Key points from article :
Many older adults are not able to exercise regularly due to physical limitations or disabilities.
After mice exercise, their livers secrete a protein called Gpld1 into the blood.
Levels of this protein in the blood correspond to improved cognitive function in aged mice.
Increasing the amount of Gpld1 produced by the liver could confer many of the same brain benefits as regular exercise.
The enzyme is also elevated in the blood of elderly humans who exercise regularly.
"At least some benefits of exercising might one day be available in pill form" - study senior author Saul Villed.
Researchers used genetic engineering to coax the livers of aged mice to overproduce Gpld1.
But Gpld1 produced by the liver does not pass through the blood-brain barrier.
Research by UC San Francisco Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research published in Science journal.
