Post-stroke Cognitive Impairment and Dementia

Overview

Projections from epidemiological studies suggest that, among the Western adult population, one in three will present a cerebrovascular accident (stroke), severe cognitive disorders, or both. To better diagnose the Vascular Cognitive Impairment, new standards were developed by a North America working group which are under validation. It is essential to adapt these standard for French-speaking population, and especially to define cutoff scores of the cognitive battery to determine cognitive deficit. The investigators propose a study coordinated by the University-Hospital of Amiens for french speaking centers. This study will investigate this battery with 906 controls to define the standards and 302 stroke affected patients to define the frequency and cognitive mechanisms. This step is essential for people to benefit from these new standards.

* Context In western countries, one in three subjects will experience a stroke, dementia or both. Recent studies have shown the major role of vascular risk factors and stroke in cognitive disorders and dementia. Poststroke cognitive and behavioral disorders are characterized by the prominence of action slowing, executive function disorders and apathy. They are due to vascular lesions or to associated pathology, mainly Alzheimer's disease. In order to determine diagnosis criteria of Vascular Cognitive Impairment, it is necessary to develop a standardized assessment of post-stroke cognitive and behavioral disorders (Hachinski et al Stroke 2006; 37; 2220-2241). For this purpose, the NINDS (National Institute of Neurological Disorders and Stroke ) and the Canadian Stroke Network have jointly developed a specific standardized battery which is currently under validation. Its use in France requires first a normalization of some tests in French speaking healthy controls. This study is supported by the SFNV (Société Française NeuroVasculaire) and GRECO (Groupe de Réflexion sur les Evaluations Cognitives). * Primary Objectives of the project: to determine the frequency of cognitive and behavioral disorders 6 months post-stroke assessed with this new NINDS-Canadian Stroke Network battery Primary endpoints: disorders on cognitive tests and on behavioral and depression questionnaires (defined by performance outside normal ranges determined in healthy controls); * Population Patients consecutive French-speaking patients with an informant assessed 6 months post-stroke and free from mental retardation, psychosis, illiteracy, previously diagnosed dementia, comorbidity known to impair cognitive abilities, MRI contraindication or refusal to participate. Controls from the general population not presenting any condition known to impair cognitive abilities stratified according to age and schooling levels * Design Prospective multicenter study comparing performance of patients and controls Sample size: the frequencies of cognitive and behavioral disorders are considered as significantly different if the null hypothesis (lack of difference between groups at the 0.05 quantile) is rejected. Considering that each patient is matched with 3 controls, it will be necessary to evaluate 302 patients with the battery 6 months poststroke and 906 controls to detect a difference between groups of at least 5% with α risk =0.05 and power= 80%. In addition, the inclusion of 302 patients allows to determine the frequency of impaired patients with a confidence interval CI95% ≤12%. * Feasibility: based on a previous similar study, 50 stroke patients (range 40-60) and 150 controls (range: 100-200) will be included per year in the University Hospital of Amiens. Thus 10 centers with similar inclusion rates will be able to include 302 patients and 906 controls within 6 years. * Secondary objectives: (1) to determine the frequency of poststroke dementia; (2) to determine the frequency of cognitive disorders on screening tests; (3) to examine correlations between cerebral MRI and cognitive impairment; (4) to determine correlations between cognitive disorders and activities of daily living. Secondary endpoints: (1) dementia (DSMIV and NINDS-AIREN criteria ;National Institute of Neurological Disorders and Stroke and the Association Internationale pour la Recherche et l'Enseignement en Neurosciences ); (2) screening tests (MiniMental Status Examination, Montreal Cognitive Assessment);(3) MRI abnormalities (cerebral atrophy, white matter abnormalities, stroke type, stroke volume and location) using 3D T1-weighted (axial bicommissural plane), T2-weighted (coronal plan), FLAIR, gradient-echo, diffusion-weighted (with calculation of the apparent diffusion coefficient) performed at 6 months post-stroke at the same time than the cognitive assessment; (4) disability in activities of daily living (Rankin scale, Barthel index, Instrumental Activities of Daily Living).