Existing data for the association between late-life body mass index (BMI) and the risk of Alzheimer’s disease (AD) in the underweight population are limited with conflicting results. A large population-based cohort study of 148,534 individuals aged ≥ 65 years who participated in the national health screening program from 2002 to 2005 was performed using the Korean National Health Insurance Service-Senior cohort database 2006–2015. The risk of AD according to BMI category (kg/m2) in Asians was evaluated using a multivariable Cox regression model, after adjustments for age, sex, lifestyle, low-income status, and comorbidities. To evaluate the association between BMI and AD risk, the underweight population was further subdivided according to the degree of thinness. During the 10-year follow-up period, 22,279 individuals developed AD. Relative to the normal-weight population, the estimated adjusted hazard ratio (HR) for incident AD in the underweight, overweight, and obese populations was 1.17 (95% confidence interval [CI], 1.09–1.24), 0.90 (0.87–0.93), and 0.83 (0.80–0.85), respectively. In the underweight population, AD risk increased as the degree of thinness increased (p for the trend, < .001). Late-life BMI showed a significant inverse relationship with AD risk, especially in the underweight population. Public health strategies to screen for AD more actively in the underweight population and improve their weight status may help reduce the burden of AD.

Background: Housing poverty is a potential risk factor for depression in elderly people; however, this relationship depends on the socio-cultural background. This study aimed to determine if housing poverty is a risk factor for depression in Korean elderly people. Methods: A total of 10,083 people aged 65 or older who participated in the National Survey of Older Koreans in 2017 were included. Housing poverty was defined as "living underground, " "semi-basement, " or "rooftop. " Depression was assessed using the Short Form of the Geriatric Depression Scale (SGDS). Comparisons of baseline variables were analyzed using the χ 2 test or student' s t-test, as appropriate. Logistic regression was used to analyze the risk of depression, with or without adjustment. Results: The odds ratio (OR) of depression was higher in the housing poverty group (OR, 1.55; 95% confidence interval [CI], 1.15-2.09), even after adjusting for age and sex (adjusted odds ratio [aOR], 1.43; 95% CI, 1.05-1.95). However, after adjusting for income levels, ADL, and IADL disability, there was no significant association between housing poverty and depression (aOR, 1.11; 95% CI, 0.79-1.56). People with ADL or IADL disability also showed nonsignificant results. Conclusion:In Korea, even though elderly people with housing poverty are a high-risk group for depression, housing poverty is not an independent risk factor. It is thought that low socioeconomic status and functional disabilities of people with housing poverty are associated with depression. To reduce the risk of depression, comprehensive intervention is needed for elderly people with housing poverty.