Microbleeds in vascular dementia: Clinical aspects

Microbleeds are small dot-like lesions which can be appreciated on gradient echo, T2*-weighted magnetic resonance images as hypointensities. They are considered as an expression of small vessel disease on MRI, next to lacunes and white matter hyperintensities (WMH). Microbleeds are relatively common in vascular dementia, with reported prevalences between 35% and 85%. In the context of vascular dementia, microbleeds are mainly thought to result from hypertensive vasculopathy, but the frequent co-occurrence of lobar microbleeds suggests that neurodegenerative pathology and/or cerebral amyloid angiopathy is also of importance. The presence of multiple microbleeds in vascular dementia or in patients with vascular cognitive impairment is related to worse performance on cognitive tests, mainly in psychomotor speed and executive functioning. They may have some predictive value in terms of predicting development of (vascular) dementia, mortality and disability. Data on the occurrence of stroke and post-stroke dementia in patients with microbleeds are to date not available. New definitions and diagnostic criteria for vascular dementia and vascular cognitive impairment are needed and should take into account microbleeds.