Scaling Cognitive Domains of the Montreal Cognitive Assessment: An Analysis Using the Partial Credit Model

The psychometric properties of the Montreal Cognitive Assessment (MoCA) were examined by using the Partial Credit Model. The study sample included 897 participants who were distributed into two main subgroups: (I) the clinical group (90 patients with Mild Cognitive Impairment, 90 patients with Alzheimer's disease, 33 patients with Frontotemporal Dementia, and 34 patients with Vascular dementia, whose diagnoses were previously established according to a consensus that was reached by a multidisciplinary team, based on the international criteria) and (II) the healthy group (composed of 650 cognitively healthy community dwellers). The results show (i) an overall good fit for both the items and the persons' values, (ii) high variability for the cognitive performance level of the cognitive domains (ranging between 1.90 and -3.35, where "Short-term Memory" was the most difficult item and "Spatial Orientation" was the easiest item) and between the subjects on the scale, (iii) high reliability for the estimation of the persons' values, (iv) good discriminant validity and high diagnostic utility, and (v) a minimal differential item functioning effect related to of pathology, gender, age, and educational level. MoCA and its cognitive domains are suitable measures to use for screening the cognitive status of cognitively healthy subjects and patients with cognitive impairment.