The MoCA Memory Index Score (MIS) as an indicator of episodic memory impairment and its implications for cognitive screening in a mixed clinical sample

Abstract

OBJECTIVE: The Montreal Cognitive Assessment (MoCA) Memory Index Score (MIS) has shown promise as a brief indicator of episodic memory decline, but its correspondence with standardized neuropsychological memory measures in diagnostically heterogeneous clinical populations remains poorly understood. METHODS: Participants were 119 adults referred for outpatient neuropsychological evaluation at a Southern California academic medical center for a range of neurological conditions. Hierarchical regression analyses examined whether the MIS predicted delayed recall on the Rey Auditory Verbal Learning Test (RAVLT), WMS-IV Logical Memory II, and a composite memory score, beyond age, education, and a nonmemory MoCA score. Classification accuracy for identifying memory impairment was evaluated using receiver operating characteristic (ROC) analysis. RESULTS: The MIS was a significant predictor of delayed memory performance across measures, with the strongest and most consistent contribution for list-learning (RAVLT) and comparatively weaker, less consistent incremental value for story-based recall. ROC analysis showed good classification accuracy (AUC = .874), with a preliminary cutoff of ≤8.5 yielding high sensitivity (.944) and moderate specificity (.687). MIS scores also differed significantly across diagnostic groups. CONCLUSIONS: The MIS may offer clinically meaningful, format specific information about episodic memory and support for referral decisions, though it should not substitute for comprehensive neuropsychological assessment.