Harmen Beurmanjer

53 Cognitive Impairments in Patients with GUD 4 week). The MATE has a good inter-rater reliability, ranging between 0.75 and .92 and is part of standard clinical assessment in Dutch addiction care (Schippers et al., 2010). GHB questionnaire In addition to the questions on GHB use in the MATE, the GHB questionnaire was included to obtain more detailed information on GHB use patterns(Dijkstra et al., 2017). The original questionnaire has 28 questions regarding motivation for GHB use, first introduction to GHB, location of use, frequency of use, dose, duration of use, comas, hospital admissions and experienced withdrawal symptoms. For this study we included only the five questions on the frequency of GHB use, the dose of GHB used (in millilitres), the duration of GHB use (in months), the duration of daily GHB use (in months) and how often participants experienced a coma due to GHB use in their lifetime. The Montreal Cognitive assessment (MoCA) The MoCA (Bruijnen, Jansen, et al., 2019; Nasreddine Z, 2005) was used to screen for cognitive impairment. It consists of 12 items measuring: executive functioning; visuospatial abilities; attention, concentration and working memory (referred to as ‘attention’ from now on); language; abstract reasoning; memory; and orientation. For this study the Dutch MoCA versions 7.1 and 7.2 were used to minimize learning effects, with version 7.1 administered at T1 and 7.2 at T2. The administration of the MoCA takes approximately 15 minutes. A higher score represents better cognitive performance. An adjustment for level of education is applied. Participants with a low level of education receive two extra points, and participants with an average level of education receive one extra point to their total score, while maintaining a maximum score of 30 points(Bruijnen, Jansen, et al., 2019). In line with previous studies, a cut-off score of 25 or lower was used as an indicator of cognitive impairment (Nasreddine Z, 2005). The MoCA is widely used in clinical practice for the screening on cognitive impairment in various populations and has a moderate to excellent inter-rater reliability (k=0.46 – k=0.94) (Cumming, Lowe, Linden, & Bernhardt, 2018). Treatment outcome Three months after detoxification all patients were contacted either in person (when the patient was still in treatment) or by phone when patients where no longer in treatment. During this interview patients were asked about their GHB use in the past three months and whether they had relapsed in GHB use. Patients were considered non-relapse if they had used GHB less than 5 times in the past three months. Abstinence was not confirmed using systematic urine or blood tests, due to the narrow timeframe in which GHB can be detected as a result of its short half-life (Abanades et al., 2007). When patients could not be reached, a predetermined close contact of the patient was approached about treatment outcome. In cases where nobody was available, patient