Erwin is a psychologist and researcher at ARQ National Psychotrauma Centre and Leiden University Medical Center. As part of his PhD, he is currently working on studies investigating MDMA-assisted psychotherapy for the treatment of PTSD. Before starting his PhD research, he was a research associate at Eleusis Therapeutics, where he worked on several phase 1 and 2 clinical trials with LSD and psilocybin. Since 2007, he has contributed to the organization of several international scientific conferences on psychedelic research, through the Dutch OPEN Foundation, where he currently serves as the vice-chair. He also is a lead adherence rater for European MDMA-assisted psychotherapy trials at the Multidisciplinary Association for Psychedelic Studies (MAPS), and an advisory board member of the International Society for Substance-assisted Psychotherapy.