title: Cerebrovascular function and cognition in childhood: a systematic review of transcranial Doppler studies.
abstract: BACKGROUND
  The contribution of cerebrovascular function to cognitive performance is gaining increased attention. Transcranial doppler (TCD) is portable, reliable, inexpensive and extremely well tolerated by young and clinical samples. It enables measurement of blood flow velocity in major cerebral arteries at rest and during cognitive tasks.
  
  
  METHODS
  We systematically reviewed evidence for associations between cognitive performance and cerebrovascular function in children (0-18 years), as measured using TCD. A total of 2778 articles were retrieved from PsychInfo, Pubmed, and EMBASE searches and 25 relevant articles were identified.
  
  
  RESULTS
  Most studies investigated clinical groups, where decreased blood flow velocities in infants were associated with poor neurological functioning, and increased blood flow velocities in children with Sickle cell disease were typically associated with cognitive impairment and lower intelligence. Studies were also identified assessing autistic behaviour, mental retardation and sleep disordered breathing. In healthy children, the majority of studies reported cognitive processing produced lateralised changes in blood flow velocities however these physiological responses did not appear to correlate with behavioural cognitive performance.
  
  
  CONCLUSIONS
  Poor cognitive performance appears to be associated with decreased blood flow velocities in premature infants, and increased velocities in Sickle cell disease children using TCD methods. However knowledge in healthy samples is relatively limited. The technique is well tolerated by children, is portable and inexpensive. It therefore stands to make a valuable contribution to knowledge regarding the underlying functional biology of cognitive performance in childhood.
authors.forename: Mireille J
authors.initials: MJ
authors.lastname: Bakker
authors.forename: Jessica
authors.initials: J
authors.lastname: Hofmann
authors.forename: Owen F
authors.initials: OF
authors.lastname: Churches
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Badcock
authors.forename: Mark
authors.initials: M
authors.lastname: Kohler
authors.affiliation: Cognitive Neuroscience Laboratory, School of Psychology, Social Work and Social Policy, University of South Australia, GPO BOX 2471, 5001 Adelaide, SA, Australia. Hannah.Keage@unisa.edu.au.
authors.forename: Hannah A D
authors.initials: HA
authors.lastname: Keage
mesh_terms: D000293:Adolescent; D000755:Anemia, Sickle Cell / Q000000981:diagnostic imaging / Q000503:physiopathology; D001783:Blood Flow Velocity / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods* / Q000592:standards