The Italian version of the alternative form of Parkinson's Disease-Cognitive Rating Scale (PD-CRS/AF): normative values from 260 Italian healthy subjects

Introduction: The Parkinson's Disease-Cognitive Rating Scale (PD-CRS) is a comprehensive PD-specific cognitive scale which assesses both fronto-subcortical and cortical functions. The original version of the PD-CRS is a valid and reliable instrument to screen for and diagnose PD-MCI. Although this battery was translated and validated into Italian language, an alternative form (AF) should be useful to minimize practice effect in test-retest conditions. The main aim of the present study was to validate the Italian version of the AF of the PD-CRS (PD-CRS/AF) and to collect normative values in a sample of Italian healthy adult and older population. Materials and methods: We adapted the PD-CRS/AF to Italian language, then 260 participants of different ages (age range 40-89 years) and educational levels (from primary school to university) underwent the PD-CRS/AF. Regression-based norming was used to explore the influence of demographic variables (age, education level, sex) on total score, cortical and subcortical scores, and for the score on each single subtest of the PD-CRS/AF. Results: Multiple linear regression analysis revealed that age and education are significantly associated with the total score and the two sub-scores, whereas no significant effect of sex was revealed. A correction grid for raw scores was developed and inferential cut-off and equivalent scores for each sub-test were provided. Conclusions: The present study provides the first Italian translation of PD-CRS/AF and normative data to correct the scores according to relevant demographic variables, allowing clinicians to detect cognitive changes over time by means of a valid and reliable cognitive screening instrument.