The Cerebellar Neuropsychiatric Rating Scale Version 2: Development and Validation

The affective component of the cerebellar cognitive affective / Schmahmann syndrome (CCAS) reflects neuropsychiatric symptoms across five domains: attentional control, emotional control, autism spectrum, psychosis spectrum, and social skill set, each with overshoot (hypermetric) and undershoot (hypometric) manifestations. The Cerebellar Neuropsychiatric Rating Scale (CNRS) is a 35-item informant-report questionnaire that detects and quantifies these symptoms. We amended the CNRS items to produce Self- and Informant-Report versions, conducted cognitive debrief to evaluate each item's readability, relevance, and importance, and incorporated patient feedback to generate a 50-item CNRS Version 2 (CNRS-2). We conducted psychometric evaluation via online administration in 43 individuals with cerebellar disorder (CD) and 25 healthy controls (HC) and their respective study-partners at baseline and two weeks later. Internal consistency was adequate, and the CD cohort test-retest reliability was moderate-to-good. CNRS-2 scores were unrelated to motor ataxia severity. Group analysis revealed significant differences between CD and HC mean scores (P < 0.05), and receiver operating characteristic (ROC) analysis determined that the groups could be distinguished optimally with scores of 18 and 15 for subjects and study-partners, respectively. There was concordance within subject-partner pairs, however scoring discrepancies were observed for some. CNRS-2 domains correlated highly with other scales, whether conceptually related or not. The CNRS-2 is a comprehensive screening instrument that incorporates the patient perspective and facilitates assessment of the neuropsychiatric component of the CCAS. Its broad scope and ability to detect subclinical symptoms in purportedly HC suggests that it holds promise as a transdiagnostic screening instrument in neuropsychiatry.