[Epidemiology of aging with focus on physical and mental functional ability].

In the past decades, the "graying" of the population has emerged as a world-wide phenomenon, leading to an increased interest in research on aging. Many population-based studies have been initiated in several countries, such as the Kungsholmen Project in Stockholm, Sweden. These studies have shown that older adults can be recruited to participate in intensive physiological and clinical evaluations, and that longitudinal surveys are well accepted by the elderly. Comorbidity and physical and mental functioning have emerged as important variables for describing health status and identifying risk factors. Dementia arose as one of the most common diseases in the very old, as dementia prevalence nearly doubles every fifth year. Some risk factors for Alzheimer's disease have been identified and interesting working hypotheses have been suggested. The natural history of the dementias have been sufficiently outlined for allocating medical and social resources, and for counseling patients and relatives.