Cerebrovascular disease, vascular cognitive impairment and dementia

Cerebrovascular disease (CVD) is related to a high risk of cognitive impairment and dementia. The vascular dementias (VaDs) are the second most common single causes of dementia. CVD and vascular brain injury have been seen as the primary cause of clinical deficits in vascular cognitive impairment (VCI) and the VaDs. In addition, vascular factors such as coexisting stroke and white matter lesions (WMLs) relate also to Alzheimer's disease (AD). Thus vascular causes are an important factor in cognitive impairment worldwide. In VCI, 'vascular' refers to all causes of CVD and 'cognitive impairment' encompasses all levels of cognitive decline, from the earliest step to a more severe and global cognitive syndrome. VCI is expected to include cases with cognitive impairment related to CVD (TIA, stroke), multiple cortico-subcortical infarcts, silent infarcts, strategic infarcts, small vessel disease with WMLs and lacunae, as well as AD pathology with co-existing CVD lesions. VCI and VaDs as a general entity include many syndromes, which themselves reflect a variety of vascular mechanisms and changes in the brain, with different causes and clinical manifestations. The pathophysiology incorporates interactions between vascular aetiologies (CVD and vascular risk factors), changes in the brain (infarcts, WMLs, atrophy), and host factors (age, education). The subtypes of VaD include the cortical VaD or multi-infarct dementia (MID), also referred to as post-stroke VaD; subcortical VaD, labelled as subcortical ischaemic vascular disease and dementia (SIVD) or small vessel dementia; and strategic infarct dementia.