A comparison of screening tools for the assessment of Mild Cognitive Impairment

Abstract

Background: Montreal Cognitive Assessment (MoCA) is a cognitive screening instrument, developed by Nasreddine et al. (2005), with the aim of overcoming limitations of the Mini-Mental State Examination (MMSE; Folstein et al., 1975). MoCA evaluates a large number of cognitive areas and tasks are more complex, as compared with the MMSE, which makes it a more sensitive instrument in the detection of dementia and especially in Mild Cognitive Impairment (MCI). This is a state that often progresses to Alzheimer Disease (AD). Methods: A group of MCI (N 1⁄4 90) and AD (N 1⁄4 75) were recruited at the Dementia Clinic, Neurology Department of Coimbra University Hospital. The diagnosis was previously established based on international criteria for the diagnosis of MCI (Petersen et al. 1999) and probable AD (APA, 2000). A sub-group of these patients (MCI: N 1⁄4 30; AD: N 1⁄4 30) was assessed a second time (follow-up: M 1⁄4 167 days; SD 1⁄4 55 days). All patients were evaluated with both the MMSE and MoCA. Results: The two instruments show an excellent correlation (r 1⁄4 .85, p < .0001) and good internal consistency (MoCA: a Cronbach 1⁄4 .89; MMSE: a Cronbach 1⁄4 .82). Sensitivity was calculated separately for MCI and AD groups. MoCA shows an excellent sensitivity in identifying MCI (88%) and AD (100%) while the results for MMSE proved to be poor for patients without dementia (MCI: 7% and AD: 71%). In addition, MoCA correctly detects 90% of false negatives of the MMSE. There were also significant differences between the scores in two evaluation moments MoCA (t 1⁄4 4097, p <. Ooo1), unlike what was found in the MMSE (t 1⁄4 1.744, p 1⁄4 . 089). Conclusions: Although there was a good correlation between the results obtained with both instruments, the MoCA has a better discriminate capacity, being a more sensitive test for the detection of MCI and AD. In longitudinal evaluation, MoCA is also more sensitive to cognitive decline in a short period of time, providing comprehensive information on the profile of clinical deterioration. Considering these results MoCA seems to be a privileged instrument for the early detection and follow-up of cognitive decline.