[Relationship between screen time and sub-health status among middle school students in four cities China].

Objective: To describe the prevalence and relationship between screen time and sub-health status among middle school students in weekdays and weekends.

Methods: With multistage stratified random cluster sampling, 14 400 students from junior and senior middle schools in 288 classes of 30 schools in 4 cities( Shenyang, Chongqing, Xinxiang, Guangzhou) were investigated in October, 2011. A total of 13 817 valid questionnaires were retained for analysis.

Cortisol response to the Trier Social Stress test among Chinese adolescents.

Objective: To compare obese and non-obese adolescents in terms of their salivary cortisol response to the Trier Socia l Stress Test ( TSST).

Methods: This is a cross - sectional study involving 41 healthy adolescents aged 12-14 years in the city of Shenyang, China. The TSST response was determined using salivary cortisol measurements, and measurements were repeated after the test period.

[Study on the Stroop task test in adolescents with different degrees of obesity before and after mental workload].

Objective: To observe the differences of Stroop task among adolescents with different BMIs before and after mental workload, and try to explore the change of cognition function after mental workload in students with different degrees of obesity and the relationships between cognition function and body mass index (BMI).

Methods: A total 254 adolescents were selected by convenience sampling method and were classified into different groups according to BMI. The subjects were manipulated by mental workload with the IV edition of Wechsler Intelligence Scale for Children (WISC-IV) for 60 to 70 minutes.

Is there any relationship between dietary patterns and depression and anxiety in Chinese adolescents?

Objective: To determine the association between major dietary patterns characterized by factor analysis and risk of depression and anxiety symptoms among adolescents.

Design: Diet and symptoms of depression and anxiety were assessed in a cross-sectional survey among students attending junior high school. Dietary patterns were derived from a self-reported FFQ, which consisted of thirty-eight items.