The ageing population

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The demographic structure and dynamic have been in focus among Swedish scientists and politicians on several occasions during the previous century. It is currently a prioritized issue because of the rapid increase in the number and percentage of old and very old people. This will have a big impact on society through increased demands on the health care system and through consequences for social security systems, including retirement age. A drastic reduction in the number of births in combination with a continuous reduction in mortality has led to the present population structure.

Mortality can be followed in Sweden for over 250 years. Over that period, life expectancy has increased from 40 to 80 years, an average of 2 months per year. This trend continues to date. Reduction in childhood mortality explains most of this change during the early period, but there have been reductions over the entire age span and during the last decades it is primarily improvements in mortality above the age of 65 that drives the increase in life expectancy. Currently, mortality reduction among the old and very old attracts considerable interest. Two questions are at the forefront of interest among scientists.

First, is it reasonable to assume that the mortality reduction will continue or is it approaching an end; linked to this is the question of what causes the mortality reduction. A commonly held view is that the survival curve is becoming increasingly rectangular since more and more people survive to an age closer to maximum life span. If this were true, the life expectancy increase would gradually slow down as it approaches the maximum life span. However, this hypothesis is not supported by data which show that life expectancy (in the record keeping countries) continues to increase almost linearly with no indications of leveling off. At the same time we have seen in analyses of the oldest old in Sweden and Denmark that the mortality risks among these have not improved the past decades, the risk of dying once you turn 100 is thus the same today as it was 40 years ago. Also the maximum age of death has not improved the past decade either. Directly linked to this are questions about determinants of longevity. These questions are addressed from several different angles including molecular genetics using telomere length as a biomarker of ageing and of course by close scrutiny of mortality patterns. Doll and Peto discussed this in a BMJ paper in 1997 postulating that there is no such thing as ageing, but only a lifelong accumulation of risk factors. Another important aspect of this research is whether the extended lifespan has been characterized by healthy or unhealthy years.

The research area of ageing and longevity, its determinants and consequences is of major societal importance and at the heart of public health sciences. It is an area that links public health, epidemiology and demography. Sweden has unique data for research along these lines because of very long historical records and excellent current mortality data along with other relevant information.

Aims of project

The overall aim of this project is to investigate to what extent is the reduction in old age mortality due to a delayed onset of diseases, to a higher survival rate or a longer survival time among those with disease?

Another aim is to investigate how healthy the very old people will be in the future? The core of this question is whether it is reasonable to assume that age specific health will remain unchanged over time, despite the decrease in age specific mortality rates, or whether it is more likely to assume that age-specific disease rates (for example CHD and stroke) will decrease in parallel with decreasing mortality rates? This question is of utmost importance for society because it affects health care demands and retirement age

Material

The studies are primarily based on Swedish national register data of the total population.

Time plan

The project is planned to continue at least to 2019.

Contact person

Assistant professor

Karin Modig

Phone: +46-(0)8-524 801 53
Organizational unit: Epidemiology
E-mail: Karin.Modig@ki.se