Alzheimer's Blood Marker Could Improve Detection of Heart and Kidney Diseases

A blood protein widely used as an early indicator of Alzheimer’s disease may not be as specific as once thought. Researchers have now found that phosphorylated tau (pTau), a key biomarker linked to neurodegeneration, is also elevated in other serious conditions affecting the heart and kidneys. The discovery suggests that this commonly used Alzheimer’s marker may reflect broader disease processes in the body.

In a new study, researchers from the German Center for Neurodegenerative Diseases (DZNE, Germany) and the Hertie Institute for Clinical Brain Research at the University of Tübingen (Tübingen, Germany) analyzed data from 280 older individuals across Germany, Italy, and the Netherlands to investigate the role of pTau beyond Alzheimer’s disease.

Image: pTau, a key Alzheimer’s biomarker, is also elevated in systemic amyloidosis affecting the heart and kidneys (Photo courtesy of 123RF)

The researchers examined two forms of systemic amyloidosis, transthyretin amyloidosis and immunoglobulin light-chain amyloidosis. These conditions are characterized by the accumulation of misfolded proteins, known as amyloids, which primarily accumulate in the heart and kidneys rather than in the brain. Despite these differences, individuals with these diseases exhibited elevated blood pTau levels, consistent with patterns observed in Alzheimer’s disease. This suggests that pTau may be part of a broader biological response to amyloid accumulation, regardless of where it occurs in the body.

The findings indicate that elevated pTau levels are not exclusive to Alzheimer’s disease and should not be used as a standalone diagnostic marker. Instead, clinicians may need to interpret pTau levels alongside other clinical data, especially in early-stage disease or in patients without clear cognitive symptoms. At the same time, the results open new possibilities for diagnosing systemic amyloidosis.

Since pTau can be measured relatively easily through blood tests, it may serve as an additional tool for identifying or confirming these conditions earlier in the disease course. The study, published in Nature Medicine, also highlights potential applications in diagnosing polyneuropathy, a condition that causes tingling and numbness in the extremities. Systemic amyloidosis is one possible cause, and pTau measurements may help distinguish it from other forms of the condition.

“Our results underscore that high pTau levels in blood are not specific to Alzheimer’s, but can also occur in other amyloid diseases,” said Mathias Jucker, professor and scientist at DZNE and HIH. “Our results could open up new possibilities for diagnosis of systemic amyloidosis. The blood marker pTau can be measured relatively easy. It may facilitate earlier detection and help confirm or rule out suspected cases.”

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