The association between adverse experiences throughout the life-course and risk of dementia in the English Longitudinal Study of Ageing

BackgroundPrevious studies investigating associations between adverse experiences across the life-course and dementia consider a narrow range of experiences and use sum scores which assume each experience has the same impact on dementia risk.ObjectiveTo develop a greater understanding of how patterns of adversity influence associations with dementia through consideration of timing, type and cumulation of adverse experiences.MethodsThe English Longitudinal Study of Ageing measured adverse life experiences in a life history interview. Cox proportional hazard models were used to investigate associations between dementia and three types of exposure: sum scores, individual experiences, and categories of similar experiences. We used linear hypothesis testing to assess whether associations between each experience and dementia differed significantly.ResultsA linear relationship between dementia and number of adult adverse experiences (HR:1.09, 95% CI:1.01-1.16), but not total or childhood experiences, was observed. When adverse experiences were considered separately, child abuse was associated with a 74% higher hazard of dementia (HR:1.74, 95% CI:1.25-2.43) and adult economic hardship was associated with a 32% higher hazard of dementia (HR:1.32, 95% CI:1.06-1.66). Associations between dementia and adverse experiences in childhood were heterogenous, showing greater variability than expected about a common hazard ratio (p = 0.01).ConclusionsAdulthood adverse experiences associate with dementia in a cumulative risk manner. In childhood, only abuse was associated with dementia. Use of sum scores to operationalize adverse experiences throughout the life-course may oversimplify associations with dementia. Both type and timing of experience influence the association. Work to prevent adverse experiences must span the life-course.