Carolien Zeetsen

74 Discussion To our knowledge this is the first study in addiction care in which a large and heterogeneous group of patients with SUD are assessed on cognitive impairments. The current study found a prevalence of cognitive impairments of 31% in the total sample, ranging from 21% for cannabis to 39% for opioids. Patients using alcohol had a significantly lower MoCA–TS than those using cannabis and it was found that in the total sample younger patients scored significantly higher than older patients. Years of regular use, abstinence (duration), severity of dependence and/or abuse, polysubstance use, depression, anxiety and stress were not related to MoCA outcomes. Previous research shows a prevalence of cognitive impairments in patients with SUD ranging from 30% – 80% (Copersino et al., 2009). The prevalence in our study falls at the bottom of this range, yet is still remarkable as cognitive impairments are found to affect treatment outcomes. Differences between primary–problem substances on MoCA performance were not as profound as expected. Patients using alcohol had lower outcomes than those using cannabis, both on the MoCA–TS and on MoCA–DS memory, and patients using opioids had lower outcomes on visuospatial abilities in comparison to those using cannabis and stimulants. The lack of significant differences could be influenced by the high percentage of polysubstance users in our sample and the relatively small number of patients using opioids (see Table 4.1). There was a significant difference in age between substance types, and age was found to have an effect on MoCA performance in this study. The finding that age is negatively correlated to MoCA scores is in line with findings in a sample of patients with AUD aged > 18 (Alarcon et al., 2015) and also in a sample of healthy controls aged 25–91 (Freitas et al., 2012). It is, however, striking that the directionality of the correlation between age and MoCA–TS was different for stimulants than for the other substances. This may be a consequence of the primarily enhancing effects of stimulant intoxication at low doses (Scott et al., 2007; Spronk et al., 2013), although abstinence was no significant factor on MoCA performance in the total sample. Substance type and age are thus factors that should be taken into account when interpreting the MoCA–TS. SUD patients may experiencemore psychological complaints than healthy people, and they are not always abstinent at intake. In our sample, none of the variables (abstinence, abstinence duration, polysubstance use, years of regular use, severity of dependence and/or abuse, depression, anxiety and stress) were related to MoCA outcome. The lack of relations between MoCA–TS and depression, anxiety and stress is in line with recent findings in a sample of polysubstance users where the MoCA–TS was not related to results on a (psychiatric) symptom checklist (Hagen et al., 2019). As for abstinence and abstinence duration, our findings are not in line with the literature, as a review by Walvoort et al. (2013) points to a minimum period of six weeks abstinence before an extensive (neuro)psychological assessment can be carried out validly.