Abstract In recent years, child and adolescent health problems such as myopia, obesity, and mental health have attracted the attention of society as a whole and have become important public health issues. Considering high prevalence in each of the major health problems among children and adolescents in China, current high prevalence of co morbidities of these health problems needs further attention. Shared behavioral and environmental risk and protective factors make it possible to improve the co morbidities among children and adolescents through the same interventions. It is urgent to explore the Co morbidity，Shared Etiology，and Shared Prevention mechanism of common diseases of children and adolescents in China, and to explore standardized programs and processes for the implementation of comorbidity intervention for children and adolescents across varied scenarios including families, schools, communities and medical institutions, so as to improve the health level of children and adolescents.

Objective: To analyze the prevalence of overweight, obesity and depression among students in the Inner Mongolia Autonomous Region in 2019-2022 and explore the relevant factors affecting the co-morbidity of overweight,obesity and depression among students, so as to provide scientific basis for the prevention of co-morbidity. Methods: From September 2019 to 2022, used stratified random cluster sampling, 90 519,71 560,90 079,91 089 students were selected from all 12 leagues in Inner Mongolia Autonomous Region for questionnaire survey and physical examination. The χ 2 test was used for demographic characteristics and univariate analysis, and a binary Logistic regression model was used to explore the association between lifestyle behaviors and co-morbidity. Results: The detection rate of overweight,obesity among students from 2019-2022 was 29.21%,34.38%,35.20%,34.61%, the detection rate of depression was 18.35%，17.53%，16.43%，16.00%, and the co-morbidity detection rate of the two was 5.52%，5.93%，5.76%，5.46%. The number of overweight,obesity and depression co-morbidity students in 2022 was 4 978 students, and the co-morbidity detection rates of the students were significantly different in terms of the school segments and the family structures ( χ 2=103.51, 99.90, P <0.01). Multivariate Logistic regression analysis showed that consuming sugar sweetened beverages or fried food ≥1 time/d, sometimes or never eat breakfast, watching computer or TV ≥2 h/d, and less than 1 h of moderate-to-vigorous physical activity on weekends were positively correlated with the occurrence of the co-morbidity of overweight,obesity and depression, with the value of OR ranging from 1.17 to 1.59 ( P <0.05). Eated fresh fruits or drinking milk and soy milk ≥1 time/d, outdoor activities ≥1 h/d, sleep ≥8 h/d, not smoking and not drinking alcohol were negatively correlated with the occurrence of comorbid overweight,obesity and depression, with the value of OR ranging from 0.47 to 0.92 ( P < 0.05). Conclusion The occurrence of overweight,obesity and depressive symptoms co-morbidity in students is associated with dietary, exercise and lifestyle behavior. Targeted measures should be taken to maintain students healthy weight and prevent the occurrence of depression from the aspects of diet, exercise and life habits.

Objective: To explore the epidemiological trend of overweight and obesity, elevated blood pressure and their comorbidities in children and adolescents from Inner Mongolia Autonomous Region during 2016-2021, and to analyze its association with lifestyle, so as to provide reference for formulating prevention and control strategies of regional common comorbidities in schools. Methods: A total of 8 908, 8 222, 9 448, 127 068, 100 778, and 138 540 students aged 10-18 years in Inner Mongolia were selected by stratified random cluster sampling in September each year from 2016 to 2021. Physical examination and questionnaire survey were conducted on the included students. The prevalence trends of overweight，obesity, elevated blood pressure and their co-occurrence were analyzed. Logistic regression was used to compare the prevalence of elevated blood pressure in different body mass index (BMI) groups. After excluding individuals without lifestyle information in 2021, Logistic regression analysis was used on 136 374 subjects to analyze the association between overweight，obesity, elevated blood pressure and their co-occurrence and lifestyle factors. Results: During 2016 to 2021, the prevalence of comorbidity of overweight, obesity with elevated blood pressure among students in Inner Mongolia Autonomous Region were 5.04%，5.14%，4.99%，7.51%，7.60% and 9.45%， respectively . The prevalence of overweight and obesity was 26.94%, 28.07%, 29.62%, 34.19%, 36.71% and 37.53%, respectively. The prevalence of elevated blood pressure were 16.05%, 11.54%, 13.12%, 14.85%, 14.12% and 18.40%, respectively. Except for 2016, the risk of elevated blood pressure in overweight and obese people was higher than that in normal BMI group in other years, and there was a positive correlation between overweight and obesity and elevated blood pressure after gender and urban and rural areas ( P < 0.05 ). In 2021, the detection rate of comorbidity of overweight and obesity with elevated blood pressure among children and adolescents in urban areas was higher than that in suburban counties, and the reporting rate of healthy lifestyle was lower than that in suburban counties ( P <0.05).Skipping breakfast ( OR =1.11，95% CI =1.07-1.16) and non daily moderate and high intensity physical activity( OR =1.27，95% CI =1.20-1.34) were positively correlated with the co-occurrence of overweight，obesity and elevated blood pressure among children and adolescents in Inner Mongolia Autonomous Region. Non daily moderate and high intensity physical activity ≥60 min was positively correlated with elevated blood pressure ( OR =1.11，95% CI =1.07-1.16), and insufficient sleep was positively correlated with overweight，obesity ( OR =1.04, 95% CI =1.01-1.06)（ P ＜0.05）. Conclusion The prevalence of overweight，obesity, elevated blood pressure and their co-occurrence among children and adolescents in Inner Mongolia Autonomous Region is relatively high. Overweight/obesity is an important risk factor for elevated blood pressure, and unhealthy lifestyles are risk factors for co-occurrence of overweight，obesity and elevated blood pressure. Region specific lifestyle interventions are indispensable for the prevention and control of regional common comorbidities. Urban areas may be a key focus for lifestyle interventions.

Objective: To investigate the prevalence of Internet addiction and depression of students, and to analyze the co-occurrence and trend, so as to provide a theoretical basis for prevention and controlling measures of Internet addiction and depression. Methods: A total of 6 317,7 152,81 808,71 180 and 89 932 students aged 10 to 24 years from 12 leagues (103 banners) in Inner Mongolia Autonomous Region were selected by stratified random cluster sampling in September each year from 2017 to 2021. The Internet Addiction Scale and the Central for Epidemiologic Studies Depression Scale(CES-D) was used to measure Internet addiction and depression. And the annual inspection rate, group difference and annual change trend in students were calculated. Multivariate linear regression and restricted cubic spline analysis were used to estimate the linear and non linear associations between Internet addiction and depression in students. Results: The Internet addiction proportion in students gradually decreased from 4.1% in 2017 to 2.1% in 2020, but increased to 3.9% in 2021. And the depressive symptoms proportion increased from 20.9% in 2017 to 28.0% in 2020 and 27.0% in 2021. The detection rate of Internet addiction and depression comorbidities remained at 1.8% to 2.5 %. The Internet addiction proportion in boys was higher than that in girls( χ 2=42.82， P <0.05). The depressive symptoms prevalence in girls was higher than that in boys( χ 2= 553.90， P <0.05). Taking reversal in prevalence of Internet addiction in urban and rural areas was observed in 2019. The detection rates of depressive symptoms and comorbidity were higher in urban areas than these in suburban counties on the whole, and the difference showed a trend of decreasing or even equalizing year by year. Internet addiction was positively correlated with depressive symptoms score ( B=1.67, 95%CI =1.64-1.71), the proportion of depressive symptoms ( OR=1.39, 95%CI =1.38-1.41) and the proportion of major depressive symptoms ( OR=1.35, 95%CI =1.33-1.36) among students in 2021 ( P <0.05). An N-shaped curve was found in the significant nonlinear associations between internet addiction and depression across sex, region and school stage. Conclusion Internet addiction and depression in students show significant linear and non-linear associations, which are consistent in different sexes, regions and school stages. Therefore, relevant measures should be made and implemented in each region, especially in suburb areas, so as to prevent the increasingly development of adolescents and children s Internet addiction and depression.

Objective:To investigate the risk factors and cumulative risk of myopia in children and adolescents, providing a basis for identifying cumulative risk factors in preventing and controlling myopia.Methods:Baseline data from the mental and physical health cohort of children and adolescents established in Inner Mongolia Autonomous Region were used. A stratified random cluster sampling method was adopted to select 138 974 students from fourth to twelfth grade as participants. Distance visual exams, refractive assessments, and questionnaires were conducted on the included students. Logistic regression analysis was used to evaluate each risk factor's impact on myopia's prevalence. The number of risk factors was summed to form a cumulative risk score, and logistic regression analysis was conducted to examine the association between the cumulative risk score and the prevalence of myopia. Additionally, the association between the cumulative risk score of myopic students and their degree of refractivity was analyzed using a generalized estimating equation.Results:The study found a high prevalence of myopia among children and adolescents at baseline (70.2%). Girls exhibited a higher prevalence (74.8%) than boys (65.6%), urban areas (74.3%) surpassed suburban ones (68.6%), and the incidence was greater in high schools (80.3%) compared to middle schools (75.3%), which, in turn, was higher than in elementary schools (57.7%) (all P<0.05). Analysis of risk factors revealed that children and adolescents experiencing improper reading and writing distances ( OR=1.10, 95% CI: 1.07-1.13), excessive homework ( OR=1.09, 95% CI: 1.06-1.12), insufficient sleep ( OR=1.10, 95% CI: 1.07-1.13), having myopic father ( OR=1.98, 95% CI: 1.91-2.05), having myopic mother ( OR=2.04, 95% CI: 1.97-2.10), or using classroom chairs not matched to their height faced ( OR=1.04, 95% CI: 1.01-1.07) increased myopia risks. Additionally, the prevalence and significant odds ratio of myopia increased with the increase in cumulative risk score, with every additional unit of cumulative risk score increasing the right eye's refractive error by -0.10 D. Conclusion:The presence of multiple factors and their comprehensive score increases the prevalence of myopia in children and adolescents.

Objective: To describe the current status of the prevalence of co-morbid myopia and obesity among 7-18 years students in the Inner Mongolia Autonomous Region in 2021 and to analyze the moderating effect of lifestyle in this association ，so as to provide scientific basis for the establishment of the mechanism of Co-morbidity，Shared Etiology，and Shared Prevention of common diseases in children and adolescents. Methods: A total of 139 630 primary and secondary school students aged 7-18 years from Inner Mongolia Autonomous Region were selected by stratified random cluster sampling method in September,2021. Myopia was determined using distance visual acuity examination and refractive error examination, and obesity was determined according to the BMI classification criteria for overweight, obesity screening of Chinese school age children and adolescents. Used a questionnaire, healthy lifestyles were determined according to the American Heart Association s Healthy Lifestyle Score by totaling the six scores for smoking, alcohol consumption, diet, exercise, screen time, and sleep duration.The χ 2 test was used to compare the association between group differences in the co-morbidity rate of myopia and obesity. The multivariable Logistic regression model was used to explore the influencing factors of the co-morbidity of myopia and obesity, and the stratified analysis was used to analyze the moderating effect of lifestyles on the prevalence of the co-morbidity. Results: The prevalence of myopia and obesity co-morbidity among students aged 7-18 years old in the Inner Mongolia Autonmous Region in 2021 was 13.7%, higher among boys than girls ( 15.5 % vs. 11.8%), higher among those aged 10-12 years old than 7-9,13-15,and 16-18 years old (14.7%,13.7%, 13.3%, 12.0%), higher among other ethnic minorities than Han Chinese and Mongolians (15.3%, 14.0%, 12.5%), higher in urban areas than that in suburban areas(15.3%, 13.0%), and middle economic level tracts were higher than poor and good tracts (14.8%, 12.9 %, 12.6%) ( χ 2=392.37，115.73，62.80，119.02，121.60, P <0.05). Multivariable Logistic regression modeling showed that unhealthy lifestyles ( OR=1.24, 95%CI=1.19-1.29 ) and middle level of lifestyle score ( OR=1.15, 95%CI=1.10-1.19 ) students had higher prevalence of co-morbidity, and the results were statistically significant among both boys and girls, the age groups of 10- 12, 13-15, and 16-18 years old, as well as the Han and Mongolian ethnic groups (all P <0.05). Conclusion In 2021, the current situation of myopia and obesity co-morbidity and unhealthy lifestyles among primary and secondary school students in the Inner Mongolia Autonomous Region are not optimistic.