General cognitive status among Baby boomers and pre-boomers in Taiwan: the interplay between mid-life socioeconomic status and city residence

BACKGROUND: This study seeks to assess the interaction between mid-life socioeconomic status (SES) and city residence on the cognitive status of Baby Boomers and pre-Boomers in Taiwan, a non-Western society with a distinct cultural and family context, taking apolipoprotein E (APOE) gene polymophism and life stressors into consideration. METHODS: The data used was from the Social Environment and Biomarkers of Aging Study (SEBAS) collected in Taiwan during 2006, this involved 1245 individuals from 23 communities and used multilevel regression. General cognitive status was assessed by ten questions via personal interviews. The questions were part of the Short Portable Mental Status Questionnaire, a 10-item free-recall and immediate recall test. Mid-life SES was defined by education and major mid-life occupation of the participant and/or their partner. RESULTS: Mid-life SES was positively associated with cognitive status among both Baby Boomers and pre-Boomers, even after adjusting for APOE polymorphism and stressor covariates. For Baby Boomers, city residents were more likely than town residents to show better cognition (β = 1.47, p < 0.01) and an interaction effect between mid-life SES and city residence was observed (β = −2.12, p < 0.01). While both the Baby Boomer and pre-Boomer cohorts who lived with a partner were reported better cognition, the effects of depressive symptoms and ethnicity differed by cohort. CONCLUSIONS: Having a high level of mid-life SES and living with a partner are associated with better cognition for both cohort groups. An interplay effect between mid-life SES and place of residence on cognition was only found for Baby Boomers. On the other hand, being psychologically depressed was associated with poorer cognition among pre-Boomers. These results underscore the specific roles of mid-life SES, city residence, and life stressors with regard to the cognitive status of Baby Boomers and pre-Boomers in Taiwan.