In a series of experiments, scientists infused elderly mice with blood from young mice — and the results were shocking. Simply by introducing the young blood into older mice’s systems, researchers improved the subjects’ muscle tone, endurance, smell, cognitive function, and memory. 

The studies “suggest that there might be factors in the young blood that can produce globally regenerating effects in older animals,” National Geographic reported on May 4. “In addition to reversing the normal ravages of aging, the papers suggest, young blood might help turn around declines in cognitive function associated with age-related conditions such as heart enlargement and Alzheimer’s disease.”

Subsequent research showed injecting mice with a specific protein found in young blood — and just that protein — had similar health benefits. Scientists drew blood from mice the same age as people in their 20s, The Washington Post continues. All studies conducted on mice have had positive effects on cognitive and muscular function.

This, of course, raises questions. “Will it work on humans? What is the proper dosing? Do you need a constant supply of young blood to maintain the effects? Are there long-term consequences?” The Washington Post asks. Researchers will begin injecting humans with blood from younger patients this year. The first study focus on Alzheimer’s patients.