Carolien Zeetsen

45 CHAPTER Validating the MoCA in addiction health care 3 Introduction About 0.6% of the adult population worldwide (an estimated 29.5 million) suffer from substance use disorder (SUD; United Nations Office on Drugs and Crime, 2017). SUD affects the individual in social, physical and economical ways (Laudet et al., 2002) and may result in cognitive impairments interfering with treatment (Aharonovich et al., 2006; Bates et al., 2006; Copersino et al., 2012). The Diagnostic and Statistical Manual of Mental Disorders, 5th ed. (DSM–5; APA, 2013) introduced the term ‘neurocognitive disorder’ (NCD) in which the subtype substance–induced NCD can be classified as either major or mild, based on severity and everyday limitations. Cognitive impairments in patients with SUD have an estimated prevalence of 30% – 80% (Copersino et al., 2009). The exact prevalence of substance–induced NCD is, however, difficult to establish based on the existing literature (Toledo–Fernández et al., 2018). The effects of chronic substance use on cognitive functioning are both acute and chronic and vary across substances, resulting in decreased treatment adherence, lower self–efficacy and less treatment retention (Aharonovich et al., 2006; Bates et al., 2006; Copersino et al., 2012). Therefore, insight into an individual’s cognitive functioning is crucial, as it enables to personalize and optimize treatment effectiveness (Allen et al., 1997; Sofuoglu et al., 2010; Bates et al., 2013). Often patients with SUD lack insight into their NCD, as indicated by a lack of correlation between objectively measured and subjectively experienced cognitive deficits (Horner et al., 1999; Walvoort et al., 2016). Although neurocognitive assessment can accurately detect the pattern and severity of cognitive impairment in patients with SUD, the administration of such an extensive neuropsychological assessment (NPA) is not always feasible. Therefore, this study investigated the validity of a short and easy–to–administer cognitive screen, the Montreal Cognitive Assessment (MoCA; Nasreddine et al., 2005), in patients with SUD. Originally developed to detect mild cognitive impairment (MCI), the MoCA has also been found to be valid in SUD for detecting cognitive deficits (Copersino et al., 2009; Rojo–Mota et al., 2013; Ridley et al., 2018). However, only one study in patients with alcohol use disorders (AUD) has correlated the MoCA to the gold standard NPA performance (Ewert et al., 2018), with no studies in users of other substances. The current prospective study assessed the criterion validity of the MoCA as a screen for cognitive impairment in a sample of patients with SUD. First, the optimal cut–off for use in addiction health care was established. Next, the criterion validity was assessed by comparing MoCA results with an extensive NPA. Additionally, the interaction of substance type, abstinence duration and MoCA performance has been examined. In order tomaximize the external validity of the design, this study was designed to comply as much as possible with treatment as usual in all participating institutions.