The Montreal Cognitive Assessment (MoCA) is superior to the Mini-Mental State Examination (MMSE) for the detection of vascular cognitive impairment after acute stroke

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Abstract

Background

The majority of patient with post-stroke Vascular Cognitive Impairment (VCI) have Vascular Cognitive Impairment No Dementia (VCIND). The Mini-Mental State Examination (MMSE) has been criticized as a poor screening test for VCIND due to insensitivity to visuospatial and executive function impairments. The Montreal Cognitive Assessment (MoCA) was designed to be more sensitive to such deficits and may therefore be a superior screening instrument for VCIND.

Methods

Stable patients within 14 days of their index stroke without significant physical disability, aphasia, dysarthria, active psychiatric illness or pre-existing dementia were eligible. Cognitive and neurological measures were administered after informed consent.

Results

100 patients were recruited. Of the 57 patients with unimpaired MMSE scores, 18 (32%) patients had an impaired MoCA score. By comparison, only 2 out of the 41 (4.9%) patients with unimpaired MoCA scores had impaired MMSE scores. Moreover, MMSE domain subtest scores could not differentiate between groups of differing screening test results, whilst MoCA domain subtest scores (Visuospatial/Executive Function, Attention and Recall) could.

Conclusion

The MoCA is more sensitive than the MMSE in screening for cognitive impairment after acute stroke. Longitudinal studies are required to establish the prognostic value of MoCA and MMSE evaluation in the acute post-stroke period for cognitive impairment as defined by the standard method of formal neuropsychological evaluation 3–6 months after stroke.

Introduction

Vascular Cognitive Impairment (VCI), comprising of Vascular Cognitive Impairment No Dementia (VCIND), Vascular Dementia (VaD) and mixed dementia, is a common consequence of ischemic stroke [1]. Most cases of post-stroke VCI are due to VCIND [2] with 46% of VCIND patients developing incident dementia over a 5-year period [3]. As VCIND patients with more severe impairment were found to be at higher risk of conversion to dementia compared to patients with less severe or no cognitive impairment (NCI) [4], early detection of cognitive deficits may facilitate intervention to prevent cognitive deterioration. The feasibility of cognitive screening in the subacute phase of stroke needs to be investigated as screening at the conventional 3 to 6 month period after stroke may be less practical.

The widely used Mini-Mental State Examination (MMSE) [5] was found to be inaccurate in screening post-stroke cognitive impairment as it was especially insensitive to complex cognitive deficits [6]. By comparison, the Montreal Cognitive Assessment (MoCA) has been designed to be sensitive to mild deficits [7], and may detect more cognitive abnormalities after the ischemic stroke or Transient Ischemic Attack (TIA), particularly in executive function, attention and delayed recall [8]. However, a comparison study of both screening tools for patients in the subacute phase of stroke is required.

Hence, the primary aim of the present study was to test the hypothesis that MoCA is more sensitive than MMSE for detecting cognitive impairment in a population of subacute stroke patients. The feasibility and the psychometric properties of MoCA (modified for Singaporean population) were also compared with MMSE for detecting vascular cognitive impairment.

Section snippets

Participants

One hundred stroke patients (≥ 21 years old) admitted to the stroke neurology service at the National University Health System (NUHS) of Singapore were recruited. Eligible participants had an acute ischemic stroke or TIA within the preceding 14 days and stable clinical status within the preceding 24 h. Exclusion criteria for this study were major physical disability (modified Rankin Scale (mRS) > 4) [9], significant aphasia or dysarthria that impeded cognitive assessment (National Institute of

Results

Recruited patients were mostly Chinese (76%) and males (62%) with a mean age of 61.2 ± 11.3 years. 52% had a level of education of primary and below. Most patients (84%) had ischemic stroke presenting with low disability level (median mRS score = 2 and median NIHSS score = 2). The mean interval between stroke event and assessment was 4.2 ± 2.4 days. Most patients were classified as Small Artery Occlusion by the TOAST (50%) with a further 21.4% with Large Artery Atherosclerosis, 17.9% with Cardioembolism,

Discussion

The principal finding of this study is that the MMSE is less sensitive than the MoCA in detecting VCI after acute stroke. More patients were identified with cognitive impairment by the MoCA (n = 59) compared to MMSE (n = 43). Both the mean MoCA score and several MoCA subtest scores could significantly differentiate between all three cognitive screening test result groups and had good discriminating properties, while only the mean MMSE scores but none of MMSE subtest scores could do so. Finally, 18

Acknowledgements

The study is supported by a Centre Grant from the National Medical Research Council (NMRC/CG/NUHS/2010).

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