Background: The Mini-Addenbrooke's Cognitive Examination (M-ACE) is a valid and reliable tool that accurately differentiates various types of cognitive impairment from Normal-cognition assessed in multiple settings. However, its validity among older individuals in long-term care (LTC) was not yet established. Therefore, we sought to assess the Portuguese M-ACE's validity, reliability, and accuracy in detecting cognitive impairment no-dementia (CIND) in LTC users. Methods: A comprehensive assessment was performed on 196 LTC Portuguese users aged ≥ 60 years, among whom 71 had Normal-cognition, and 125 had CIND. Results: The M-ACE was found to be reliable (McDonald's ω = .86, Cronbach's α = .85) and consistent over time (r = .72; ICC = .83) and between raters (k = .92). Strong correlations with related measures supported construct validity (both r = .67). The M-ACE accurately distinguished CIND from Normal-cognition with a cut-off of 17 points (AUC = 0.81, Sensitivity = 81.7%, Specificity = 74.4%). Conclusion: Our findings suggest that the Portuguese M-ACE is a valid and reliable cognitive assessment tool for LTC users, allowing for accurate differentiation between CIND and Normal-cognition. Thus, the M-ACE's use could contribute to the early detection and intervention of cognitive disorders, especially among older adults in LTC.
