Dementia and Cognitive Impairment in the Oldest Old in the Community Prevalence and Comorbidity

BACKGROUND: The study focuses on the prevalence of dementia in the oldest old. METHOD: A community sample (n = 402) of the oldest old in Munich (> or = 85 years) was assessed with different methods. Four instruments and a clinical examination were used for case identification: (a) the Geriatric Mental State Interview (GMS-A); (b) the Structured Interview for the Diagnosis of Dementia (SIDAM); (c) the Global Deterioration Scale (GDS); and (d) the Mini Mental State Examination (MMSE). The clinical examination was performed by the interviewing physicians, who made their diagnoses according to ICD-10 and DSM-III-R. RESULTS: The structured interviews (GMS-A: 25.4%; SIDAM/SISCO: 28.0%; SIDAM/DSM-III-R: 27.8%; SIDAM/ICD-10: 16.1%) gave lower point prevalence rates of dementia than physicians' clinical diagnoses (43.1%). The rates were 21.2% based on the MMSE. Depressive syndromes and anxiety syndromes were the most frequent psychiatric disturbances associated with dementia in the very old. CONCLUSION: Dementia rates were high in the oldest old, showed an increase with age but no sex differences. Interview methodology has a major impact on results.