European addiction research
January 1, 2021
Matthijs Blankers, Daan van der Gouwe, Lavinia Stegemann et al.
21 citations
During the COVID-19 pandemic, online trade in psychoactive substances via Telegram in the Netherlands shifted: stimulant-related posts (ecstasy, cocaine, amphetamine) decreased during the spring 2020 lockdown, while posts about psychedelics (ketamine, LSD, 2C-B) and other substances increased and remained higher afterward. Of 70,226 posts in two Telegram groups from December 2019 to June 2020, 5,643 were substance-related, and only 6.3% were requests, indicating a sellers' market.
European addiction research
January 1, 2024
Ruben Johannes Jacob Van Beek, Matthijs Blankers, Marloes Kleinjan et al.
3 citations
Young adults who use ecstasy in the United Kingdom and the Netherlands show three similar patterns of polydrug use: traditional polydrug use (UK 28%, NL 40%), stimulant and ketamine use (UK 48%, NL 52%), and extensive polydrug use involving stimulants, depressants, and psychedelics (UK 24%, NL 8%). UK users more often consume MDMA as powder/crystalline at higher doses, while Dutch users prefer tablets. Most respondents in both countries intend to reduce but not quit their use. The patterns are structurally similar across countries, though individual substance frequencies and preferred MDMA form differ.
Drug and alcohol dependence
September 12, 2025
Matthijs Blankers, Ruben Van Beek, Desirée Spronk et al.
1 citation
In the three days after using ecstasy/MDMA, young adults who regularly use the drug report a small but significant drop in mental well-being, even after accounting for other substance use, sleep, and baseline depression or anxiety. Cocaine co-use and poor sleep further worsened the effect. No similar drop was seen after use of other common substances. The findings suggest the post-acute mood decline is specifically linked to ecstasy/MDMA, not just party or lifestyle factors.