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Designing prevention programmes to reduce incidence of dementia: prospective cohort study of modifiable risk factors

BMJ 2010; 341 doi: (Published 05 August 2010) Cite this as: BMJ 2010;341:c3885
  1. K Ritchie, senior research director123,
  2. I Carrière, research fellow12,
  3. C W Ritchie, consultant psychiatrist3,
  4. C Berr, research director12,
  5. S Artero, research fellow12,
  6. M-L Ancelin, research director12
  1. 1Inserm, U888 Nervous System Pathologies: Epidemiological and Clinical Research, La Colombière Hospital, 34093 Montpellier Cedex 5, France
  2. 2Université de Montpellier 1, Montpellier, F-34000, France
  3. 3Faculty of Medicine, Imperial College, St Mary’s Hospital, London
  1. Correspondence to: K Ritchie karen.ritchie{at}
  • Accepted 14 June 2010


Objective To estimate the percentage reduction in incidence of dementia that would be obtained if specific risk factors were eliminated.

Design Prospective seven year cohort study.

Setting General population, Montpellier, France.

Participants 1433 people aged over 65 with a mean baseline age of 72.5 (SD 5.1) years.

Main outcome measures Diagnosis of mild cognitive impairment or dementia established by a standardised neurological examination.

Results Cox models were constructed to derive hazard ratios and determine confounding and interaction effects for potentially modifiable risk factors for dementia. Mean percentage population attributable fractions were calculated with 95% confidence intervals derived from bootstrapping for seven year incidence of mild cognitive impairment or dementia. The final model retained crystallised intelligence (population attributable fraction 18.11%, 95% confidence interval 10.91% to 25.42%), depression (10.31%, 3.66% to 17.17%), fruit and vegetable consumption (6.46%, 0.15% to 13.06%), diabetes (4.88%, 1.87% to 7.98%), and apolipoprotein E ε4 allele (7.11%, 2.44% to 11.98%).

Conclusions Increasing crystallised intelligence and fruit and vegetable consumption and eliminating depression and diabetes are likely to have the biggest impact on reducing the incidence of dementia, outweighing even the effect of removing the principal known genetic risk factor. Although causal relations cannot be concluded with certainty, the study suggests priorities that may inform public health programmes.


  • Contributors: M-LA and KR are the principal co-investigators of the Esprit Project. CB directed data collection. KR proposed the analysis, and the methods were developed by KR, M-LA, SA, and IC. IC did the analyses. KR wrote the article. KR, M-LA, CWR, and IC participated equally in the development of the discussion section. KR and IC are joint first authors. All authors read and commented on the final manuscript. Guilhem de Roquefeuil did the population sampling procedure for the Esprit Project. KR is the guarantor.

  • Funding: The Esprit Study was funded by an unconditional grant from Novartis and from the National Research Agency (ANR Project 07 LVIE004). Funding from Novartis was used to purchase equipment and pay for secretarial assistance. ANR funding provided salaries for the interviewers and the costs of clinical and biological examinations. Neither body was involved in the statistical analyses or preparation of the manuscript.

  • Competing interests: All authors have completed the Unified Competing Interest form at disclosure.pdf and declare that (1) KR, IC, CWR, CB, SA, and M-LA have technical support from Novartis for the submitted work; (2) KR, IC, CWR, CB, SA, and M-LA have no relationships with companies that might have an interest in the submitted work in the previous 3 years; (3) their spouses, partners, or children have no specified financial relationships that may be relevant to the submitted work; and (4) KR, IC, CWR, CB, SA, and M-LA have no non-financial interests that may be relevant to the submitted work.

  • Ethical approval: The ethics committee of the University-Hospital of Kremlin-Bicêtre approved the study protocol, and each participant gave written informed consent.

  • Data sharing: No additional data available.

  • Accepted 14 June 2010

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