Heterogeneity in cognitive disability after a major disaster : A natural experiment study

Cognitive disability following traumatic experiences of disaster has been documented; however, little is known about heterogeneity in the association across individuals. In this natural experiment study of approximately 3000 Japanese older adults in an area directly affected by the 2011 Great East Japan Earthquake, the baseline survey was established 7 months before the 2011 earthquake. To inductively identify heterogeneity in post-disaster cognitive disability by predisaster characteristics, we applied a machine learning-based causal inference approach-generalized random forest. We identified strong evidence for heterogeneity in the association between home loss and cognitive disability objectively assessed 2.5 and 5.5 years after the 2011 earthquake. The subgroups with the strongest disaster-dementia associations tended to be from low socioeconomic backgrounds and have predisaster health problems. The study demonstrated that some subpopulations are particularly prone to experience cognitive disability after disasters, which could be overlooked in studies assessing population average associations only.Funding Agencies|National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R01 AG042463]; Japan Society for the Promotion of ScienceMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science [KAKENHI 23243070, KAKENHI 22390400, KAKENHI 20H00557, KAKENHI 24390469]; Japanese Ministry of Health, Labour, and WelfareMinistry of Health, Labour and Welfare, Japan [H24-Choju-Wakate-009]; Strategic Research Foundation Grant-Aided Project for Private Universities from the Japanese Ministry of Education, Culture, Sports, Science, and Technology [S0991035]; Japan Agency for Medical Research and Development (AMED)Japan Agency for Medical Research and Development (AMED) [JP17dk0110017, JP18dk0110027, JP18ls0110002, JP18le0110009, JP19dk0110034, JP19dk0110037, JP20dk0110034]