Introduction Excessive Internet use can negatively affect academic performance, family relationships and emotional development among the youth. Such issues have been identified as Internet addiction (IA). We aimed to determine the prevalence of IA among Portuguese adolescents and assess how parental control can relate to IA. Methods An observational cross-sectional study was performed at public schools within a Portuguese region, using Young’s Internet Addiction Test survey. General sociodemographic and emotional well-being data were obtained. A descriptive and bivariate analysis was done among Internet-addicted and average users, followed by a logistic regression analysis. Adjusted odds ratios (aORs) were computed with two-sided P values < .05 for statistical significance. Results A total of 1916 eligible responses were obtained. Mean age was 15 ± 1.8 years, with a slight predominance of female (53.3%) participants. In our sample, 16.5% were deemed Internet addicted and less likely to have any parental control over Internet use (aOR 0.74, P <.05). Moreover, 28% of the Internet-addicted users were less likely to have control over time spent online (aOR 0.72, P < .05), and close to half were unlikely to have online content restrictions (aOR 0.56, P < .01). Conclusions Our findings reported a significant rate of Internet-addicted youth. IA was negatively related to parental control. Whenever any kind of parental control over Internet use was reported, IA was less likely to occur. Healthcare professionals should be aware of the risks of IA in adolescents to improve its prevention and intervention.

Background: Health behaviours are shaped early in life and tend to occur in complex specific patterns. We aimed to characterise these patterns among Portuguese adolescents and their association with individual and contextual factors. Methods: This study was based in the Portuguese 2009/10 survey of Health Behaviour in School-Aged Children Study, comprising 4036 adolescents. Individuals were grouped using two-step cluster analysis based on 12 behaviours regarding diet, physical activity, screen use and substance use. The association between clusters and individual and contextual factors was analysed using multinomial regression. Results: The median age was 13,6, and 54% were female. Overweight and obesity were highly prevalent (25%). We identified four behavioural clusters: "Active screen users", "Substance users", "Healthy" and "Inactive low fruit and vegetable eaters". Sociodemographics varied across clusters. The "Substance users" and "Active screen users" clusters were associated with poor family communication, academic performance and school attachment and violent behaviours, and the "Inactive low fruit and vegetable eaters" were associated with lower socioeconomic status. Conclusion: The understanding of these health-compromising patterns and their social determinants is of use to Public Health, allowing tailored health-promoting interventions. Further research is needed to understand how cluster membership evolves and its influence on nutritional status.

Background Adolescence is a critical period of vulnerability to substance use. Recent research has shown that gender differences in adolescence substance use are complex and in constant flux. The present study aims to investigate gender differences in substance use and initiation patterns in male and female adolescents, and to assess individual, family, peer, and school associated factors of these patterns. Methods We applied latent class regression analysis to a Portuguese representative population sample of 1551 15-year-old adolescents, drawn from the 2010 ‘Health Behavior in School-Aged Children’ survey, to characterise different profiles of substance use and initiation for boys and girls, and to identify factors associated with latent class membership, stratifying the associations analysis by gender. Results Three common classes were found for both genders, specifically, Non - Users (boys [B] 34.42%, girls [G] 26.79%), Alcohol Experimenters (B 38.79%, G 43.98%) and Alcohol and Tobacco Frequent Users (B 21.31%, G 10.36%), with two additional unique classes: Alcohol Experimenters and Tobacco Users in girls (18.87%), and Early Initiation and Poly - Substance Users in boys (5.48%). Poor school satisfaction, bullying, fighting and higher family affluence scale score formed a common core of associated factors of substance use, although we found gender differences in these associations. In girls, but not in boys, family factors were associated with more problematic substance use. Not living with both parents was associated with girl’s Alcohol and Tobacco Frequent Users (gATFU) class (OR 3.78 CI 1.18–12.11) and Alcohol Experimenters and Tobacco Users (AETU) class (OR 3.22 CI 1.4–7.44). Poor communication with mother was also associated with gATFU class membership (OR 3.82 CI 1.26–11.53) and AETU class (OR 3.66 CI 1.99–6.75). Additionally, a higher psychological symptoms score was associated with gATFU class membership (OR 1.16 CI 1.02–1.31). Conclusion Although we found common patterns and associated factors between boys and girls, we report two unique patterns of substance use in boys and girls and specific associations between family, school and peers, and individual factors with these patterns. These findings underscore the need for substance use prevention and health promotion programmes that address potential differences in substance use patterns and associated factors. Electronic supplementary material The online version of this article (10.1186/s13034-019-0281-4) contains supplementary material, which is available to authorized users.