title: Blood pressure levels before dementia.
abstract: BACKGROUND
  The association between blood pressure (BP) and dementia is not easily interpreted, but some prospective studies suggest that dementia may lower BP.
  
  
  OBJECTIVE
  To examine the relationship between BP during a 10-year period and the prevalence of dementia.
  
  
  METHODS
  Comparison of longitudinal BP between participants who had dementia, participants who were cognitively impaired, and unimpaired participants selected from an ongoing cohort study.
  
  
  METHODS
  A prepaid health plan in southern California.
  
  
  METHODS
  Three hundred participants had dementia, 285 were cognitively impaired, and 585 were unimpaired.
  
  
  METHODS
  Retrospective medical record review of up to 3 randomly selected BP measurements per year for the 10 years before cognitive classification of each participant.
  
  
  RESULTS
  Systolic BP increased with time in the unimpaired participants, and increased less in women who developed cognitive impairment and in women who developed dementia. Diastolic BP declined significantly (P<.001) with time in all 3 groups. Compared with unimpaired women, the adjusted rate of decline in diastolic BP was significantly (P = .04) greater for the women who developed dementia.
  
  
  CONCLUSIONS
  These findings are consistent with previous findings that the relationship between BP and dementia is affected by age at data collection. Valid inferences about the effect of BP on the development of dementia require prospective data collection in which subjects are free of dementia or cognitive impairment at enrollment.
authors.affiliation: Department of Research and Evaluation, Kaiser Permanente Southern California, 100 S. Los Robles, Pasadena, CA 91101, USA.
authors.forename: Diana B
authors.initials: DB
authors.lastname: Petitti
authors.forename: Valerie C
authors.initials: VC
authors.lastname: Crooks
authors.forename: J Galen
authors.initials: JG
authors.lastname: Buckwalter
authors.forename: Vicki
authors.initials: V
authors.lastname: Chiu
mesh_terms: D001794:Blood Pressure / Q000502:physiology*; D016009:Chi-Square Distribution; D003072:Cognition Disorders / Q000453:epidemiology / Q000503:physiopathology; D015331:Cohort Studies; D003704:Dementia / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D016014:Linear Models; D012016:Reference Values; D012189:Retrospective Studies; D013997:Time Factors