The health of the elderly population: results from longitudinal studies with age-cohort comparisons.

In the longitudinal study of 70-year-olds in Göteborg the first age cohort (born 1901-1902) has now been followed for 15 years and the second cohort (born 1906-1907) for nine years; an intervention study has been added to the third age cohort (born 1911-1912). These longitudinal perspectives (derived from studies of samples shown to be representative of the total population) have successively improved the possibilities of distinguishing between ageing manifestations and symptoms caused by definable diseases. In addition to previously reported figures on the proportions of apparently healthy people at age 70 and 75, preliminary conclusions from the follow-up periods from age 79 indicate that at that age at least 20% do not suffer from symptoms of definable diseases. These findings have allowed detailed analyses to be made of the morphological and functional consequences of ageing as well as the calculation of clinical reference values for the age interval 70-79. The improving possibilities for distinguishing between ageing and morbidity have allowed certain conclusions to be drawn on obvious differences between age cohorts relating to the prevalence of disease and manifestations of ageing. These age-cohort differences could not be related to migration and ongoing genetic changes but there is indirect evidence for relationships to lifestyle and certain environmental factors. The reasons for these age-cohort differences in the manifestations of ageing are being analysed retrospectively through information on differences in living conditions between the cohorts and prospectively through the intervention programme (InterVention Elderly in Göteborg, IVEG).