Harmen Beurmanjer

93 Summary and Discussion 7 Discussion Part 1: Understanding the GHB using population GUD: similarities and differences with other SUDs GHB is a relatively new substance and its addictive properties were first described twenty years ago (Galloway et al., 1997; K. Miotto et al., 2001). While it is broadly acknowledged that GHB use can lead to a substance use disorder (Craig et al., 2000; K. Miotto et al., 2001; O. C. Snead & Gibson, 2005), it is not mentioned in the DSM-5 (American Psychiatric Association. & American Psychiatric Association. DSM-5 Task Force, 2013). Prevalence seems limited (Addiction, 2019), but the problems associated with GUD are substantial (Dijkstra et al., 2017; M. S. van Noorden et al., 2009). Furthermore, there are reports of increasing prevalence of GHB use (Addiction, 2019; Arunogiri et al., 2020), which could result in increased prevalence of GUD. The relative novelty combined with a very limited number of studies into GUD could explain why it is often seen as a special group of patients. GUD is often perceived as one of the most severe and dangerous to treat substance use disorders by clinicians (Krul & Girbes, 2011; M. S. van Noorden et al., 2009). The literature in combination with the research from this thesis shows however that GUD is in many ways a regular substance use disorder. Below I will outline where GUD is much alike other substance use disorders and what seems rather specific for GUD. Staging In Chapter 3 we described a model for the development of GUD when people start using GHB on a regular basis, consisting of three stages, based on in depth interviews. These stages are rather similar to the stages of development as described for other substance use disorders (Volkow et al., 2016). We have labelled these as positive reinforcement phase, dose escalation phase and the negative reinforcement phase. First, the substance is used for fun or other positive reinforcement. After a while, when tolerance develops, the substance needs to be used in other to feel and function normally. In the final stage the main motivation to use substances is to prevent withdrawal, and negative affect, often called negative reinforcement (Volkow et al., 2016). Figure 1 shows the schematic development of substance use disorders based on Koob, 2013 (Koob, 2013), which we here translate to GUD. Anxiety Many substances can dampen feelings of anxiety, like alcohol, cannabis and benzodiaze- pines (Vorspan, Mehtelli, Dupuy, Bloch, & Lépine, 2015). However, feelings of anxiety generally return after the acute effects of substance wear off. Repeated intake of these substances can paradoxically lead to increased feelings of anxiety, which can drive further substance use, starting a downward spiral (Becker, 2017; Koob, 2013). GHB seems no