A certain hormone essential to the aging process is apparently under genetic control, opening up a pathway that regulates disease and aging, a new study has revealed.

Researchers from the University of Georgia (USG) have discovered that levels of the hormone growth differentiation factor 11 (GDF11) are actually determined by genetics. This finding represents another mechanism wherein aging is encoded in the genes.

Past studies found that blood levels of GDF11 decrease over time. By restoring GDF11, cardiovascular aging in mice was reversed. At the same time, the muscles and the brain are rejuvenated. This discovery was listed as one of the top 10 scientific breakthroughs in 2014.

Now, the new study can help scientists find out why the GDF11 decrease with age and whether they can be sustained to prevent disease.

"Finding that GDF11 levels are under genetic control is of significant interest," said senior author of the study Rob Pazdro, who is an associate professor in USG's Food and Nutrition department. "Since it is under genetic control, we can find the genes responsible for GDF11 levels and its changes with age."

Pazdro and his colleagues' findings confirmed the results from previous experiments which showed that GDF11 levels are reduced over time. These experiments also showed that most of the GDF11 depletion takes place by middle age.

Additionally, the new study examined the link between levels of GDF11 and markers of aging such as lifespan in 22 genetically varied inbred mice strains. The strains with the highest GDF11 levels appeared to live longer than the others.

Pazdro's team used gene mapping to identify seven candidate genes that may distinguish blood concentration levels of GDF11 at middle age. For the first time, this demonstrates that GDF11 levels are strongly heritable and may be passed on.

"Essentially, we found a missing piece of the aging/genetics puzzle," said Pazdro.

He said they have made a vital step toward understanding the process of aging, why humans age, and what pathways are responsible for driving the process.

"It's the first step down a long road, but it's an important step," added Pazdro.

The findings of the study are issued in the Journals of Gerontology Series A Biological Sciences and Medical Sciences.