BioEd Online

A group of drugs already approved for humans can prolong the lifespan of worms. So, will these medicines be sought after by those seeking eternal youth?

Researchers have long been trying to find drugs or elixirs that can stave off ageing. But they have met with little success, partly because it is laborious and time-consuming to show that a drug adds years to our lives.

To get around this problem, Kerry Kornfeld of Washington University in St Louis, Missouri, and his team tested drugs on a tiny, short-lived worm called Caenorhabditis elegans. Researchers have shown before that tweaking certain genes can prolong this worm's life.

The team split the worms into groups and doped their food with 19 prescription medicines, from steroids to diuretics to anti-inflammatory drugs. "We went through a pharmaceutical textbook and picked a drug from each class," Kornfeld says.

Most of the drugs had no effect, or even killed the worms at high doses. But an anticonvulsant used to fight epilepsy, and two other similar compounds, lengthened the animals' lives by as much as 50%. Normal signs of ageing were also delayed in the animals.

Broad sweep

There is no proof that these drugs will extend lifespan in people. But Kornfeld says it is possible, because the genes and molecules that control the ageing process in worms generally exist in mammals too.

"It has the potential to be a real breakthrough," agrees David Sinclair who studies ageing at Harvard Medical School in Boston. "Fifty years from now people could look back and think that this was a turning point."

Researchers already know about a number of genes that influence lifespan in worms and other animals. But the hunt for drugs that defy ageing has only just begun, and much of the work has focused on one main group of genes that work together.

The anticonvulsant drugs appear to work without the help of these genes, because they prolong lifespan even when those genes are crippled. So the study is important because it hints at a new way in which ageing might be controlled, Sinclair says.

Scatter shot

Nobody knows exactly how the anticonvulsants work. The drugs are known to act on the nervous system, but they were developed in the 1950s and their exact mode of action has never been worked out.

But Kornfeld believes that the anti-ageing effects come from altering the nervous system, because the drugs prompted the worms' nerves to trigger egg laying and movement. He suggests that the nervous system somehow influences the rate of ageing in the rest of the body.

In theory, doctors could start prescribing the anticonvulsants tomorrow because they are already approved for human use. But experts say that this would be premature because there could be unknown long-term risks.

Testing the drugs in humans remains difficult. Because the drugs are prescribed mainly to children, there is no suitable human group already taking them that could be studied. If their anti-ageing effects were to be tested in people, doctors would probably have to examine their effect on diseases associated with ageing such as diabetes or Alzheimer's, as it would take many decades for any effects on lifespan to show up.

For now, Kornfeld and his team plan to test the drugs in flies and mice, and to widen their search to other types of chemical. "There may be other goodies in the pharmacy," Kornfeld says.