Prospects for extending lifespans have generated some striking headlines in recent weeks. “Tantalising drug lets mice live longer but retain youthful looks,” the Times announced. “Anti-ageing drug is ‘holy grail’ of cancer fight,” claimed the Telegraph.
Nor is the agent of this media adulation – antibodies that block the action of the inflammatory chemical IL-11 – the only wonder anti-ageing medication to make news over the past few months. In March, researchers announced that, by properly balancing two types of immune cells, they had managed to improve the ability of elderly mice to fight off viral infections and so live longer. This came on top of research last year from another group revealing they had used injections of the drugs dasatinib and quercetin to rejuvenate the hearts of mice and make them less frail.
It sounds very encouraging. Medical science is clearly progressing, and laboratory mice are living longer – though some caution should be noted. For a start, translating experiments from rodents to humans is a notoriously tricky business. An example is provided by the drug fialuridine, which was developed in the 1990s to treat people with hepatitis B. It worked well in mice (and in rats, dogs and primates) but in human trials it triggered liver failure. Five individuals died as a result.
It remains to be seen how treatments involving the blocking of the action of IL-11 will fare when the results of human trials are published, a point stressed by Ilaria Bellantuono, professor of musculoskeletal ageing at Sheffield University. “The problem with all these interventions is that we do not have evidence in patients,” she argues. “Although trials are under way in the US, there are scientific hurdles to overcome to use these interventions in patients, such as understanding who would benefit from the intervention. Every drug has side effects and there is a cost associated with it.”
In any case, simply pursuing the lengthening of human lifespans for its own sake is being questioned by a growing number of scientists who believe we should be tackling healthspans, not longevity, as the main aim of ageing research. In other words, we need to do much more than boost longevity for its own sake and instead pursue the specific goal of increasing the number of extra years we experience when we are independent, free of chronic disease and wealthy enough to lead fulfilling lives.
It is a point summed up by Susan Howlett, professor of pharmacology and medicine at Dalhousie University in Nova Scotia. “Who wants to improve lifespan if you are in terrible shape and you cannot enjoy your life? Something’s going to get you in the end. We all know that. What we should really fear is a long period of impairment before that happens.”
It is an approach to senescence that is perfectly summed up by the response to the age-old question: “What is the best way to die?” Being shot by a jealous lover when you are aged 85 remains my favourite answer.
Or as Howlett puts it, we should aim for the simple goal of dying healthily. “You want to spend the largest portion of your older years in the best possible health. That should be our prime aim.” A glance at British population statistics reveals the importance of this approach. Life expectancy has plateaued in the UK. However, numbers of those living to relatively old age have soared. In a decade, there will be about 13 million people over the age of 65 in the United Kingdom, when they will form more than a fifth of the nation’s population.
This is a very different picture from the one experienced in Britain only a few decades ago when those over retirement age were in a distinct minority. In 1950, for example, there were 5.3 million people over 65, a number that accounted for only 10.8% of the overall population.
From this perspective, it is clear that elderly people will need to be fit and able to make the most of their lives, not just for their own sake but to avoid becoming a burden on the relatively youthful remainder of our society, a group that is shrinking in numbers as the population ages.
We need, in short, to prepare for a society that has a functioning population of elderly individuals. Think of it as a die healthy campaign. The trick, of course, is achieving this ambitious aspiration.
The critical factor will be mental health, insists Dr Richard Siow, director of ageing research at King’s College London. “We need to start preparing for the onset of old age while we are still in middle age. We need to walk rather than take the bus, use stairs not the lift, avoid stress, adopt a healthy sleep pattern and not look at Netflix until 3am, eat properly and take care how we use social media.
“We need to go into old age with a healthy mindset, otherwise it will become oppressive for many people and they will sink into anxiety and depression. It really does not have to be that way, but we have to think about the issue now if we want people to enjoy their later years in a fulfilling way. That is the real issue about old age that we face today.”
• Robin McKie is science and environment editor for the Observer
