Volunteers in a California study were given a cocktail of three common drugs for one year-- a growth hormone and two diabetes medications. Scientists had been testing the drugs in the hope of regenerating the thymus gland.
But upon further analysis, they found that participants had lost an average of 2.5 years on their "epigenetic clock," measured by analyzing marks on a person's genomes, according to the journal Nature. Participants' immune systems also showed signs of rejuvenation.
Even the scientists who conducted the study were shocked by the results. "I’d expected to see slowing down of the clock, but not a reversal," UCLA researcher Steve Horvath told Nature. "That felt kind of futuristic."
Researchers warn the findings are preliminary: the study only included nine participants and did not include a control group. But if further research confirms the findings, the impact on health care and society's relationship with aging as a whole could be massive.
The epigenetic clock is measured by a record of chemical changes to an organism's DNA. The trial's main purpose was to test whether growth hormone could be used to restore tissue in the thymus gland, which is crucial for immune function. The gland starts to shrink after puberty and becomes clogged by fat. Previous studies had shown growth hormone stimulates regeneration in the thymus, but it can also cause diabetes, which is why the diabetes medications were included in the most recent study.
Scientists only even checked the epigenetic clocks in the participants as an afterthought. Horvath looked at four different measures of the epigenetic clocks of each of the participants. He found all of them had reversed significantly.
"This told me that the biological effect of the treatment was robust," said Horvath. Six participants provided blood samples six months after the trial. and the effect had remained the same. Given that the effect was so strong in each participant, Horvath is optimistic for future testing.
The researchers are planning a larger study with more diverse participants by age, gender, and ethnicity, and the three drugs are being tested independently to determine specific effects.