Carolien Zeetsen

62 performance (Scott et al., 2007; Spronk et al., 2013). Cognitive impairments that occur after short–term abstinence in executive functioning, inhibition, (verbal) memory, psychomotor functions and attention disappear again after long–term remission (Jovanovski et al., 2005; Scott et al., 2007; Woicik et al., 2009; van Holst et al., 2011; Spronk et al., 2013; Schulte et al., 2014; Zhong et al., 2016). After one year of complete abstinence cognitive function has been found to be at the level of healthy controls (Iudicello et al., 2010; Vonmoos et al., 2014). There are case studies, however, that report major cognitive impairments in patients with a history of chronic stimulant use, with dosage being the critical determinant (Spronk et al., 2013; Wood et al., 2014; Jacobs et al., 2016). Regarding opioid abuse, relatively few studies have assessed the acute cognitive sequelae. There is, however, ample evidence of impairments in the memory domain (Gruber et al., 2007), and impairments are also found after short–term abstinence in executive functioning, such as verbal fluency, inhibition and decision–making. These impairments have been demonstrated after up to one year of abstinence (van Holst et al., 2011). Whether full recovery occurs is largely unknown, although it has been found that at least some recovery is possible after long term abstinence of opioid abuse (Davis et al., 2002). Cognitive deficits in chronic substance abuse are clinically relevant, as they affect treatment outcome and predict dropout rates as compared to cognitively intact users (Teichner et al., 2002). In AUD, cognitive impairments are associated with worse treatment compliance and lower self–efficacy, which in turn result in a drinking outcome with fewer abstinent days and more drinks per drinking day (Bates et al., 2006; Walvoort et al., 2016). Poorer treatment outcomes, lower treatment retention and less abstinence are also found in cocaine users with mild cognitive impairments (Aharonovich et al., 2003; Aharonovich et al., 2006). Poor executive function performance is associated with worse recognition of problem use and hampers the intention to stop using in both opioid and cocaine users (Yücel & Lubman, 2007; Severtson et al., 2010). Interventions targeting cognitive functioning, or taking cognitive impairments into account, may lead to a better treatment outcome both regarding the addiction and in everyday functioning (Forsberg et al., 1987; Roehrich et al., 1993). Although the literature carefully suggests that full recovery of cognitive impairments may be possible for all substances, the influence of cognitive impairments on treatment outcome shows the importance of detecting these impairments for each individual at an early stage, so that personalised treatment can be implemented. The current study focuses on the prevalence of cognitive impairments and differences in cognitive functioning across substances by means of a cognitive screen, the Montreal Cognitive Assessment (MoCA; Nasreddine et al., 2005) at the early stage of addiction treatment right before interventions