Blood-based detection of pTau181 could identify pathological Alzheimer’s disease

Written by Sharon Salt, Senior Editor

A recent advancement in the development of a blood test to detect pathological Alzheimer’s disease in people showing signs of dementia has been reported by researchers at the University of California San Francisco (UCSF; CA, USA). Their test focuses on the abnormal accumulation of pTau181.

Within the study, which has recently been published in Nature Medicine, researchers used this new test to measure the concentration of pTau181 in plasma samples of more than 400 participants (aged from 58 to 70). Their analysis demonstrated that pTau181 in plasma could differentiate healthy participants from those with Alzheimer’s pathology, as well as differentiate those with Alzheimer’s pathology from frontotemporal lobar degeneration.

The investigators reported that blood measures of pTau181 were 2.4 pg/ml among healthy controls, 3.7 pg/ml among participants with mild cognitive impairment and 8.4 pg/ml for individuals with Alzheimer’s. In study participants who had variants of frontotemporal dementia, these levels ranged from 1.9–2.8 pg/ml.

“These results gave similar information to the more established diagnostic tools of PET scan measures of amyloid or tau protein,” commented senior author of the study, Adam Boxer (UCSF).

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This study follows research conducted by other investigators published last year, which found high levels of plasma amyloid were a predictor of Alzheimer’s. “However, amyloid accumulates in the brain many years before symptoms emerge, if they emerge,” said Boxer. “In contrast, the amount of tau that accumulates in the brain is very strongly linked to the onset, the severity and characteristic symptoms of the disease.”

Corroborating these results, a companion study from Oskar Hansson (Lund University, Sweden) was published in the same issue of Nature Medicine. Hansson’s research concluded that pTau181 was a stronger predictor of developing Alzheimer’s in healthy elders than amyloid.

The researchers hope that this blood test could be available to doctors within the next 5 years.

Sources: Thijssen EH et al. Diagnostic value of plasma phosphorylated tau181 in Alzheimer’s disease and frontotemporal lobar degeneration. Nat. Med. doi:10.1038/s41591-020-0762-2 (2020) (Epub ahead of print);;–mcb022620.php