The connection between chronic inflammation and diseases of aging
Is there a problem with increasing life expectancy? If you look at the graph of average life years alone, the development over the last fifty years looks very positive. This graph shows a steady upward trend, especially in Western countries. People are getting older continuously.
There is, however, a second graph that has risen much slower: that of healthy life expectancy. People are getting older, but in the last years or decades of their lives they are more and more susceptible to chronic diseases.
In medical research, a number of theories have been developed to explain this discrepancy. Cell aging, chronic inflammation, fat or glucose metabolism or telomere shortening (a natural degeneration of the genome quality). All these factors may be responsible for the increasing susceptibility to disease in old age. Or a combination of these factors.
Yet dwindling health is not a law of nature. There is a group of people whose health is maintained above average, both physically and mentally. People for whom the two curves life expectancy and healthy life expectancy do not diverge.
These are people who reach an above-average age. Science sees an ideal model population in these Centenerians and Supercentenerians. It can be used to investigate which factors enable both a long and a healthy life.
In a large international study, all these observations and hypotheses were combined to comprehensively study a group of Japanese volunteers aged between 50 and 115. Almost 700 of the 1554 study participants were 100 years old and older. The question was: Are there general, measurable factors that promote healthy ageing?
The researchers themselves were surprised by the conclusiveness of their findings. In particular, they had expected a close connection between telomere shortening and health scores – this newly discovered genetic phenomenon had been the subject of intensive research in recent years. But it was another, a single parameter that correlated with both physical and cognitive performance in old age: low inflammatory markers.
There had been a scientific consensus for many years that age-related diseases can be caused by chronic inflammation, for example osteoporosis, arthritis or Alzheimer’s disease. In the year 2000, the Italian immunologist Claudio Franceschi coined the term InflammAging. And numerous animal models and human studies have confirmed this hypothesis in the meantime.
Nevertheless, the scientific team of the study was astonished that the connection between health in old age and low inflammation markers was so clear – while no conclusive evidence could be found for other theories. The title of the study sums up the clarity of its findings: “Inflammation, not telomere length, as an indicator of successful aging”.
Arai et al.: Inflammation, But Not Telomere Length, Predicts Successful Ageing at Extreme Old Age: A Longitudinal Study of Semi-supercentenarians. EBioMedicine 2 (2015).
This insight has practical consequences for the research and development of new therapeutic concepts. A safe and technically sophisticated inflammation therapy – as the authors of the study say in their concluding discussion – would be an essential step in bringing the two curves together. The result would be high life expectancy and good health for people in all aging societies.
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