Dementia is one of the most common neurological diseases in old age. In Germany, around 1.8 million people live with the diagnosis. The long lead time of the disease is treacherous. If Memory lapses, orientation problems or language disorders If you notice something, pathological development has usually been building up in the brain for years.

That’s why research is increasingly focusing on early warning signs in the body. A blood test could indicate an increased risk of dementia long before the first symptoms appear. New results suggest: A certain protein in the blood is linked to a later onset of the disease. The changes may be detectable up to 25 years before the first symptoms.

Protein shows early changes

In particular, a protein called phosphorylated tau protein 217 (p-tau217) was examined. This molecule is closely related to processes that occur in the brain in Alzheimer’s disease. If pathological deposits form there, the concentration of this protein in the blood also changes. The results come from a large long-term study. Blood samples from 2766 women were available for analysis.

At the start of the study, all participants were between 65 and 79 years old and mentally healthy. There was no evidence of a cognitive disorder. The women then received medical support and regular examinations for many years.

The blood samples from the starting phase were initially stored in a biobank. It was only many years later that scientists analyzed them again and determined the concentration of the protein p-tau217.

Accompanied women for decades

The observation period for this study is unusually long. Some participants received medical support for up to 25 years. During the course of the study, numerous women developed memory problems or dementia:

• 1,311 participants later received a diagnosis of mild cognitive impairment or dementia
• 849 women developed mild cognitive impairment (MCI)
• 752 women suffered from dementia

The evaluation showed a clear connection between the blood marker and the later risk. Even moderately elevated levels of p-tau217 were associated with significantly higher disease rates.

“Our study suggests that we may be able to identify women at increased risk of dementia decades before symptoms appear,” says study author Aladdin H. Shadyab from the University of California San Diego.

P-tau217 increases risk of dementia

The analysis of the study data shows a clear connection between the protein in the blood and later diseases. The higher the value of the biomarker p-tau217, the more often the participants developed it over the years Memory problems or dementia.

The most important results:

• When the p-tau217 level increased, the risk of dementia or mild memory impairment was almost two and a half times so high.
• If you look at dementia alone, the risk was more than three times as high.
• Women with the highest measured p-tau217 values ​​had a more than sevenfold increased Risk of developing dementia later.

Age, genes and hormones are also important

The connection between p-tau217 and later dementia was not equally strong in all participants. Some known risk factors significantly increased the effect.

The connection was particularly pronounced for:

• Women over 70 years old
• Carriers of the Alzheimer’s risk gene APOE ε4
• Participants with hormone therapy consisting of estrogen and gestagen

The connection was particularly clear in this group. Women with elevated p-tau217 levels were significantly more likely to develop dementia.

Simplify diagnostics using a blood test?

Alzheimer’s disease is often only diagnosed when memory problems are already clearly noticeable in everyday life. In order to make a reliable diagnosis, doctors usually resort to complex examinations.

These include, for example:

• Brain imaging procedures, such as special brain scans
• Examinations of cerebrospinal fluid taken from the spinal cord
• detailed memory and thinking tests

A blood test would be much easier. It could be carried out more quickly and could reach many more people in the future.

“Blood-based biomarkers are particularly promising because they are significantly less invasive and easier to access than brain scans or cerebrospinal fluid studies,” says study author Linda McEvoy.

Blood test not yet routine

Despite the strong results, the biomarker is currently not a routine tool in medical practice. The researchers still see open questions. Further studies must clarify:

1. how such a test can be used in everyday life
2. whether early risk detection can actually change the course of the disease
3. what role Lifestyle, medication or prevention play at this early stage

Another point is important: the study only included older women. Future studies will have to show whether the results can also be transferred to men.

The data still provides an important clue to the origins of the disease. Changes in the brain can apparently occur unnoticed over many years before the first memory problems appear.

At the same time, another approach is emerging

Something has also changed recently in diagnostics. It has already been done in the USA a blood test is allowedwhich can detect Alzheimer’s markers via two proteins in the blood. The “Lumipulse G pTau217/ß-Amyloid 1-42 Plasma Ratio” procedure measures the ratio of p-Tau217 and beta-amyloid 1-42.

In studies, the hit rate was over 90 percent. The test is aimed primarily at people over 55 with initial memory problems and could partially replace complex brain scans or cerebrospinal fluid examinations in the future.

Briefly summarized:

• A certain protein in the blood (p-tau217) can provide evidence of a later risk of dementia in women – possibly up to 25 years before the first memory problems.
• A long-term study with 2,766 initially healthy women showed that the higher the value of this biomarker, the more frequently memory problems or dementia occurred later.
• A blood test could therefore help to detect dementia much earlier in the future, even if it is not currently a routine procedure in medical practice.

By Anne Bajrica