title: Cerebrovascular hemodynamics, gait, and falls in an elderly population: MOBILIZE Boston Study.
abstract: OBJECTIVE
  To determine whether alterations in cerebral blood flow regulation are associated with slow gait speed and falls in community-dwelling elderly individuals.
  
  
  METHODS
  The study sample consisted of 419 individuals from the MOBILIZE Boston Study (MBS) who had transcranial Doppler ultrasound measures of cerebral blood flow velocity. The MBS is a prospective cohort study of a unique set of risk factors for falls in seniors in the Boston area. We measured beat-to-beat blood flow velocity in the middle cerebral artery in response to 1) changes in end-tidal CO(2) (cerebral vasoreactivity) and 2) blood pressure changes during a sit-to-stand protocol (cerebral autoregulation). Gait speed was measured during a 4-meter walk. Falls were tracked by monthly calendars, and demographic and clinical characteristics were assessed at baseline.
  
  
  RESULTS
  A multivariate linear regression analysis showed that cerebral vasoreactivity was cross-sectionally related to gait speed (p = 0.039). Individuals in the lowest quintile of vasoreactivity had lower gait speeds as compared to those in the highest quintile (p = 0.047). In a negative binomial regression analysis adjusted for relevant covariates, the relationship between cerebral vasoreactivity and fall rate did not reach significance. However, when comparing individuals in the lowest to highest quintile of cerebral vasoreactivity, those in the lowest quintile had a higher fall rate (p = 0.029).
  
  
  CONCLUSIONS
  Impaired cerebral blood flow regulation, as measured by cerebral vasoreactivity to CO(2), is associated with slow gait speed and may lead to the development of falls in elderly people.
authors.affiliation: Department of Neurology, Stroke Division, Brigham and Women's Hospital, 45 Francis St., Boston, MA 02115, USA. fsorond@partners.org
authors.forename: F A
authors.initials: FA
authors.lastname: Sorond
authors.forename: A
authors.initials: A
authors.lastname: Galica
authors.forename: J M
authors.initials: JM
authors.lastname: Serrador
authors.forename: D K
authors.initials: DK
authors.lastname: Kiely
authors.forename: I
authors.initials: I
authors.lastname: Iloputaife
authors.forename: L A
authors.initials: LA
authors.lastname: Cupples
authors.forename: L A
authors.initials: LA
authors.lastname: Lipsitz
mesh_terms: D000058:Accidental Falls; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D016009:Chi-Square Distribution; D005260:Female; D005684:Gait / Q000502:physiology*; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D004856:Postural Balance / Q000502:physiology; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors; D017585:Ultrasonography, Doppler, Transcranial