To create the Cerebellar Impulsivity-Compulsivity Assessment (CIA), a newly modified scale for the measurement of impulsive and compulsive behavior (ICB) in people with cerebellar disorders.

The cerebellum has been identified as the key brain region that modulates reward processing in animal models. We recently found that people with cerebellar ataxia have domain-specific ICB, unlike in those with Parkinson’s disease, which further supports the role of the cerebellum in reward processing. However, there are no validated scales that quantitatively measure ICB in cerebellar disorders to propel future research.

To develop this scale, we recruited 73 cerebellar ataxia cases and 67 controls. We administered the Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease–Rating Scale (QUIP-RS) on these 140 participants. All subjects received baseline self-rating assessment. Thirty-one cerebellar ataxia cases received repeated self-rating and trained rater-rating. We examined Cronbach’s alpha for internal consistency to formulate CIA, and we investigated the test-retest reliability and inter-rater reliability using interclass correlation analysis. The receiver operating characteristic curve (ROC) was generated to assess the sensitivity and specificity of CIA.

Cerebellar ataxia has higher total QUIP-RS than controls (18.58 ± 13.03 vs. 8.91 ± 7.62, p < 0.001). Cronbach’s alpha revealed that the gambling subscale lacks internal consistency; therefore, we excluded gambling from QUIP-RS to formulate CIA (Cronbach’s alpha > 0.70), which showed high test-retest reliability (r > 0.85, n = 31) and inter-rater reliability (r > 0.70, n = 31). Based on the ROC, a score of 9.5 was chosen as the cutoff to diagnose cerebellar ICB with 75.3% sensitivity and 61.2% specificity. 

This newly proposed and validated CIA scale can be used to assess ICB and study cerebellum-related cognitive and behavioral non-motor symptoms.