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.