Cognitive Improvement After Stroke: Prevalence and Trend During the First Three Months

Abstract

Introduction: With similar estimates at 3 and 12 months after stroke, 4 out of 10 individuals have cognitive impairment that does not match the criteria for dementia. Cognitive impairment contributes significantly to disability in these patients and has been the subject of numerous studies. However, few studies have focused on improvement of cognition after stroke. Therefore, this study aimed to determine the prevalence and trend of cognitive improvement within three months after stroke. Methods: A total of 85 stroke patients with supratentorial ischemic stroke, aged between 40 and 79 years, with an MMSE score ≥23 were included in this study. All participants underwent neuropsychological testing at 1 week and 3 months post-stroke in order to assess learning, recall, recognition, working memory, verbal fluency, naming, executive function, attention and processing speed. A hierarchical cluster analysis based on Ward's method and squared Euclidean distance was performed on changes in neuropsychological tests over three months in order to identify homogeneous groups of patients. The within- and between-group differences were presented descriptively with respect to changes in each cognitive domain. Results: The cluster analysis identified 2 groups of patients, where 22 patients improved overall cognitively and 63 declined or remained stable from 1 week to 3 months after stroke. Within the improvement group, learning, recall, recognition, working memory and verbal fluency improved significantly. However, there was a significant decline in 8 out of 10 measures of attention and executive function. Within the decline/stable group, cognitive function remained stable for almost all domains, aside from significant decline in 1 out of 5 measures of executive function, and significant improvement in verbal fluency and 2 out of 3 measures of working memory. In 13 out of 20 measures, the changes were significantly different between the 2 groups. Discussion: About 25% of patients showed overall cognitive improvement within three months after stroke. Knowing the prevalence and trend of cognitive improvement after stroke, can serve as a foundation for future research focused on cognitive improvement and its predictors.