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What’s there to like? The causal effects of alcohol-related Facebook posts on drinking behavior (Preprint)


 BACKGROUND
 Adolescents and young adults frequently post alcohol-related content (i.e., alcoholposts) on social media. This is problematic, because both social norms theory and social learning theory suggest that viewing alcoholposts could increase drinking behavior. It is therefore paramount to understand the effects of alcoholposts on their viewers.
 
 
 OBJECTIVE
 This study aims to investigate the causal effects of exposure to alcoholposts on alcohol consumption by employing a rigorous design.
 
 
 METHODS
 We conducted a longitudinal study (6 weeks), during which alcoholposts were measured by a newly developed app that copied participants’ (N = 281) Facebook posts to a new secure social media environment. Daily questionnaires assessed alcohol use. Effects of existing alcoholposts were assessed in Phase 1, and effects of experimental posts (i.e., posted by fake participants) were explored in Phase 2.
 
 
 RESULTS
 Results showed that existing alcoholposts increased the occurrence and quantity of drinking the following day. That is, exposure to a single additional alcoholpost increased the log odds of drinking the next day by 0.27 (b = 0.27, CI = [0.18, 0.35]). Furthermore, the number of alcoholposts also had a positive (predictive) effect on the number of glasses drunk the next day (b = 0.21, CI = [0.14, 0.29]). In Phase 2, when experimental posts were also present, these effects decreased. Experimental posts themselves had hardly any effects.
 
 
 CONCLUSIONS
 This study illustrates clear and direct causal effects of alcoholposts on next day alcohol consumption and suggest that alcoholposts represent an important societal problem that interventions need to address.
