Harmen Beurmanjer

94 Chapter 7 exception to this ( Beurmanjer et al., 2019). The very short half-life of GHB might even speed up this process (Schep, Knudsen, Slaughter, Vale, & Mégarbane, 2012). It could be argued that people with high levels of anxiety who use GHB are more likely to use GHB more frequently because of its anxiolytic effects. This might make them more vulnerable to develop GUD and as a result they are overrepresented in the GUD patient population. However, as mentioned before frequent GHB use itself might also increase feelings of anxiety as part of withdrawal (Beurmanjer et al., 2019). While intoxicated, or passed out, this numbs their emotional states. However, during detoxification feelings of anxiety commonly return with increased intensity (Dijkstra et al., 2017). Feelings of anxiety can maintain for a prolonged period of time after detoxification, which might contribute to the risk of relapse, as also shown in other substances of abuse with temporarily dampening effects on anxiety, like alcohol (Schellekens et al., 2015). While a causal relationship has not yet been established, the interaction between feelings of anxiety and GHB use is frequently observed and has been suggested as an important explanation for the high relapse rates associated with GUD by patients themselves in chapter 3. Cognitive impairments An important predictive factor of relapse in patients with SUD are cognitive impairments (Czapla et al., 2016; Turner et al., 2009). Our study in chapter 4 showed that the majority of patients with GUD had an indication for cognitive impairment at the start of detoxification. This could be attributed to the active GHB use at the time of measuring and the known Figure 1 The development of GUD and motivation for GHB use, based on the model of Koob (Koob, 2013) P o s i t i v e R e i n f o r c e m e n t N e g a t i v e R e i n f o r c e m e n t Development of GHB Use Disorder Intensity Mot i vation