The aging process of the brain cannot yet be reversed – at best it can be slowed down. But now researchers have succeeded in animal experiments in rejuvenating a brain and improving cognitive abilities again. This could be a milestone in the treatment of dementia.

Around 1.6 million people with dementia live in Germany. Researchers assume that the number of people affected will increase massively in the coming years. The World Health Organization (WHO) expects an increase of 40 percent worldwide by 2030. There is still no cure for age-related brain decline.

However, an international study in which researchers from Stanford University in California and Saarland University were involved, among others, could be groundbreaking for new research and therapy approaches. It was recently published in the science magazine ” Nature “.

The researchers were able to show that the brain performance of old mice improved significantly when they were injected with the brain fluid of young mice. The so-called cerebrospinal fluid (CSF), also known as liquor, which supplies the brain cells with nutrients, was taken from ten-week-old mice and injected into mice that were over 18 months old over a period of seven days. After about two weeks, a test actually showed improved memory performance in the old mice. Similar effects occurred when the researchers injected the mice with the brain fluid from young people.

According to the researchers, a specific protein is responsible for the rejuvenation effect in the brains of the mice: the fibroblast growth factor Fgf17. If the scientists injected the mice with Fgf17 in isolation, the same rejuvenation effects occurred.

Fgf17 is also found in human cerebrospinal fluid and decreases with age. Among other things, the protein ensures that the transmission of electrical signals works better. “The results demonstrate the rejuvenating power of young CSF,” the study states. Fgf17 is the key to restoring the function of the so-called oligodendrocytes in the aging brain. These cells produce myelin, which electrically insulates the nerve tracts and thus ensures faster signal transmission.

To what extent therapeutic approaches against dementia can be derived from this study is questionable, but many experts still consider the results to be important. “Even if it is largely unclear how this finding can be transferred in detail to humans – not least because a very old mouse brain is many decades younger than an old human brain – the principle described is still very important,” said such as Gerd Kempermann from the German Center for Neurodegenerative Diseases (DZNE) to the Science Media Center (SMC).

“Through such work, we are learning to understand better and better what aging really means in the brain and which processes are perhaps not as inevitable as we often think.” However, young cerebral fluid does not make a young brain, he qualifies, even if it does they apparently support the regeneration. The doctor emphasized that this does not result in any direct therapy.

Matteo Bergami from the Cluster of Excellence for Aging Research CECAD at the Cologne University Hospital described the study as “pioneering work”: “This is an important study that shows that the brain water obtained from young subjects (mice or humans) and given to aged mice via an infusion enough to improve aspects relevant to brain cognition – like memory formation and retention,” he also told SMC.

“Whether this can be conclusively proven at the cellular level remains to be seen, but the experiments presented provide clear evidence for improved plasticity of the OPCs and the hippocampal brain circuits through the supplementation with young cerebrospinal fluid or the specific factors contained therein. This is quite remarkable,” continued Bergami.

Bergami also thinks it is “very exciting” that the administration of Fgf17 could be responsible for significant changes in brain functions. “If these results are confirmed in further work, they will go beyond age-related cognitive decline as they may also have important therapeutic applicability in demyelinating diseases such as multiple sclerosis.”

The molecular biologist Frank Edenhofer from the University of Innsbruck also underlined the importance of the research results: “The present study marks an important step in understanding age-dependent processes in the brain and possible interventions to mitigate cognitive decline.” The hypothesis that cerebrospinal fluid plays a role in brain aging games are not new.

“Previous studies have shown that the protein composition of the CSF changes with age: for example, pro-inflammatory substances are increased and nerve-specific growth factors are decreased. “However, the causal relationship between age-related CSF and changes in cognitive performance has so far been unclear.

Edenhofer also sees a few methodological flaws in the study: According to him, the rejuvenating effect could have been overestimated because the study authors used artificial CFS in the control group instead of CFS preparations from old animals, the researcher criticized. Edenhofer also complained that the scientists only used “fear conditioning” when analyzing the behavior of the mice. Other analysis methods would have been helpful to map a broader spectrum of behavior.

The research work with the brain water that has now been published builds on existing research results with blood. These studies have already shown in the past that the blood of young mice can also reverse the brain aging of old mice.

But since the brain is protected by the blood-brain barrier, only certain substances can get into the brain. That’s why the researchers came up with the idea of ​​putting young CSF directly into the brain – apparently with initial success. Further studies have to show exactly what this means for a possible further development of the treatment of Alzheimer’s and dementia.