How fit the brain is, how long life expectancy is, or whether dementia is present – what proteins in the blood reveal

If the brain and immune system have remained young, i.e., are significantly more efficient than their age would suggest, then a person can hope to have many more years ahead of them. This is the primary finding of a research group at Stanford University. The second: Various factors in the blood reveal how young the brain or another organ has remained.

Blood samples from more than 44,000 people between the ages of 40 and 70 were analyzed. The data were published in the journal Nature Medicine at the beginning of July. The authors searched for proteins released into the blood by various organs, the amounts of which change over the years.

The heart and brain of younger people work slightly differently than those of older people. Thus, a young brain produces more of some proteins and less of others. This results in age-typical protein patterns. These can be measured not only in the brain cells but also in the blood.

When the patterns typical of the brain and immune system changed little over the years, life expectancy increased. The fact that only the protein patterns of these two organs provided evidence of longevity demonstrates their great importance in controlling aging, the authors emphasize.

Blood abnormalities also provided predictions of unhealthy aging. For example, a certain protein pattern indicated a higher risk of Alzheimer's disease. A person with an aging heart had a higher risk of cardiac arrhythmias and heart failure.

However, there is still no test available for doctors' offices that can measure protein patterns in someone's blood and confirm what they've always suspected: that they are years younger than their passport indicates. Or that can determine their risk of age-related organ diseases. Such tests now need to be tested in clinical trials.

However, the presence and absence of numerous proteins in the blood have much more far-reaching significance than simply enabling an approximate age determination. "In terms of protein patterns, we are at the beginning of a completely new era," says Stefan Lichtenthaler of the German Center for Neurodegenerative Diseases in Munich. "We have now come very close to the goal of using protein patterns for both the diagnosis and prognosis of Alzheimer's, Parkinson's, and other brain diseases."

An important milestone for Lichtenthaler are the studies of the Global Neurodegeneration Proteomics Consortium published in mid-July in the journal "Nature Medicine." Research teams worldwide have pooled and standardized data from numerous smaller studies in Europe and the USA, including one from Tübingen. Protein patterns from people with and without brain diseases were compared. Dozens of different proteins revealed patterns that are characteristic of specific brain diseases.

In many neurodegenerative diseases, such as Alzheimer's or Parkinson's, the disease process begins years or even decades before the first symptoms appear. For example, in Alzheimer's: Due to unknown triggers, small clumps of protein fragments form in the brain. Initially, communication between the nerves is disrupted. Later, they die. All of these processes leave characteristic traces in the blood.

The first blood test that reliably diagnoses Alzheimer's dementia was recently approved in the EU when the patient is already exhibiting initial symptoms, such as memory impairment or disorientation. This blood test simplifies the diagnosis.

But what patients need even more urgently are blood tests that detect harmful processes in the brain, such as clot formation or nerve changes, years before the onset of visible symptoms. The brain usually still functions well at this stage, but those affected are at very high risk of dementia, Parkinson's disease, or another brain disease. "Early detection tests like these can now also be developed using the new data," says Lichtenthaler.

An early diagnosis is especially important when therapies are available that, if applied early, can delay the onset of the disease by years. This could soon be the case with Alzheimer's. There are now medications available that dissolve the aforementioned clumps in the brain. The hope is that the initial clumps can be destroyed at a very early stage of the disease, thus largely preventing or at least significantly slowing down the death of the nerves. Then, hopefully, patients would never experience the dreaded symptoms of disability and personality changes.

One of these drugs, called Leqembi , was approved in the EU a few weeks ago, and another received approval from the expert panel at the end of July. Currently, however, it is only being administered to patients who already exhibit mild symptoms of dementia. In these patients, the substance can at least slow the progression of the disease somewhat. Studies are now being conducted to determine whether very early administration can delay dementia in asymptomatic people who, due to their genetic makeup, are certain to develop Alzheimer's.

The new protein patterns are also very important for monitoring this and other clinical trials of drugs for brain diseases, as they indicate whether a therapy is effective.

Unfortunately, the Stanford researchers didn't discover a panacea for healthy aging. However, when subjects smoked, consumed alcohol, processed meat products, or were poor, several of their organs aged prematurely. On the other hand, plenty of exercise, the consumption of oily fish and chicken, and higher education gave people younger organs.

It was already known from previous studies that these factors cause premature aging or protect against it. And experience shows that even if someone bravely follows all the recommendations, they are still not guaranteed to live to a healthy 100 years. Because not only the environment but also genetics plays an important role in aging.