Carolien Zeetsen

46 Methods Design A prospective study was performed with two time points of assessment using two authorized and validated parallel versions of the MoCA (Costa et al., 2012). MoCA version 7.1 was administered at intake (baseline) and MoCA version 7.2 directly preceding the NPA at follow–up approximately eight weeks later. Data were collected between August 2012 and March 2015. The study was approved by the internal review boards of all participating health care centres and the research board of the Nijmegen Institute for Scientist– Practitioners in Addiction. Participants The aim was to recruit a total of 100 outpatients seeking treatment for SUD from four participating addiction health care centres in the Netherlands (IrisZorg, Novadic–Kentron, Tactus and Vincent van Gogh Institute for Psychiatry). This study is part of a larger study ( N = 691), for which the inclusion criteria were 1) dependency or abuse of a substance (excluding nicotine) or behaviour; 2) age 18–75; and 3) signed informed consent for participation at baseline and/or follow–up. The exclusion criterion was an inability to administer the MoCA, due to for instance: a neurological (e.g. stroke, dementia, traumatic brain injury) or very unstable acute psychiatric disorder, severe lack of motivation, or insufficient Dutch language skills. Patients were included regardless of abstinence to increase the external validity of the design. Materials Montreal Cognitive Assessment The MoCA (Nasreddine et al., 2005) consists of 12 elements measuring seven cognitive domains. These domains include executive functioning; visuospatial abilities; attention, concentration and working memory (called ‘attention’ from now on); language; abstract reasoning; memory; and orientation. A total score is calculated, with a maximum of 30 points. Nasreddine et al. (2005) found a score of ≤ 25 to be indicative of MCI. However, several studies have identified different cut–off scores for different populations (Julayanont et al., 2013). The validity of the MoCA, including both alternate forms, has been established in detecting MCI, with sensitivities and specificities ranging from 0.90 to 1.00 and 0.57 to 0.62, respectively. Alternate–form reliability for healthy controls ranged from 0.52 to 0.69 and all versions were found to be equivalent in previous research (Costa et al., 2012; Nasreddine et al., 2016). The authorized Dutch translations of two parallel versions were used.