Biological and clinical manifestations of Huntington's disease in the longitudinal TRACK-HD study: cross-sectional analysis of baseline data

The meaning of apathy in Huntington's disease: A qualitative study of caregiver perspectives

Although one of the most prevalent and impactful features of Huntington's disease (HD), little is known about the impact of apathy on HD caregivers, although there is evidence it affects perceptions of distress and burden. Given the importance of the caregivers, we aimed to explore the lived experience of people supporting someone with HD and associated apathy. Semi-structured interviews were conducted with 11 caregivers and analysed using reflective thematic analysis, informed by a phenomenological framework. Five overarching themes were produced: (1) What even is apathy? (2) It makes my life harder: the practical impact of apathy, (3) They haven't forgotten me, but they have forgotten that they ever loved me, (4) I'm grieving for someone who hasn't died yet, and (5) I need a safe space to say what I really feel without fear of judgement. Inter-woven between these themes were complex narratives about the unspoken nature of HD, the invisibility of caregivers who felt trapped and unheard, and the one-sided nature of loving someone with the disease. Findings are discussed in relation to theoretical frameworks of anticipatory grief and ambiguous loss, and situated within the wider literature on caregiving for people with a neurodegenerative condition.

Neural Mechanisms of Object Location Memory in Huntington's Disease

BACKGROUND

Object-location memory impairment in Huntington's disease (HD) occurs from premanifest period and declines as HD progresses, however, pathogenesis of object-location memory is unknown. The striatum and hippocampus are affected in HD, functionally interacting allowing intact object-location memory.

OBJECTIVES

The present study investigated if object location memory impairment in premanifest and manifest HD was associated with aberrations in effective connectivity between striatum and hippocampal formation.

METHODS

Using dynamic causal modelling, we examined effective connectivity between the striatum and hippocampus and association with object-location memory in 35 HD participants (23 premanifest, 12 early manifest) and 32 controls.

RESULTS

HD participants' object-location memory was worse than controls, with performance associated with aberrant effective connectivity from the striatum to hippocampal formation, lower connectivity was associated with poorer object-location memory. Connectivity from hippocampal formation to the striatum was lower in manifest HD. In premanifest HD, connectivity from parahippocampal gyrus to the striatum was stronger and associated with better object-location memory.

CONCLUSIONS

Findings raise questions regarding compensatory neural processes in HD and other neurodegenerative diseases, providing pathophysiological evidence that cognitive impairment may be related to connectopathy. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Neuroimaging Techniques in Huntington's Disease: A Critical Review

BACKGROUND

Huntington's disease (HD) is a hereditary neurodegenerative disorder characterized by cognitive, neuropsychiatric and motor symptoms caused by a CAG trinucleotide repeat expansion in the huntingtin gene. Imaging techniques are crucial for understanding HD pathophysiology and monitoring disease progression.

OBJECTIVES

This review is targeted at general neurologists and movement disorders specialists with an interest in HD and aims to bring complex imaging, including new experimental techniques, closer to the practicing clinician.

METHODS

We provide a summary of findings from conventional structural, diffusion and functional imaging in HD studies, together with an update on emerging novel techniques, including multiparametric mapping, multi-shell diffusion techniques, ultra-high field 7-Tesla MRI, positron emission tomography and magnetoencephalography.

RESULTS

Conventional imaging techniques have deepened our understanding of neuropathological progression in HD, from striatal atrophy to widespread cortical and white matter changes. The integration of novel imaging techniques reviewed has further improved our ability to interrogate, quantify and visualize disease-specific alterations with high precision.

CONCLUSIONS

Novel imaging techniques have promising roles to further our understanding of HD pathology and as imaging markers for clinical trials, disease staging and therapeutic monitoring. Additionally, the synergistic potential of combining imaging modalities with molecular and genetic data, along with wet biomarkers and clinical data, will help provide a complete and comprehensive view of HD pathology and progression.

Sleep abnormalities are associated with greater cognitive deficits and disease activity in Huntington's disease: a 12-year polysomnographic study

Increasing evidence suggests that the sleep pathology associated with neurodegenerative diseases can in turn exacerbate both the cognitive deficits and underlying pathobiology of these conditions. Treating sleep may therefore bear significant, even disease-modifying, potential for these conditions, but how best and when to do so remains undetermined. Huntington's disease, by virtue of being an autosomal dominant neurodegenerative disease presenting in mid-life, presents a key 'model' condition through which to advance this field. To date, however, there has been no clinical longitudinal study of sleep abnormalities in Huntington's disease and no robust interrogation of their association with disease onset, cognitive deficits and markers of disease activity. Here, we present the first such study. Huntington's disease gene carriers (n = 28) and age- and sex-matched controls (n = 21) were studied at baseline and 10- and 12-year follow-up. All Huntington's disease gene carriers were premanifest at baseline and were stratified at follow-up into 'prodromal/manifest' versus 'premanifest' groups. Objective sleep abnormalities were assessed through two-night inpatient polysomnography and 2-week domiciliary actigraphy, and their association was explored against Montreal Cognitive Assessment, Trail A/B task, Symbol Digit Modalities Task (SDMT), Hopkins Verbal Learning Task (HVLT) and Montgomery-Asberg Depression Rating Scale (MADRS) scores, plus serum neurofilament light levels. Statistical analysis incorporated cross-sectional ANOVA, longitudinal repeated measures linear models and regressions adjusted for multiple confounders including disease stage. Fifteen Huntington's disease gene carriers phenoconverted to prodromal/early manifest Huntington's disease by study completion. At follow-up, these gene carriers showed more frequent sleep stage changes (P ≤ 0.001, ηp 2 = 0.62) and higher levels of sleep maintenance insomnia (defined by wake after sleep onset, P = 0.002, ηp 2 = 0.52). The latter finding was corroborated by nocturnal motor activity patterns on follow-up actigraphy (P = 0.004, ηp 2 = 0.32). Greater sleep maintenance insomnia was associated with greater cognitive deficits (Trail A P ≤ 0.001, R 2 = 0.78; SDMT P = 0.008, R 2 = 0.63; Trail B P = 0.013, R 2 = 0.60) and higher levels of neurofilament light (P = 0.015, R 2 = 0.39). Longitudinal modelling suggested that sleep stage instability accrues from the early premanifest phase, whereas sleep maintenance insomnia emerges closer to phenoconversion. Baseline sleep stage instability was able to discriminate those who phenoconverted within the study period from those who remained premanifest (area under curve = 0.81, P = 0.024). These results demonstrate that the key sleep abnormalities of premanifest/early Huntington's disease are sleep stage instability and sleep maintenance insomnia and suggest that the former bears value in predicting disease onset, while the latter is associated with greater disease activity and cognitive deficits. Intervention studies to interrogate causation within this association could not only benefit patients with Huntington's disease but also help provide fundamental proof-of-concept findings for the wider sleep-neurodegeneration field.

Peripheral and central elevation of IL-8 in patients with Huntington's disease

OBJECTIVES

Huntington's Disease (HD) is a debilitating neurodegenerative condition characterized by motor, cognitive and psychiatric abnormalities. Immune hyperactivity and dysregulation are common in HD. In addition to the central nervous system, HD patients exhibit systemic innate immune activation and inflammation, which has been shown to contribute to the pathogenic effects of the Huntingtin gene mutation. Upregulation of inflammatory mediators including interferon gamma (IFN-γ) and interleukin (IL)-8 has been observed in animal Huntington's disease models. However, studies on HD patients remain limited.

METHODS

In this study, serum samples from 58 HD patients and 59 age- and gender-matched healthy control individuals were analysed using a bead-based assay, that enabled simultaneous measurement of 13 cytokines and chemokines. Additionally, publicly available transcriptomic data from brain tissues of HD patients and controls were examined.

RESULTS

Our results confirm that IL-8 protein levels are significantly higher in HD patients compared to non-HD controls, with the highest levels observed in the moderate HD group. In the control group, we found significant positive correlations between IL-8 levels and both IL-17A and IL-10. However, these correlations were not observed in HD patients, where IL-8 levels were notably positively correlated with pro-inflammatory markers including IFNγ and IL-23. Interestingly, IL-17A levels demonstrated a negative correlation with disease parameters, including CAG trinucleotide repeat expansion and disease burden score. Furthermore, cytokines and chemokines such as IFNγ and monocyte chemoattractant protein 1 (MCP-1; CCL2) demonstrated positive correlations with the same disease parameters. In-depth analysis of publicly available bulk RNAseq, and single-nucleus RNA-sequencing (snRNAseq) data from two key HD-affected brain regions- the prefrontal cortex and striatum revealed that IL-8 expression is significantly increased in cortex samples from individuals with HD compared to non-HD controls. Moreover, snRNAseq data in the striatum showed higher IL-8 expression in HD patients than in non-HD controls, with a predominant expression in microglia.

CONCLUSION

Overall, our findings support an upregulation of IL-8 in patients with HD, evident in both central degenerating brain regions, and peripheral blood samples. We identified unique immunological signatures associated with the severity of HD and provide potential biomarkers that may reflect immune-pathological mechanisms in HD patients.

The Role of MicroRNAs in Neurodegeneration: Insights from Huntington's Disease

MicroRNA (miRNAs) is a single non-coding strand with a small sequence of approximately 21-25 nucleotides, which could be a biomarker or act as a therapeutic agent for disease. This review explores the dynamic role of miRNAs in Huntington's disease (HD), encompassing their regulatory function, potential as diagnostic biomarker tools, and emerging therapeutic applications. We delved into the dysregulation of specific miRNAs in HD, for instance, downregulated levels of miR-9 and miR-124 and increased levels of miR-155 and miR-196a. These alterations highlight the promise of miRNAs as non-invasive tools for early HD detection and disease progression monitoring. Moving beyond diagnosis, the exciting potential of miRNA-based therapies. By mimicking downregulated miRNAs or inhibiting dysregulated ones, we can potentially restore the balance of mutant target gene expression and modify disease progression. Recent research using engineered miRNAs delivered via an adeno-associated virus (AAV) vector in a transgenic HD minipig model demonstrates encouraging results in reducing mutant HD and improving motor function.

A randomized clinical trial to evaluate the efficacy of cognitive rehabilitation and music therapy in mild cognitive impairment in Huntington's disease

BACKGROUND

Cognitive impairment is a core feature of Huntington's disease (HD), yet no disease-modifying or symptomatic interventions have demonstrated efficacy in addressing these deficits. Non-pharmacological interventions, particularly cognitive training (CT), are promising options for maintaining neural plasticity, enhancing cognition, and improving emotional well-being.

METHODS

This 24-week, single-center, randomized, single-blind study evaluated the safety and efficacy of two cognitive rehabilitation strategies in early-to-middle-stage HD patients. Participants were randomized into a computerized cognitive training (CT; n = 13) intervention or a music therapy (MT; n = 16) intervention. A standard of care (SoC; n = 15) group with no active intervention was also involved. Weekly 45-min sessions were conducted. Baseline and endpoint assessments included measures of global cognition, functional, motor, and neuropsychiatric assessments, along with structural and functional neuroimaging.

RESULTS

Both CT and MT groups demonstrated significant improvements in primary and secondary cognitive endpoints, including global cognition an composite measures of disease severity. Regression analysis identified longitudinal cognitive score changes as independent predictors of the rate of atrophy in the caudate, putamen, and inferior frontal gyrus. Functional connectivity analysis showed distinct intervention-related effects: CT group exhibited increased connectivity between the central executive and sensorymotor networks, while MT group reduced aberrant connectivity between the central executive and the default-mode network.

CONCLUSION

This is the first randomized-controlled trial to evaluate two cognitive rehabilitation strategies in HD using multimodal neuroimaging. Both interventions were effective in improving cognition and modulating structural and functional brain changes in regions critical to HD. Trial Registration ClinicalTrials.gov (ID: NCT05769972).

Mapping Longitudinal Psychiatric Signatures in Huntington's Disease

OBJECTIVE

Although Huntington's disease is characterized by motor onset, psychiatric disturbances may present years prior and affect functioning. However, there is inter-individual variability in psychiatric expression and progression. This study therefore strives to stratify longitudinal psychiatric signatures that may inform Huntington's disease prognosis, with potential clinical applications.

METHODS

Forty-six Huntington's disease gene carriers (21 premanifest, 25 manifest; 31 female; age range 25-69) underwent short-Problem Behavior Assessment for depression, irritability, apathy, and dysexecutive behaviors for up to six longitudinal visits. The Disease Trajectories software, a machine-learning approach, was employed to perform unsupervised clustering of psychiatric trajectories. Linear fits were calculated for each cluster. Lastly, the main clusters of shared trajectories were assessed for group differences in demographic and clinical characteristics.

RESULTS

The Disease Trajectories analysis software identified two main psychiatric patterns comprising premanifest and manifest patients that explained 54% of the sample. These two clusters evinced a dissociation in the development of depression and irritability; the first cluster was defined by increasing irritability with no depression and the second by a rise-and-fall in depression with no irritability. Both clusters showed a longitudinal increase in clinically relevant apathy and dysexecutive behaviors.

CONCLUSIONS

Ultimately, through the detection of individual-level psychiatric trajectories with machine-learning, this exploratory study reveals that a dissociation of depression and irritability is apparent even in premanifest stages. These findings underscore individual differences in the severity of longitudinal multivariate clinical characteristics for real-world patient stratification, with implications for precision medicine.

Comparative analysis of neurofilament light chain in Huntington's disease like 2 and Huntington's disease

Huntington's disease-like 2 (HDL2) closely resembles Huntington's disease (HD) in clinical and pathological features. Neurofilament light chain (NfL) is an important biomarker in HD research and holds potential in HDL2. To evaluate NfL's utility in HDL2, a comparative analysis among HDL2 (n = 12), HD (n = 9), and unaffected controls (n = 9) was conducted. Employing a cross-sectional design, NfL levels were assessed in blood plasma. Concentrations were notably elevated in both HD and HDL2 groups compared to controls. HD patients displayed higher NfL levels than HDL2, possibly reflecting disease duration differences. NfL effectively distinguished HDL2 from controls, highlighting its promise as a possible biomarker in HDL2 research.

Huntington Disease Health Related Quality of Life, Function and Well Being: The Patient's Perspective

BACKGROUND

Limited information is available on patients' experience living with Huntington's disease (HD). The primary objective of this study was to assess the health-related quality of life and well being of patients with HD.

METHODS

A non-interventional, cross-sectional study was conducted in 17 hospitals-based movement disorders units in Spain. Patients aged ≥ 18 years, genetically HD diagnosed [with a diagnostic confidence level score of 4, and an Independence Scale (IS) score ≥ 70] were included. The primary variables were the Huntington's Disease Health-related Quality of Life (HDQLIFE) scores and results of the Satisfaction with Life Scale (SWLS). Secondary outcomes include the Unified HD Rating Scale (UHDRS), Beck Hopelessness Scale (BHS), Stigma Scale for Chronic Illness (SSCI-8), Beck Depression Inventory-Fast Screen (BDI-FS) and Problem Behaviours Assessment for HD short Version (PBA-S).

RESULTS

A total of 102 patients were included. The mean age (SD) was 53.1 (12.1) years and 56% were male. Most of the patients (99.0%) showed motor symptoms (87.3%), behavioural and psychiatric disturbances (59.8%), or cognitive impairment (20.6%). HDQLIFE domain score means (SD) includes concern with death and dying 45.97 (9.60) end-of-life planning 37.91 (8.84), and meaning and purpose 44.74 (9.05). SWLS score mean was 24.25 (7.33). Depressive symptoms were found in 37.4% of patients and moderate-to-severe feelings of hopelessness in 32.9%. The prevalence of stigma was 55.9% (n = 57).

CONCLUSION

HD impacted quality of life, with prevalent motor, psychiatric symptoms and cognitive impairment. Patient perspectives may provide complementary information to implement specific interventions.

Advances in Huntington's Disease Biomarkers: A 10-Year Bibliometric Analysis and a Comprehensive Review

Neurodegenerative disorders (NDs) cause progressive neuronal loss and are a significant public health concern, with NDs projected to become the second leading global cause of death within two decades. Huntington's disease (HD) is a rare, progressive ND caused by an autosomal-dominant mutation in the huntingtin (HTT) gene, leading to severe neuronal loss in the brain and resulting in debilitating motor, cognitive, and psychiatric symptoms. Given the complex pathology of HD, biomarkers are essential for performing early diagnosis, monitoring disease progression, and evaluating treatment efficacy. However, the identification of consistent HD biomarkers is challenging due to the prolonged premanifest HD stage, HD's heterogeneous presentation, and its multiple underlying biological pathways. This study involves a 10-year bibliometric analysis of HD biomarker research, revealing key research trends and gaps. The study also features a comprehensive literature review of emerging HD biomarkers, concluding the need for better stratification of HD patients and well-designed longitudinal studies to validate HD biomarkers. Promising candidate wet HD biomarkers- including neurofilament light chain protein (NfL), microRNAs, the mutant HTT protein, and specific metabolic and inflammatory markers- are discussed, with emphasis on their potential utility in the premanifest HD stage. Additionally, biomarkers reflecting brain structural deficits and motor or behavioral impairments, such as neurophysiological (e.g., motor tapping, speech, EEG, and event-related potentials) and imaging (e.g., MRI, PET, and diffusion tensor imaging) biomarkers, are evaluated. The findings underscore that the discovery and validation of reliable HD biomarkers urgently require improved patient stratification and well-designed longitudinal studies. Reliable biomarkers, particularly in the premanifest HD stage, are crucial for optimizing HD clinical management strategies, enabling personalized treatment approaches, and advancing clinical trials of HD-modifying therapies.

Associations between CAG repeat size, brain and spinal cord volume loss, and motor symptoms in spinocerebellar ataxia type 3: a cohort study

BACKGROUND

Spinocerebellar ataxia type 3 (SCA3) is a hereditary disease caused by abnormally expanded CAG repeats in the ATXN3 gene. The study aimed to identify potential biomarkers for assessing therapeutic efficacy by investigating the associations between expanded CAG repeat size, brain and spinal cord volume loss, and motor functions in patients with SCA3.

METHODS

In this prospective, cross-observational study, we analyzed 3D T1-weighted MRIs from 92 patients with SCA3 and 42 healthy controls using voxel-based morphometry and region of interest approaches. Associations between expanded CAG repeat size, brain and spinal cord volume loss, and International Cooperative Ataxia Rating Scale (ICARS) scores were investigated using partial correlation and mediation analyses. Sample sizes of potential biomarkers were calculated.

RESULTS

Compared with healthy controls, SCA3 patients had lower cerebellar volume and cervical spinal cord area. SCA3 patients evolved along a stage-independent decline that began in the cerebellum, progressed to spinal cord, brainstem, thalami, and basal ganglia, and extensive subcortex. Expanded CAG repeat size was associated with right cerebellar lobule IV volume (r = - 0.423, P < 0.001) and cervical spinal cord area (r = - 0.405, P < 0.001), and higher ICARS (r = 0.416, P < 0.001). Mediation analysis revealed an indirect effect of expanded CAG repeat size on ICARS through spinal cord. Sample sizes estimation revealed that a minimum sample size was achieved with spinal cord measures.

CONCLUSIONS

Our results indicate the potential of cervical spinal cord area as a biomarker for disease progression and a minimum sample size estimation in future clinical studies of SCA3.

Advanced Magnetic Resonance Imaging for Early Diagnosis and Monitoring of Movement Disorders

Advanced magnetic resonance imaging (MRI) techniques are transforming the study of movement disorders by providing valuable insights into disease mechanisms. This narrative review presents a comprehensive overview of their applications in this field, offering an updated perspective on their potential for early diagnosis, disease monitoring, and therapeutic evaluation. Emerging MRI modalities such as neuromelanin-sensitive imaging, diffusion-weighted imaging, magnetization transfer imaging, and relaxometry provide sensitive biomarkers that can detect early microstructural degeneration, iron deposition, and connectivity disruptions in key regions like the substantia nigra. These techniques enable earlier and more accurate differentiation of movement disorders, including Parkinson's disease, progressive supranuclear palsy, multiple system atrophy, corticobasal degeneration, Lewy body and frontotemporal dementia, Huntington's disease, and dystonia. Furthermore, MRI provides objective metrics for tracking disease progression and assessing therapeutic efficacy, making it an indispensable tool in clinical trials. Despite these advances, the absence of standardized protocols limits their integration into routine clinical practice. Addressing this gap and incorporating these techniques more systematically could bring the field closer to leveraging advanced MRI for personalized treatment strategies, ultimately improving outcomes for individuals with movement disorders.

Olfactory dysfunction as potential biomarker in neurodegenerative diseases: a narrative review

Neurodegenerative diseases represent a group of disorders characterized by progressive degeneration of neurons in the central nervous system, leading to a range of cognitive, motor, and sensory impairments. In recent years, there has been growing interest in the association between neurodegenerative diseases and olfactory dysfunction (OD). Characterized by a decline in the ability to detect or identify odors, OD has been observed in various conditions, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and Amyotrophic Lateral Sclerosis (ALS). This phenomenon often precedes the onset of other clinical symptoms, suggesting its potential utility as an early marker or prodromal symptom of neurodegenerative diseases. This review provides a vast literature overview on the current knowledge of OD in PD, AD, ALS, and HD in order to evaluate its potential as a biomarker, particularly in the early and prodromal stages of these diseases. We summarize the most common methods used to measure olfactory function and delve into neuropathological correlations and the alterations in neurotransmitter systems associated with OD in those neurodegenerative diseases, including differences in genetic variants if applicable, and cater to current pitfalls and shortcomings in the research.

Eye Movement and Gait Variability Analysis in Chinese Patients With Huntington's Disease

OBJECTIVE

Huntington's disease (HD) is characterized by motor, cognitive, and neuropsychiatric symptoms. Oculomotor impairments and gait variability have been independently considered as potential markers in HD. However, an integrated analysis of eye movement and gait is lacking. We performed multiple examinations of eye movement and gait variability in HTT mutation carriers, analyzed the consistency between these parameters and clinical severity, and then examined the associations between oculomotor impairments and gait deficits.

METHODS

We included 7 patients with pre-HD, 30 patients with HD and 30 age-matched controls. We collected demographic data and assessed the Unified Huntington's Disease Rating Scale (UHDRS) score. Examinations, including saccades, smooth pursuit tests, and optokinetic (OPK) tests, were performed to evaluate eye movement function. The parameters of gait include stride length, walking velocity, step deviation, step length, and gait phase.

RESULTS

HD patients have significant impairments in the latency and velocity of saccades, the gain of smooth pursuit, and the gain and slow phase velocities of OPK tests. Only the speed of saccades significantly differed between pre-HD patients and controls. There are significant impairments in stride length, walking velocity, step length, and gait phase in HD patients. The parameters of eye movement and gait variability in HD patients were consistent with the UHDRS scores. There were significant correlations between eye movement and gait parameters.

CONCLUSION

Our.

RESULTS

show that eye movement and gait are impaired in HD patients and that the speed of saccades is impaired early in pre-HD. Eye movement and gait abnormalities in HD patients are significantly correlated with clinical disease severity.

Neuroglia in neurodegeneration: Alzheimer, Parkinson, and Huntington disease

The conspicuous rise of chronic neurodegenerative diseases, including Alzheimer (AD), Parkinson (PD), and Huntington (HD) diseases, is currently without disease-modifying therapies and accompanied by an excessive rate of unsuccessful clinical trials. This reflects a profound lack of understanding of the pathogenesis of these diseases, indicating that the current paradigms guiding disease modeling and drug development are in need of reconsideration. The role of neuroglia, namely astrocytes, microglial cells, and oligodendrocytes, in the pathogenesis of neurodegenerative diseases emerged during the last decades. This chapter provides the state-of-the-art update on the changes of astrocytes, microglial cells, and oligodendrocytes in AD, PD, and HD. A growing body of evidence suggests that homeostatic and defensive functions of glial cells are compromised at different disease stages, leading to increased susceptibility of neurons to noxious stimuli, eventually resulting in their malfunction and degeneration. Investments are needed in the generation of novel preclinical models suitable for studying glial pathology, in "humanizing" research, and in-depth investigation of glial cell alterations to slow down and, possibly, halt and prevent the rise of neurodegenerative disease. Targeting glial cells opens new therapeutic avenues to treat AD, PD, and HD.

Medication Use and Treatment Indications in Huntington's Disease; Analyses from a Large Cohort

BACKGROUND

Huntington's Disease is a rare neurodegenerative disorder in which appropriate medication management is essential. While many medications are prescribed based on expert knowledge, overviews of actual medication use in HD are sparse.

OBJECTIVES

We provide a detailed overview of medication use and associated indications across HD disease stages, considering sex and regional differences.

METHODS

Data from the largest observational HD study, ENROLL-HD, were used. We created HD-related medication and indication classes to identify medication trends in manifest, premanifest and control subjects. We studied medication use in adult, childhood- and adolescent-onset HD, incorporating disease stage (including phenoconverters), sex and regional differences.

RESULTS

In 8546 manifest HD patients, 84.6% used medication (any type), with the average number of medications per user rising from 2.5 in premanifest HD to 5.2 in end stage disease. Antipsychotics (29.2%), SSRIs (27.5%) and painkillers (21.8%) were most often used. Medication use varied with disease progression. Several differences were observed between the sexes, and notably between Europe and Northern America as well. Medication use increased after phenoconversion (from 64.8% to 70.6%, P < 0.05), with the largest difference in antipsychotic use (4.4%-7.8%, P < 0.05). Medication patterns were different in childhood-onset HD, with no use of painkillers, less use of anti-chorea and antidepressant drugs, and more for aggression and irritability.

CONCLUSIONS

Medication use in HD increases with disease progression, with varying types of medications prescribed based on disease stage, sex, and region of living. Recognizing these medication trends is vital for further personalized HD management.

Myelin Lipid Alterations in Neurodegenerative Diseases: Landscape and Pathogenic Implications

Significance: Lipids, which constitute the highest portion (over 50%) of brain dry mass, are crucial for brain integrity, energy homeostasis, and signaling regulation. Emerging evidence revealed that lipid profile alterations and abnormal lipid metabolism occur during normal aging and in different forms of neurodegenerative diseases. Moreover, increasing genome-wide association studies have validated new targets on lipid-associated pathways involved in disease development. Myelin, the protective sheath surrounding axons, is crucial for efficient neural signaling transduction. As the primary site enriched with lipids, impairments of myelin are increasingly recognized as playing significant and complex roles in various neurodegenerative diseases, beyond simply being secondary effects of neuronal loss. Recent Advances: With advances in the lipidomics field, myelin lipid alterations and their roles in contributing to or reflecting the progression of diseases, including Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, multiple sclerosis, and others, have recently caught great attention. Critical Issues: This review summarizes recent findings of myelin lipid alterations in the five most common neurodegenerative diseases and discusses their implications in disease pathogenesis. Future Directions: By highlighting myelin lipid abnormalities in neurodegenerative diseases, this review aims to encourage further research focused on lipids and the development of new lipid-oriented therapeutic approaches in this area. Antioxid. Redox Signal. 00, 000-000.

Changes in 24(S)-Hydroxycholesterol Are Associated with Cognitive Performance in Early Huntington's Disease: Data from the TRACK and ENROLL HD Cohorts

BACKGROUND

There is evidence for dysregulated cholesterol homeostasis in Huntington's disease (HD). The brain-specific cholesterol metabolite 24(S)-hydroxycholesterol (24(S)-OHC) is decreased in manifest HD. 24(S)-OHC is an endogenous positive allosteric modulator (PAM) of the N-methyl-D-aspartate (NMDA) receptor, suggesting lower 24(S)-OHC may contribute to NMDA receptor hypofunction in HD. We hypothesized changes in 24(S)-OHC would be associated with cognitive impairment in early HD.

OBJECTIVE

To determine the interactions between oxysterols (24(S)-OHC, 25-OHC, and 27-OHC) at the NMDA receptor, the plasma levels of these oxysterols, and how these levels relate to cognitive performance.

METHODS

An in vitro competition assay was used to evaluate interactions at the NMDA receptor, liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) was used to measure plasma 24(S)-OHC, 25-OHC, and 27-OHC levels, and correlation analyses investigated their relationship to performance on cognitive endpoints in TRACK and ENROLL-HD (NCT01574053).

RESULTS

In vitro, 25-OHC and 27-OHC attenuated the PAM activity of 24(S)-OHC on the NMDA receptor. Lower plasma 24(S)-OHC levels and 24(S)/25-OHC ratios were detected in participants with early HD. Moderate and consistent associations were detected between plasma 24(S)/25-OHC ratio and performance on Stroop color naming, symbol digit modality, Trails A/B, and emotion recognition. Little association was observed between the ratio and psychiatric or motor endpoints, suggesting specificity for the relationship to cognitive performance.

CONCLUSIONS

Our findings support growing evidence for dysregulated CNS cholesterol homeostasis in HD, demonstrate a relationship between changes in oxysterols and cognitive performance in HD, and propose that NMDA receptor hypofunction may contribute to cognitive impairment in HD.

Delineating the neural substrates of autobiographical memory impairment in Huntington's disease

Emerging evidence suggests that autobiographical memory (ABM) is altered in Huntington's disease (HD). While these impairments are typically attributed to frontostriatal dysfunction, the neural substrates of ABM impairment in HD remain unexplored. To this end, we assessed ABM in 30 participants with genetically confirmed HD (18 premanifest, 12 manifest) and 24 age-matched healthy controls. Participants completed the Autobiographical Interview to assess free and probed ABM recall and underwent structural brain imaging. Whole-brain voxel-based morphometry (VBM) was used to explore voxel-wise associations between ABM performance and grey matter intensity (False Discovery Rate corrected at q = 0.05). Relative to controls, HD participants displayed significantly less detailed ABM retrieval across free and probed recall conditions, irrespective of disease stage. Recall performance did not differ significantly between manifest and premanifest HD groups. VBM analyses indicated that poorer ABM performance was associated with atrophy of a distributed cortico-subcortical network. Key regions implicated irrespective of ABM condition included the bilateral occipital cortex, left precuneus, right parahippocampal gyrus and right caudate nucleus. In addition, probed ABM recall was associated with the superior and inferior frontal gyri, frontal pole, right hippocampus, nucleus accumbens, paracingulate gyrus and cerebellum. Overall, our findings indicate that ABM impairments in HD reflect the progressive degeneration of a distributed cortico-subcortical brain network comprising medial temporal, frontal, striatal and posterior parietal cortices. Our findings advance our understanding of the neurocognitive profile of HD, providing an important foundation for future interventions to support memory function in this population.

Study protocol for the iMarkHD study in individuals with Huntington's disease

Background: Huntington's disease (HD) is still often defined by the onset of motor symptoms, inversely associated with the size of the CAG repeat expansion in the huntingtin gene. Although the cause of HD is known, much remains unknown about mechanisms underlying clinical symptom development, disease progression, and specific clinical subtypes/endophenotypes. Objective: In the iMarkHD study, we aim to investigate four discrete molecular positron emission tomography (PET) tracers and magnetic resonance imaging (MRI) markers as biomarkers for disease and symptom progression. Methods: Following MRI optimization in five healthy volunteers (cohort 1), we aim to recruit 108 participants of whom 72 are people with HD (PwHD) and 36 healthy volunteers (cohort 2). Pending interim analysis, these numbers could increase to 96 PwHD and 48 healthy controls. Participants will complete a total of 10 study visits, consisting of a screening visit followed by a clinical and MRI visit and PET visits at baseline, year 1, and year 2. PET targets include the cannabinoid 1, histamine 3, and serotonin 2A receptors, and phosphodiesterase 10A, whereas MRI will be multimodal, including, but not limited to, the assessment of cerebral blood flow, functional connectivity, and brain iron. Results: Recruitment is currently active and started in September 2022. Conclusions: By combining PET and multi-modal MRI assessments we expect to provide a comprehensive examination of the molecular, functional, and structural framework of HD progression. As such, the iMarkHD study will provide a solid base for the identification of treatment targets and novel outcome measures for future clinical trials.

Social cognition profile in early Huntington disease: Insight from neuropsychological assessment and structural neuroimaging

BACKGROUND

Huntington's disease (HD) is traditionally associated with motor, cognitive, and neuropsychiatric symptoms. Recent observations suggest that disturbances in social cognition may feature prominently in HD, potentially contributing to behavioral challenges.

OBJECTIVE

This study aims to explore the onset and neural mechanisms underlying social cognition disturbances in HD, which are not yet well understood despite increasing recognition of these symptoms.

METHODS

This study compared 20 individuals in the early stages of HD with 20 healthy controls across a range of cognitive tests, in-depth social cognition assessments, and structural MRI evaluations.

RESULTS

The findings revealed alterations in various aspects of social cognition, particularly cognitive and affective Theory of Mind, in the early HD group. Some of these alterations correlated with the neurodegeneration of the striatum (caudate), suggesting that social cognition deficits may serve as early indicators of disease progression.

CONCLUSIONS

This research underscores the importance of integrating social cognition evaluations into the clinical assessment of HD and hints at a complex interplay between these deficits and the broader neuropsychological impact of the disease. The results thus advocate for a more holistic approach to understanding and managing HD, considering the potential interdependencies between social cognition and other cognitive functions.

Oral functions in adult persons with spinal muscular atrophy compared to a healthy control group: a prospective cross-sectional study with a multimodal approach

BACKGROUND

Oral function tests have been shown to reliably detect impaired bulbar function in adults with spinal muscular atrophy (SMA). Although not routinely recorded, it is known that persons with SMA are affected to varying degrees. Detecting differences in bite and tongue force, endurance, and maximum mouth opening has become particularly promising since the introduction of causal therapy for SMA. This study aimed to compare oral function among adult persons with SMA with different SMA types, walking abilities, and treatment status to a healthy control group.

METHODS

Data from oral function tests conducted on 58 persons with SMA and 45 healthy individuals were analyzed. Differences in oral function between SMA subgroups were pairwise tested and compared to the healthy control group using Wilcoxon rank sum tests.

RESULTS

In an overall comparison, three out of five oral function tests revealed lower values for the SMA group compared to the control group. Subgroup analyses indicated lower scores for most oral function tests in non-ambulatory, untreated patients with SMA type 2 compared to controls. Ambulatory, treated patients with SMA type 3 achieved strength and endurance values comparable to those of healthy individuals.

CONCLUSIONS

The impairment of oral function varies across persons with SMA. Routine measurement of oral function is warranted to determine individual bulbar involvement stages. Further evaluation should be scheduled if indicators such as restricted maximum mouth opening arise. Trial registration DRKS, DRKS00015842. Registered 30 July 2019, https://drks.de/register/de/trial/DRKS00015842/preview .

Brain Volumetric Analysis Using Artificial Intelligence Software in Premanifest Huntington's Disease Individuals from a Colombian Caribbean Population

Background and objectives: The premanifest phase of Huntington's disease (HD) is characterized by the absence of motor symptoms and exhibits structural changes in imaging that precede clinical manifestation. This study aimed to analyze volumetric changes identified through brain magnetic resonance imaging (MRI) processed using artificial intelligence (AI) software in premanifest HD individuals, focusing on the relationship between CAG triplet expansion and structural biomarkers. Methods: The study included 36 individuals descending from families affected by HD in the Department of Atlántico. Sociodemographic data were collected, followed by peripheral blood sampling to extract genomic DNA for quantifying CAG trinucleotide repeats in the Huntingtin gene. Brain volumes were evaluated using AI software (Entelai/IMEXHS, v4.3.4) based on MRI volumetric images. Correlations between brain volumes and variables such as age, sex, and disease status were determined. All analyses were conducted using SPSS (v. IBM SPSS Statistics 26), with significance set at p < 0.05. Results: The analysis of brain volumes according to CAG repeat expansion shows that individuals with ≥40 repeats evidence significant increases in cerebrospinal fluid (CSF) volume and subcortical structures such as the amygdalae and left caudate nucleus, along with marked reductions in cerebral white matter, the cerebellum, brainstem, and left pallidum. In contrast, those with <40 repeats show minimal or moderate volumetric changes, primarily in white matter and CSF. Conclusions: These findings suggest that CAG expansion selectively impacts key brain regions, potentially influencing the progression of Huntington's disease, and that AI in neuroimaging could identify structural biomarkers long before clinical symptoms appear.

Impairments of social cognition significantly predict the progression of functional decline in Huntington's disease: A 6-year follow-up study

This study sought to investigate if there was a significant difference between the Huntington's Disease gene expansion carriers who were impaired on the cognitive domains, social cognition and executive functions. Also, it was investigated which of the cognitive domains could predict the decrease in total functional capacity over a 6-year follow-up period. Premanifest and motor-manifest Huntington's Disease gene expansion carriers (N = 98), were examined with a neurological and neuropsychological examination at Time 1 (year 2012-2013). Regression-based normative data was used to classify impairments on the two cognitive domains. Follow-up participants (N = 80) had their functional capacity reexamined at Time 2 (year 2018-2020), to examine which cognitive domain could predict the decrease in functional capacity over the 6-year follow-up. More than 50% of the participants were impaired on the domain of social cognition. These participants were significantly different from the participants who were impaired on executive functions. The motor function and impairments on social cognition significantly predicted the decline in functional capacity. The Emotion Hexagon test was the only significant social cognitive task, that predicted the decline in functional capacity. Social cognition includes unique and separate functions in Huntington's Disease, unaffected by executive functions. This study emphasizes the importance of regular assessment of social cognition in Huntington's Disease and the clinical relevance of impaired social cognitive function.

Prognostic enrichment for early-stage Huntington's disease: An explainable machine learning approach for clinical trial

BACKGROUND

In Huntington's disease clinical trials, recruitment and stratification approaches primarily rely on genetic load, cognitive and motor assessment scores. They focus less on in vivo brain imaging markers, which reflect neuropathology well before clinical diagnosis. Machine learning methods offer a degree of sophistication which could significantly improve prognosis and stratification by leveraging multimodal biomarkers from large datasets. Such models specifically tailored to HD gene expansion carriers could further enhance the efficacy of the stratification process.

OBJECTIVES

To improve stratification of Huntington's disease individuals for clinical trials.

METHODS

We used data from 451 gene positive individuals with Huntington's disease (both premanifest and diagnosed) from previously published cohorts (PREDICT, TRACK, TrackON, and IMAGE). We applied whole-brain parcellation to longitudinal brain scans and measured the rate of lateral ventricular enlargement, over 3 years, which was used as the target variable for our prognostic random forest regression models. The models were trained on various combinations of features at baseline, including genetic load, cognitive and motor assessment score biomarkers, as well as brain imaging-derived features. Furthermore, a simplified stratification model was developed to classify individuals into two homogenous groups (low risk and high risk) based on their anticipated rate of ventricular enlargement.

RESULTS

The predictive accuracy of the prognostic models substantially improved by integrating brain imaging features alongside genetic load, cognitive and motor biomarkers: a 24 % reduction in the cross-validated mean absolute error, yielding an error of 530 mm3/year. The stratification model had a cross-validated accuracy of 81 % in differentiating between moderate and fast progressors (precision = 83 %, recall = 80 %).

CONCLUSIONS

This study validated the effectiveness of machine learning in differentiating between low- and high-risk individuals based on the rate of ventricular enlargement. The models were exclusively trained using features from HD individuals, which offers a more disease-specific, simplified, and accurate approach for prognostic enrichment compared to relying on features extracted from healthy control groups, as done in previous studies. The proposed method has the potential to enhance clinical utility by: i) enabling more targeted recruitment of individuals for clinical trials, ii) improving post-hoc evaluation of individuals, and iii) ultimately leading to better outcomes for individuals through personalized treatment selection.

[Severe choreiform movement disorder following COVID-19]

Bár a SARS-CoV-2-fertőzés során elsődlegesen a cardiovascularis és légzőszervek érintettek, az utóbbi időben egyre nagyobb számban jelennek meg közlemények, melyek COVID–19-et követően fellépő változatos neurológiai tünetekről számolnak be. Jelen ismertetésünkben egy 54 éves férfi beteg esetét mutatjuk be, akinél közel három hónappal a súlyos tünetekkel járó COVID–19-et követően kifejezett choreiform mozgászavar jelent meg. Az eset kapcsán bemutatjuk a chorea lehetséges etiológiai tényezőit, valamint összegezzük a poszt-COVID-mozgászavarokat és feltételezett patogenezisüket. Orv Hetil. 2024; 165(29): 1130–1134.

Graph methods to infer spatial disturbances: Application to Huntington's Disease's speech

OBJECTIVE

Huntington's Disease (HD) is an inherited neurodegenerative disease caused by the mutation of the Htt gene, impacting all aspects of living and functioning. Among cognitive disabilities, spatial capacities are impaired, but their monitoring remains scarce as limited by lengthy experts' assessments. Language offers an alternative medium to evaluate patients' performance in HD. Yet, its capacities to assess HD's spatial abilities are unknown. Here, we aimed to bring proof-of-concept that HD's spatial deficits can be assessed through speech.

METHODS

We developed the Spatial Description Model to graphically represent spatial relations described during the Cookie Theft Picture (CTP) task. We increased the sensitivity of our model by using only sentences with spatial terms, unlike previous studies in Alzheimer's disease. 78 carriers of the mutant Htt, including 56 manifest and 22 premanifest individuals, as well as 25 healthy controls were included from the BIOHD & (NCT01412125) & Repair-HD (NCT03119246) cohorts. The convergence and divergence of the model were validated using the SelfCog battery.

RESULTS

Our Spatial Description Model was the only one among the four assessed approaches, revealing that individuals with manifest HD expressed fewer spatial relations and engaged in less spatial exploration compared to healthy controls. Their graphs correlated with both visuospatial and language SelfCog performances, but not with motor, executive nor memory functions.

CONCLUSIONS

We provide the proof-of-concept using our Spatial Description Model that language can grasp HD patient's spatial disturbances. By adding spatial capabilities to the panel of functions tested by the language, it paves the way for eventual remote clinical application.

Environmental Deprivation Effects on Myelin Ultrastructure in Huntington Disease and Wildtype Mice

Environmental deprivation can have deleterious effects on adaptive myelination and oligodendroglia function. Early stage Huntington disease (HD) is characterised by white-matter myelin abnormalities in both humans and animal models. However, whether deprived environments exacerbate myelin-related pathological features of HD is not clearly understood. Here, we investigated the impact of deprivation and social isolation on ultrastructural features of myelin in the corpus callosum of the YAC128 mouse model of HD and wildtype (WT) mice using transmission electron microscopy. HD pathology on its own leads to increased representation of altered myelin features, such as thinner sheaths and compromised morphology. Interestingly, deprivation mirrors these effects in WT mice but does not greatly exacerbate the already aberrant myelin in HD mice, indicating a disease-related floor effect in the latter animals. These novel findings indicate that environmental deprivation causes abnormalities in myelin ultrastructure in the otherwise healthy corpus callosum of wild-type mice but has distinct effects on HD mice, where compromised myelin integrity is manifest from early stages of the disease.

Cognitive reserve involves decision making and is associated with left parietal and hippocampal hypertrophy in neurodegeneration

Cognitive reserve is the ability to actively cope with brain deterioration and delay cognitive decline in neurodegenerative diseases. It operates by optimizing performance through differential recruitment of brain networks or alternative cognitive strategies. We investigated cognitive reserve using Huntington's disease (HD) as a genetic model of neurodegeneration to compare premanifest HD, manifest HD, and controls. Contrary to manifest HD, premanifest HD behave as controls despite neurodegeneration. By decomposing the cognitive processes underlying decision making, drift diffusion models revealed a response profile that differs progressively from controls to premanifest and manifest HD. Here, we show that cognitive reserve in premanifest HD is supported by an increased rate of evidence accumulation compensating for the abnormal increase in the amount of evidence needed to make a decision. This higher rate is associated with left superior parietal and hippocampal hypertrophy, and exhibits a bell shape over the course of disease progression, characteristic of compensation.

Prevalence and burden of pain across the entire spectrum of Huntington's disease

BACKGROUND

Pain is an important symptom in Huntington's disease (HD), however, not systematically studied and understood. The objective of the current study is to assess the prevalence of pain, pain interference in daily activities, painful conditions, analgesic use and the severity of the pain burden across different disease stages and 'Age at symptom Onset' groups. Additionally, the association between pain and disease burden was investigated.

METHODS

A cross-sectional analysis was conducted within two large data sets, which included different types of pain scales. Multivariable logistic regression analyses and analyses of variance were performed to compare the pain levels with those in the general population. The analyses were adjusted for sex and age. Locally Estimated Scatterplot Smoothing was used to test the association between pain and the HD pathology score: a measure of disease burden.

RESULTS

The mean prevalence of pain in the HD population was 40% and for pain interference around 35% in both data sets. Patients in the early, middle and late stage of HD experience more pain burden compared with what is reported in patients with chronic pain (p<0.01). A positive and significant association was demonstrated between pain and disease burden. Patients in late stage HD with pain use significantly less analgesics compared with the general population (5% vs 13%, respectively (p<0.01)).

CONCLUSIONS

Pain is a prevalent and important symptom in HD. Severe pain burden in the HD population is present and positively associated with disease burden. Risk for undertreatment with analgesics is nevertheless present. Awareness of pain in HD needs to be increased, both clinically and scientifically.

Therapeutic validation of MMR-associated genetic modifiers in a human ex vivo model of Huntington disease

The pathological huntingtin (HTT) trinucleotide repeat underlying Huntington disease (HD) continues to expand throughout life. Repeat length correlates both with earlier age at onset (AaO) and faster progression, making slowing its expansion an attractive therapeutic approach. Genome-wide association studies have identified candidate variants associated with altered AaO and progression, with many found in DNA mismatch repair (MMR)-associated genes. We examine whether lowering expression of these genes affects the rate of repeat expansion in human ex vivo models using HD iPSCs and HD iPSC-derived striatal medium spiny neuron-enriched cultures. We have generated a stable CRISPR interference HD iPSC line in which we can specifically and efficiently lower gene expression from a donor carrying over 125 CAG repeats. Lowering expression of each member of the MMR complexes MutS (MSH2, MSH3, and MSH6), MutL (MLH1, PMS1, PMS2, and MLH3), and LIG1 resulted in characteristic MMR deficiencies. Reduced MSH2, MSH3, and MLH1 slowed repeat expansion to the largest degree, while lowering either PMS1, PMS2, or MLH3 slowed it to a lesser degree. These effects were recapitulated in iPSC-derived striatal cultures where MutL factor expression was lowered. CRISPRi-mediated lowering of key MMR factor expression to levels feasibly achievable by current therapeutic approaches was able to effectively slow the expansion of the HTT CAG tract. We highlight members of the MutL family as potential targets to slow pathogenic repeat expansion with the aim to delay onset and progression of HD and potentially other repeat expansion disorders exhibiting somatic instability.

PET Ligands for Imaging Mutant Huntingtin Aggregates: A Case Study in Non-For-Profit Scientific Management

Positron emission tomography imaging of misfolded proteins with high-affinity and selective radioligands has played a vital role in expanding our knowledge of neurodegenerative diseases such as Parkinson's and Alzheimer's disease. The pathogenesis of Huntington's disease, a CAG trinucleotide repeat disorder, is similarly linked to the presence of protein fibrils formed from mutant huntingtin (mHTT) protein. Development of mHTT fibril-specific radioligands has been limited by the lack of structural knowledge around mHTT and a dearth of available hit compounds for medicinal chemistry refinement. Over the past decade, the CHDI Foundation, a non-for-profit scientific management organisation has orchestrated a large-scale screen of small molecules to identify high affinity ligands of mHTT, with lead compounds now reaching clinical maturity. Here we describe the mHTT radioligands developed to date and opportunities for further improvement of this radiotracer class.

Auditory mismatch negativity in pre-manifest and manifest Huntington's disease

AIM

The aim of this study was to investigate the characteristics of the electrophysiological brain response elicited in a passive acoustic oddball paradigm, i.e. mismatch negativity (MMN), in patients with Huntington's disease (HD) in the premanifest (pHD) and manifest (mHD) phases. In this regard, we correlated the results of event-related potentials (ERP) with disease characteristics.

METHODS

This was an observational cross-sectional MMN study. In addition to the MMN recording of the passive oddball task, all subjects with first-degree inheritance for HD underwent genetic testing for mutant HTT, the Huntington's Disease Rating Scale, the Total Functional Capacity Scale, the Problem Behaviors Assessment short form, and the Mini-Mental State Examination.

RESULTS

We found that global field power (GFP) was reduced in the MMN time window in mHD patients compared to pHD and normal controls (NC). In the pHD group, MMN amplitude was only slightly and not significantly increased compared to mHD, while pHD patients showed increased theta coherence between trials compared to mHD. In the entire sample of HD gene carriers, the main MMN traits were not correlated with motor performance, cognitive impairment and functional disability.

CONCLUSION

These results suggest an initial and subtle deterioration of pre-attentive mechanisms in the presymptomatic phase of HD, with an increasing phase shift in the MMN time frame. This result could indicate initial functional changes with a possible compensatory effect.

SIGNIFICANCE

An initial and slight decrease in MMN associated with increased phase coherence in the corresponding EEG frequencies could indicate an early functional involvement of pre-attentive resources that could precede the clinical expression of HD.

Unraveling progression subtypes in people with Huntington's disease

Background

Huntington's disease (HD) is a progressive neurodegenerative disease caused by a CAG trinucleotide expansion in the huntingtin gene. The length of the CAG repeat is inversely correlated with disease onset. HD is characterized by hyperkinetic movement disorder, psychiatric symptoms, and cognitive deficits, which greatly impact patient's quality of life. Despite this clear genetic course, high variability of HD patients' symptoms can be observed. Current clinical diagnosis of HD solely relies on the presence of motor signs, disregarding the other important aspects of the disease. By incorporating a broader approach that encompasses motor as well as non-motor aspects of HD, predictive, preventive, and personalized (3P) medicine can enhance diagnostic accuracy and improve patient care.

Methods

Multisymptom disease trajectories of HD patients collected from the Enroll-HD study were first aligned on a common disease timescale to account for heterogeneity in disease symptom onset and diagnosis. Following this, the aligned disease trajectories were clustered using the previously published Variational Deep Embedding with Recurrence (VaDER) algorithm and resulting progression subtypes were clinically characterized. Lastly, an AI/ML model was learned to predict the progression subtype from only first visit data or with data from additional follow-up visits.

Results

Results demonstrate two distinct subtypes, one large cluster (n = 7122) showing a relative stable disease progression and a second, smaller cluster (n = 411) showing a dramatically more progressive disease trajectory. Clinical characterization of the two subtypes correlates with CAG repeat length, as well as several neurobehavioral, psychiatric, and cognitive scores. In fact, cognitive impairment was found to be the major difference between the two subtypes. Additionally, a prognostic model shows the ability to predict HD subtypes from patients' first visit only.

Conclusion

In summary, this study aims towards the paradigm shift from reactive to preventive and personalized medicine by showing that non-motor symptoms are of vital importance for predicting and categorizing each patients' disease progression pattern, as cognitive decline is oftentimes more reflective of HD progression than its motor aspects. Considering these aspects while counseling and therapy definition will personalize each individuals' treatment. The ability to provide patients with an objective assessment of their disease progression and thus a perspective for their life with HD is the key to improving their quality of life. By conducting additional analysis on biological data from both subtypes, it is possible to gain a deeper understanding of these subtypes and uncover the underlying biological factors of the disease. This greatly aligns with the goal of shifting towards 3P medicine.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00368-2.

Multifeature quantitative motor assessment of upper limb ataxia including drawing and reaching

OBJECTIVE

Voluntary upper limb movements are an ecologically important yet insufficiently explored digital-motor outcome domain for trials in degenerative ataxia. We extended and validated the trial-ready quantitative motor assessment battery "Q-Motor" for upper limb movements with clinician-reported, patient-focused, and performance outcomes of ataxia.

METHODS

Exploratory single-center cross-sectional assessment in 94 subjects (46 cross-genotype ataxia patients; 48 matched controls), comprising five tasks measured by force transducer and/or position field: Finger Tapping, diadochokinesia, grip-lift, and-as novel implementations-Spiral Drawing, and Target Reaching. Digital-motor measures were selected if they discriminated from controls (AUC >0.7) and correlated-with at least one strong correlation (rho ≥0.6)-to the Scale for the Assessment and Rating of Ataxia (SARA), activities of daily living (FARS-ADL), and the Nine-Hole Peg Test (9HPT).

RESULTS

Six movement features with 69 measures met selection criteria, including speed and variability in all tasks, stability in grip-lift, and efficiency in Target Reaching. The novel drawing/reaching tasks best captured impairment in dexterity (|rho9HPT| ≤0.81) and FARS-ADL upper limb items (|rhoADLul| ≤0.64), particularly by kinematic analysis of smoothness (SPARC). Target hit rate, a composite of speed and endpoint precision, almost perfectly discriminated ataxia and controls (AUC: 0.97). Selected measures in all tasks discriminated between mild, moderate, and severe impairment (SARA upper limb composite: 0-2/>2-4/>4-6) and correlated with severity in the trial-relevant mild ataxia stage (SARA ≤10, n = 20).

INTERPRETATION

Q-Motor assessment captures multiple features of impaired upper limb movements in degenerative ataxia. Validation with key clinical outcome domains provides the basis for evaluation in longitudinal studies and clinical trial settings.

External evaluation of a deep learning-based approach for automated brain volumetry in patients with huntington's disease

A crucial step in the clinical adaptation of an AI-based tool is an external, independent validation. The aim of this study was to investigate brain atrophy in patients with confirmed, progressed Huntington's disease using a certified software for automated volumetry and to compare the results with the manual measurement methods used in clinical practice as well as volume calculations of the caudate nuclei based on manual segmentations. Twenty-two patients were included retrospectively, consisting of eleven patients with Huntington's disease and caudate nucleus atrophy and an age- and sex-matched control group. To quantify caudate head atrophy, the frontal horn width to intercaudate distance ratio and the intercaudate distance to inner table width ratio were obtained. The software mdbrain was used for automated volumetry. Manually measured ratios and automatically measured volumes of the groups were compared using two-sample t-tests. Pearson correlation analyses were performed. The relative difference between automatically and manually determined volumes of the caudate nuclei was calculated. Both ratios were significantly different between the groups. The automatically and manually determined volumes of the caudate nuclei showed a high level of agreement with a mean relative discrepancy of - 2.3 ± 5.5%. The Huntington's disease group showed significantly lower volumes in a variety of supratentorial brain structures. The highest degree of atrophy was shown for the caudate nucleus, putamen, and pallidum (all p < .0001). The caudate nucleus volume and the ratios were found to be strongly correlated in both groups. In conclusion, in patients with progressed Huntington's disease, it was shown that the automatically determined caudate nucleus volume correlates strongly with measured ratios commonly used in clinical practice. Both methods allowed clear differentiation between groups in this collective. The software additionally allows radiologists to more objectively assess the involvement of a variety of brain structures that are less accessible to standard semiquantitative methods.

Mild cognitive impairment in Huntington's disease: challenges and outlooks

Although Huntington's disease (HD) has classically been viewed as an autosomal-dominant inherited neurodegenerative motor disorder, cognitive and/or behavioral changes are predominant and often an early manifestation of disease. About 40% of individuals in the presymptomatic period of HD meet the criteria for mild cognitive impairment, later progressing to dementia. The heterogenous spectrum of cognitive decline is characterized by deficits across multiple domains, particularly executive dysfunctions, but the underlying pathogenic mechanisms are still poorly understood. Investigating the pathophysiology of cognitive changes may give insight into important and early neurodegenerative events. Multimodal imaging revealed circuit-wide gray and white matter degenerative processes in several key brain regions, affecting prefronto-striatal/cortico-basal ganglia circuits and many other functional brain networks. Studies in transgenic animal models indicated early synaptic dysfunction, deficient neurotrophic transport and other molecular changes contributing to neuronal death. Synaptopathy within the cerebral cortex, striatum and hippocampus may be particularly important in mediating cognitive and neuropsychiatric manifestations of HD, although many other neuronal systems are involved. The interaction of mutant huntingtin protein (mHTT) with tau and its implication for cognitive impairment in HD is a matter of discussion. Further neuroimaging and neuropathological studies are warranted to better elucidate early pathophysiological mechanisms and to develop validated biomarkers to detect patients' cognitive status during the early stages of the condition significantly to implement effective preventing or management strategies.

Prodromal Cognitive Changes as a Prognostic Indicator of Forthcoming Huntington's Disease Severity: A Retrospective Longitudinal Study

BACKGROUND

Cognitive changes in Huntington's disease (HD) precede motor manifestations. ENROLL-HD platform includes four cognitive measures of information processing speed (IPS). Our group is eager to seek clinical markers in the life stage that is as close as possible to the age of onset (ie, the so called prodromal HD phase) because this is the best time for therapeutic interventions.

OBJECTIVES

Our study aimed to test whether cognitive scores in prodromal ENROLL-HD mutation carriers show the potential to predict the severity of motor and behavioral changes once HD became fully manifested.

METHODS

From the global ENROLL-HD cohort of 21,343 participants, we first selected a premanifest Cohort#1 (ie, subjects with Total Motor Score (TMS) <10 and Diagnostic Confidence Level (DCL) <4, N = 1.222). From this cohort, we then focused on a prodromal Cohort#2 of subjects who were ascertained to phenoconvert into manifest HD at follow-up visits (ie, subjects from 6 ≤ TMS≤9 and DCL <4 to TMS≥10 and DCL = 4, n = 206).

RESULTS

The main results of our study showed that low IPS before phenoconversion in Cohort#2 predicted the severity of motor and behavioral manifestations. By combining the four IPS cognitive measures (eg, the Categorical Verbal Fluency Test; Stroop Color Naming Test; Stroop Word Reading; Symbol Digit Modalities Test), we generated a Composite Cognition Score (CCS). The lower the CCS score the higher the TMS and the apathy scores in the same longitudinally followed-up patients after phenoconversion.

CONCLUSIONS

CCS might represent a clinical instrument to predict the prognosis of mutation carriers who are close to manifesting HD.

Associations of inflammatory cytokines and cortisol with nonmotor features of Huntington's disease

OBJECTIVE

Huntington's disease (HD) is an inherited neurodegenerative disease involving progressive motor abnormalities, cognitive decline, and psychiatric disturbances. Depression and cognitive difficulties are among the most impactful symptoms of HD, yet the pathogenesis of these symptoms is not fully understood. HD involves low-level chronic inflammation and dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which are linked to depression and cognitive impairment in non-HD populations. However, previous research on the relationships of these pathologies with depression and cognition in HD is limited and inconsistent.

METHODS

Fifty-three adults with the HD gene expansion (30 premanifest and 23 manifest) completed measures of depression and cognitive functioning. Forty-eight out of 53 participants provided hair samples for quantification of cortisol, and 34 participants provided blood samples for quantification of peripheral inflammatory cytokines. We examined the associations of four cytokines (interleukin [IL]-6, IL-10, IL-1β, and tumor necrosis factor [TNF]-α) and cortisol levels with depression and cognitive scores.

RESULTS

In unadjusted models, higher levels of plasma IL-6, IL-10, and TNF-α correlated with higher depression scores, and higher levels of IL-10 and TNF-α correlated with poorer cognitive performance. After controlling for age, sex, and body mass index, only the correlations of IL-10 with depression and cognitive performance remained significant. No correlations were evident with hair cortisol.

INTERPRETATIONS

Peripheral inflammation is associated with depression symptoms and cognitive impairment in HD. Our findings suggest that interactions between the immune and nervous systems are important in HD, and highlight the potential of chronic inflammation as a therapeutic target in early stages of HD.

High Levels of Mutant Huntingtin Protein in Tear Fluid From Huntington's Disease Gene Expansion Carriers

OBJECTIVE

Huntington's disease (HD) is an autosomal dominant, fully penetrant, neurodegenerative disease that most commonly affects middle-aged adults. HD is caused by a CAG repeat expansion in the HTT gene, resulting in the expression of mutant huntingtin (mHTT). Our aim was to detect and quantify mHTT in tear fluid, which, to our knowledge, has never been measured before.

METHODS

We recruited 20 manifest and 13 premanifest HD gene expansion carriers, and 20 age-matched controls. All patients underwent detailed assessments, including the Unified Huntington's Disease Rating Scale (UHDRS) total motor score (TMS) and total functional capacity (TFC) score. Tear fluid was collected using paper Schirmer's strips. The level of tear mHTT was determined using single-molecule counting SMCxPRO technology.

RESULTS

The average tear mHTT levels in manifest (67,223 ± 80,360 fM) and premanifest patients (55,561 ± 45,931 fM) were significantly higher than those in controls (1,622 ± 2,179 fM). We noted significant correlations between tear mHTT levels and CAG repeat length, "estimated years to diagnosis," disease burden score and UHDRS TMS and TFC. The receiver operating curve demonstrated an almost perfect score (area under the curve [AUC] = 0.9975) when comparing controls to manifest patients. Similarly, the AUC between controls and premanifest patients was 0.9846. The optimal cutoff value for distinguishing between controls and manifest patients was 4,544 fM, whereas it was 6,596 fM for distinguishing between controls and premanifest patients.

CONCLUSION

Tear mHTT has potential for early and noninvasive detection of alterations in HD patients and could be integrated into both clinical trials and clinical diagnostics.

Safety and efficacy of laquinimod for Huntington's disease (LEGATO-HD): a multicentre, randomised, double-blind, placebo-controlled, phase 2 study

BACKGROUND

Laquinimod modulates CNS inflammatory pathways thought to be involved in the pathology of Huntington's disease. Studies with laquinimod in transgenic rodent models of Huntington's disease suggested improvements in motor function, reduction of brain volume loss, and prolonged survival. We aimed to evaluate the safety and efficacy of laquinimod in improving motor function and reducing caudate volume loss in patients with Huntington's disease.

METHODS

LEGATO-HD was a multicentre, double-blind, placebo-controlled, phase 2 study done at 48 sites across ten countries (Canada, Czech Republic, Germany, Italy, Netherlands, Portugal, Russia, Spain, UK, and USA). Patients aged 21-55 years with a cytosine-adenosine-guanine (CAG) repeat length of between 36 and 49 who had symptomatic Huntington's disease with a Unified Huntington's Disease Rating Scale-Total Motor Score (UHDRS-TMS) of higher than 5 and a Total Functional Capacity score of 8 or higher were randomly assigned (1:1:1:1) by centralised interactive response technology to laquinimod 0·5 mg, 1·0 mg, or 1·5 mg, or to matching placebo, administered orally once daily over 52 weeks; people involved in the randomisation had no other role in the study. Participants, investigators, and study personnel were masked to treatment assignment. The 1·5 mg group was discontinued before recruitment was finished because of cardiovascular safety concerns in multiple sclerosis studies. The primary endpoint was change from baseline in the UHDRS-TMS and the secondary endpoint was percent change in caudate volume, both comparing the 1·0 mg group with the placebo group at week 52. Primary and secondary endpoints were assessed in the full analysis set (ie, all randomised patients who received at least one dose of study drug and had at least one post-baseline UHDRS-TMS assessment). Safety measures included adverse event frequency and severity, and clinical and laboratory examinations, and were assessed in the safety analysis set (ie, all randomised patients who received at least one dose of study drug). This trial is registered with ClinicalTrials.gov, NCT02215616, and EudraCT, 2014-000418-75, and is now complete.

FINDINGS

Between Oct 28, 2014, and June 19, 2018, 352 adults with Huntington's disease (179 [51%] men and 173 [49%] women; mean age 43·9 [SD 7·6] years and 340 [97%] White) were randomly assigned: 107 to laquinimod 0·5 mg, 107 to laquinimod 1·0 mg, 30 to laquinimod 1·5 mg, and 108 to matching placebo. Least squares mean change from baseline in UHDRS-TMS at week 52 was 1·98 (SE 0·83) in the laquinimod 1·0 mg group and 1·2 (0·82) in the placebo group (least squares mean difference 0·78 [95% CI -1·42 to 2·98], p=0·4853). Least squares mean change in caudate volume was 3·10% (SE 0·38) in the 1·0 mg group and 4·86% (0·38) in the placebo group (least squares mean difference -1·76% [95% CI -2·67 to -0·85]; p=0·0002). Laquinimod was well tolerated and there were no new safety findings. Serious adverse events were reported by eight (7%) patients on placebo, seven (7%) on laquinimod 0·5 mg, five (5%) on laquinimod 1·0 mg, and one (3%) on laquinimod 1·5 mg. There was one death, which occurred in the placebo group and was unrelated to treatment. The most frequent adverse events in all laquinimod dosed groups (0·5 mg, 1·0 mg, and 1·5 mg) were headache (38 [16%]), diarrhoea (24 [10%]), fall (18 [7%]), nasopharyngitis (20 [8%]), influenza (15 [6%]), vomiting (13 [5%]), arthralgia (11 [5%]), irritability (ten [4%]), fatigue (eight [3%]), and insomnia (eight [3%]).

INTERPRETATION

Laquinimod did not show a significant effect on motor symptoms assessed by the UHDRS-TMS, but significantly reduced caudate volume loss compared with placebo at week 52. Huntington's disease has a chronic and slowly progressive course, and this study does not address whether a longer duration of laquinimod treatment could have produced detectable and meaningful changes in the clinical assessments.

FUNDING

Teva Pharmaceutical Industries.

Identifying and verifying Huntington's disease subtypes: Clinical features, neuroimaging, and cytokine changes

AIMS

Huntington's disease (HD) is a progressive neurodegenerative disorder with heterogeneous clinical manifestations. Identifying distinct clinical clusters and their relevant biomarkers could elucidate the underlying disease pathophysiology.

METHODS

Following the Enroll-HD program initiated in 2018.09, we have recruited 104 HD patients (including 21 premanifest) and 31 health controls at Beijing Tiantan Hospital. Principal components analysis and k-means cluster analysis were performed to determine HD clusters. Chi-square test, one-way ANOVA, and covariance were used to identify features among these clusters. Furthermore, plasma cytokines levels and brain structural imaging were used as biomarkers to delineate the clinical features of each cluster.

RESULTS

Three clusters were identified. Cluster 1 demonstrated the most severe motor and nonmotor symptoms except for chorea, the lowest whole brain volume, the plasma levels of IL-2 were higher and significantly associated with cluster 1. Cluster 2 was characterized with the most severe chorea and the largest pallidum volume. Cluster 3 had the most benign motor symptoms but moderate psychiatric problems.

CONCLUSION

We have identified three HD clusters via clinical manifestations with distinct biomarkers. Our data shed light on better understanding about the pathophysiology of HD.

Underestimated olfactory domains in Huntington's disease: odour discrimination and threshold

BACKGROUND

Olfaction has recently found clinical value in prediction, discrimination and prognosis of some neurodegenerative disorders. However, data originating from standard tests on olfactory dysfunction in Huntington's disease are limited to odour identification, which is only one domain of olfactory perceptual space.

METHOD

Twenty-five patients and 25 age- and gender-matched controls were evaluated by the Sniffin' Sticks test in three domains of odour threshold, odour discrimination, odour identification and the sum score of them. Patients' motor function was assessed based on the Unified Huntington's Disease Rating Scale.

RESULTS

Compared with controls, patients' scores of all olfactory domains and their sum were significantly lower. Besides, our patients' odour threshold and odour discrimination impairments were more frequently impaired than odour identification impairment (86 per cent and 81 per cent vs 34 per cent, respectively).

CONCLUSION

Olfactory impairment is a common finding in patients with Huntington's disease; it is not limited to odour identification but is more pronounced in odour discrimination and odour threshold.

Obsessive-compulsive and perseverative behaviors in Huntington's disease

Obsessive-compulsive and perseverative behaviors (OCBs/PBs) are characteristic features of Huntington's Disease (HD). Although a few recent research have attempted to discriminate between OCBs and PBs, most of the available evidence on OCBs does not consistently make this distinction. In this article, we aimed to explore the current inconsistencies in assessing and reporting OCBs/PBs and map the body of existing evidence. Up to half of the patients with motor manifest HD can experience OCBs. Separate reporting of PBs in HD patients has been uncommon among the studies and was frequently reported as a part of obsessive-compulsive symptoms. The structural limitation of the currently used rating scales and the overlaps in neuropathology and definition of OCBs and PBs are among the main reasons for the mixed reporting of OCBs/PBs. Perseverative thinking or behavior as a separate item is found in a few assessment tools, such as the Problem Behaviors Assessment - Short form (PBA-s). Even when the item exists, it is commonly reported as a composite score in combination with the obsessive-compulsive item. In addition to the significant psychological burden in individuals with HD, PBs are associated with somatic effects (e.g., cardiovascular symptoms) and high-risk behaviors (e.g., suicide). Recognition and monitoring of PBs in HD can aid in early detection of concerning symptoms and differentiating overlapping illnesses.

The contribution of preclinical magnetic resonance imaging and spectroscopy to Huntington's disease

Huntington's disease is an inherited disorder characterized by psychiatric, cognitive, and motor symptoms due to degeneration of medium spiny neurons in the striatum. A prodromal phase precedes the onset, lasting decades. Current biomarkers include clinical score and striatal atrophy using Magnetic Resonance Imaging (MRI). These markers lack sensitivity for subtle cellular changes during the prodromal phase. MRI and MR spectroscopy offer different contrasts for assessing metabolic, microstructural, functional, or vascular alterations in the disease. They have been used in patients and mouse models. Mouse models can be of great interest to study a specific mechanism of the degenerative process, allow better understanding of the pathogenesis from the prodromal to the symptomatic phase, and to evaluate therapeutic efficacy. Mouse models can be divided into three different constructions: transgenic mice expressing exon-1 of human huntingtin (HTT), mice with an artificial chromosome expressing full-length human HTT, and knock-in mouse models with CAG expansion inserted in the murine htt gene. Several studies have used MRI/S to characterized these models. However, the multiplicity of modalities and mouse models available complicates the understanding of this rich corpus. The present review aims at giving an overview of results obtained using MRI/S for each mouse model of HD, to provide a useful resource for the conception of neuroimaging studies using mouse models of HD. Finally, despite difficulties in translating preclinical protocols to clinical applications, many biomarkers identified in preclinical models have already been evaluated in patients. This review also aims to cover this aspect to demonstrate the importance of MRI/S for studying HD.

Revisiting the Mitochondrial Function and Communication in Neurodegenerative Diseases

Neurodegenerative disorders are distinguished by the progressive loss of anatomically or physiologically relevant neural systems. Atypical mitochondrial morphology and metabolic malfunction are found in many neurodegenerative disorders. Alteration in mitochondrial function can occur as a result of aberrant mitochondrial DNA, altered nuclear enzymes that interact with mitochondria actively or passively, or due to unexplained reasons. Mitochondria are intimately linked to the Endoplasmic reticulum (ER), and ER-mitochondrial communication governs several of the physiological functions and procedures that are disrupted in neurodegenerative disorders. Numerous researchers have associated these disorders with ER-mitochondrial interaction disturbance. In addition, aberrant mitochondrial DNA mutation and increased ROS production resulting in ionic imbalance and leading to functional and structural alterations in the brain as well as cellular damage may have an essential role in disease progression via mitochondrial malfunction. In this review, we explored the evidence highlighting the role of mitochondrial alterations in neurodegenerative pathways in most serious ailments, including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD).

Huntington disease-like 2: insight into neurodegeneration from an African disease

Huntington disease (HD)-like 2 (HDL2) is a rare genetic disease caused by an expanded trinucleotide repeat in the JPH3 gene (encoding junctophilin 3) that shows remarkable clinical similarity to HD. To date, HDL2 has been reported only in patients with definite or probable African ancestry. A single haplotype background is shared by patients with HDL2 from different populations, supporting a common African origin for the expansion mutation. Nevertheless, outside South Africa, reports of patients with HDL2 in Africa are scarce, probably owing to limited clinical services across the continent. Systematic comparisons of HDL2 and HD have revealed closely overlapping motor, cognitive and psychiatric features and similar patterns of cerebral and striatal atrophy. The pathogenesis of HDL2 remains unclear but it is proposed to occur through several mechanisms, including loss of protein function and RNA and/or protein toxicity. This Review summarizes our current knowledge of this African-specific HD phenocopy and highlights key areas of overlap between HDL2 and HD. Given the aforementioned similarities in clinical phenotype and pathology, an improved understanding of HDL2 could provide novel insights into HD and other neurodegenerative and/or trinucleotide repeat expansion disorders.