title: Oophorectomy, hysterectomy, and risk of Alzheimer's disease: a nationwide case-control study.
abstract: BACKGROUND
  Association between oophorectomy and/or hysterectomy and dementia in context of hormone therapy (HT) use is ambiguous.
  
  
  OBJECTIVE
  To assess whether oophorectomy, hysterectomy, and hysterectomy with bilateral oophorectomy are related to risk of Alzheimer's disease (AD), whether the possible indication for surgery plays a role, and if the associations are modified by HT.
  
  
  METHODS
  Our nationwide register based case-control (1 : 1) study included all women with clinically-verified AD diagnoses, residing in Finland on December 31, 2005 (n of cases = 19,043, n of controls = 19,043). AD cases, diagnosed according to NINCS-ADRDA and the DSM-IV criteria, were identified from Special Reimbursement Register. Information on HT use was collected from national prescription register, and data on surgery and uterine/ovarian/cervical cancer were obtained from the hospital discharge register. Most of the women (91.8%) were over 51 years of age when the surgery was performed.
  
  
  RESULTS
  Oophorectomy, hysterectomy, and hysterectomy with bilateral oophorectomy were associated with lower risk of AD (OR/95% CI: 0.85/0.75-0.97, 0.89/0.81-0.97 and 0.85/0.75-0.98, respectively) among women without the history of uterine/ovarian/cervical cancer, although the absolute risk difference was small. The association was not evident in women with uterine/ovarian/cervical cancer history (3.00/0.20-44.87 for all surgeries). The associations were not modified by HT use, which was independently associated with AD risk, with longer use showing protective association.
  
  
  CONCLUSIONS
  Our findings indicate that oophorectomy with or without hysterectomy after commencement of natural menopause is not an important determinant of AD risk in older age and support the critical window hypothesis for HT use.
authors.affiliation: Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland.
authors.forename: Bushra
authors.initials: B
authors.lastname: Imtiaz
authors.affiliation: Bone and Cartilage Research Unit, Clinical Research Center, University of Eastern Finland, Kuopio, Finland Department of Obstetrics and Gynecology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Marjo
authors.initials: M
authors.lastname: Tuppurainen
authors.affiliation: Department of Pharmacy, Social Pharmacy, University of Eastern Finland, Kuopio, Finland.
authors.forename: Miia
authors.initials: M
authors.lastname: Tiihonen
authors.affiliation: Department of Neurology, University of Eastern Finland, Kuopio, Finland Aging Research Center (ARC), Karolinska Institute and Stockholm University, Stockholm, Sweden.
authors.forename: Miia
authors.initials: M
authors.lastname: Kivipelto
authors.affiliation: Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Hilkka
authors.initials: H
authors.lastname: Soininen
authors.affiliation: Kuopio Research Center of Geriatric Care, University of Eastern Finland, Kuopio, Finland School of Pharmacy, Social Pharmacy, University of Eastern Finland, Kuopio, Finland.
authors.forename: Sirpa
authors.initials: S
authors.lastname: Hartikainen
authors.affiliation: Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland.
authors.forename: Anna-Maija
authors.initials: AM
authors.lastname: Tolppanen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology* / Q000209:etiology*; D016022:Case-Control Studies; D005260:Female; D005387:Finland; D006801:Humans; D007044:Hysterectomy / Q000009:adverse effects*; D008875:Middle Aged; D010052:Ovariectomy / Q000009:adverse effects*; D012189:Retrospective Studies
keywords: Alzheimer's disease; cognition; dementia; estrogen; hormone therapy; hysterectomy; menopause; oophorectomy; radical hysterectomy