Non-motor symptoms in patients with autosomal dominant spinocerebellar ataxia

Cognitive Impairment Is Part of the Phenotype of Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome (CANVAS)

BACKGROUND

Little is known about the impact of the cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) on cognition.

OBJECTIVE

Our objective was to determine the frequency and severity of cognitive impairment in RFC1-positive patients and describe the pattern of deficits.

METHODS

Participants underwent a comprehensive neuropsychological assessment. Volume of the cerebellum and its lobules was measured in those who underwent a 3 Tesla-magnetic resonance scan.

RESULTS

Twenty-one patients underwent a complete assessment, including 71% scoring lower than the cutoff at the Montreal Cognitive assessment and 71% having a definite cerebellar cognitive affective/Schmahmann syndrome. Three patients had dementia and seven met the criteria of mild cognitive impairment. Severity of cognitive impairment did not correlate with severity of clinical manifestations. Performance at memory and visuospatial functions tests negatively correlated with the severity of cerebellar manifestations.

CONCLUSION

Cognitive manifestations are frequent in RFC1-related disorders. They should be included in the phenotype and screened systematically. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Clinical features, disease progression, and nuclear imaging in ATXN2-related parkinsonism in a longitudinal cohort

BACKGROUND

Spinocerebellar ataxia 2 (SCA2) with a low range of CAG repeat expansion of ATXN2 gene can present with predominant or isolated parkinsonism that closely resembles Parkinson's disease (PD). This study is aimed at comparing clinical features, disease progression, and nuclear imaging between ATXN2-related parkinsonism (ATXN2-P) and PD.

METHODS

Three hundred and seventy-seven clinically diagnosed PD with family history were screened by multiplex ligation-dependent probe amplification, whole-exome sequencing or target sequencing, and dynamic mutation testing of 10 SCA subtypes. The baseline and longitudinal clinical features as well as the dual-tracer positron emission tomography (PET) imaging were compared between ATXN2-P and genetically undefined familial PD (GU-fPD).

RESULTS

Fifteen ATXN2-P patients from 7 families and 50 randomly selected GU-fPD patients were evaluated. Significantly less resting tremor and more symmetric signs were observed in ATXN2-P than GU-fPD. No significant difference was found in motor progression and duration from onset to occurrence of fluctuation, dyskinesia, and recurrent falls between the two groups. Cognitive impairment and rapid-eye-movement sleep behavior disorder were more common in ATXN2-P. During follow-up, olfaction was relatively spared, and no obvious progression of cognition dysfunction evaluated by Mini-Mental State Examination scores was found in ATXN2-P. PET results of ATXN2-P demonstrated a symmetric, diffuse, and homogenous dopamine transporter loss of bilateral striatum and a glucose metabolism pattern inconsistent with that in PD.

CONCLUSIONS

Symmetric motor signs and unique nuclear imaging might be the clues to distinguish ATXN2-P from GU-fPD.

Memory decline, anxiety and depression in the mouse model of spinocerebellar ataxia type 3

Spinocerebellar ataxia type 3 (SCA3) is an autosomal dominant hereditary disorder, caused by an expansion of polyglutamine in the ataxin-3 protein. SCA3 symptoms include progressive motor decline caused by an atrophy of the cerebellum and brainstem. However, it was recently reported that SCA3 patients also suffer from the cerebellar cognitive affective syndrome. The majority of SCA3 patients exhibit cognitive decline and approximately half of them suffer from depression and anxiety. The necessity to find a combined therapy for both motor and cognitive deficits in a SCA3 mouse model is required for the development of SCA3 treatment. Here, we demonstrated that the SCA3-84Q transgenic mice exhibited anxiety over the novel brightly illuminated environment in the open field, novelty suppressed feeding, and light-dark place preference tests. Moreover, SCA3-84Q mice also suffered from a decline in recognition memory during the novel object recognition test. SCA3-84Q mice also demonstrated floating behavior during the Morris water maze that can be interpreted as a sign of low mood and aversion to activity, i.e. depressive-like state. SCA3-84Q mice also spent more time immobile during the forced swimming and tail suspension tests which is also evidence for depressive-like behavior. Therefore, the SCA3-84Q mouse model may be used as a model system to test the possible treatments for both ataxia and non-motor symptoms including depression, anxiety, and memory loss.

Cognitive Decline and Mood Alterations in the Mouse Model of Spinocerebellar Ataxia Type 2

Spinocerebellar ataxia type 2 (SCA2) is a hereditary disorder, caused by an expansion of polyglutamine in the ataxin-2 protein. Although the mutant protein is expressed throughout all the cell and organ types, the cerebellum is primarily affected. The disease progression is mainly accompanied by a decline in motor functions. However, the disturbances in cognitive abilities and low mental state have also been reported in patients. Recent evidence suggests that the cerebellar functionality expands beyond the motor control. Thus, the cerebellum turned out to be involved into the language, verbal working, and spatial memory; executive functions such as working memory, planning, organizing, and strategy formation; and emotional processing. Here, we used the transgenic SCA2-58Q mice to evaluate their anxiety, cognitive functions, and mood alterations. The expression of the mutant ataxin-2 specifically in the cerebellar Purkinje cells (PCs) in SCA2-58Q mice allowed us to study the direct involvement of the cerebellum into the cognitive and affective control. We determined that SCA2-58Q mice exhibit anxiolytic behavior, decline in spatial memory, and a depressive-like state. Our results support the idea of cerebellar involvement in cognitive control and the handling of emotions.

The Cerebellar Cognitive Affective/Schmahmann Syndrome Scale in Spinocerebellar Ataxias

The Cerebellar Cognitive Affective/Schmahmann Syndrome (CCAS) manifests as impaired executive control, linguistic processing, visual spatial function, and affect regulation. The CCAS has been described in the spinocerebellar ataxias (SCAs), but its prevalence is unknown. We analyzed results of the CCAS/Schmahmann Scale (CCAS-S), developed to detect and quantify CCAS, in two natural history studies of 309 individuals Symptomatic for SCA1, SCA2, SCA3, SCA6, SCA7, or SCA8, 26 individuals Pre-symptomatic for SCA1 or SCA3, and 37 Controls. We compared total raw scores, domain scores, and total fail scores between Symptomatic, Pre-symptomatic, and Control cohorts, and between SCA types. We calculated scale sensitivity and selectivity based on CCAS category designation among Symptomatic individuals and Controls, and correlated CCAS-S performance against age and education, and in Symptomatic patients, against genetic repeat length, onset age, disease duration, motor ataxia, depression, and fatigue. Definite CCAS was identified in 46% of the Symptomatic group. False positive rate among Controls was 5.4%. Symptomatic individuals had poorer global CCAS-S performance than Controls, accounting for age and education. The domains of semantic fluency, phonemic fluency, and category switching that tap executive function and linguistic processing consistently separated Symptomatic individuals from Controls. CCAS-S scores correlated most closely with motor ataxia. Controls were similar to Pre-symptomatic individuals whose nearness to symptom onset was unknown. The use of the CCAS-S identifies a high CCAS prevalence in a large cohort of SCA patients, underscoring the utility of the scale and the notion that the CCAS is the third cornerstone of clinical ataxiology.

A chlorzoxazone-folic acid combination improves cognitive affective decline in SCA2-58Q mice

Spinocerebellar ataxia type 2 (SCA2) is a polyglutamine disorder caused by a pathological expansion of CAG repeats in ATXN2 gene. SCA2 is accompanied by cerebellar degeneration and progressive motor decline. Cerebellar Purkinje cells (PCs) seem to be primarily affected in this disorder. The majority of the ataxia research is focused on the motor decline observed in ataxic patients and animal models of the disease. However, recent evidence from patients and ataxic mice suggests that SCA2 can also share the symptoms of the cerebellar cognitive affective syndrome. We previously reported that SCA2-58Q PC-specific transgenic mice exhibit anxiolytic behavior, decline in spatial memory, and a depressive-like state. Here we studied the effect of the activation of the small conductance calcium-activated potassium channels (SK channels) by chlorzoxazone (CHZ) combined with the folic acid (FA) on the PC firing and also motor, cognitive and affective symptoms in SCA2-58Q mice. We realized that CHZ-FA combination improved motor and cognitive decline as well as ameliorated mood alterations in SCA2-58Q mice without affecting the firing rate of their cerebellar PCs. Our results support the idea of the combination therapy for both ataxia and non-motor symptoms in ataxic mice without affecting the firing frequency of PCs.

P300 Wave Alterations and Cognitive Impairment in Cerebellum Lesions

Patients with cognitive deficits have a prolonged latency and reduced amplitude of the P300 wave. However, no study has correlated P300 wave alterations with the cognitive performance of patients with cerebellar lesions. We aimed to determine if the cognitive status of these patients was associated with P300 wave alterations. We recruited 30 patients with cerebellar lesions from the wards of the N.R.S. Medical College, Kolkata, in West Bengal (India). The Kolkata Cognitive Screening Battery tasks and the Frontal Assessment Battery (FAB) were used to assess the cognitive status and the International Cooperative Ataxia Rating Scale (ICARS) for cerebellar signs. We compared the results with the normative data of the Indian population. Patients had P300 wave alterations with a significant increase in latency and a non-significant trend in amplitude. In a multivariate model, P300 wave latency was positively associated with the ICARS kinetic subscale (p = 0.005) and age (p = 0.009), regardless of sex and years of education. In the model that included cognitive variables, P300 wave latency was negatively associated with performance in phonemic fluency (p = 0.035) and construction (p = 0.009). Furthermore, P300 wave amplitude was positively associated with the FAB total score (p < 0.001). In closing, patients with cerebellar lesions had an increase in latency and a decrease in the amplitude of the P300 wave. These P300 wave alterations were also associated with worse cognitive performance and some of the subscales of the ICARS, reinforcing that the cerebellum has motor, cognitive, and affective functions.

Neuropsychiatric symptoms in spinocerebellar ataxias and Friedreich ataxia

Apart from its role in motor coordination, the importance of the cerebellum in cognitive and affective processes has been recognized in the past few decades. Spinocerebellar ataxias (SCA) and Friedreich ataxia (FRDA) are rare neurodegenerative diseases of the cerebellum presenting mainly with a progressive loss of gait and limb coordination, dysarthria, and other motor disturbances, but also a range of cognitive and neuropsychiatric symptoms. This narrative review summarizes the current knowledge on neuropsychiatric impairment in SCA and FRDA. We discuss the prevalence, clinical features and treatment approaches in the most commonly reported domains of depression, anxiety, apathy, agitation and impulse dyscontrol, and psychosis. Since these symptoms have a considerable impact on patients' quality of life, we argue that further research is mandated to improve the detection and treatment options of neuropsychiatric co-morbidities in ataxia patients.

Machado Joseph disease severity is linked with gut microbiota alterations in transgenic mice

Emerging evidence suggests the presence of bidirectional interactions between the central nervous system and gut microbiota that may contribute to the pathogenesis of neurodegenerative diseases. However, the potential role of gut microbes in forms of spinocerebellar ataxia, such as the fatal neurodegenerative disease Machado Joseph disease (MJD), remains unexplored. Here, we examined whether gut microbiota alterations may be an early disease phenotype of MJD. We profiled the gut microbiota of male and female transgenic MJD mice (CMVMJD135) expressing human ATXN3 with expanded CAG repeats (133-143 CAG) at pre-symptomatic, symptomatic and well-established stages of the disease (7, 11 and 15 weeks of age, respectively). We compared these profiles with the gut microbiota of male and female wild-type (WT) littermate control mice at same ages. Correlation network analyses were employed to explore the relevance of microbiota changes to disease progression. The results demontrated distinct sex-dependent effects in disease development whereby male MJD mice displayed earlier motor impairments than female MJD mice. The gut microbiota community structure and composition also demonstrated sex-specific differences between MJD and WT mice. In both male and female MJD mice, the shifts in the microbiota were present by 7 weeks, before the onset of any symptoms. These pre-symptomatic microbial changes correlated with the severity of neurological impairments present at later stages of the disease. Previous efforts towards developing treatments for MJD have failed to yield meaningful outcomes. Our study reports a novel relationship between the gut microbiota and MJD development and severity. Elucidating how gut microbes are involved in MJD pathogenesis may offer new and efficacious treatment strategies for this currently untreatable disease.

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.

Altered cerebral blood flow in patients with spinocerebellar degeneration

Objectives

Spinocerebellar degeneration (SCD) comprises a multitude of disorders with sporadic and hereditary forms, including spinocerebellar ataxia (SCA). Except for progressive cerebellar ataxia and structural atrophy, hemodynamic changes have also been observed in SCD. This study aimed to explore the whole-brain patterns of altered cerebral blood flow (CBF) and its correlations with disease severity and psychological abnormalities in SCD via arterial spin labeling (ASL).

Methods

Thirty SCD patients and 30 age- and sex-matched healthy controls (HC) were prospectively recruited and underwent ASL examination on a 3.0T MR scanner. The Scale for Assessment and Rating of Ataxia (SARA) and the International Cooperative Ataxia Rating Scale (ICARS) scores were used to evaluate the disease severity in SCD patients. Additionally, the status of anxiety, depression and sleep among all patients were, respectively, evaluated by the Self-Rating Anxiety Scale (SAS), Self-Rating Depression Scale (SDS) and Self-Rating Scale of Sleep (SRSS). We compared the whole-brain CBF value between SCD group and HC group at the voxel level. Then, the correlation analyses between CBF and disease severity, and psychological abnormalities were performed on SCD group.

Results

Compared with HC, SCD patients demonstrated decreased CBF value in two clusters (FWE corrected P < 0.05), covering bilateral dentate and fastigial nuclei, bilateral cerebellar lobules I-IV, V and IX, left lobule VI, right lobule VIIIb, lobules IX and X of the vermis in the cerebellar Cluster 1 and the dorsal part of raphe nucleus in the midbrain Cluster 2. The CBF of cerebellar Cluster 1 was negatively correlated with SARA scores (Spearman’s rho = –0.374, P = 0.042) and SDS standard scores (Spearman’s rho = –0.388, P = 0.034), respectively. And, the CBF of midbrain Cluster 2 also had negative correlations with SARA scores (Spearman’s rho = –0.370, P = 0.044) and ICARS scores (Pearson r = –0.464, P = 0.010).

Conclusion

The SCD-related whole-brain CBF changes mainly involved in the cerebellum and the midbrain of brainstem, which are partially overlapped with the related function cerebellar areas of hand, foot and tongue movement. Decreased CBF was related to disease severity and depression status in SCD. Therefore, CBF may be a promising neuroimaging biomarker to reflect the severity of SCD and suggest mental changes.

Genetic Modeling of the Neurodegenerative Disease Spinocerebellar Ataxia Type 1 in Zebrafish

Dominant spinocerebellar ataxias (SCAs) are progredient neurodegenerative diseases commonly affecting the survival of Purkinje cells (PCs) in the human cerebellum. Spinocerebellar ataxia type 1 (SCA1) is caused by the mutated ataxin1 (Atx1) gene product, in which a polyglutamine stretch encoded by CAG repeats is extended in affected SCA1 patients. As a monogenetic disease with the Atx1-polyQ protein exerting a gain of function, SCA1 can be genetically modelled in animals by cell type-specific overexpression. We have established a transgenic PC-specific SCA1 model in zebrafish coexpressing the fluorescent reporter protein mScarlet together with either human wild type Atx1[30Q] as control or SCA1 patient-derived Atx1[82Q]. SCA1 zebrafish display an age-dependent PC degeneration starting at larval stages around six weeks postfertilization, which continuously progresses during further juvenile and young adult stages. Interestingly, PC degeneration is observed more severely in rostral than in caudal regions of the PC population. Although such a neuropathology resulted in no gross locomotor control deficits, SCA1-fish with advanced PC loss display a reduced exploratory behaviour. In vivo imaging in this SCA1 model may help to better understand such patterned PC death known from PC neurodegeneration diseases, to elucidate disease mechanisms and to provide access to neuroprotective compound characterization in vivo.

Quality of Life since Pre-Ataxic Phases of Spinocerebellar Ataxia Type 3/Machado-Joseph Disease

Although health-related quality of life (HRQoL) has been increasingly valued in healthcare and in clinical trials, there is scarce information about it in spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD). This study describes the HRQoL results obtained from ataxic SCA3/MJD subjects, and their non-ataxic offspring included in the BIGPRO (Biomarkers and genetic modifiers in a study of presymptomatic and symptomatic SCA3/MJD carriers) study. Demographic data, clinical scales, and HRQoL instruments EQ-5D-3L and SF-36 were collected. Subjects at 50% risk were genotyped in a double-blind manner. The time left until the onset of the disease was estimated for mutation carriers with a SARA < 3 and combined with disease duration of ataxic subjects (TimeToAfterOnset). Analyses were performed using PASW Statistics version 18.0, R version 4.0.0, and G*Power 3.1, and p < 0.05 was considered statistically significant. Twenty-three ataxic carriers, 33 pre-ataxic carriers, and 21 controls were enrolled. Significant differences between ataxic carriers and controls were seen in EQ-VAS, EQ-5D Index, and in some domains of EQ-5D-3L and SF-36. EQ-5D Index showed the best effect size between ataxic and controls (Cohen's d = 2.423). Stepwise changes were seen in pre-ataxic subjects, although not statistically significant. TimeToAfterOnset correlated with EQ-5D Index, EQ-VAS, and SF-36 Physical functioning, Role Physical, Pain, and General Health. EQ-5D Index and EQ-VAS correlated with clinical scales in the ataxic group. These results suggest that HRQoL worsens among carriers since pre-ataxic stages and that they might encompass the underlying disease process. In this cohort, SF-36 Physical Functioning, SF-36 General health, and especially EQ-5D Index and EQ-VAS were the best HRQoL instruments to be used as ancillary evidence to support biological and social meanings for future interventions.