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Original research
Number of children and risk of dementia: a cohort study
  1. Katrin Wolfova1,2,3,
  2. Rebecca A Hubbard4,
  3. Pavla Brennan Kearns2,
  4. Virginia W Chang5,
  5. Paul Crane6,
  6. Andrea Z LaCroix6,
  7. Eric B Larson7,
  8. Sarah Tom3,8
  1. 1 Department of Psychiatry and Medical Psychology, Third Faculty of Medicine, Charles University, Prague, Czech Republic
  2. 2 Department of Epidemiology, Second Faculty of Medicine, Charles University, Prague, Czech Republic
  3. 3 Department of Neurology, Columbia University, New York, New York, USA
  4. 4 Department of Biostatistics, Brown University School of Public Health, Providence, Rhode Island, USA
  5. 5 Department of Social and Behavioral Sciences, New York University School of Global Public Health, New York, New York, USA
  6. 6 Department of Medicine, University of Washington, Seattle, Washington, USA
  7. 7 Herbert Wertheim School of Public Health and Human Longevity Science, UC San Diego, La Jolla, California, USA
  8. 8 Department of Epidemiology, Columbia University, New York, New York, USA
  1. Correspondence to Dr Sarah Tom; st3144{at}cumc.columbia.edu

Abstract

Background Findings on the link between the number of children and dementia risk are inconsistent, mostly studied in females, suggesting pregnancy-related changes may be a key factor in this association.

Methods The Adult Changes in Thought Study is a cohort of adults aged ≥65 years from Kaiser Permanente Washington. The primary exposure was the number of children (0, 1, 2, 3 or ≥4), and the outcome was an incident dementia diagnosis. Cox proportional-hazards models were adjusted for demographic and early-life socioeconomic confounders. Models were then stratified by sex and by birth year <1928 versus ≥1928.

Results Among 4668 participants (average age at enrolment 74.1±SD 6.3 years; 59% female), 967 (21%) had 0 children, 484 (10%) had one child, 1240 (27%) had two children, 968 (21%) had three children and 1009 (22%) had four or more children. We found no association between the number of children and dementia overall or after stratification by birth cohort. When stratified by sex and adjusting for confounders, having ≥4 children compared with two children was associated with a higher rate of dementia in males (HR=1.31, 95% CI 1.01 to 1.71).

Conclusions The number of children was not consistently associated with the risk of dementia. We observed a greater risk of dementia only among males who had ≥4 children, with the lower bound of the 95% CI marginally exceeding 1. These findings suggest that the number of children may influence the risk of dementia through other than pregnancy-related pathways.

  • DEMENTIA
  • Parity
  • COGNITION
  • Life course epidemiology

Data availability statement

Data may be obtained from a third party and are not publicly available. Data are not publicly available. Data from the Adult Changes in Thought Study may be requested at: https://actagingresearch.org/collaboration/work-with-us/request-act-data.

https://doi.org/10.1136/jech-2024-222717

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    Data availability statement

    Data may be obtained from a third party and are not publicly available. Data are not publicly available. Data from the Adult Changes in Thought Study may be requested at: https://actagingresearch.org/collaboration/work-with-us/request-act-data.

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    Footnotes

    • Contributors KW and ST generated the idea for the paper and drafted the text. KW conducted the analysis. RAH served as a scientific advisor. RAH, PBK, VWC, PC, AZL and EBL contributed to the interpretation of the results and critical revisions of the paper. ST is the paper guarantor.

    • Funding This research was funded by the National Institute on Aging (U19AG066567). Data collection for this work was additionally supported, in part, by prior funding from the National Institute on Aging (U01AG006781). The authors were supported by the National Institute on Aging (grant K01AG050723 to ST), by the Grant Agency of Charles University in Prague (grant GAUK: 416122 to KW and PBK); and by the PRIMUS Research Programme (22/MED/012 to KW) conducted at Charles University. RAH, VWC, PC, AZL and EBL report no disclosures relevant to the manuscript.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.