Stroke is the primary cause of morbidity and disability throughout the world, mainly because of its effect on cognitive functions. After stroke, individuals can recover from physical disability, but might be unable to return to their previous occupation or independent living because of cognitive impairments. Cognitive dysfunction encompasses all deficits, which range from local ones resulting directly from the area of infarction or from hypoperfusion of the adjacent tissue, to more global cognitive impairment that is usually related to other underlying subclinical cerebrovascular disease, such as white matter disease or subclinical infarcts. Research of cognitive dysfunction after stroke is complicated because of its varying definitions and lack of cognitive function measurement before stroke. Additionally, stroke can affect white matter connectivity, so newer imaging techniques, such as diffusion tensor imaging and magnetisation transfer imaging, which can be used to assess subclinical damage are important tools for better assessment of cognitive dysfunction following stroke. Recent and current studies are increasingly focused on the role of preventable risk factors in the development of dementia. Since stroke is one such preventable risk factor, its role is a new issue that requires attention and treatment.