Smartphone Use and Inflammation at 2-Year Follow-Up in College Students: The Mediating Role of Physical Activity

Purpose: Smartphone use could lead to being physically inactive and a greater risk for health problems, such as inflammation. However, the associations between smartphone use, physical activity (PA), and systemic low-grade inflammation remained unclear. This study aimed to examine the potential mediating effect of PA on the association between smartphone use and inflammation.

Patients and methods: A two-year follow-up study was conducted between April 2019 and April 2021. Duration of smartphone use, smartphone dependence and PA were assessed by a self-administered questionnaire. Laboratory analysis of blood samples was performed to evaluate the levels of TNF-α, IL-6, IL-1β, and CRP as biomarkers of systemic inflammation. The correlations between smartphone use, PA, and inflammation were analyzed using Pearson correlation. Structural equation modelling was used to analyze the potential mediating effect of PA on the associations between smartphone use and inflammation.

Results: A total of 210 participants were included with a mean (standard deviation) age of 18.7 (1.0) years, 82 (39%) of whom were males. Smartphone dependence was negatively associated with the total PA level (r=-0.18, P<0.01). PA mediated the associations between the duration of smartphone use and smartphone dependence with inflammatory markers. Specifically, as PA decreased, the duration of smartphone use was more negatively associated with TNF-α (ab=-0.027; 95% CI: -0.052, -0.007) and more positively correlated to IL-6 (ab=0.020; 95% CI: 0.001, 0.046) and CRP (ab=0.038; 95% CI: 0.004, 0.086); smartphone dependency was more negatively associated with TNF-α (ab=-0.139; 95% CI: -0.288, -0.017) and more positively related to CRP (ab=0.206; 95% CI: 0.020, 0.421).

Conclusion: Our study illustrates that there are no direct associations between smartphone use and systemic low-grade inflammation, however, PA level plays a weak but significant mediating effect on the associations between smartphone use and inflammation among college students.