Cerebrovascular disease is the second most common cause of acquired cognitive impairment and dementia and contributes to cognitive decline in the neurodegenerative dementias. The current narrow definitions of vascular dementia should be broadened to recognise the important part cerebrovascular disease plays in several cognitive disorders, including the hereditary vascular dementias, multi-infarct dementia, post-stroke dementia, subcortical ischaemic vascular disease and dementia, mild cognitive impairment, and degenerative dementias (including Alzheimer's disease, frontotemporal dementia, and dementia with Lewy bodies). Here we review the current state of scientific knowledge on the subject of vascular brain burden. Important non-cognitive features include depression, apathy, and psychosis. We propose use of the term vascular cognitive impairment, which is characterised by a specific cognitive profile involving preserved memory with impairments in attentional and executive functioning. Diagnostic criteria have been proposed for some subtypes of vascular cognitive impairment, and there is a pressing need to validate and further refine these. Clinical trials in vascular cognitive impairment are in their infancy but support the value of therapeutic interventions for symptomatic treatment.