title: Increased risk of cognitive impairment or dementia in women who underwent oophorectomy before menopause.
abstract: OBJECTIVE
  There is increasing laboratory evidence for a neuroprotective effect of estrogen; however, the clinical and epidemiologic evidence remains limited and conflicting. We studied the association of oophorectomy performed before the onset of menopause with the risk of subsequent cognitive impairment or dementia.
  
  
  METHODS
  We included all women who underwent unilateral or bilateral oophorectomy before the onset of menopause for a non-cancer indication while residing in Olmsted County, MN, from 1950 through 1987. Each member of the oophorectomy cohort was matched by age to a referent woman from the same population who had not undergone oophorectomy. In total, we studied 813 women with unilateral oophorectomy, 676 women with bilateral oophorectomy, and 1,472 referent women. Women were followed through death or end of study using either direct or proxy interviews.
  
  
  RESULTS
  Women who underwent either unilateral or bilateral oophorectomy before the onset of menopause had an increased risk of cognitive impairment or dementia compared to referent women (hazard ratio [HR] = 1.46; 95% CI 1.13 to 1.90; adjusted for education, type of interview, and history of depression). The risk increased with younger age at oophorectomy (test for linear trend; adjusted p < 0.0001). These associations were similar regardless of the indication for the oophorectomy, and for women who underwent unilateral or bilateral oophorectomy considered separately.
  
  
  CONCLUSIONS
  Both unilateral and bilateral oophorectomy preceding the onset of menopause are associated with an increased risk of cognitive impairment or dementia. The effect is age-dependent and suggests a critical age window for neuroprotection.
authors.affiliation: Division of Epidemiology, Department of Health Sciences Research, Mayo Clinic, Rochester, MN 55905, USA. rocca@mayo.edu
authors.forename: W A
authors.initials: WA
authors.lastname: Rocca
authors.forename: J H
authors.initials: JH
authors.lastname: Bower
authors.forename: D M
authors.initials: DM
authors.lastname: Maraganore
authors.forename: J E
authors.initials: JE
authors.lastname: Ahlskog
authors.forename: B R
authors.initials: BR
authors.lastname: Grossardt
authors.forename: M
authors.initials: M
authors.lastname: de Andrade
authors.forename: L J
authors.initials: LJ
authors.lastname: Melton
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging; D015984:Causality; D003072:Cognition Disorders / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D015331:Cohort Studies; D003704:Dementia / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D004967:Estrogens / Q000378:metabolism*; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D008594:Menopause, Premature / Q000378:metabolism*; D008875:Middle Aged; D018696:Neuroprotective Agents / Q000378:metabolism*; D010052:Ovariectomy / Q000009:adverse effects*; D012307:Risk Factors; D011795:Surveys and Questionnaires
chemical_list: D004967:Estrogens; D018696:Neuroprotective Agents