{"doi":"10.1111/add.70217","title":"We need more rigorous research on social media and substance use to move from association to causation","abstract":"In their editorial, ‘We need better measures to understand the influence of social media on substance use’, Riordan et al. [1] called for greater use of objective indicators of social media use (e.g. smartphone usage logs) and exposure to substance-related content [e.g. passive data collection via browser plug-ins, artificial intelligence (AI)-enabled apps that automatically capture frequency and type of exposures]. We strongly agree, and, in this letter, aimed to highlight the equally important need for research that builds causal evidence concerning social media's influence on substance use. Recent systematic reviews and meta-analyses consistently find statistically significant associations between substance use-related social media exposure and substance use-related attitudes and behaviors among adolescents and young adults [2-5]. Yet, these reviews also emphasize a persistent limitation: many studies to date are cross-sectional, leaving a critical gap in establishing temporality and causation. Without stronger causal data, alcohol, tobacco and other corporate interests—including social media companies—can continue to cast doubt on the idea that exposure to substance use-related content causes harmful outcomes among youth. These industries have repeatedly exploited gaps in causal evidence to delay regulation and accountability [6-10]. There is an urgent need for research designs that strengthen causal inference regarding substance use-related social media exposure and its effects on youth and young adults' substance use-related attitudes and behaviors (e.g. alcohol initiation, escalation and binge drinking). Randomized controlled trials are feasible in this context, as are other approaches, including longitudinal cohort studies with repeated objective measures of social media use, exposures and outcomes over time; and quasi-experimental designs that leverage policy or platform changes to demonstrate population-level effects. For example, provisions of the European Union Digital Services Act restrict targeted advertising to European minors [11]. It also requires social media platforms to give European users the option to choose whether to view posts with or without algorithmic recommendations based on personal data, and to filter out of certain types of content. As a recent parallel, the e-cigarette industry was meaningfully reined in after a compelling evidence base through rigorous experimental studies demonstrated both immediate and long-term harms of youth-targeted marketing (e.g. product placement in music videos; cartoon branding) [12, 13]. This evidence underpinned successful litigation against e-cigarette companies and spurred regulatory reforms (e.g. restrictions on vaping product placement in music videos) [14]. Parallel approaches are essential to build the evidence base at the intersection of social media and all forms of substance use in adolescents and young adults, thereby informing prevention strategies, supporting policymakers and equipping litigators to protect young people from the harms of digital spaces. These efforts are especially urgent, as social media companies face increasing scrutiny for exposing young audiences to harmful content and as awareness grows of the serious health risks associated with substance use. Alex M. Russell: Conceptualization; writing—original draft. Jon-Patrick Allem: Conceptualization; writing—review and editing. During manuscript preparation, generative artificial intelligence tools (GPT-5, Open AI) were used to enhance readability and assist with formatting references. However, these tools did not generate original ideas, contribute substantive text or perform any data analysis. The authors take full responsibility for the content of the manuscript. J.P.A. has received fees for consulting services in court cases pertaining to content on social media platforms. The other authors declare no conflicts of interest.","journal":"Addiction","year":2025,"id":535052,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":2,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9533,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1229875,"name":"Jon‐Patrick Allem","orcid":null,"position":1,"is_corresponding":false},{"id":732604,"name":"Alex M. 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