I went to a fascinating conference at the start of the year organised by the Society of Actuaries. It’s a triennial conference entitled “Living to 100“, which looks at actuarial, epidemiological and medical developments in longevity. Apparently, this title attracted some interesting delegates the first time the conference was run – in particular, a number of people came because they wanted to know how to live to 100 rather than how to value annuity portfolios, and were very disappointed by the absence of seminars on crystals and dietary supplements! However, the delegates these days include a range of academics and practitioners interested in how long we are all likely to live.
So, accepting that not everything I found interesting would be of interest to a wider audience – although I maintain that creating a continuous mortality surface using two-dimensional p-splines is interesting – what can I say about the conference?
Let’s start with a bit on caloric restriction – in other words eating very, very little. This has been shown to extend life in a number of studies on small mammals, so it might be thought that humans could also benefit. Indeed, there are long-term studies in place to investigate the longevity of those who are voluntarily restricting their calorie intake. For mice, caloric restriction also seems to have a positive impact on energy levels, but in humans it seems to have the opposite effect. Another adverse side-effect in humans is reduced libido. So whilst eating much, much less might add a few years to your life, you’ll be permanently hungry, lethargic and celibate – not an attractive option.
What about dietary supplements? We’re all familiar with the supposed benefits of red wine. This benefit derives from a chemical known as resveratrol, and there is evidence that resveratrol can have a beneficial effect on longevity. However, this effect has been shown only in mice. Furthermore, all it does for mice is negate the effect of a high-fat diet – in other words, the mice live just as long if they eat healthily as mice on high fat diets live when given resveratrol. Importantly, resvertatrol does not increase longevity for mice on already-healthy diets. Finally there is the doseage. Even if resveratrol had a positive impact on human longevity, you’d need to drink hundreds of litres of wine a day to get enough resveratrol. As the presenter helpfully pointed out, drinking this amount of wine would have an entirely different impact on health.
At this point, it’s worth considering the two broad approaches to extending longevity. Most of the attempted cures and indeed preventions are aimed at treating the illnesses of old age, such as heart disease. However, it is helpful to consider these diseases as a symptom of the body’s reduced ability to repair itself. We all have built-in mechanisms for the repair of damage that our bodies accumulate. As we age, these mechanisms become less effective. Trying to help the body’s repair mechanisms – in other words, trying to treat each disease – is one way of dealing with this reduced effectiveness; however, a more attractive approach would be to help to repair the body’s own repair mechanisms. This means tying to treat the ageing process itself.
If research were focussed on this area, rather than on illnesses, then people might be able to look forward to a longer healthy old age. For example, which is more attractive – to help add a few months or years to those suffering from cancer, or to delay the onset of cancer in the first place with the trade off that the illness, once developed, will become untreatable more quickly? Whilst both might offer the same overall life expectancy, the first scenario offers more years of healthy life.
Is there a dietary supplement that can offer this? Perhaps. There is an immunosuppressant (anti-rejection) drug called rapamycin that does appear – in mice – to slow the ageing process. Of course, as an immunosuppressant, you’d need to come off the drug at once if you had to fight an infection, and the attraction of taking a drug that dampens the immune response isn’t strong; however, it is interesting that a drug with such life-extending properties has already been discovered.
Unfortunately, however, the best chance you have of gaining longevity – probably through having better in-built rpair mechanisms – is to choose the right parents. A number of genetic profiles, or groups of genes, have been found that seem to be associated with exceptional longevity. Interestingly, these genetic profiles also tend to “trump” any genetic profiles associated with increased risks of various illnesses. So, for example, if you have a genetic predisposition to type II diabetes, you don’t need to worry about it if you also have the genetic footprint associated with “super-centenarianism” – that is, living to over 110.
Family history can be interesting in this regard. Whether you have a mother or father that reaches extreme old age is important, and whether it is your mother or your father and whether you are male or female is particularly important. Certain longevity genes are found on the X chromosome and others on the Y chromosome, so since only a son will inherit his father’s Y chromosome, some longevity traits can be passed only along this line.
This only touches the surface of the topics covered at this year’s conference, most of which made my own paper – on statistical credibility – seem pedestrian by comparison. If you’re interested I can strongly recommend reading some of the papers from the conference to see what the latest thinking is on longevity.