 It has long been known that parabiosis, or using the blood from young animals, can alleviate and even reverse age-related changes in old animals. Now, scientists have taken this a step further, and have shown that using cerebrospinal fluid from young mice can improve the memory of old mice. We'll explore the science in this episode of Lifespan News. Similarly to blood, the composition of cerebrospinal fluid, or CSF, changes with age, but scientists still know very little about how these changes contribute to aging. One human study has shown that CSF from young healthy donors increases neuronal viability. In this new study, researchers infused 20-month-old mice with CSF drawn from young mice. Three weeks later, the researchers performed a simple experiment in which they gauged how well the mice remember stimuli associated with discomfort in the past. The researchers found that the mice that received a transfusion of CSF performed significantly better than controls. The scientists then ran a transcriptomic analysis of the hippocampus and identified 271 genes that were differentially expressed following the procedure. One of the proteins most upregulated by young CSF was serum response factor, or SRF, a ubiquitous transcription factor that is found not just in the brain, but also in skeletal muscle and the heart. Wherever it is expressed, SRF is known to increase cell motility, proliferation, and differentiation. The effects of an SRF knockout seen in the study strongly suggest that the effect of young cerebral spinal fluid is mediated by SRF and specifically its induced cytoskeleton growth. So something in young CSF was boosting the production of SRF, but there are hundreds of proteins that could be responsible for this. After another battery of experiments, the researchers narrowed down their search to fibroblast growth factor 17, or FGF 17. Interestingly, the levels of FGF 17 and human cerebral spinal fluid decreased with age. Supplementation of this protein was shown to have results similar to that of treatment with young CSF and was demonstrated to improve memory and mice. Infusing young mice with FGF-blocking antibodies, however, impaired their performance on cognitive tests. While the rejuvenating properties of young blood were widely known, the discovery that the aged brain can be improved by young CSF opens up an entirely new avenue of research into the aging brain. Importantly, although both blood and CSF consist of hundreds of components, the scientists can narrow down the ones responsible for particular outcomes, such as FGF 17, and turn them into therapeutic targets. No need more studies, but these early results are promising. Young CSF, like young blood, can provide benefits, but this doesn't mean we need to live like vampires to extend our lives. Though that was the topic of a recent video from Life Noggin, see you can watch that if you want to learn more. Vampire or not, we hope you'll subscribe and come back to join us again. But vampires, please note that this is not an invitation into my house. I'm not taking any chances. I'm Ryan O'Shea and we'll see you next time on Lifespan News.