目的·了解中国5省初中生视屏时间和饮食行为与抑郁症状的关联。方法·采用分层随机整群抽样方法，对中国东部地区的浙江、广东，中部地区的江西，西部地区的四川、贵州共5省1 067名初中生进行问卷调查，包括一般人口学特征、健康行为情况、饮食行为情况、抑郁情况。采用单因素分析比较不同人口学特征的初中生的抑郁症状报告率、每日视屏时间和饮食行为，采用Logistic回归分析每日视屏时间和饮食行为与抑郁症状的关联，并分析前两者的交互作用。结果·中国5省初中生抑郁症状报告率为12.9%，西部地区、非独生子女、每周零花钱超过100元、有过吸烟行为、有过饮酒行为、每日视屏时间≥2 h、有不健康饮食行为的初中生抑郁症状报告率较高，差异均有统计学意义（均P<0.05）。15.2%初中生每日视屏时间≥2 h；调整混杂因素后，与每日视屏时间<2 h组相比，≥2 h组抑郁症状报告率更高（OR=1.89，95%CI 1.22~2.95）。29.5%的初中生有不健康饮食行为；调整混杂因素后，与健康饮食行为组相比，不健康饮食行为组抑郁症状报告率更高（OR=2.16，95%CI 1.47~3.19）。6.4%的初中生每日视屏时间≥2 h且有不健康饮食行为；调整混杂因素后，这部分学生比每日视屏时间<2 h且饮食行为健康学生抑郁症状报告率更高（OR=4.26，95%CI 2.24~7.56）。调整混杂因素后，每日视屏时间与饮食行为的交互作用分析结果显示，两者存在相加交互作用，超额相对危险度（relative excess risk due to interaction，RERI）为1.21（95%CI 1.02~1.51），交互作用归因比（attributable proportion due to interaction，AP）为0.19（95%CI 0.13~0.31），交互作用指数（synergy index，S）为1.35（95%CI 1.12~1.69）。结论·视屏时间过长且有不健康饮食行为的中国初中生更容易出现抑郁症状，且两者对抑郁症状有相加交互作用。

Objective ·To explore the relationship of screen time and dietary behaviors with depressive symptoms in junior high school students in 5 provinces in China. Methods ·A total of 1 067 junior high school students were selected from Zhejiang and Guangdong in the eastern region, Jiangxi in the central region, Sichuan and Guizhou in the western region of China by using stratified random cluster sampling method for a questionnaire survey, which included general demographic characteristics, health behaviors, diatery behaviors, and depressive symptoms. Univariate analysis was used to analyze the report rates of depressive symptoms, daily screen time and dietary behaviors of the students with variant demographic characteristics, and Logistic regression analysis was used to analyze the relationship of daily screen time and dietary behaviors with depressive symptoms and the interaction effects as well. Results ·The report rate of depressive symptoms was 12.9% in the junior high school students in 5 provinces. The students who were in the western region, were not only children, had a weekly allowance of over 100 yuan, had smoked or consumed alcohol, had daily screen time≥2 h, or had unhealthy dietary behaviors, had higher reporting rates of depressive symptoms (P<0.05). A total of 15.2% students had daily screen time≥2 h, who had a higher reporting rate of depressive symptoms than the others after the confounding factors being adjusted (OR=1.89, 95%CI 1.22?2.95). A total of 29.5% of students had unhealthy dietary behaviors, who had a higher reporting rate of depressive symptoms than the others after the confounding factors being adjusted (OR=2.16, 95%CI 1.47?3.19). A total of 6.4% of students had both daily screen time≥2 h and unhealthy dietary behaviors, who had a higher reporting rate of depressive symptoms than the students having daily screen time<2 h and healthy dietary behaviors after the confounding factors being adjusted (OR=4.26, 95%CI 2.24?7.56). After adjusting for the confounding factors, the analysis of the interaction between daily screen time and dietary behaviors showed an additive interaction with the relative excess risk due to interaction (RERI) of 1.21 (95%CI 1.02?1.51), the attributable proportion due to interaction (AP) of 0.19 (95%CI 0.13?0.31), and the synergy index (S) of 1.35 (95%CI 1.12?1.69). Conclusion ·The junior high school students with both long screen time and unhealthy dietary behaviors are more likely to suffer from depressive symptoms in China; long screen time and unhealthy dietary behaviors have an additive interactive effect on depressive symptoms.