Objective: To determine whether and how age at retirement influences the risk of dementia. The association between the age at retirement, the number of working years and the risk of dementia was evaluated over 12 years of follow-up.
Design: A prospective population-based study.
Setting: Three-City cohort, a French population-based study of community-dwelling individuals aged 65 to 95.
Participants: The sample consisted of 1,658 non-demented participants at baseline.
Measurements: All participants were evaluated at home at the initial visit and at two years interval for a period of 12 years. An active research of dementia was conducted at each follow-up; all suspected cases were analysed by an independent committee of neurologists. Information regarding retirement age and number of working years was collected at baseline using a structured questionnaire.
Results: The multivariate Cox model, including both the age at retirement and the number of working years and adjusted for potential confounders, revealed that the risk of dementia was independently associated with the age at retirement (p=0.022) but not with the number of working years (p=0.296).
Conclusion: Although our results are in accordance with previous studies (i.e., older age at retirement is associated with decreased risk of dementia), it provides additional information regarding the possible explanation for such results. Given that a longer working life did not reduce the risk of dementia, the age at retirement cannot be considered as a new factor of cognitive reserve but rather seems to be a psycho-social vulnerability factor. Further evidence is necessary to identify work and retirement related factors that influence the association between the age at retirement and the risk of dementia.