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

Background The impact of different case definitions on incidence rates remains unclear. Aims To compare incidence rates of dementia according to DSM–III–Rand ICD–10. Method A two-wave community study was conducted ( n =1692, age 75+ years follow-up period 1.6 years). Cognitive function was assessed by the Structured Interview for Diagnosis of Dementia of Alzheimer Type, Multiinfarct Dementia and Dementia of other Aetiology according to ICD–10 and DSM–III–R (SIDAM). Results The annual incidence rate for dementia by applying different case definitions was found to be quite similar (DSM–III–R: 47.4 (95% Cl=36.1–61.2) per 1000 person-years; ICD–10: 45.8 (95% Cl= 35.0–59.0) per 1000 person-years). Age-specific incidence rates increase steeply with age. Conclusions The impact of different case definitions on incidence rates of dementia appears limited if case definitions and case-finding procedures at baseline and follow-up are applied consistently.