title: Decline in blood pressure over time and risk of dementia: a longitudinal study from the Kungsholmen project.
abstract: OBJECTIVE
  Low blood pressure has been related to an increased risk of dementia. We sought to verify blood pressure variations before and after a dementia diagnosis and to relate blood pressure decline to subsequent Alzheimer disease and dementia.
  
  
  METHODS
  A community dementia-free cohort aged > or =75 years (n=947) underwent follow-up examinations twice over a period of 6 years to detect dementia cases (Diagnostic and Statistical Manual of Mental Disorders, 3rd edition, revised [DSM-III-R] criteria, n=304). Blood pressure variation before and after dementia diagnosis was verified with linear mixed-effects models. Using the dementia-free cohort identified at first follow-up (n=719), the association between blood pressure decline from baseline to first follow-up and subsequent risk of dementia was examined.
  
  
  RESULTS
  Blood pressure markedly decreased over 3 years before dementia diagnosis and afterward, whereas no substantial decline was present 3 to 6 years before the diagnosis. However, among subjects with baseline systolic pressure <160 mm Hg, systolic pressure decline > or =15 mm Hg occurring 3 to 6 years before diagnosis was associated with relative risks (95% CI) of 3.1 (1.3 to 7.0) for Alzheimer disease and 3.1 (1.5 to 6.3) for dementia. There was a dose-response relationship between systolic pressure decline and dementia risk in subjects with vascular disease.
  
  
  CONCLUSIONS
  Blood pressure starts to decrease only 3 years before dementia diagnosis and continues to decline afterward. A greater decline in systolic pressure occurring 3 to 6 years before diagnosis is associated with an increased risk of dementia only in older people with already low blood pressure or affected by vascular disorders.
authors.affiliation: Aging Research Center, Division of Geriatric Epidemiology and Medicine, Department of Neurotec, Karolinska Institutet, Stockholm, Sweden. chengxuan.qiu@neurotec.ki.se
authors.forename: Chengxuan
authors.initials: C
authors.lastname: Qiu
authors.forename: Eva
authors.initials: E
authors.lastname: von Strauss
authors.forename: Bengt
authors.initials: B
authors.lastname: Winblad
authors.forename: Laura
authors.initials: L
authors.lastname: Fratiglioni
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology; D001794:Blood Pressure; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000503:physiopathology; D003704:Dementia / Q000453:epidemiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D012307:Risk Factors; D013997:Time Factors