Determinant of the cerebellar cognitive affective syndrome in Friedreich's ataxia

Cerebellar grey matter volume predicts cerebellar tDCS efficacy in individuals with Friedreich ataxia

OBJECTIVE

To determine the impact of cerebellar anatomy on ctDCS efficacy in individuals with Friedreich ataxia (FA).

METHODS

We included 24 FA patients (mean age 31 ± 14 years) and 24 age- and sex-matched healthy controls. Patients underwent a 5-day ctDCS intervention, with cerebellar motor and non-motor symptoms assessed using the Scale for the Assessment and Rating of Ataxia (SARA) and the Cerebellar Cognitive Affective Syndrome Scale (CCAS-S), before and after stimulation. MRI was used to measure cerebellar gray matter volume, superior cerebellar peduncle (SCP) diameter, and skin-to-cerebellum distance. Stepwise linear regression analyses examined predictors of motor and cognitive improvements following ctDCS.

RESULTS

FA patients exhibited significantly reduced cerebellar gray matter volume compared to controls (p = 0.024) after intracranial volume correction, skin-to-cerebellum distance did not differ between groups (p = 0.11). Stepwise linear regression analysis disclosed that the anterior cerebellar gray matter volume was a significant predictor of SARA improvement (β = -0.18, p < 0.001) and the posterior cerebellar gray matter volume of CCAS-S improvement (β = -0.13, p 0.023). Neither SCP diameter nor skin-to-cerebellum distance significantly impacted ctDCS efficacy.

CONCLUSION

Cerebellar gray matter volume is associated to ctDCS-induced symptoms improvements in FA.

SIGNIFICANCE

These findings suggest that cerebellar gray matter volume influences ctDCS responsiveness.

Validation of the Spanish version of the cerebellar cognitive-affective syndrome scale

Objective: To validate the Spanish version of the Cerebellar Cognitive-Affective Syndrome scale (CCAS-S), originally published in 2018, in patients with cerebellar ataxia and healthy subjects, as an adapted Spanish version based on normative data has not yet been published or validated. Methods: Spanish CCAS-S was -administered prospectively to 158 patients with cerebellar ataxia and 164 matched healthy subjects from -different regions of Spain. Discriminant validity and reliability were evaluated. A subgroup of 30 patients underwent detailed neuropsychological examinations to confirm the construct validity. The Scale for the Assessment and Rating of Ataxia (SARA) and the Brief Ataxia Rating Scale (BARS) were used to assess motor performance. Results: This Spanish instrument demonstrates reliability and exhibits statistically significant differences in performance between patients and healthy subjects. Our analysis revealed lower values for specificity in detecting possible, probable, or definite CCAS compared to those reported in the US validation study when utilizing the original cutoff values. Upon application of the appropriate -correction factor for education, the specificity values approximated those reported for probable and definite CCAS diagnostics in the original investigation. Conclusions: The adapted Spanish CCAS-S has demonstrated validity and good reliability in this cohort. Discriminant validity was satisfactory for probable and definite CCAS when the correction for education was applied, and modified template and instructions have been developed. Further research is necessary to investigate the significance of the possible CCAS category, as diagnosed using the Spanish version, as well as to assess the performance of the corrected scale in other Spanish-speaking countries.

The Role of Verbal Fluency in the Cerebellar Cognitive Affective Syndrome Scale in Friedreich Ataxia

Cerebellar pathology engenders the disturbance of movement that characterizes Friedreich ataxia (FRDA), yet the impact of cerebellar pathology on cognition in FRDA remains unclear. Numerous studies have unequivocally demonstrated the role of the cerebellar pathology in disturbed cognitive, language and affective regulation, referred to as Cerebellar Cognitive Affective Syndrome (CCAS), and quantified by the CCAS-Scale (CCAS-S). The presence of dysarthria in many individuals with ataxia, particularly FRDA, may confound results on some items of the CCAS-S resulting in false-positive scores. This study explored the relationship between performance on the CCAS-S and clinical metrics of disease severity in 57 adults with FRDA. In addition, this study explored the relationship between measures of intelligibility and naturalness of speech and scores on the CCAS-S in a subgroup of 39 individuals with FRDA. We demonstrated a significant relationship between clinical metrics and performance on the CCAS-S. In addition, we confirmed the items that returned the greatest rate of failure were based on Verbal Fluency Tasks, revealing a significant relationship between these items and measures of speech. Measures of speech explained over half of the variance in the CCAS-S score suggesting the role of dysarthria in the performance on the CCAS-S is not clear. Further work is required prior to adopting the CCAS-S as a cognitive screening tool for individuals with FRDA.

Cognitive, Emotional, and Other Non-motor Symptoms of Spinocerebellar Ataxias

PURPOSE OF REVIEW

Spinocerebellar ataxias (SCAs) are autosomal dominant degenerative syndromes that present with ataxia and brain stem abnormalities. This review describes the cognitive and behavioral symptoms of SCAs in the context of recent knowledge of the role of the cerebellum in higher intellectual function.

RECENT FINDINGS

Recent studies suggest that patients with spinocerebellar ataxia can display cognitive deficits even early in the disease. These have been given the term cerebellar cognitive affective syndrome (CCAS). CCAS can be tracked using newly developed rating scales. In addition, patients with spinocerebellar ataxia also display impulsive and compulsive behavior, depression, anxiety, fatigue, and sleep disturbances. This review stresses the importance of recognizing non-motor symptoms in SCAs. There is a pressing need for novel therapeutic interventions to address these symptoms given their deleterious impact on patients' quality of life.