Prevalence of dementia in old age

Clinical diagnoses in subjects aged 95 years and older

Wernicke, Thomas F. MD
Reischies, Friedel M. MD

Academy of Sciences and Technology in Berlin (Dr. Wernicke) and the Department of Psychiatry (Dr. Reischies), Free University of Berlin, Berlin, Germany.

Address correspondence and reprint requests to Dr. Thomas F. Wernicke, Department of Psychiatry of the Free University of Berlin (Director: Prof. Dr. H. Helmchen), Eschenallee 3, 14050 Berlin, Germany.

The Berlin Aging Study (BASE) was initiated by the Academy of Sciences and Technology in Berlin and is financially supported by two German Federal Departments: the Department of Research and Technology (13 TA 011 + 13 TA 011/A: 1988 to 1991) and the Department of Family and Senior Citizens (1992 to present). The institutions involved are the Free University of Berlin and the Max Planck Institute for Human Development and Education, where the study is housed.

Received May 3, 1993. Accepted for publication in final form August 12, 1993.

Neurology 44(2):p 250-253, February 1994.

Article abstract

Epidemiologic studies have consistently shown an exponential increase in the prevalence of dementia in the very old, but different standards of the investigators and the instruments, as well as the selection of the samples, limit the comparison of these studies. They usually include only a small number of participants aged 90 years and older. This investigation focuses on whether there is an exponential increase in the prevalence of dementia in people aged 90 years and older. The Berlin Aging Study (BASE) consists of a representative sample of elderly aged 70 to 105 years stratified by age and gender. Analyses of a BASE first sample (N = 156) with 52 participants aged 90 years and older showed an exponential increase in dementia from age 70 up to age 94 years, but the group aged 95 years and older (N = 26) showed a plateau near 45%, with no further increase in dementia prevalence.