Background: The prevalence of age-related neurodegenerative diseases has risen in conjunction with an increase in life expectancy. Although there is emerging evidence that air pollution might accelerate or worsen dementia progression, studies on Asian regions remains limited. This study aimed to investigate the relationship between long-term exposure to PM₁₀ and the risk of developing Alzheimer’s disease and vascular dementia in the elderly population in South Korea. Methods: The baseline population was 1.4 million people aged 65 years and above who participated in at least one national health checkup program from the National Health Insurance Service between 2008 and 2009. A nationwide retrospective cohort study was designed, and patients were followed from the date of cohort entry (January 1, 2008) to the date of dementia occurrence, death, moving residence, or the end of the study period (December 31, 2019), whichever came first. Long-term average PM₁₀ exposure variable was constructed from national monitoring data considering time-dependent exposure. Extended Cox proportional hazard models with time-varying exposure were used to estimate hazard ratios (HR) for Alzheimer’s disease and vascular dementia. Results: A total of 1,436,361 participants were selected, of whom 167,988 were newly diagnosed with dementia (134,811 with Alzheimer’s disease and 12,215 with vascular dementia). The results show that for every 10 µg/m³ increase in PM₁₀, the HR was 0.99 (95% CI 0.98-1.00) for Alzheimer’s disease and 1.05 (95% CI 1.02–1.08) for vascular dementia. Stratified analysis according to sex and age group showed that the risk of vascular dementia was higher in men and in those under 75 years of age. Conclusion: The results found that long-term PM₁₀ exposure was significantly associated with the risk of developing vascular dementia but not with Alzheimer’s disease. These findings suggest that the mechanism behind the PM₁₀-dementia relationship could be linked to vascular damage.

Background: The compliance with the follow-up examination after a positive fecal occult blood test (FOBT) is lower than expected. We aimed to evaluate the adherence rate to the follow-up examination in patients with a positive FOBT and to identify the clinical factors associated with this adherence. Methods: The study population comprised adults aged ≥50 years who participated in the National Cancer Screening Program for colorectal cancer (CRC) in 2013. Compliance was defined as undergoing follow-up examination within 1 year of a positive FOBT. Results: From 214,131 individuals with a positive FOBT, 120,911 (56.5%) were in the compliance group and 93,220 (43.5%) were in the non-compliance group. On multivariate analysis, good compliance was associated with men (odds ratio (OR) = 1.12, 95% confidence interval (CI) (1.09–1.15)), younger ages (70–79 years, OR = 2.19 (2.09–2.31); 60–69 years, OR = 3.29 (3.13–3.46); 50–59 years, OR = 3.57 (3.39–3.75) vs. >80 years), previous experience of CRC screening (a negative FOBT, OR = 1.18 (1.15–1.21); a positive FOBT, OR = 2.42 (2.31–2.54)), absent previous experience of colonoscopy or barium enema (OR = 2.06 (1.99–2.13)), higher economic income (quartile, 75%, OR = 1.14 (1.11–1.17); 100%, OR = 1.22 (1.19–1.25)), current smokers (OR = 1.12 (1.09–1.15)), alcohol intake (OR = 1.03 (1.01–1.05)), active physical activity (≥3 times/week, OR = 1.13 (1.11–1.15)), depression (OR = 1.11 (1.08–1.14)), and present comorbidities (Charlson Comorbidity Index, ≥1). Conclusion: This study identified clinical factors, namely, male, younger ages, prior experience of fecal test, absent history of colonoscopy or double-contrast barium enema (DCBE) within 5 years, and high socioeconomic status to be associated with good adherence to the follow-up examination after a positive FOBT.

Many epidemiological studies have suggested that air pollution adversely affects neurodevelopment in children; however, evidence is still lacking. This study aimed to determine the association between particulate matter (PM) exposure and attention-deficit/hyperactivity disorder (ADHD) in children and adolescents. Data were obtained from the Korean National Health and Nutrition Examination Survey 2008–2018. Outcomes were defined from parental reports of ever doctor-diagnosed ADHD, and ADHD cases were matched to non-cases with 1:10 age–sex matching. Individual exposure levels were assigned according to each study participant’s administrative address during the year of diagnosis. Multivariate logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). After age–sex matching at a 1:10 ratio, the final study participants comprised 1,120 children aged 6–19 years old. A unit increase in the PM₁₀ concentration was significantly associated with ADHD (OR, 1.44; 95% CI, 1.02–2.02 per 10 µg/m³). The association with ADHD was stronger at higher quartiles than in the lower quartiles of PM₁₀ exposure; however, it was not statistically significant. Our results suggested that long-term PM₁₀ exposure was associated with increased ADHD in children and adolescents. Children diagnosed with ADHD suffer from a variety of social activity and have a significant economic burden. Therefore, it is considered an important role to find out the effects of environmental risk factors, including air pollution, on children and adolescents. This may also help to increase the body of knowledge in this field and to stimulate further research.