Aging is a complex biological process. Professor Karl-Heinz Krause of the University of Geneva explains its contours to us.
Health Planet: Life expectancy has increased significantly. Why are we living longer today?

Prof. K.-H. Krause: No, not really. We know that the decline in infant mortality at the start of the 20th century has increased life expectancy. Today it is the decline in mortality among the elderly (over 65) which is increasing very significantly. There are several hypotheses to explain it. First, better food may have something to do with it. However, increasing longevity is also a reality in poor countries. Second, modern medicine probably has a role to play. An 80-year-old man suffering from pneumonia will see his life extended today thanks to the antibiotics available. Finally, the security of modern life should not be overlooked. Humanity has never known this before. The probability of dying by murder is very low. For most people, food and clothing resources are good. Compared to 150 years ago, living conditions are almost heavenly.

Will the life expectancy curve continue to progress?

Yes, the predictions are clear. If we base ourselves on all the existing data, we don't see a reversal point. Which is surprising to say the least when we think of the poor nutrition and obesity that our societies are experiencing. I think that these problems should eventually decrease our longevity, but, for the moment, we don't see it. In the United States, on the other hand, there is a fairly significant drop in life expectancy in the middle and poor classes. Taking morphine painkillers, supported by aggressive marketing, has a major impact on mortality. The tragic end of singer Prince is an example. But alcoholism, other drugs and suicide also contribute to the problem.

Are we aging healthier?

Yes, healthy lifespan is increasing, but the data is mixed. It increases in people with a healthy lifestyle (quality food, physical activity, etc.). And the lifespan "on disability" is also increasing. This notion concerns people who have undergone a medical intervention such as the fitting of prostheses or artificial organs. These devices or techniques of modern medicine prolong life. It is not always a healthy life, but nevertheless a life which is considered positive by at least some of the patients.

What is aging from a strictly biological point of view?

Aging does not consist of a single clear and simple mechanism. On the contrary, it is something very complex, which brings together at least a hundred different processes. Simply put, when you get older, everything in your body works a little worse. We speak of aging when the whole system is concerned, and of illness when only one element of the body is affected. In people aged 65 to 80, aging does not have many consequences. This is arguably the best time in life for those who feel satisfied with their lives. From the age of 80, we enter a period of fragility. Suddenly, a small event can have major consequences. The classic example is that of the elderly who have poor vision and whose balance is precarious. One day, she falls. She fractures her hip or femur because her bones are not strong enough. Since the fracture does not heal on its own, a prosthesis is placed. Hospitalization and bed rest will decrease mobility. This is a cog and, by the way, a real challenge for hospitals.

Beyond that, there are the “supra-centenarians”. This sub-population is aging extremely well, due to optimal environmental (lifestyle, in particular) and genetic factors. Some people over 100 are healthier than others between the ages of 80 and 90. These heroes of old age are little concerned with dementias.

From what age do we age?

Some say that you age from birth. This is probably a bit of an exaggeration, however aging begins relatively early. I would say from 30 years old. Before, we build. Afterwards, the organism begins to have small problems, hiccups that are not serious, but that exist.

Do the external signs of aging such as gray hair or wrinkles reflect internal aging?

No. It's more complicated than that. A person can be very wrinkled for having been exposed to a lot of sun - at sea or in the mountains - but this does not reflect their internal state of health. The outward appearance tells us very little about the quality of the bones, muscles and brain, which are decisive in the aging process. People with dementia are sometimes extremely well preserved, which is misleading because their brains are in fact very damaged. However, there is no complete dissociation between appearance and the interior of the body. We find that people who age well tend to take care of their appearance. Neglect can be a sign of poor aging.

How do you estimate someone's biological age?

Its pretty hard. There are no biomarkers (blood for example) to determine biological age, so we use functional approaches. We assess the person's ability to walk, we test their ability to answer certain questions and accomplish certain tasks.

What to do to “stay young” and age less quickly?

To begin with, we can say what is not working. All epidemiological studies show that over-the-counter dietary supplements do not prolong life and are rather associated with a decrease in longevity. On the other hand, five factors are major for staying young as long as possible. They are trivial, but very important. If you respect these "big five", you can gain more than 20 years of healthy life compared to someone who does not respect them. The first is not to smoke, tobacco being the most important pro-geriatric factor. Then aim for normal weight and avoid obesity. Eat a healthy diet, either favor products of plant origin and reduce those of animal origin, avoid "processed food" (industrial food) and cook as much as possible yourself. Avoid a sedentary lifestyle. Exercise works miracles against cardiovascular disease, cancer and Alzheimer's disease. Scientific data is extremely strong in this area. Social integration in any way is also very important.

What role does genetics play in the speed of aging?

The influence of genetics is real, but it is much less important than lifestyle and the environment, estimated to be around 20%. Childhood plays only a minor role, unless the person has experienced extreme events. Its impact on aging is estimated to be between 5 and 10%. So about 70% of aging is determined by lifestyle in adulthood.

Will the anti-aging pill ever exist?

We can not exclude it, but for the moment it does not exist, to the great despair of those who do not like sport, nor cook good food! At the moment, apart from the "big five" (see above), there is no miracle cure.

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