Purpose: Compulsive Internet Use (CIU) has increasingly become an area of research among process addictions. Largely based on data from cross-sectional studies, a positive association between CIU and substance use has previously been reported. This study presents gender and country-specific longitudinal findings on the relationships between CIU and substance use. Methods: Data were drawn from youth attending non-conventional high schools, recruited into two similarly implemented trials conducted in China and the USA. The Chinese sample included 1,761 students (49% male); the US sample included 1,182 students (57% male) with over half (65%) of the US youth being of Hispanic ethnicity. Path analyses were applied to detect the concurrent and predictive relationships between baseline and one-year follow-up measures of CIU level, 30-day cigarette smoking, and 30-day binge drinking. Results: (1) CIU was not positively related with substance use at baseline. (2) There was a positive predictive relationship between baseline CIU and change in substance use among female, but not male students. (3) Relationships between concurrent changes in CIU and substance use were also found among female, but not male students. (4) Baseline substance use did not predict an increase in CIU from baseline to 1-year follow-up. Conclusions: While CIU was found to be related to substance use, the relationship was not consistently positive. More longitudinal studies with better measures for Internet Addiction are needed to ascertain the detailed relationship between Internet addiction and substance use.

Exposure to environmental tobacco smoke (ETS) is a widespread source of nicotine exposure, and an estimated 540 million Chinese are exposed to ETS in mainland China. We aimed to investigate associations of ETS exposure and metabolic syndrome (MetS) as well as its individual components independent of active smoking status in Chinese adults. A cross-sectional data of 304 randomly selected Chinese households with fourth (elementary school) and seventh (middle school) graders in Qingdao city was used. Assessments of fat mass, metabolic biomarkers, personal history of illness, and health behaviors were conducted. Proportions of current smokers were 3% in women and 60.5% in men, and more men reported exposure to ETS 5–7 days per week than women (60.8% vs. 48.1%). Exposure to ETS was significantly associated with enhanced risks of MetS (odds ratio [OR] = 2.8, p = .01), hypertriglyceridemia (OR = 2.1, p = .02), and central obesity (OR = 2.7, p < .001) and reduced levels of high-density lipoprotein cholesterol (OR = 1.9, p = .02) and elevated mean levels of fasting insulin (p < .01). These observed associations were independent of active smoking status and were successfully replicated in female never-smokers. Results of our study support the hypothesis that ETS exposure is independently associated with MetS and its individual components. Further large-scale studies with longitudinal design and objective assessment of ETS exposure are needed to elucidate the underlying mechanisms and the causal effects of passive smoking on MetS. Findings of this work emphasize the importance of developing community intervention to reduce smoking, ETS, and promote healthy lifestyle.