title: Brain microbleeds: Epidemiology and clinical implications.
abstract: BACKGROUND
  Brain microbleeds (BMB) are haemosiderin deposits contained within macrophages, which are displayed as hypointense images in some T2-weighted magnetic resonance imaging sequences. There are still many questions to be answered about the pathophysiology and clinical relevance of BMB.
  
  
  METHODS
  We conducted a literature review of the main epidemiological, clinical, and anatomical pathology studies of BMB performed in the general population, in patients at risk of or already suffering from a vascular disease, and in patients with cognitive impairment. We analysed the prevalence of BMB, risk factors, and potential pathophysiological mechanisms and clinical implications.
  
  
  CONCLUSIONS
  The prevalence of BMB is highly variable (3%-27% in the general population, 6%-80% in patients with vascular risk factors or vascular disease, and 16%-45% in patients with cognitive impairment). BMB are associated with ageing, Alzheimer disease (AD), and in particular haemorrhagic or ischaemic cerebrovascular disease. The pathological substrate of BMB is either lipohyalinosis (subcortical BMB) or cerebral amyloid angiopathy (lobar BMB). BMB exacerbate cognitive impairment, possibly through cortical-subcortical and intracortical disconnection, and increase the risk of death, mostly due to vascular causes. BMB also increase the risk of cerebral haemorrhage, particularly in patients with multiple lobar BMB (probable erebral amyloid angiopathy). Therefore, anticoagulant treatment may be contraindicated in these patients. In patients with lower risk of bleeding, the new oral anticoagulants and the combination of clinical and magnetic resonance imaging follow-up could be helpful in the decision-making process.
authors.affiliation: Servicio de Geriatría, Hospital Universitario de Móstoles, Madrid, España.
authors.forename: I
authors.initials: I
authors.lastname: Boyano
authors.affiliation: Servicio de Neurología, Hospital General Universitario Gregorio Marañón, Madrid, España.
authors.forename: N
authors.initials: N
authors.lastname: Bravo
authors.affiliation: Servicio de Neurología, Hospital General Universitario Gregorio Marañón, Madrid, España.
authors.forename: J
authors.initials: J
authors.lastname: Miranda
authors.affiliation: Servicio de Geriatría, Hospital Clínico Universitario San Carlos, Madrid, España.
authors.forename: P
authors.initials: P
authors.lastname: Gil-Gregorio
authors.affiliation: Servicio de Neurología, Hospital General Universitario Gregorio Marañón, Madrid, España. Electronic address: javier@mariawolff.es.
authors.forename: J
authors.initials: J
authors.lastname: Olazarán
mesh_terms: D000328:Adult; D000368:Aged; D000544:Alzheimer Disease / Q000503:physiopathology; D001921:Brain / Q000098:blood supply*; D002543:Cerebral Hemorrhage / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000453:epidemiology* / Q000503:physiopathology; D060825:Cognitive Dysfunction / Q000503:physiopathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged
keywords: Alzheimer disease; Angiopatía amiloide cerebral; Brain microbleeds; Cerebral amyloid angiopathy; Cerebrovascular disease; Cognitive impairment; Deterioro cognitivo; Enfermedad cerebrovascular; Enfermedad de Alzheimer; Lipohialinosis; Lipohyalinosis; Microhemorragias cerebrales