The Cerebellar Cognitive Affective/Schmahmann Syndrome Scale: Updates and Insights

The Cerebellar Cognitive Affective / Schmahmann Syndrome scale (CCAS-S) detects cognitive and neuropsychiatric changes in cerebellar disease (CD). It has good sensitivity and specificity, but a false positive rate ~ 5%. We determined that healthy controls (HC) fail digit span tasks (DS) when presented with one repetition opportunity. We tested the hypothesis that providing participants a second attempt at DS would improve performance and decrease false positive rate. We also evaluated influence of age and education on CCAS-S scores. We administered the CCAS-S to 50 CD and 85 HC, providing a second attempt at forward / reverse DS for each failed number sequence, using either the same numbers, or a different set of numbers of the same length. Performance with same vs different digits was identical. After second DS attempt, raw score increased: HC, 106.1 ± 9.4 to 106.8 ± 9.2; CD, 89.2 ± 15.5 to 90.6 ± 15.8, and failed domains decreased: HC, 0.67 ± 0.89 to 0.4 ± 0.73; CD, 2.62 ± 1.9 to 2.24 ± 1.9. False positive definite CCAS (≥ 3 failed domains) decreased in HC, 4.7% to 1.2%. In CD, definite CCAS remained high, 48% to 38%. Some older HC failed ≥ 3 domains. Education (all ≥ 12 years) did not impact performance in HC; CD with more education failed fewer domains. False positive definite CCAS-S was reduced to 1.2% by second attempt at forward and backward DS. The CCAS-S detected incipient cognitive impairment in older individuals. Education effects were modest, but cohorts with education ≤ 11 years need further study.