Incidence of Dementia According to DSM–III–R and ICD–10

Abstract

Background The prevalence of dementia diagnosis according to ICD–10 and DSM–III–R in population surveys remains poorly understood. Aims To report and compare prevalence rates according to DSM–III–R and ICD–10. Method A population-based sample ( n =1692, age 75+ years) was investigated by a Structured Interview for Diagnosis of Dementia of Alzheimer Type, Multiinfarct Dementia and Dementia of other Aetiology according to DSM–III–R and ICD–10 (SIDAM). Results Whereas 17.4% (95% CI=15.9–19.5) of individuals aged 75+ years suffer from dementia according to DSM–III–R, only 12.4% (95% CI=10.6–14.2) are diagnosed as having dementia according to ICD–10. The results revealed lower ICD–10 rates in all investigated age groups. The largest differences appear in the oldest of the elderly. Conclusions The ICD–10 sets a higher threshold for dementia diagnosis. Larger differences in the eldest age groups might reflect difficulties in applying case definitions, especially in those beyond 90 years old.