Utility of the Parkinson’s disease-Cognitive Rating Scale for the screening of global cognitive status in Huntington’s disease

Background: Cognitive impairment is an essential feature of Huntington’s disease (HD) and dementia is a predictable outcome in all patients. However, validated instruments to assess global cognitive performance in the field of HD are lacking. Objectives: We aimed to explore the utility of the Parkinson’s disease-Cognitive Rating Scale (PD-CRS) for the screening of global cognition in HD. Methods: A multicenter cohort of 132 HD patients at different disease stages and 33 matched healthy controls were classified as having preserved cognition, mild cognitive impairment (HD-MCI) or dementia (HD-Dem) according to the Clinical Dementia Rating and Functional Independence Score. The PD-CRS and the Mini-Mental State Examination were administered. Receiver operating characteristic curve analysis was used to determine optimal cutoffs to differentiate patients according to their cognitive status. Results: A PD-CRS cutoff score ≤ 81/82 was optimal to detect HD-MCI (sensitivity = 93%; specificity = 80%; area under the curve (AUC) = 0.940), and ≤ 63/64 was optimal to detect HD-Dem (sensitivity = 90%; specificity = 87%; AUC = 0.933). MMSE scores failed to show robust psychometric properties in this context. Discussion: The PD-CRS is a valid and reliable instrument to assess global cognition in HD in routine clinical care and clinical trials.