IUSSP Seminar 2019 • 15.03.2019“Theoretically, No Obvious Limit in Life Expectancy“

Prof. Dr. Dr. med. Ulrich Mueller Source: BiB

Professor Mueller, what are the topics addressed at the seminar?

We have observed that the distribution of causes of death – such as cardiovascular diseases, cancer, metabolic diseases, neurodegenerative diseases, rheumatic diseases, infectious diseases – varies considerably in societies that are otherwise becoming more similar in life expectancy. For more than a generation, men in Upper Franconia have been dying more than 1.5 times more frequently from coronary heart disease than in Upper Bavaria. Over the years, such differences between nations or regions have changed little in other places as well. The question is: Why is that the case, what are the causes?

Why is research on the causes of death an important issue?

The causes of death do not affect everybody at the same age, i.e. some diseases can kill you earlier, some at a later time. The question is: is there a causal relationship? For instance, if a population dies less frequently from cause A, deaths from other causes will become more frequent. The question is whether a random lottery procedure applies here, or whether there are replacement schemes in the form of an exchange relationship, i.e. a trade-off, which apply here. These are the issues for specific research.

What potential do you see for increasing life expectancy?

First of all, there seems to be no obvious threshold to life expectancy at which one can say that life is most often at an end. However, there is a limit in human lifetime, i.e. some kind of mechanism that switches us off. Think, for instance, that the median age of death of German men is just under 80 years while that of German women is 85 years. The oldest men were about 115 and the oldest women about 120 years old. In other words: 50 percent of all those born in Germany reach more than two thirds of the maximum life time recorded so far. On the other hand, in the vast majority of plants or invertebrates the median age of death is a very small fraction of the maximum life span observed.

Are there differences in life expectancy across Europe?

Yes, and Germany does not belong to the leading group. According to current figures, Germany ranks 16th, showing a gap of 2.7 years towards the leading country Switzerland (1.9 years among women, 3.6 years among men). Even within Germany there are considerable differences in life expectancy. If, for example, you compare Saarland and Saxony-Anhalt with the south of Baden-Württemberg, you can see differences ranging from two to two and a half years.

Why is Germany not one of the top countries in Europe?

No one knows for sure, but there are a few options. For instance, the older male cohorts in the former GDR, who had jobs that were very harmful to their health, are now reaching the age when most deaths will occur. This causes a decrease in average life expectancy. In addition, unhealthy lifestyles also play a role. Even if a high amount of money is invested in medical care, the question must be raised as to whether this is being done in an optimal way. As an example, I would like to mention the UK: the country’s health care system is not as good as Germany’s, but it provides better integrated ambulant and hospital care for people suffering from diabetes.

Which findings from the contributions at the seminar have surprised you?

I was surprised by the presentations of my Indian colleagues. I did not know how huge the differences in life expectancy in India were. For example, in the federal state of Kerala in the south/south-west of the country the population has a life expectancy of about 75 years which is comparable to that in Bulgaria or Romania. In contrast, life expectancies observed in federal states like Uttar Pradesh and Assam in the north, respectively north-east of India, do not differ considerably from middle-ranking African societies.

What are the current research topics in the field of longevity?

Well, the current question is: in what way do genes control longevity? It’s important to understand how they interact with the environment and to learn how the ageing process is controlled both internally and externally. Imaging methods such as magnetic resonance therapy or X-rays are used to determine the causes of death. The future perspectives are to determine, with the help of technical possibilities of artificial intelligence, the causes of death of all deceased without medical dissection, only through imaging procedures and evaluation by appropriate software. However, how quickly this can be implemented is, as always, a question of money. For the time being, there is no such software available, but possibly in the near future. For aircraft safety and air traffic, for weather forecasting, for forecasting ocean currents and similar public-interest tasks, huge amounts of data must also be analysed.

The seminar was designed to be interdisciplinary. What can you conclude by comparing the different approaches?

I would say that demography, like demographic epidemiology, is more advanced in methodology than most quantitative social sciences, but not yet at the level of clinical epidemiology, i.e. intervention effectiveness epidemiology. Both in demography and in population epidemiology explorative studies are conducted: We look at what is going on, then we find a somehow stable statistical context and subsequently come up with an answer to what might be the cause. This, however, puts us far behind clinical epidemiology in terms of methodological discipline. This is an intervention effectiveness test under controlled conditions and more than pure speculation.

What is the benefit of linking research on the causes of death with regard to the extension of life expectancy?

Let me reply with an example: cervical cancer starts earlier than breast cancer and this in turn starts earlier than esophageal cancer. The distribution of the mortality rates from these three cancers has shifted as a result of early screening measures, shifting the mortality rates from these three cancers as well as the average age at death due to these three cancers.

The interview with Prof. Mueller was conducted by Yvonne Halfar (BiB). A detailed report on the seminar has been published on the BiB website as well (see the link on the right).