title: Childhood cognitive ability and age at menopause: evidence from two cohort studies.
abstract: OBJECTIVE
  To investigate whether poorer cognitive ability in childhood is associated with an earlier menopause.
  
  
  METHODS
  Two cohorts were included: a nationally representative British birth cohort study of 1,350 women born in March 1946 and followed up to age 54 years, and an Aberdeen cohort study of 3,465 women born in Aberdeen from 1950 to 1956 and followed up to age 44 to 50 years. Both cohorts had prospective information on childhood cognitive ability at age 7 or 8 years.
  
  
  RESULTS
  In both cohorts, women with lower cognitive scores in childhood reached menopause earlier than women with higher scores. With follow-up of menopause to 49 years, the hazard ratio (HR) for one standard deviation of the cognitive score was 0.80 (95% CI, 0.72-0.90) in the Aberdeen cohort and 0.84 (95% CI, 0.73-0.97) in the older 1946 birth cohort. The effect was still evident in the 1946 birth cohort with follow-up of menopause to 53 years (HR = 0.87; 95% CI, 0.79-0.95). These ratios were weakly attenuated by adjustment for potential confounding effects of lifetime socioeconomic circumstances, parity, and smoking.
  
  
  CONCLUSIONS
  The association between early cognitive ability and timing of menopause only partially reflects common risk factors, although residual confounding remains a possibility. Alternatively, early environmental or genetic programming may explain this association, perhaps through setting lifelong patterns of hormone release or causing transient hormonal changes at sensitive periods of development. These findings have implications for the interpretation of studies investigating an association between age at menopause and adult cognitive function.
authors.affiliation: MRC National Survey of Health and Development, Department of Epidemiology and Public Health, Royal Free and University College Medical School, London. d.kuh@nhsd.mrc.ac.uk
authors.forename: Diana
authors.initials: D
authors.lastname: Kuh
authors.forename: Suzanne
authors.initials: S
authors.lastname: Butterworth
authors.forename: Helen
authors.initials: H
authors.lastname: Kok
authors.forename: Marcus
authors.initials: M
authors.lastname: Richards
authors.forename: Rebecca
authors.initials: R
authors.lastname: Hardy
authors.forename: Michael E J
authors.initials: ME
authors.lastname: Wadsworth
authors.forename: David A
authors.initials: DA
authors.lastname: Leon
mesh_terms: D000328:Adult; D000367:Age Factors; D003071:Cognition / Q000502:physiology*; D004522:Educational Status; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007361:Intelligence Tests; D008593:Menopause / Q000502:physiology*; D008875:Middle Aged; D009790:Occupations; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012907:Smoking / Q000009:adverse effects; D012923:Social Class; D006113:United Kingdom