Anyone keen on achieving increased longevity would seem to have had some good news of late. Gene manipulation in laboratory worms, flies and mice have enabled them to live beyond their normal life spans, raising the possibility that scientists might find a way to extend human life as well.
Last month, researchers at the University of California reported that ageing rats had been rejuvenated dramatically with a cocktail of dietary supplements. A combination of acetyl-l-caritine and alpha-lipoic acid was found to reduce the number of free radicals in the "engines" of cells. Free radicals are destructive substances associated with the development of cancer and other diseases.
But just because some older rats have begun to buzz around with energy, or a fruit fly can now live 50 per cent longer than normal, does not mean that we are in any way closer to realising the proverbial fountain of youth, as some of the more lurid headlines have suggested. Regenerative and indeed rejuvenative medicine is still a long way off.
Other recent research, by scientists from the Baylor College of Medicine in Houston, reported in Nature, suggests a possible association between the effects of ageing and living longer. The research team inadvertently created mice that possessed large amounts of p53 protein, which forces cells to self-destruct rather than become cancerous.
However, the mice paid a price for avoiding cancer. They lost weight and muscle, developed hunched backs and brittle bones. Their skin was thinner and their wounds took longer to heal. The genetically-altered mice died much sooner than normal rodents.
The researchers hypothesised that the overactive p53 protein disrupted not only cancer cells, its normal target, but also skin cells that replenish muscle, bone and other tissues.
In effect, they raised the "shocking possibility" that ageing is simply a side effect of the natural safeguards that protect us against cancer. The same p53 mechanism that protects us from tumours early in life may turn later into an "age-accelerator".
It was an unexpected finding, which needs further research. At the very least, it points to a huge uncertainty for those who would have us believe regenerative medicine - the concept of repairing the body by developing new tissue and organs to replace those wearing out - is around the corner.
Perhaps we should be concentrating more energy on less dramatic, but more immediate issues to do with ageing. Even with no change in life span, we are looking at some major challenges in the next 30-50 years. The percentage of those aged 65 or over is set to rise from 11.2 to 23.9 per cent of the population by 2050, with particularly rapid growth after 2025. At the same time, there will be relatively fewer people of working age in the population, which raises some serious issues. A 100 per cent increase in the dependency ratio between young and old, and those who work and those who are retired, is forecast.
Even now, the pressure on individuals - rather than the State - to act as carers is immense. Nine out of 10 carers are women, most of whom give at least 50 hours a week to the task. They are the unpaid and certainly unsung heroes of our health service.
What will happen when the number of carers diminishes relative to those who require care, and indeed when the vocational element of such caring ceases to be valued, as seems likely?
There are so many economic, medical and social conundrums associated with the increased life expectancy we already enjoy as to make it almost immoral to consider adding to our longevity by genetic therapy. Surely we need to address issues such as mandatory retirement at the age of 65, the provision of adequate health resources for the predicted increase in the elderly and the fundamental question of "who is responsible for my ageing parent?" first.
Within the health service, it is time we addressed issues of ageism. The first five-year report of the National Cancer Registry, published last month, contained statistics which suggest that a subtle form of rationing, based on age, may be present within the system.
Studies of the care of people with heart disease in general practice have also hinted at less comprehensive treatment for those aged over 65.
It may well be that society will choose to exercise rationing of health care on age grounds. But before this happens, it requires a full and open debate about the implications of such a decision.
And until such time as we address such issues, I would humbly submit that we have no business pursuing the holy grail of Methuselah. The elixir of youth could turn out to be a very bitter drink indeed.
•E-mail Dr Muiris Houston at mhouston@irish-times.ie or leave a message at 01-6707711 ext 8511. He regrets he cannot reply to individual medical problems
•Following an article on Lasik eye treatment, which appeared in The Irish Times on January 21st, we have been asked to point out that the Wellington Ophthalmic Laser Clinic in Dublin carries out the procedure on people with presbyopia. Surgeons at the clinic report that they "have excellent results for this group of patients using a technique called monovision"