Validation of the Polish Version of Addenbrooke’s Cognitive Examination III in Mild Cognitive Impairment and Alzheimer’s Disease Dementia

INTRODUCTION: The Addenbrooke's Cognitive Examination III (ACE-III) is a widely recognized cognitive screening tool; however, its diagnostic accuracy and optimal cutoff values for distinguishing mild cognitive impairment (MCI) and Alzheimer's disease dementia (AD-D) have not been established in the Polish population. This study aimed to evaluate the reliability, diagnostic performance, and optimal cutoff scores of the ACE-III in differentiating between controls, MCI, and AD-D patients. METHODS: A total of 1,265 Polish participants were assessed: 767 with AD-D (321 men; mean age, 74.9 ± 8.2 years), 216 with MCI (90 men; mean age, 72.2 ± 8.4 years), and 282 controls (77 men; mean age, 67.1 ± 8.7 years). All underwent cognitive screening using the ACE-III and the Mini-Mental State Examination (MMSE). Group differences were examined using the Kruskal-Wallis test, while receiver operating characteristic analyses determined diagnostic accuracy and optimal cutoff points. ANCOVA with bootstrap resampling was used to control for age and education. RESULTS: Internal consistency of the ACE-III was strong (McDonald's ω = 0.889). The ACE-III demonstrated superior diagnostic accuracy compared with the MMSE, with optimal cutoffs of 88.5 (sensitivity, 98%; specificity, 92%) for distinguishing controls from MCI and 72.5 (sensitivity, 90%; specificity, 76%) for distinguishing MCI from AD-D. CONCLUSIONS: The ACE-III is a reliable and sensitive tool for detecting early cognitive decline in the Polish population. Its superior diagnostic utility compared with the MMSE, particularly in identifying early neurocognitive impairment, supports its use in timely diagnosis and intervention.