A population-based study on dementia and stroke in 97 year olds.

ABSTRACT

BACKGROUND: the number of nonagenarians increases dramatically worldwide. OBJECTIVES: to examine the prevalence of stroke/transient ischaemic attack (TIA) and dementia, their inter-relationship and their relation to 2-year mortality and institutionalisation in 97 year olds. METHODS: a population-based sample of 97 year olds (n=591) was examined. Information on stroke/TIA was obtained from self-reports, key informants and hospital discharge registers. Dementia was diagnosed according to DSM-III-R criteria. RESULTS: the response rate was 65%. The prevalence of dementia was 32.7% in men and 59.3% in women (P<0.001). The prevalence of stroke/TIA was 21.5% (17.8% in men, 22.3% in women). Stroke/TIA was related to dementia in women (odds ratio=1.9, 95% CI 1.2-3.0), but not in men. Dementia, but not stroke/TIA, was related to 2-year mortality and institutionalisation in logistic regression models. CONCLUSION: dementia was very common in this age group, and related to mortality and institutionalisation. Stroke/TIA in 97 year olds showed less association with dementia, mortality and institutionalisation than reported in studies of younger elderly populations. The finding that stroke was not associated with dementia in men needs to be taken cautiously due to the small number of men. The findings also emphasise that more studies are needed to scrutinise the aetiology of dementia in nonagenarians.