Increasing prevalence of dementia among very old people

Methods: this study compares the prevalence of dementia in two population-based cross-sectional samples of very old people in northern Sweden in 2000-02 and in 2005-07. In total, 430 individuals aged 85 and older (mean age 89.5 years, 71.4% women) were evaluated for dementia in the first cross-section and 465 individuals (mean age 90.2 years, 70.9% women) in the second. Trained assessors performed assessments and interviews during home visits and collected information from carers, relatives and medical records. Dementia was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, fourth edition criteria. Results: the prevalence of dementia in the total sample was 26.5% in 2000-02 and 37.2% in 2005-07 (P = 0.001). There was also an increase in the prescription of different antihypertensive agents, antilipemic agents and choline esterase inhibitors, and more people had had heart surgery in the later sample. Conclusions: in this sample of very old people, an increase in the age-specific prevalence of dementia was detected over 5 years. Possible reasons for this may be extended survival among individuals with risk factors for dementia and among individuals with established dementia.