Not only have researchers identified a new cause of aging, but they found it also may be reversible.
In a study published Thursday in the journal Cell, researchers from Harvard Medical School -- in conjunction with the National Institute on Aging and the University of New South Wales in Australia -- identified a breakdown in cell communication in animals that causes aging to accelerate.
But after repairing the breakdown, scientists saw that tissue samples in older mice resembled those of much younger animals. The discovery potentially could lead to new treatments for age-related diseases, such as muscle deterioration and Type 2 diabetes.
"The aging process we discovered is like a married couple — when they are young, they communicate well, but over time, living in close quarters for many years, communication breaks down," David Sinclair, professor of genetics at Harvard Medical School, said in a statement. "And just like with a couple, restoring communication solved the problem."
The breakdown in communication within cells occurred between the nucleus and mitochondria, the study says. That communication is important because the mitochondria, often referred to as the "powerhouses" of the cell, generate the energy needed to carry out critical biological functions and have been identified as key players in aging, according to the researchers. When the mitochondria become less functional, age-related symptoms and diseases start to occur.
One chemical, NAD, starts the communication process. But as people age, the levels of NAD begin to decline. Without the chemical, a security-like gene called SIRT1 loses its ability to block an intrusive molecule (HIF-1) from interfering with communication. That interference reduces a cell's ability to make energy.
But researchers were able to use a compound that cells could transform into NAD to repair the broken communication network. And if they did so soon enough, some signs of the aging process appeared to be reversed within days.
When the researchers looked at the muscle from 2-year-old mice that had been given the compound, they found that in three indicators of aging (insulin resistance, inflammation and muscle wasting), the tissue in the mice looked like that of 6-month old mice.
In humans, that would be like the muscle of a 60-year-old transforming into the muscle of a 20-year-old, according to the researchers.
"There's clearly much more work to be done here, but if these results stand, then many aspects of aging may be reversible if caught early," Sinclair said.