Current efforts to extend lifespan have traditionally resulted in a longer period of old age. In a new study, published in the journal eLife, researchers called the extension of youth "'transcriptional drift" and said the findings could aid research into conditions where aging starts earlier, like Hutchinson-Gilford progeria syndrome.
The team, from The Scripps Research Institute in California, administered either water or mianserin to thousands of roundworms and documented changes to their genes. These roundworms normally reach reproductive maturity after one day and they live for between two to three weeks.
Previously, scientists had found mianserin extended the lives of roundworms, so they were looking to find out why that was. They measured the activity of genes as they aged, measuring activity in young adults first as a reference from which to monitor the ageing process.
As they aged, there were big changes in gene expression that came as a massive surprise. Groups of genes that normally work together to play a role in the same function changed expression to go in opposite directions. Essentially, it is like having all of the light switches in a building suddenly change position from off to on.
"The orchestration of gene expression no longer seemed co-ordinated as the organism aged and the results were confusing because genes related to the same function were going up and down at the same time," said lead author Michael Petrascheck.
At 10 days old, worms that had been treated were physiologically seven days younger than those that had not. By day 12, however, changes were complete and exposure to the antidepressant had no additional effect. Treated worms died an average of seven to eight days later.
Scientists dubbed this phenomena transcriptional drift and later analysis of mice and human brains showed mianserin has the same effect on mammals. However, the authors said people should not go out and start taking the antidepressant in the hope of extending their own youth
"We don't want people to get the impression they can take the drug we used in our study to extend their own teens or early twenties," Petrascheck said.
"We may have done this in worms, but there are millions of years of evolution between worms and humans. We think it is exciting to see that extending lifespan by extending young adulthood can be done at all. How much of our findings with regards to lifespan extension will spill over to mammals is anyone's guess, for example the extension of lifespan might not be as dramatic. However, we are already excited about the fact that we observed the phenomenon of transcriptional drift in species ranging from worms, mice to humans."