4-Fluoramphetamine in the Netherlands: Text-mining and sentiment analysis of internet drug discussion forums

Users of new psychoactive substances including 4-fluoroamphetamine (4-FA/4-FMP) frequently share their experiences or opinions in online drug forums. We have tested the potential of computerised analysis of drug users’ forum posts for monitoring and early detection of trends. Specifically, we tested whether changes in the volume of 4-FA related posts and sentiments expressed in those posts can be observed around the time 4- FA was increasingly reported by Dutch drug monitoring sources (2012–2017). Opening posts from two popular Dutch internet-based drug discussion forums, written between January 1st, 2012 and January 1st, 2018 were scraped: Portions of the forum posts about 4-FA were collected. Sentiments expressed in these posts were inferred using text recognition software, and analysed for trends using linear mixed modelling. Over time, a decrease in positive sentiment towards 4-FA can be observed starting in 2015, compared to the period before 2015, coinciding with more news searches and reports on adverse events related to 4-FA use. Linear mixed modelling analysis confirmed a significantly higher sentiment score in 2015 compared to 2017 for 4-FA. Changes in the volume and sentiments of forum posts coincided with news media exposure related to 4-FA and with trends observed by established drug monitoring sources. Hence, internet forum monitoring facilitates early discovery of trends in the popularity, prevalence and adverse events related to new psychoactive substances.