[Effect of network literacy on depression levels among young adults: an analysis based on China Family Panel Studies]

To investigate the effect of network literacy on depression levels among young adults, and to provide a reference for understanding the relationship between internet use and mental health in this population.

Data from 28 312 young adults (aged 18-35) were extracted from the China Family Panel Studies (CFPS) 2014, 2018, 2020, and 2022. Depression level served as the dependent variable, network literacy (comprising network usage literacy and network awareness literacy) served as the independent variable, and multiple variables from basic demographic characteristics and socioeconomic characteristics were included as control variables. First, a panel data fixed-effects model was employed to assess the effect of network literacy on depression. Second, an instrumental variable set was constructed to address endogeneity. Finally, heterogeneity analyses were conducted to evaluate the differential effects of network literacy across subgroups.

The overall depression level of the sample was relatively low (the median values were mostly 0.167). Network awareness literacy was at a relatively high level (the median values were mostly 0.680), whereas network usage literacy was slightly lower (median ranging from 0.199 to 0.555). Baseline linear regression showed no significant effects for either type of network literacy on depression in young adults (both P>0.05). However, after introducing quadratic terms, both network usage literacy and network awareness literacy exhibited a significant inverted U-shaped relationship with depression (linear term positive, quadratic term negative; both P<0.01). This inverted U-shaped relationship remained robust after controlling for endogeneity using a panel data fixed-effects two-stage least squares instrumental variable model. Heterogeneity analyses revealed that the inverted U-shaped effects of both literacy types were stronger in females than in males. The curvilinear effect of network usage literacy was more pronounced among young adults aged 25-35, whereas the inflection-point effect of network awareness literacy was more evident in the 18-<25 age group. Furthermore, the effects of both types of network literacy on depression were significantly stronger among rural youth than among urban youth.

The effect of network literacy on depression levels among young adults follows an inverted U-shaped trajectory. Females, individuals aged 25-35, and rural youth are more susceptible to changes in depression levels as their network literacy fluctuates.