Social Cognition in Patients With Cerebellar Neurodegenerative Disorders

Cerebellar Neurostimulation for Boosting Social and Affective Functions: Implications for the Rehabilitation of Hereditary Ataxia Patients

Beyond motor deficits, spinocerebellar ataxia (SCA) patients also suffer cognitive decline and show socio-affective difficulties, negatively impacting on their social functioning. The possibility to modulate cerebello-cerebral networks involved in social cognition through cerebellar neurostimulation has opened up potential therapeutic applications for ameliorating social and affective difficulties. The present review offers an overview of the research on cerebellar neurostimulation for the modulation of socio-affective functions in both healthy individuals and different clinical populations, published in the time period 2000-2022. A total of 25 records reporting either transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) studies were found. The investigated clinical populations comprised different pathological conditions, including but not limited to SCA syndromes. The reviewed evidence supports that cerebellar neurostimulation is effective in improving social abilities in healthy individuals and reducing social and affective symptoms in different neurological and psychiatric populations associated with cerebellar damage or with impairments in functions that involve the cerebellum. These findings encourage to further explore the rehabilitative effects of cerebellar neurostimulation on socio-affective deficits experienced by patients with cerebellar abnormalities, as SCA patients. Nevertheless, conclusions remain tentative at this stage due to the heterogeneity characterizing stimulation protocols, study methodologies and patients' samples.

Effective connectivity analysis of resting-state mentalizing brain networks in spinocerebellar ataxia type 2: A dynamic causal modeling study

Neuroimaging studies on healthy subjects described the causal effective connectivity of cerebellar-cerebral social mentalizing networks, revealing the presence of closed-loops. These studies estimated effective connectivity by applying Dynamic Causal Modeling on task-related fMRI data of healthy subjects performing mentalizing tasks. Thus far, few studies have applied Dynamic Causal Modeling to resting-state fMRI (rsfMRI) data to test the effective connectivity within the cerebellar-cerebral mentalizing network in the absence of experimental manipulations, and no study applied Dynamic Causal Modeling on fMRI data of patients with cerebellar disorders typically showing social cognition deficits. Thus, in this research we applied spectral Dynamic Causal Modeling, to rsfMRI data of 13 patients affected by spinocerebellar ataxia type 2 (SCA2) and of 23 matched healthy subjects. Specifically, effective connectivity was tested between acknowledged mentalizing regions of interest: bilateral cerebellar Crus II, dorsal and ventral medial prefrontal cortex, bilateral temporo-parietal junctions and precuneus. SCA2 and healthy subjects shared some similarities in cerebellar-cerebral mentalizing effective connectivity at rest, confirming the presence of closed-loops between cerebellar and cerebral mentalizing regions in both groups. However, relative to healthy subjects, SCA2 patients showed effective connectivity variations mostly in cerebellar-cerebral closed loops, namely weakened inhibitory connectivity from the cerebellum to the cerebral cortex, but stronger inhibitory connectivity from the cerebral cortex to the cerebellum. The present study demonstrated that effective connectivity changes affect a function-specific mentalizing network in SCA2 patients, allowing to deepen the direction and strength of the causal effective connectivity mechanisms driven by the cerebellar damage associated with SCA2.

Cognitive Complaints and Their Impact on Daily Life in Patients with Degenerative Cerebellar Disorders

Cognitive and affective sequelae of cerebellar disease are receiving increased attention, but their actual rate of occurrence remains unclear. Complaints may have a significant impact on patients, affecting social behavior and psychological well-being. This study aims to explore the extent of subjective cognitive and affective symptoms in patients with degenerative ataxias in the Netherlands. An explorative study was set up in a heterogeneous group of degenerative ataxia patients. Self-reported cognition was evaluated in terms of executive functioning and affect (Dysexecutive Questionnaire/DEX), and memory/attention (Cognitive Failures Questionnaire/CFQ). The Daily Living Questionnaire (DLQ) was administered to quantify the impact on daily life. Furthermore, informants completed questionnaires to obtain insight into patients' self-awareness and social cognition (Observable Social Cognition Rating Scale/OSCARS). This study shows that subjective complaints in the domains of (1) executive functioning and/or (2) memory and attention were reported by 29% of all patients (n = 24/84). In addition, more difficulties in daily life in terms of language/comprehension and community/participation were reported, and this was more common for patients with cognitive complaints than those without. Discrepancies between patients and informants about executive functioning were present in both directions. Deficits in social cognition were not identified at the group level, but more social-cognitive problems were observed in patients with more executive problems rated by informants. Taken together, our findings indicate that cognitive complaints are common in patients with degenerative cerebellar disorders and have an impact on daily life functioning. These results may help to increase awareness of cognitive symptoms and their impact in patients with cerebellar ataxia, their significant others, and professional caregivers.

ANO10-Related Spinocerebellar Ataxia: MDSGene Systematic Literature Review and a Romani Case Series

BACKGROUND

Biallelic pathogenic variants in the ANO10 gene cause autosomal recessive progressive ataxia (ATX-ANO10).

METHODS

Following the MDSGene protocol, we systematically investigated genotype-phenotype relationships in ATX-ANO10 based on the clinical and genetic data from 82 published and 12 newly identified patients.

RESULTS

Most patients (>80%) had loss-of-function (LOF) variants. The most common variant was c.1150_1151del, found in all 29 patients of Romani ancestry, who had a 14-year earlier mean age at onset than patients homozygous for other LOF variants. We identified previously undescribed clinical features of ATX-ANO10 (e.g., facial muscle involvement and strabismus) suggesting the involvement of brainstem pathology, and we propose a diagnostic algorithm that may aid clinical ATX-ANO10 diagnosis.

CONCLUSIONS

The early disease onset in patients with c.1150_1151del may indicate the existence of genetic/environmental disease-modifying factors in the Romani population. Our findings will inform patient counseling and may improve our understanding of the disease mechanism. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Transcranial Sonography Characteristics of Cerebellar Neurodegenerative Ataxias

Cerebellar neurodegenerative ataxias are a group of disorders affecting the cerebellum and its pathways with different neurological structures. Transcranial sonography (TCS) has been used for the evaluation of brain parenchymal structures in various diseases because of its fast and safe utilization, especially in neuropsychiatric and neurodegenerative diseases. The aim of our study was to investigate TCS characteristics of patients with neurodegenerative cerebellar ataxias. In our study, we included 74 patients with cerebellar degenerative ataxia; 36.5% had autosomal dominant onset, while 33.8% had sporadic onset. Standardized ultrasonographic planes were used for the identification of brain structures of interest. The SARA, INAS, neuropsychological and psychiatric scales were used for the further clinical evaluation of our study participants. The brainstem raphe was discontinued in 33.8% of the patients. The substantia nigra (SN) hyperechogenicity was identified in 79.7%. The third and fourth ventricle enlargement had 79.7% and 45.9% of patients, respectively. A positive and statistically significant correlation was found between SN hyperechogenicity with dystonia (p < 0.01), rigidity and dyskinesia (p < 0.05). The higher SARA total score is statistically significantly correlated with the larger diameter of the III (r = 0.373; p = 0.001) and IV ventricles (r = 0.324; p = 0.005). In such patients, the echogenicity of substantia nigra has been linked to extrapyramidal signs, and raphe discontinuity to depression. Furthermore, ataxia and its clinical subtypes have positively correlated with the IV ventricle diameter, indicating brain atrophy and brain mass reduction.

The Impact of Demographic and Clinical Factors on the Quality of Life in Patients with Neurodegenerative Cerebellar Ataxias

In neurodegenerative cerebellar ataxias, not only ataxia but also extra-cerebellar signs have a significant impact on patients' health related to quality of life (HRQoL). The aim of this study was to evaluate the various aspects of HRQoL and predictors of QoL in patients with neurodegenerative cerebellar ataxias. We included a total of 107 patients with cerebellar degenerative ataxia. Patients filled out the validated Serbian version of the SF-36 used for the assessment of HRQoL. All patients were clinically evaluated using SARA, INAS, and neuropsychological tests to assess their global cognitive status and different psychiatric scales. The most frequent types of neurodegenerative cerebellar ataxias were autosomal dominant ataxias (38.3%) and sporadic ataxias (32.7%). Mean age at diagnosis was 35.3 ± 16.23 years, and disease duration was on average 12.1 ± 9.91 years. Mean total SF-36 score was 50.63 ± 20.50. Hierarchical regression analysis showed that in the case of the PHC score, the most significant predictors are the patient's actual age, severity of ataxia, and ACE total score. For MHC, the Hamilton depression score was the most important predictor. Our study has shown that HRQoL measured by SF-36 in patients with neurodegenerative cerebellar disorders is strongly influenced by impaired mobility and depression.

The Cerebellum Gets Social: Evidence from an Exploratory Study of Cerebellar, Neurodevelopmental, and Psychiatric Disorders

Social prediction is a key feature of social cognition (SC), a function in which the modulating role of the cerebellum is recognized. Accordingly, cerebellar alterations are reported in cerebellar pathologies, neurodevelopmental disorders, and psychiatric conditions that show SC deficits. Nevertheless, to date, no study has directly compared populations representative of these three conditions with respect to SC and cerebellar alterations. Therefore, the present exploratory study aimed to compare the SC profiles of individuals with cerebellar neurodegenerative disorders (CB), autism (ASD), bipolar disorder type 2 (BD2), or healthy subjects (HS) using a battery of social tests requiring different degrees of prediction processing. The patterns of cerebellar gray matter (GM) alterations were compared among the groups using voxel-based morphometry. Compared to HS, the clinical groups showed common SC deficits in tasks involving a moderate to high level of prediction. The behavioral results of the clinical groups are consistent with the presence of overlapping GM reduction in cerebellar right Crus II, an area notably involved in complex social processing and prediction. Although exploratory and preliminary, these results deepen the cerebellar role in social prediction and highlight the transdiagnostic value of the cerebellum in social functioning and prediction in pathologies of different aetiologies, forecasting novel possibilities for shared interventions.

A Systematic Review of the Spectrum and Prevalence of Non-Motor Symptoms in Adults with Hereditary Cerebellar Ataxias

Background

Cerebellar ataxias comprise a large group of heterogeneous disorders with both motor and non-motor symptoms (NMS).

Objective

We wanted to ascertain the reported prevalence of NMS in different subtypes of hereditary cerebellar ataxias.

Methods

Systematic review of studies of hereditary cerebellar ataxias (involving >5 patients) who were assessed for NMS, published in the English literature in PUBMED and EMBASE databases from 1947 to 2021.

Results

A total of 35 papers, with data from 1311 autosomal dominant spinocerebellar ataxia (SCA), 893 autosomal recessive cerebellar ataxia (ARCA), and 53 X-linked ataxia cases were included with a total of 450 controls. Mean age for SCA cases at diagnosis was 47.6 (SD, 14.9) years, for ARCA cases was 34.6 (SD, 14.7) years and for X-linked ataxia cases was 68.6 (9.1) years. The prevalence of cognitive problems in SCAs was between 23% and 75% (ranging from mild to severe), being least prevalent in SCA6. The prevalence of depression in SCAs was between 13% and 69% and sleep disorders were between 7% and 80%. Pain was reported by 18% to 60% of patients, especially in SCA3, and fatigue by 53% to 70%. The prevalence of reported cognitive dysfunction in ARCA was 12.5% to 100% and depression between 14% and 51%. The prevalence of anxiety in X-linked ataxias (FXTAS) was 17 % and depression 55%.

Conclusions

The presence of NMS in hereditary cerebellar ataxias is common. The prevalence and spectrum of NMS in SCAs, ARCAs, and X-linked ataxias vary. In routine clinical practice, NMS in cerebellar ataxias are under-recognized and certainly under-reported. Therefore, they are unlikely to be addressed adequately. Improved ascertainment of NMS in cerebellar ataxias in clinical practice will enable holistic treatment of these patients.

Cerebellar cognitive affective syndrome after acute cerebellar stroke

Introduction

The cerebellum modulates both motor and cognitive behaviors, and a cerebellar cognitive affective syndrome (CCAS) was described after a cerebellar stroke in 1998. Yet, a CCAS is seldom sought for, due to a lack of practical screening scales. Therefore, we aimed at assessing both the prevalence of CCAS after cerebellar acute vascular lesion and the yield of the CCAS-Scale (CCAS-S) in an acute stroke setting.

Materials and methods

All patients admitted between January 2020 and January 2022 with acute onset of a cerebellar ischemic or haemorrhagic first stroke at the CUB-Hôpital Erasme and who could be evaluated by the CCAS-S within a week of symptom onset were included.

Results

Cerebellar acute vascular lesion occurred in 25/1,580 patients. All patients could complete the CCAS-S. A definite CCAS was evidenced in 21/25 patients. Patients failed 5.2 ± 2.12 items out of 8 and had a mean raw score of 68.2 ± 21.3 (normal values 82–120). Most failed items of the CCAS-S were related to verbal fluency, attention, and working memory.

Conclusion

A definite CCAS is present in almost all patients with acute cerebellar vascular lesions. CCAS is efficiently assessed by CCAS-S at bedside tests in acute stroke settings. The magnitude of CCAS likely reflects a cerebello-cortical diaschisis.