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.