Worms live longer on antidepressants

It seems antidepressants don't just help humans. Roundworms given a particular antidepressant lived longer -- possibly because they were fooled into behaving as though they'd run short of food.

A low-calorie lifestyle is known to boost the lifespan of worms and some mammals, so it might be possible to use the drug as an aid to longevity in humans.

Michael Petrascheck and his colleagues at the Fred Hutchinson Cancer Research Center in Seattle exposed the worm Caenorhabditis elegans to 88,000 chemicals to see which, if any, caused them to live longer.

Petrascheck noticed that one of the successful compounds resembled a class of antidepressants that work by blocking the action of the neurotransmitter serotonin. When he tested these drugs, he found that some of them, too, extended the worm's lifespan. The best, mianserin, made the worms live 31 per cent longer than untreated worms.

Further tests showed that mianserin blocks two specific receptors, SER-4 and SER-3, that are involved in keeping the balance between hunger and satiety. When the researchers repeated the test using worms on calorie-restricted diets -- known to make them live longer -- they found that mianserin did not extend their lifespans any further.

This suggests that the drug works by mimicking the sensation of starvation. "The animal perceives that it's starving, and that's enough to increase lifespan," says Petrascheck. Tests in mice are under way.