The combined effect of age, education, and stroke on dementia and cognitive impairment no dementia in the elderly

BACKGROUND: This study aims to detect the impact of stroke on the occurrence of dementia and cognitive impairment/no dementia (CIND) in different age, sex, and education groups. METHODS: Persons with dementia (DSM-III-R) or CIND were identified by a two-phase study design among 7,930 persons from the population-based Faenza Community Aging Study. RESULTS: Subjects with a history of stroke had increased risk of both dementia [risk ratio (RR) = 3.7; 95% confidence interval (CI) = 3.1-4.4] and CIND (RR = 1.7, 95% CI = 1.4-2.2). These associations were stronger in the younger-old (61-74 years) than in the older-old (75+ years), and among higher-educated (4+ years) than lower-educated (0-3 years of schooling) persons. Dementia and CIND prevalence among stroke subjects was similar to the prevalence detected among subjects 10 years older but without a history of stroke. In stroke subjects, dementia prevalence became higher than CIND prevalence 10 years earlier than in non-stroke subjects. A combined effect for dementia due to a history of stroke, increasing age, and decreasing years of schooling was detected. CONCLUSIONS: Stroke is a strong risk factor for dementia among younger-old and higher-educated subjects; in the presence of a stroke, dementia onset might occur about 10 years earlier, possibly by accelerating the progression from CIND to dementia.