Harmen Beurmanjer

57 Cognitive Impairments in Patients with GUD 4 cognitive impairment and the number of comas, GHB use patterns, or severity of GUD. Cognitive impairment before detoxification, particularly on the subscale memory, was associated with relapse. In the current sample, more than half of the patients had an indication for cognitive impairment during admittance, with a total average score on the MoCA of about 24. A recent study observed similar to slightly better MoCA scores in patients admitted with alcohol, cannabis, stimulant and opioids use disorders (scores: 25, 26, 26, and 25 respectively) (Bruijnen, Dijkstra, et al., 2019). Though no direct comparison between these samples can be made, this does raise the question whether the observed cognitive impairments in patients with GUD are specific for excessive GHB use or related to (indirect) negative effects of substances of abuse on cognitive performance in general. Furthermore, it is important to note that most patients with primary GUD have poly substance use problems, often stimulants (Beurmanjer et al., 2019; Dijkstra et al., 2017), making it difficult to differentiate between effects of GHB and other substances. Patients showed a trend towards improvement in total scores and a significant decrease in scoring below cut-off score between T1 and T2, indicating that cognitive functioning partially recovered during detoxification. This is in line with studies in SUD patients using other sedatives, including alcohol (Wobrock et al., 2009) and benzodiaze- pines (Ros-Cucurull et al., 2018), who also show improvement of cognitive functioning during abstinence. It is important to note that patients in the current study were only abstinent of GHB for several days when T2 was administered. Therefore, further improvement with prolonged abstinence cannot be ruled out and is to be expected. Literature on alcohol has for instance shown that cognitive function can improve up to after six weeks to over a year of abstinence (Walvoort, Wester, Doorakkers, Kessels, & Egger, 2016). Future studies should further investigate recovery of cognitive impairment in patients with GUD with long-term abstinence. Patients with GUD scored particularly low on the subdomain Memory, also when compared to studies in patients with other SUDs (Bruijnen, Dijkstra, et al., 2019). Since GHB receptors are predominantly expressed in the hippocampus, this observation might reflect the direct effects of GHB in the brain (Carter, Griffiths, et al., 2009; Castelli et al., 2000; Xie & Smart, 1992). GHB-induced comas have also been suggested to affect hippocampal activity, both in humans (Raposo Pereira, McMaster, Polderman, de Vries, et al., 2018) and animals (Johansson, Grönbladh, & Hallberg, 2014), which could also contribute to the observed memory problems. Since memory is a broad concept (Chaudhuri & Fiete, 2016), with various sub domains (e.g. working memory, long-termmemory, declarative memory, etc), future studies should explore which specific memory domains are most affected in patients with GUD. Despite several studies suggest that cognitive impairment in patients with GUD might be caused by GHB-induced comas (Raposo Pereira, McMaster, Polderman, de Vries, et al., 2018; Raposo Pereira, McMaster, Polderman, DAT de Vries, et al., 2018) the current