Chapter 3 66 ABSTRACT Objectives: The Montreal Cognitive Assessment (MoCA) is an increasingly used screening tool for cognitive impairment. While it has been validated in multiple settings and languages, most studies have used a biased case-control design including healthy controls as comparisons not representing a clinical setting. Methods: Thepurpose of thepresent cross-sectional study is to test the criterion validity of theMoCA for MCI and mild dementia (MD) in an old age psychiatry cohort (n=710). The reference standard consists of a multidisciplinary, consensus-based diagnosis in accordance with international criteria. As a secondary outcome the use of healthy community dwelling older adults as additional comparisons allowed us to underscore the effects of case-control spectrum-bias. Results: The criterion validity of the MoCA for cognitive impairment (MCI+MD) in a case-control design, using healthy controls, was satisfactory (AUC 0.93; specificity of 73% <26), but declined in the cross-sectional design using referred but not cognitive impaired as comparisons (AUC 0.77; specificity of 37% <26). In an old age psychiatry setting the MoCA is valuable for: confirming normal-cognition (≥26, 95% sensitivity), excluding MD (≥21;NPV 98%) and excluding MCI (≥26;NPV 94%); but not for diagnosing MD (<21;PPV 31%) or MCI (<26;PPV 33%). Conclusions: This study shows that validating the MoCA using healthy controls, overestimates specificity. Taking clinical and demographic characteristics into account, the MoCA is a suitable screening tool – in an old age psychiatry setting – for distinguishing between those in need of further diagnostic investigations and those who are not, but not for diagnosing cognitive impairment.
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