Prevalence of very mild to severe dementia in Denmark

Objectives - The prevalence of dementia has been estimated in several countries and a meta-analysis has shown moderate and severe dementia in people aged 65 years and older to be between 4% and 6%. The Odense study is aiming to estimate the prevalence and incidence of dementia and to identify risk factors. Material and methods - A total of 3346 persons, equivalent to 64.5% of a random sample of 5237 persons aged 65–84 years living in the municipality of Odense, Denmark, underwent a two phase diagnostic procedure including a screening with CAMCOG, the cognitive section of The Cambridge Examination for Mental Disorders of the Elderly, seven neuropsychological tests, medical examination, and CT scan. The severity of dementia was assessed by the CDR (Clinical Dementia Rating). Results - The prevalence rate was 7.1%, including the very mildly demented, defined as persons rated questionably demented according to the CDR scale. The prevalence rate of very mild dementia was 2.8%. The proportion of cases with very mild dementia decreased with increasing age while the prevalence rate increased. Conclusion - Inclusion of very mild cases of dementia resulted in a higher prevalence rate than generally reported, and the prevalence rate increased exponentially with age which was mainly due to Alzheimer's disease.