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There is increasing interest in cognitive function after stroke episodes as medical management and care improve with patients surviving long periods. The development of cognitive impairment and incident dementia or post-stroke dementia (PSD) is relatively common following stroke [1,2]. While delirium may be a frequent immediate consequence after stroke injury [3,4], cognitive decline following an index stroke could be insidious with the latent appearance of dementia. PSD is a clinical entity to define any dementia occurring after stroke, irrespective of whether it involves vascular, degenerative or mixed processes. Therefore, PSD can entail a complex etiology with varying combinations of large and small vessel disease as well as non-vascular neurodegenerative pathology. The development of PSD depends on several factors including the location and volume of the stroke, degree of related neuronal damage, presence of pre-existing cognitive impairment or cerebral pathology. At this stage, the contribution of any specific genetic factors is not clear. PSD is generally defined by dementia that occurred within 3 months after stroke onset. However, many may develop dementia well beyond 3 months after the stroke or only after recurrent stroke(s). The recognition of cognitive impairment in the acute phase after stroke may offer vital information to the clinician for early cognitive rehabilitation [5] and preventing early fatality by improved management [6].
Recent prospective studies suggest stroke survivors may unmask or trigger additional pathologies including those attributed to our current understanding of subcortical vascular dementia (VaD), multi-infarct dementia and even strategic infarct dementia [1,7,8] (Figure 1). Given this definition, most PSD may be described under the umbrella term of vascular cognitive impairment (VCI) [9,10], which has been introduced to describe the full spectrum of cognitive change related to all causes of vascular disease from VCI no-dementia to variable degrees of frank dementia of vascular origin. It is suggested that dysfunction of the neurovascular unit and mechanisms regulating cerebral blood flow particularly in the deep white matter (WM) are important components of the pathophysiological processes underlying VCI. The continuum of VCI is also discussed broadly under the rubric of vascular cognitive disorders (VCDs) [11], which comprise many diseases, each with varying severity and patterns of dysfunction. The categorical diagnosis of VCDs encompasses mild impairment, pre-dementia and dementia syndrome, and major VCD category is...