Objectives: Anxiety disorder is among the most prevalent mental illnesses among adolescents. Early detection and proper treatment are important for preventing sequelae such as suicide and substance use disorder. Studies have suggested that sleep duration is associated with anxiety disorder in adolescents. In the present study, we investigated the association between sleep quality and anxiety in a nationally representative sample of Korean adolescents.Methods: This cross-sectional study was conducted using data from the 2020 Korea Youth Risk Behavior Web-based Survey. The Generalized Anxiety Disorder-7 questionnaire was used to evaluate anxiety. The chi-square test was used to investigate and compare the general characteristics of the study population, and multiple logistic regression analysis was used to analyze the relationship between sleep quality and anxiety.Results: In both sexes, anxiety was highly prevalent in participants with poor sleep quality (adjusted odds ratio [aOR], 1.56; 95% confidence interval [CI], 1.43 to 1.71 in boys; aOR, 1.30; 95% CI, 1.19 to 1.42 in girls). Regardless of sleep duration, participants with poor sleep quality showed a high aOR for anxiety.Conclusions: This study identified a consistent relationship between sleep quality and anxiety in Korean adolescents regardless of sleep duration.

Depression is considered a predictive factor for cognitive impairments. At the same time, Parkinson's disease (PD) is a growing public health problem. The aim of this study is to examine the association between depression and PD risk among South Korean adults. Data from 21,766 participants aged over 40, derived from the National Health Insurance Service National Sample Cohort (2002-2013), were included. Propensity score matching (1:1) was used to match participants with and without depression (case: 10,875, control: 10,875). The dependent variable was PD risk. A Cox proportional hazards regression model was built to analyze the associations between variables. People with depression had a higher risk of PD than those without depression (hazard ratio (HR) = 1.61, 95% confidence interval (CI) = 1.26-2.06). Among individuals with disabilities, those with depression had a higher risk of PD (HR = 2.31, 95% CI = 1.08-4.94). According to the Charlson Comorbidity Index (CCI) score, those with depression had a higher risk of PD than their counterparts (CCI score ≥ 5: HR = 1.63, 95% CI = 1.21-2.20). The limitations include the inability to 1) explore factors such as smoking and drinking status, which could be related to PD risk and 2) identify undiagnosed PD that already existed at the time of diagnosis of depression. The results suggest that having depression places individuals at a higher risk of PD. Interventions to alleviate the risk of PD should focus on adequate depression management.

Background: Muscular function, such as handgrip strength, has been suggested as an associated factor for cognitive impairment. This study investigated the association between temporal change in handgrip strength and cognitive function using longitudinal, nationwide data from Korean older adults. Methods: Our study used data from the Korean Longitudinal Study of Aging (KLoSA). The analysis covered 6696 participants who had taken the handgrip strength test and Mini-Mental State Examination (MMSE) from 2006 to 2018. We adopted general estimating equations to assess the temporal effect of handgrip strength change on cognitive function. Results: After adjusting for covariates, we observed an association between handgrip strength and low MMSE scores (β = − 0.3142 in men, β = − 0.2685 in women). Handgrip strength as a continuous variable was positively correlated with MMSE scores after adjustment (β = 0.0293 in men, β = 0.0347 in women). The group with decreased handgrip strength over time also showed greater odds for mild cognitive impairment (OR = 1.23, 95%CI = 1.05–1.27 in men, OR = 1.15, 95%CI = 1.05–1.27 in women) and dementia (OR = 1.393, 95%CI = 1.18–1.65 in men, OR = 1.19, 95%CI = 1.08–1.32 in women). Conclusions: This study identified the relationship between handgrip strength change and cognitive function among South Korean adults. According to our large, longitudinal sample, decreasing handgrip strength was associated with decline in cognitive function.

Background: As excessive caffeine intake may be associated with anxiety disorders, one of the most prevalent mental illnesses among adolescents globally, this study investigated the association between high caffeine consumption and anxiety in a nationally representative sample of South Korean adolescents. Methods: 46,873 participants from the Korea Youth Risk Behavior Web-based Survey (KYRBS) 2022 were included. The Generalized Anxiety Disorder-7 (GAD-7) questionnaire was used to evaluate anxiety symptoms. Survey questions determined the number of times each participant consumed high-caffeine drinks per week. The chi-square test was used to investigate and compare the general characteristics of the study population, and a modified Poisson regression was used to analyze the relationship. Results: Both male and female participants reporting excessive high-caffeine drink consumption exhibited higher anxiety levels (adjusted prevalence ratio [aPR]: 1.19, 95% confidence interval [CI]: 1.08–1.31 in males; aPR: 1.14, CI: 1.05–1.23 in females). This association remained statistically significant in subgroup analyses, particularly among high school students and those with a shorter sleep duration. The relationship between high-caffeine drink consumption and anxiety strengthened with increasing anxiety levels. Additionally, there was a dose-dependent relationship between the prevalence of anxiety and high-caffeine drinks. Conclusion: High caffeine consumption increases anxiety in South Korean adolescents. This association proved consistent regardless of sex or other socioeconomic factors.

In this cohort study, we assessed the association between depression and the risk of Alzheimer’s disease from data obtained from the 2002 to 2013 Korean National Health Insurance Service-Elderly Cohort Database, which accounts for 10% of the South Korean population aged > 60 years. A total 518,466 patients were included in the analysis and followed up, unless they were excluded due to death or migration. Patients who sought treatment for depression or dementia within 1 year of the washout period and who were diagnosed with dementia within the 1-year period of the diagnosis of depression were excluded from the study. The risk of dementia was analysed using Cox proportional hazards models. Patients with a history of depression during the follow-up period were at a higher risk of Alzheimer’s disease than those without a history of depression (HR 3.35, CI 3.27–3.42). The severe-depression group exhibited the highest risk of Alzheimer’s disease (HR 4.41, CI 4.04–4.81), while the mild-depression group exhibited a relatively lower risk of Alzheimer’s disease (HR 3.31, CI 3.16–3.47). The risk of Alzheimer’s disease was associated with depression history and an increased severity of depression increased the risk of Alzheimer’s disease.