By FIONA MACCRAE

Last updated at 09:24 30 November 2007

Some put their faith in expensive face creams, while others go under the surgeon's knife. But, no matter which route they choose, they will never regain the dewy skin of their youth.

Now scientists may have found a way of turning back the hands of time, returning ageing skin to a more youthful state. It raises the prospect of an elixir of youth being developed.

The breakthrough hinges around a gene that acts as a master-switch in the aging process.

Research showed that blocking its action in mice had a rapid and dramatic effect on their skin. Within just two weeks, the skin of elderly mice had rejuvenated to such a degree that it was comparable to that of a newborn.

The US researchers said: 'We found a pretty striking reversal to that of the young skin.

'The implication is that the aging process is plastic and potentially amenable to intervention.'

The study, carried out Stanford University in California, showed, that as well as looking young, the skin also exhibited biological features of youthfulness, including being thicker and having more cells dividing inside it.

The researchers said that the gene, known as NF-kappa-B, is a master-switch in the ageing process in both humans and mice, switching on and off other age-related genes as we get older.

'Here we show that aging in mouse skin can be reversed by blocking a single gene,' they said.

'These findings suggest that aging is not just a result of wear and tear but is also the consequence of a continually active genetic programme that might be blocked for improving human health.'

Developing a drug that shuts off the gene in people could have a dramatic effect on human skin.

However, fears that interfering with the gene could trigger cancer mean that such a drug would be unlikely to be used as a cosmetic.

Lead researcher Dr Howard Chang cautioned: 'You might get a longer lifespan but at the expense of something else.'

Instead, it would be more likely to be used as a short-term medical treatment, with possible applications speeding up wound healing in the elderly

The research, published in the journal Genes and Development, follows yesterday's announcement that a drug said to hold back ageing and prevent diabetes is to undergo testing next year.

US firm Sirtris Pharmaceuticals believes its concentrated pill form of the red wine chemical resveratrol could help prevent a raft of ills, including cancer, heart disease and Alzheimer's.