Spanish and Swedish scientists develope simple blood test for early detection of Alzheimer's disease

Joint research by Spanish and Swedish scientists has found a method that makes it possible to determine with very high reliability whether a person is suffering from Alzheimer's at a very early stage, based on blood levels of a specific biomarker, the protein p-tau217. This is how the researchers, who have published the results of their work in the scientific journal Nature Medicine, summarise their findings.

This is an important clinical advance that opens the door to generalised screening by specialists for the early detection of Alzheimer's disease in patients with symptoms of cognitive impairment, an early diagnosis that would be key to being able to apply existing palliative treatments, which will allow better management of the disease and an improvement in their quality of life.

Early diagnosis is essential in the treatment of a disease that already affects 800,000 Spaniards - it is the dementia with the highest mortality rate - and which each year sees higher numbers of diagnoses due, among other factors, to the ageing population. Until now, the existing early screening methods for this disease have been lumbar punctures or positron emission tomography (PET), which are more expensive, more traumatic for the patient and, in the case of PET, not available in all regions.

The authors of the finding are researchers from the Pasqual Maragall Foundation and Barcelona's Hospital del Mar Research Institute, who have worked in coordination with colleagues from the Swedish universities of Gothenburg and Lund. They have managed to prove the 90 per cent accuracy in clinical trials which involved 1,767 people at the Barcelona hospital, the Swedish hospitals of Gothenburg and Malmö, the Italian hospital of Brescia and a Swedish primary care area.

Using an automated blood test, the researchers have been able to determine the levels at which the presence of the p-tau217 protein can be used to determine whether a person will develop the disease or not. They have been able to establish two cut-off points according to the level of presence of the biomarker. If the test says that the level is below the low cut-off point, the result is negative. If it is above the high point, it is positive.

If it is somewhere in between, the risk exists and the diagnosis should be confirmed or ruled out with a lumbar puncture or a PET scan. However, Marc Suárez-Calvet, one of the authors of the study, stresses that "the results of this biomarker must always be interpreted by a neurologist or other specialised health professional, after a proper neurological assessment and never as an isolated test".

The Spanish scientific team highlights the clear possibility they see of implementing their method as the standard form of reliable early detection of Alzheimer's disease in Spanish clinical practice. They say that the test is simple and very easy to use, as it can be performed "in any clinical laboratory", which opens the door to widespread use and "more equitable access to care and better treatment".

The analysis is 60-80 per cent cheaper than existing methods. The researchers believe that the test's "low economic impact, coupled with its large-scale applicability, can contribute to improving access to early diagnosis of Alzheimer's and to improving the clinical approach to the disease".