[Post-stroke cognitive deficits and dementia]

Post-stroke cognitive deficits and dementia Abstract. Prediction of stroke outcome remains challenging due to a large inter-individual variability. For a long time, research on stroke outcome has been mainly confined to post-stroke motor deficits, whereas post-stroke cognitive decline has been less investigated though being an often reason for dependency and disability. Post-stroke cognitive impairment demonstrate high inter-individual variability, which is expected to increase further due to the increasing life expectancy and number of patients with pre-stroke brain pathology and cognitive deficits. There exist different types and patterns of post-stroke cognitive impairment: i) the deficits in one or several cognitive domains meaning the variability in neuropsychological profiles; ii) the decline might vary from mild to manifested dementia comprising a wide spectrum in severity; iii) with occurrence immediately after stroke or with delayed manifestation several months later without obvious reasons. Patients at risk for post-stroke cognitive impairment cannot be reliably identified. Many factors have been shown to worsen post-stroke cognitive outcome, but their effects have been only investigated in isolation by ignoring their potential interactions. An overall model sufficiently predicting post-stroke cognitive outcome was therefore missing until now. We recently suggested that the concepts of brain reserve and cognitive reserve, which are established for neurodegeneration, may represent a valuable theoretical framework to predict stroke-induced cognitive decline and disability. Cognitive stroke outcome can be defined as a result of an interaction between brain reserve (e. g. brain volume), cognitive reserve (e. g. level of education, cognitive-stimulation leisure activities) and lesion load. Our recent findings supported this hypothesis also for functional stroke outcome. By representing a valuable model comprehensively incorporating an individual's characteristics, the concepts of brain and cognitive reserve might help in screening of risk patients, establishment of individualized therapeutic approaches, and enable knowledge transfer.