PREEXISTING DEMENTIA IN STROKE PATIENTS - BASE-LINE FREQUENCY, ASSOCIATED FACTORS, AND OUTCOME

Background and Purpose The link between stroke and degenerative dement ia, especially Alzheimer's disease, is closer than expected by chance. Dementia after stroke may be due to the cumulative effect of vascular and degenerative changes. The prevalence of dementia just before stro ke onset remains unsettled. The aim of this study was to determine the frequency of preexisting dementia in stroke patients, associated fact ors, and consequences on outcome. Methods We evaluated the cognitive f unctioning prior to stroke in 202 consecutive patients with ischemic o r hemorrhagic stroke by means of the Informant Questionnaire on Cognit ive Decline in the Elderly (IQCODE). We classified in the dementia gro up patients with IQCODE scores of 104 or more. Six months after stroke onset, survivors underwent a battery of neuropsychological tests. Res ults Thirty-three patients were demented before stroke (16.3%; 95% con fidence interval, 11.2 to 21.4). There was no diagnosis of dementia in 32 of these 33 patients. We determined by logistic regression analysi s that female sex, family dementia, leukoaraiosis, and cerebral atroph y are independently associated with prestroke dementia. All survivors who had IQCODE scores of 104 or more at the acute stage met criteria f or dementia 6 months later. Conclusions Our study showed that one sixt h of stroke patients have preexisting dementia. Therefore, some patien ts with so-called ''poststroke dementia'' probably had unrecognized pr eexisting dementia.