Detecting Subtle Cognitive Impairment in Multiple Sclerosis with the Montreal Cognitive Assessment.

Background: Although cognitive deficits are frequent in multiple sclerosis (MS), screening for them with tools such as the Montreal Cognitive Assessment (MoCA) test is usually not performed unless there is a subjective complaint. The Multiple Sclerosis Neuropsychological Questionnaire (MSNQ) is among the instruments most commonly used to assess self-reported subjective complaints in MS. Nonetheless, it does not always accurately reflect cognitive status; many patients with cognitive deficits thus fail to receive appropriate referral for detailed neuropsychological evaluation. The objective of this study was to examine the validity of the MoCA test to detect the presence of objective cognitive deficits among patients with MS without subjective complaints using the Minimal Assessment of Cognitive Function in MS (MACFIMS) as the gold standard.

Methods: The sample included 98 patients who were recruited from a university hospital MS clinic. The MSNQ was used to select patients without subjective cognitive complaints who also completed the MACFIMS, MoCA test and MSQOL-54.

Results: 23.5% of patients without subjective cognitive complaints had evidence of objective cognitive impairment on the MACFIMS (z score < -1.5 on two or more tests). The MoCA had a sensitivity of 87% and a specificity of 68% for detecting objective cognitive impairment in this patient population using a cut-off score of 27.

Conclusion: A significant proportion of patients without self-reported cognitive impairment do have evidence of cognitive deficits on more exhaustive cognitive assessment. The MoCA is a rapid screening test that could be used to target patients for whom a more detailed neuropsychological assessment would be recommended.