Background: To qualify dementia's severity, in Peru, there is only the Global Deterioration Scale. To date, the Spanish translation and cultural adaptation of the Clinical Dementia Rating (CDR) scale is currently used locally; its definitive formal psychometric validation, specific to the local socio-cultural and linguistic context, is needed. The present study aims to formally validate the CDR within the Peruvian population, ensuring its accuracy and reliability as the essential staging tool.

Methods: This study involved a total of 1600 older adults, who were divided into three groups: normal control, mild cognitive impairment, and Alzheimer's disease, to explore two different CDR scoring methods: CDR Global Score (CDR-GS) and CDR Sum of Boxes Score (CDR-SB). The discriminative validity, inter-item reliability, and concurrent validity of the CDR. The scores on the Mini-Mental State Examination, Rowland Universal Dementia Assessment Scale, Pfeffer Functional Activities Questionnaire, and components of the Uniform Data Set version 3 Neuropsychological Battery were examined for correlations.

Results: The CDR demonstrated high reliability and validity in distinguishing among normal cognition, mild cognitive impairment, and Alzheimer’s Disease. When screening for AD, CDR-SB had a relatively high sensitivity (98.2%) and specificity (99.6%), while CDR-GS had a relatively better sensitivity (99.8%) and ideal specificity (100%).

Conclusion: The Peruvian version of the CDR demonstrated good psychometric properties (internal consistency, discriminant, and concurrent validity) comparable to those obtained in CDR evaluation in Latin America.