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Blood tests approved by the FDA in 2025 are promising to look at amyloid and tau levels via blood samples.

These proteins are present in blood at much weaker levels than in brain tissue.

The results may determine one's risk for AD, exclude AD, or, in the presence of symptoms, confirm a diagnosis.

Discussing any cognitive changes with your doctor is important; testing is one part of a wider conversation.

Going to the doctor to have tests done has become part of our everyday lives. Often, these checks are done because of symptoms you have experienced, and the doctor is looking to rule in or rule out the possibility that particular causes are behind how you are feeling. But sometimes blood tests can be used as a means of risk assessment. Rather than telling the clinician and patient whodunnit, they merely suggest which way around the board you’d benefit from moving to.

Historically, Alzheimer’s disease was only diagnosed postmortem

When a patient’s brain was dissected, a series of consistent changes found within brain cells and surrounding tissues confirmed that they had indeed had Alzheimer’s disease. Key to these findings was the visibility of excessive amyloid plaques—a specific type of protein—between brain cells. Alongside this finding was that of tau, another protein, that caused tangles within these brain cells. This, combined with inflammation, increased brain cell shrinkage, and premature death, is a key finding in the brains of those with Alzheimer’s disease.

Scientists knew they had to find a way to see this buildup of excessive amyloid earlier to aid diagnosis and ultimately treatment

Testing and diagnosis evolved for both imaging—in the form of PET scans, a type of MRI scan that uses a radioactive tracer to confirm or rule out the presence of amyloid and tau proteins—and biology. A lumbar puncture could be done to take a sample of spinal fluid, which could be looked at under a microscope for these two proteins. For the last few years, this has become the gold standard for making a diagnosis of Alzheimer’s disease.

But problems remain in real life—the reluctance of patients to attend an assessment for fear of this condition, then the long delays in assessment at specialist services, combined with a lack of access to these expensive scanners and/or accessibility for lumbar puncture tests. Researchers have known this for decades. Clinicians and patients have done the best they can with the tools at their disposal. The results often include delays in diagnosis, a........

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