Risk of dementia high before, after stroke
The risk of dementia is elevated before and after an index stroke even in women, a recent study has found.
The study included 1,460 women (mean age 46.8±6.2 years) without stroke or dementia at baseline, and who were followed-up for 44 years. Neuropsychiatric examinations and informant interviews, as well as reviews of hospital registries and medical records, were used to identify the development of stroke or dementia.
A total of 362 participants developed first-onset stroke during 49,623 person-years of follow-up at a mean age of 77.8±8.7 years. In comparison, 325 cases of dementia were reported during 49,663 person-years at a mean age of 79.8±7.9 years. Mortality rates were 81 percent and 69 percent, respectively.
The cumulative incidence of prestroke dementia was 13.8 percent (n=50), majority of whom developed the neurological condition 5 years before the index stroke. Poststroke dementia was reported in 54 women (18.4 percent).
During 44 years of follow-up, 33.7 percent of women with a history of stroke developed dementia. This was significantly higher than in those without such history (18.5 percent; age-adjusted hazard ratio [HR] without competing risk, 1.44; 95 percent CI, 1.14–1.81). The age of dementia onset was similar in both groups (78.9±6.8 vs 77.3±7.8 years).
Notably, the increase in age-adjusted dementia risk achieved significance 5 years before the index stroke event (HR, 1.57; 1.03–2.40) and gradually increased to stroke onset (1 year before: HR, 2.65; 1.48–4.75; the same year: HR, 3.85; 2.37–6.26), reaching its peak during the year after stroke (HR, 4.17; 2.46–7.07).
The associated dementia risk remained significant 2–5 years after stroke event (HR, 1.78; 1.08–2.94).