Estimates suggest high-speed wireless internet significantly increased teen girls' mental health diagnoses--by 90%--relative to teen boys over the period when visual social media became dominant among teenagers

Social Media and Teenage Mental Health: Quasi-Experimental Evidence. Nov 2022. Elaine Guo. Working Paper. https://www.dropbox.com/s/5v9c6ajvmu2of8d/Guo_social_media.pdf

Abstract: Teenage mental health has been a source of growing concern over the past decade, with recent whistleblower testimony pointing to the mental health risks of spending time on social media platforms, especially for girls. This paper investigates the extent to which social media are harmful for teenagers, leveraging rich administrative data from the Canadian province of British Columbia and quasi-experimental variation related to the rollout of wireless internet there. I show neighbourhoods covered by high-speed wireless internet have significantly higher social media use, based on Google search volumes. In the main analysis, I link federally-collected broadband data with 20 years of student records that provide detailed information about individual student health. I then estimate a triple-difference model using this novel data linkage, comparing teen girls to teen boys in terms of school-reported mental health diagnoses, before and after major social media launches, and across neighbourhoods with and without access to high-speed wireless internet. Estimates suggest high-speed wireless internet significantly increased teen girls' mental health diagnoses -- by 90\% -- relative to teen boys over the period when visual social media became dominant among teenagers. I find similar effects across all subgroups, indicating they are not driven by differences in confounding characteristics.  When applying the same strategy, I find null effects for placebo health conditions -- ones for which there is no clear channel for social media to operate. The evidence points to adverse effects of visual social media, in light of large gender gaps in visual social media use and documented risks. In turn, the analysis calls attention to policy interventions that could mitigate the harm to young people due to their online activities.