Carolien Zeetsen

128 This replicated the findings of Chertkow et al. (2011) and Nasreddine et al. (2016) using the English and French–language versions of the MoCA in older adults. At the level of individual items, however, small but systematic differences were found for the items animal naming, sentence repetition and abstract reasoning, mostly in favour of the alternate forms except for sentence repetition where MoCA version 7.1 had significantly higher scores. Similar findings were reported by Lebedeva et al. (2016) for both the items animal naming and abstract reasoning. In addition, they also found a performance difference for the item figure copy across the different versions. The fact that this was currently not found could be explained by the thorough checking of scores and the conservative scoring method that was used, thereby eliminating ambiguities in scoring and possible inter–rater differences as previously reported by Cumming et al. (2020). In a sample of 82 patients with SUD, significant differences in performance between MoCA versions 7.1 and 7.2 were found on all MoCA–DS except abstract reasoning, memory and orientation (Chapter 3). Also, mean scores on all MoCA–DS except language, were higher on MoCA version 7.2 as compared to version 7.1. This can, however, be interpreted by a non–specific practice effect as the versions were administered in a fixed order. For test–retest reliability good to excellent results were found in Chapter 2 for MoCA–TS between versions 7.1–7.2 (ICC = 0.64) and 7.1–7.3 (ICC = 0.82). This is in line with findings of other studies (Costa et al., 2012; Feeney et al., 2016; Nasreddine et al., 2016; Kopecek, Bezdicek, et al., 2017; Wu et al., 2017). These test–retest reliabilities can be used to compute Reliable Change Indices (RCI; Chelune et al., 1993) making the MoCA–TS useful for monitoring change over time. The MoCA–MIS, on the other hand, had poor to fair test–retest reliabilities (7.1–7.2: ICC = 0.32; 7.1–7.3: ICC = 0.48), possibly due to a strong negative skewness of scores with ceiling performances in many of the cognitively unimpaired participants on both versions. In cognitively impaired individuals, the MoCA–MIS has been found to be a useful index of monitoring change over time, making it a good predictor, for example, for conversion from mild cognitive impairment to Alzheimer’s disease (Julayanont et al., 2014). Validity In addition to reliability, the validity of an instrument is also very important. In psychometrics, test validity is the extent to which an instrument is generalizable to the real world. There are many different types of validity, probably the most important being construct validity: does a test measure what it is supposed to measure? In other words, does the MoCA actually assess cognitive functioning in the domains it claims to measure? Construct validity is usually determined by comparing results on a test to results on a conceptually similar test. In Chapter 3, results on the MoCA were compared to results on an NPA that was composed on the basis of the cognitive domains that the MoCA is said to measure. It was found that results on all MoCA–DS