Association of stroke with dementia, cognitive impairment, and functional disability in the very old: a population-based study.
OBJECTIVE
Stroke is a major cause of disability in the elderly and is also related to the development of dementia, which is another important source of disability in old age. The aim of the present study was to examine the potential impact of stroke on cognitive and functional status in a community-based cohort of individuals aged 75 years and older.


METHODS
The data were derived from a cross-sectional survey on aging and dementia that included all inhabitants of the Kungsholmen district in central Stockholm who were aged >/=75 years. Cases of stroke were identified through the computerized inpatient register system that has been widely used to study stroke in Sweden. Dementia was defined according to the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised. Dementia onset was considered the appearance, according to an informant, of the first symptom. Cognitive impairment without dementia was defined as the presence of a Mini-Mental State Examination score of <24 and the absence of dementia. Functional disability was assessed according to Katz Index of independence in activities of daily living.


RESULTS
The prevalence of stroke was 10. 0% in men and 8.0% in women. One third of stroke survivors were diagnosed as demented, which was 3 times higher than those without stroke: adjusted odds ratio (OR) was 3.6 (95% confidence interval, 2. 5 to 5.8). Stroke was also significantly related to cognitive impairment without dementia (adjusted OR, 2.4 [95% confidence interval, 1.3 to 4.6]). The population-attributable risks of dementia and cognitive impairment in relation to stroke were 18.4% and 8.5%, respectively. Among the 49 stroke patients with dementia, 15 cases (30.6%) had missing information on dementia onset, 22 (44. 9%) had been reported by the informant to have dementia-related symptoms after or close to the occurrence of stroke, and 12 (24.5%) had symptoms before stroke occurrence. The prevalence rates of disability in activities of daily living were much higher among stroke patients than among stroke-free subjects, even after adjustment for age, sex, heart disease, hip fracture, and dementia: the corresponding adjusted ORs for bathing, dressing, toileting, transfer, and continence were 3.5 (2.4 to 5.3), 2.2 (1.4 to 3.3), 3. 0 (2.0 to 4.5), 3.3 (1.9 to 5.7), and 2.1 (1.3 to 3.3), respectively. After dementia and hip fracture, stroke was the third largest contributor to disability in bathing, dressing, and transfer. Stroke was the second contributor to disability in toileting.


CONCLUSIONS
Stroke is strongly associated with dementia, although it may relate to dementia in different ways: it can be the main cause or a precipitating factor of dementia, or they may share common etiological bases. Together with dementia and hip fracture, stroke is a major contributor to disability in most aspects of activities of daily living in very old people.
Stockholm Gerontology Research Center and Department of Geriatric Medicine, Karolinska Institute, Stockholm, Sweden Li.Zhu@cnsf.ki.se
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Zhu
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Fratiglioni
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Guo
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Agüero-Torres
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Winblad
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Viitanen
D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D002561:Cerebrovascular Disorders / Q000453:epidemiology / Q000503:physiopathology* / Q000523:psychology*; D003072:Cognition Disorders / Q000209:etiology*; D003430:Cross-Sectional Studies; D003704:Dementia / Q000209:etiology*; D006233:Persons with Disabilities; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D016017:Odds Ratio; D015995:Prevalence; D013548:Sweden