title: Life long endogenous estrogen exposure and later adulthood cognitive function in a population of naturally postmenopausal women from Southern China: the Guangzhou Biobank Cohort Study.
abstract: BACKGROUND
  Estrogen has neurotrophic and neuroprotective properties in animal and in vitro studies. Epidemiological studies are inconclusive, but suggest a positive association between endogenous estrogen exposure (measured by reproductive period, the number of years between menarche and menopause) and later life cognitive function.
  
  
  METHODS
  Structural equation modeling was used in a cross-sectional study of 11,094 naturally postmenopausal multiparous Chinese older (≥50 years) women from the Guangzhou Biobank Cohort Study (phases 2 and 3) to assess the interrelationship of four proxies of higher endogenous estrogen exposure (longer reproductive period, older age of first pregnancy, lower parity and shorter average duration of breast feeding per child) with immediate and the delayed 10-word recall score in phases 2 and 3, and with the mini-mental state examination (MMSE) score in phase 3 (5641 women).
  
  
  RESULTS
  Adjusted for age, education, childhood and adulthood socio-economic position and physical activity, longer reproductive period was associated with higher scores (0.02 words per year, 95% confidence interval (CI) 0.008-0.02 for delayed recall and 0.05 MMSE score, 95%CI 0.04-0.07, respectively). Lower parity and shorter average duration of breast-feeding per child were also associated with better cognitive function.
  
  
  CONCLUSIONS
  In a large cohort of naturally postmenopausal Chinese women proxies of greater endogenous estrogen exposure were associated with better cognitive function. These findings support biological evidence for a cognitively protective role of endogenous estrogen.
authors.affiliation: Department of Community Medicine, School of Public Health, The University of Hong Kong, Hong Kong, China.
authors.forename: Michelle
authors.initials: M
authors.lastname: Heys
authors.forename: Chaoqiang
authors.initials: C
authors.lastname: Jiang
authors.forename: Kar Keung
authors.initials: KK
authors.lastname: Cheng
authors.forename: Weisen
authors.initials: W
authors.lastname: Zhang
authors.forename: Shiu Lun
authors.initials: SL
authors.lastname: Au Yeung
authors.forename: Tai Hing
authors.initials: TH
authors.lastname: Lam
authors.forename: Gabriel M
authors.initials: GM
authors.lastname: Leung
authors.forename: C Mary
authors.initials: CM
authors.lastname: Schooling
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002681:China; D003071:Cognition / Q000502:physiology*; D015331:Cohort Studies; D003278:Contraceptives, Oral, Hormonal; D004967:Estrogens / Q000502:physiology*; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D007044:Hysterectomy; D007774:Lactation; D008568:Memory; D008572:Menarche; D008875:Middle Aged; D009043:Motor Activity; D009483:Neuropsychological Tests; D010052:Ovariectomy; D010298:Parity; D017698:Postmenopause / Q000097:blood / Q000523:psychology; D011247:Pregnancy; D017584:Reproductive History; D012923:Social Class
chemical_list: D003278:Contraceptives, Oral, Hormonal; D004967:Estrogens