Cerebral microbleeds and vascular cognitive impairment

Vascular cognitive impairment (VCI) is a key healthcare challenge facing all aging Western societies, second only to Alzheimer's Disease (AD) as a cause of dementia [1]. Initial concepts of VCI invoked cortical or subcortical infarction – leading to the terms “multi-infarct dementia” and “post-stroke dementia”. However subcortical small vessel disease (often not causing acute or overt clinical symptoms) also plays a critical role in VCI [2–4]. MRI is the most important tool for detecting and quantifying small vessel diseases, and forms part of current diagnostic criteria for vascular dementia [1]. MRI manifestations of small vessel diseases including white matter hyperintensities (WMH: bright signal areas on T2-weighted or FLAIR images including leukoaraiosis) and lacunes have been recognized for many years. Cerebral microbleeds (CMBs) – small, perviascular haemorrhages seen as well-demarcated, rounded lesions on MRI sequences sensitive to magnetic susceptibility – are also now recognized as a manifestation of small vessel pathology [5] (Fig. 1), but their clinical impact on cognition remains uncertain [6]. This review will consider how CMBs may be relevant in the study of VCI.