“…ies, 12 assessed e-cigarette-related content[24, 26-28, 33, 34, 36, 37, 39, 43, 48, 53], nine assessed cannabis-related content[22,23,38,41,42,46,47,50,51], five assessed opiate-related content[20,21,25,40,56], five assessed tobacco-related content[32,35,44,45,52], one assessed alcohol-related content[30], and a single study assessed polysubstance use-related content[29].SentimentTwenty-Three studies[21, 22, 25, 29, 30, 32, 34-37, 40-48, 50, 52, 53, 56] reported sentiment analyses of substance-related content on Twitter. Overall, substance-use sentiment on Twitter was positive, with 76.0% of all analysed content depicting substance use positively.…”