversible causes of cognitive decline. It means screening for depression, which can mimic or worsen memory problems in older adults. It means neuroimaging—preferably an MRI—to look for strokes, tumors, bleeds, or other structural problems that might explain the symptoms. Only after that comprehensive evaluation should a blood test be ordered.
The distinction matters because it protects patients from unnecessary testing and from the false certainty that a single biomarker can answer complex questions. A positive blood test tells you something real about what is happening in the brain. But it does not tell you everything. It does not replace clinical judgment. It does not substitute for the hard work of ruling out other causes first.
As these tests become more widely available and more clinicians learn to use them, the hope is that dementia diagnosis will become less of an art and more of a science. Patients will know what they have. Doctors will know what to treat. The vagueness that has long surrounded dementia—the sense that diagnosis is almost a guess—may finally give way to something more solid. But only if the tests are used as they are meant to be: as the final step in a careful, complete evaluation, not as a shortcut around it.
Citas Notables
Now we are getting better and better at more precisely diagnosing, not just to say dementia, but what type of dementia does Mrs Jones have?— George Grossberg, MD, Saint Louis University School of Medicine
That's a great question. But we are not there yet. The science is not there yet.— George Grossberg, responding to a patient's son in his mid-50s asking about preventive blood testing
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Lee el original en Psychiatric Times ↗