Social cognition in Huntington's disease: A meta-analysis

Social cognition in basal ganglia pathologies: Theory of Mind in Huntington's and Parkinson's diseases

Theory of Mind (ToM) is the ability to predict the behaviour of others by inferring their cognitive and affective states. The literature suggests that different neural substrates within the basal ganglia are involved in the affective (ventral striatum) and cognitive (dorsal striatum) components of ToM. We investigated ToM dysfunction in two different basal ganglia pathologies, Huntington's disease (HD) and Parkinson's disease (PD), in their early stages. Indeed, a different progression of neurodegeneration from the dorsal striatum to the ventral striatum is described in the two diseases. We also investigated whether there is a correlation between ToM and executive function. Twenty-one patients with HD, 21 with PD, and 22 healthy subjects (HS) were recruited. All participants completed a ToM assessment using the Yoni task, which assesses both cognitive and affective components at two levels of meta-representational difficulty (i.e. first-order items only require inferring the mental state of a person, while second-order items also require inferring the mental states of a person about others). The clinical groups also underwent a full neuropsychological assessment. In HD patients, both cognitive and affective ToM were equally impaired, whereas in PD patients, impairment of the cognitive component predominated. Specifically, compared to HS, HD patients scored lower on both inferential levels and on both cognitive and affective components, whereas PD patients scored lower than HS only on second-order and cognitive items. In the clinical groups, there was an imbalance between the cognitive and affective components, with higher accuracy on affective items. Performance on the Yoni task did not correlate with tests assessing executive functions. We suggest that the different pattern of ToM alteration in HD and PD may be a result of differential involvement of the ventral and dorsal striatum and that ToM abilities in these clinical populations are not directly supported by executive functioning.

Navigating competing needs: a qualitative study on parenthood with a partner with Huntington's disease

Objective

Huntington's disease (HD) is a rare neurodegenerative condition characterised by progressive symptoms affecting motricity, cognition, neuropsychiatric function and behaviour. HD develops during a period of life in which many live in partnership and have children. HD impacts all family members through its cognitive and psychological symptoms, mid-life onset, long disease trajectory and genetic risk. The aim of the study was to explore how parents without HD experience and manage parenthood when their partner is affected by HD.

Methods

Qualitative interviews with 14 caregivers were analysed using reflexive thematic analysis.

Results

Three main themes with corresponding subthemes were identified, followed by an underlying theme: Genetic risk: An underlying layer of complexity. The first theme, Balancing competing demands, describes the challenges involved when attempting to attend to conflicting needs within the family. Theme 2, Needing a shoulder to lean on, covers participants' feelings of loneliness and their need to be seen by others, whereas Theme 3, Restoring and building strength, encompasses coping strategies used by caregivers to protect themselves and their children from potential negative experiences. The underlying theme describes how the genetic aspect of the disease permeates the participants' experiences across all other themes.

Conclusion

Support providers may be unaware of the extensive repercussions HD can have on a family. Acknowledging the central role of partners without HD and their risk of psychological distress is crucial. Exhausted partners may struggle to support their children, which may lead to childhoods overshadowed by HD. For family members to prioritise their own needs, tailored support must be set in place for parents with HD.

Facial emotion recognition deficits are associated with hypomimia and related brain correlates in Parkinson's disease

Hypomimia is a frequent manifestation in Parkinson's disease (PD) that can affect interpersonal relationships and quality of life. Recent studies have suggested that hypomimia is not only related to motor dysfunction but also to impairment in emotional processing networks. Therefore, we hypothesized that the severity of hypomimia could be associated with performance on a task aimed at assessing facial emotion recognition. In this study, we explored the association between hypomimia, recognition of facial expressions of basic emotions using the Ekman 60 Faces Test (EF), and brain correlates of both hypomimia and performance on the EF. A total of 94 subjects underwent clinical assessments (neurological and neuropsychological examinations), and 56 of them participated in the neuroimaging study. We found significant correlation between hypomimia, EF Disgust (r = -0.242, p = 0.022) and EF Happiness (r = -0.264, p = 0.012); an independent reduction in Cortical Thickness (Cth) in the postcentral gyrus, insula, middle and superior temporal gyri, supramarginal gyrus, banks of the superior temporal sulcus, bilateral fusiform gyri, entorhinal cortex, parahippocampal gyrus, inferior and superior parietal cortex, and right cuneus and precuneus; and multiple correlations between negative emotions such as EF Disgust or EF Anger and a reduced Cth in fronto-temporo-parietal regions. In conclusion, these results suggest that the association between hypomimia and emotion recognition deficits in individuals with PD might be mediated by shared circuits, supporting the concept that hypomimia is not only the result of the dysfunction of motor circuits, but also of higher cognitive functions.

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.

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.

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.

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.

Social cognition in neuropsychology: A nationwide survey revealing current representations and practices

As a key domain of cognition, social cognition abilities are altered in a wide range of clinical groups. Accordingly, many clinical tests and theories of social cognition have been developed these last decades. Contrasting this abundant development from a research perspective, recent evidence suggests that social cognition remains rarely addressed from a clinial perspective. The aim of the present research was to characterize the current practices, representations, and needs linked to social cognition from the perspective of professional neuropsychologists and graduate students. A nationwide survey allowed us to determine the classical field conception of social cognition and its associated symptoms or notions. It also allowed us to quantify practice activities and the use of the different clinical tools available. This study revealed that neuropsychologists lack confidence regarding social cognition assessment and its rehabilitation, and that students are in demand for more knowledge and training. Suggestions of change in practices and dissemination of knowledge are discussed. Considering the importance of social cognition, an extension of initial and continuous training alongside an enrichment of interactions between researchers and clinicians were key recommendations to formulate, as well as the need for a consensual lexicon of current concepts.

Disruption of dopamine D2/D3 system function impairs the human ability to understand the mental states of other people

Difficulties in reasoning about others' mental states (i.e., mentalising/Theory of Mind) are highly prevalent among disorders featuring dopamine dysfunctions (e.g., Parkinson's disease) and significantly affect individuals' quality of life. However, due to multiple confounding factors inherent to existing patient studies, currently little is known about whether these sociocognitive symptoms originate from aberrant dopamine signalling or from psychosocial changes unrelated to dopamine. The present study, therefore, investigated the role of dopamine in modulating mentalising in a sample of healthy volunteers. We used a double-blind, placebo-controlled procedure to test the effect of the D2/D3 antagonist haloperidol on mental state attribution, using an adaptation of the Heider and Simmel (1944) animations task. On 2 separate days, once after receiving 2.5 mg haloperidol and once after receiving placebo, 33 healthy adult participants viewed and labelled short videos of 2 triangles depicting mental state (involving mentalistic interaction wherein 1 triangle intends to cause or act upon a particular mental state in the other, e.g., surprising) and non-mental state (involving reciprocal interaction without the intention to cause/act upon the other triangle's mental state, e.g., following) interactions. Using Bayesian mixed effects models, we observed that haloperidol decreased accuracy in labelling both mental and non-mental state animations. Our secondary analyses suggest that dopamine modulates inference from mental and non-mental state animations via independent mechanisms, pointing towards 2 putative pathways underlying the dopaminergic modulation of mental state attribution: action representation and a shared mechanism supporting mentalising and emotion recognition. We conclude that dopaminergic pathways impact Theory of Mind, at least indirectly. Our results have implications for the neurochemical basis of sociocognitive difficulties in patients with dopamine dysfunctions and generate new hypotheses about the specific dopamine-mediated mechanisms underlying social cognition.

Huntington study group's neuropsychology working group position on best practice recommendations for the clinical neuropsychological evaluation of patients with Huntington disease

Objective: Neuropsychological evaluation is critical to detection and management of cognitive and neuropsychiatric changes associated with Huntington disease (HD). Accurate assessment of non-motor complications of HD is critical given the prominent impact on functional disability, frequently commensurate with or exceeding that of motor symptoms. The increasing emphasis on developing disease-modifying therapies targeting cognitive decline in HD requires consensus on clinical neuropsychological assessment methods. The Neuropsychology Working Group (NPWG) of the Huntington Study Group (HSG) sought to provide evidence and consensus-based, practical guidelines for the evaluation of cognitive and neuropsychiatric symptoms associated with HD. Method: The NPWG recruited a multi-disciplinary group of neuropsychologists, neurologists, and psychiatrists to inform best practices in assessing, diagnosing, and treating the non-motor symptoms in HD. A review was circulated among the NPWG, and in an iterative process informed by reviewed literature, best practices in neuropsychological evaluation of patients with HD were identified. Results: A brief review of the available literature and rational for a clinical consensus battery is offered. Conclusion: Clinical neuropsychologists are uniquely positioned to both detect and characterize the non-motor symptoms in HD, and further, provide neurologists and allied health professions with clinically meaningful information that impacts functional outcomes and quality of life. The NPWG provides guidance on best practices to clinical neuropsychologists in this statement. A companion paper operationalizing clinical application of previous research-based non-motor diagnostic criteria for HD is forthcoming, which also advises on non-motor symptom screening methods for the non-neuropsychologist working with HD.

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.

Pharmacological characterization of SAGE-718, a novel positive allosteric modulator of N-methyl-d-aspartate receptors

BACKGROUND AND PURPOSE

Select neuroactive steroids tune neural activity by modulating excitatory and inhibitory neurotransmission, including the endogenous cholesterol metabolite 24(S)-hydroxycholesterol (24(S)-HC), which is an N-methyl-d-aspartate (NMDA) receptor positive allosteric modulator (PAM). NMDA receptor PAMs are potentially an effective pharmacotherapeutic strategy to treat conditions associated with NMDA receptor hypofunction.

EXPERIMENTAL APPROACH

Using in vitro and in vivo electrophysiological recording experiments and behavioural approaches, we evaluated the effect of SAGE-718, a novel neuroactive steroid NMDA receptor PAM currently in clinical development for the treatment of cognitive impairment, on NMDA receptor function and endpoints that are altered by NMDA receptor hypoactivity and assessed its safety profile.

KEY RESULTS

SAGE-718 potentiated GluN1/GluN2A-D NMDA receptors with equipotency and increased NMDA receptor excitatory postsynaptic potential (EPSP) amplitude without affecting decay kinetics in striatal medium spiny neurons. SAGE-718 increased the rate of unblock of the NMDA receptor open channel blocker ketamine on GluN1/GluN2A in vitro and accelerated the rate of return on the ketamine-evoked increase in gamma frequency band power, as measured with electroencephalogram (EEG), suggesting that PAM activity is driven by increased channel open probability. SAGE-718 ameliorated deficits due to NMDA receptor hypofunction, including social deficits induced by subchronic administration of phencyclidine, and behavioural and electrophysiological deficits from cholesterol and 24(S)-HC depletion caused by 7-dehydrocholesterol reductase inhibition. Finally, SAGE-718 did not produce epileptiform activity in a seizure model or neurodegeneration following chronic dosing.

CONCLUSIONS AND IMPLICATIONS

These findings provide strong evidence that SAGE-718 is a neuroactive steroid NMDA receptor PAM with a mechanism that is well suited as a treatment for conditions associated with NMDA receptor hypofunction.

Theory of Mind in Huntington's Disease: A Systematic Review of 20 Years of Research

Background

People with Huntington's disease (HD) exhibit neurocognitive alterations throughout the disease, including deficits in social cognitive processes such as Theory of Mind (ToM).

Objective

The aim is to identify methodologies and ToM instruments employed in HD, alongside relevant findings, within the scientific literature of the past two decades.

Methods

We conducted a comprehensive search for relevant papers in the SCOPUS, PubMed, APA-PsyArticles, Web of Science, Redalyc, and SciELO databases. In the selection process, we specifically focused on studies that included individuals with a confirmed genetic status of HD and investigated ToM functioning in patients with and without motor symptoms. The systematic review followed the PRISMA protocol.

Results

A total of 27 papers were selected for this systematic review, covering the period from 2003 to 2023. The findings consistently indicate that ToM is globally affected in patients with manifest motor symptoms. In individuals without motor symptoms, impairments are focused on the affective dimensions of ToM.

Conclusions

Based on our analysis, affective ToM could be considered a potential biomarker for HD. Therefore, it is recommended that ToM assessment be included as part of neuropsychological evaluation protocols in clinical settings. Suchinclusion could aid in the identification of early stages of the disease and provide new opportunities for treatment, particularly with emerging drugs like antisense oligomers. The Prospero registration number for this review is CRD42020209769.

Cerebral response to emotional working memory based on vocal cues: an fNIRS study

Introduction

Humans mainly utilize visual and auditory information as a cue to infer others' emotions. Previous neuroimaging studies have shown the neural basis of memory processing based on facial expression, but few studies have examined it based on vocal cues. Thus, we aimed to investigate brain regions associated with emotional judgment based on vocal cues using an N-back task paradigm.

Methods

Thirty participants performed N-back tasks requiring them to judge emotion or gender from voices that contained both emotion and gender information. During these tasks, cerebral hemodynamic response was measured using functional near-infrared spectroscopy (fNIRS).

Results

The results revealed that during the Emotion 2-back task there was significant activation in the frontal area, including the right precentral and inferior frontal gyri, possibly reflecting the function of an attentional network with auditory top-down processing. In addition, there was significant activation in the ventrolateral prefrontal cortex, which is known to be a major part of the working memory center.

Discussion

These results suggest that, compared to judging the gender of voice stimuli, when judging emotional information, attention is directed more deeply and demands for higher-order cognition, including working memory, are greater. We have revealed for the first time the specific neural basis for emotional judgments based on vocal cues compared to that for gender judgments based on vocal cues.

Can the Ability to Recognize Facial Emotions in Individuals With Neurodegenerative Disease be Improved? A Systematic Review and Meta-analysis

BACKGROUND

Facial emotion recognition (FER) is commonly impaired in individuals with neurodegenerative disease (NDD). This impairment has been linked to an increase in behavioral disorders and caregiver burden.

OBJECTIVE

To identify interventions targeting the improvement of FER ability in individuals with NDD and investigate the magnitude of the efficacy of the interventions. We also wanted to explore the duration of the effects of the intervention and their possible impacts on behavioral and psychological symptoms of dementia and caregiver burden.

METHOD

We included 15 studies with 604 individuals who had been diagnosed with NDD. The identified interventions were categorized into three types of approach (cognitive, neurostimulation, and pharmacological) as well as a combined approach (neurostimulation with pharmacological).

RESULTS

The three types of approaches pooled together had a significant large effect size for FER ability improvement (standard mean difference: 1.21, 95% CI = 0.11, 2.31, z = 2.15, P = 0.03). The improvement lasted post intervention, in tandem with a decrease in behavioral disorders and caregiver burden.

CONCLUSION

A combination of different approaches for FER ability improvement may be beneficial for individuals with NDD and their caregivers.

Social cognition in hyperkinetic movement disorders: a systematic review

Numerous lines of research indicate that our social brain involves a network of cortical and subcortical brain regions that are responsible for sensing and controlling body movements. However, it remains unclear whether movement disorders have a systematic impact on social cognition. To address this question, we conducted a systematic review examining the influence of hyperkinetic movement disorders (including Huntington disease, Tourette syndrome, dystonia, and essential tremor) on social cognition. Following the PRISMA guidelines and registering the protocol in the PROSPERO database (CRD42022327459), we analyzed 50 published studies focusing on theory of mind (ToM), social perception, and empathy. The results from these studies provide evidence of impairments in ToM and social perception in all hyperkinetic movement disorders, particularly during the recognition of negative emotions. Additionally, individuals with Huntington's Disease and Tourette syndrome exhibit empathy disorders. These findings support the functional role of subcortical structures (such as the basal ganglia and cerebellum), which are primarily responsible for movement disorders, in deficits related to social cognition.

Neural Correlates of Facial Emotion Recognition Impairment in Blepharospasm: A Functional Magnetic Resonance Imaging Study

Selective impairment in recognizing facial expressions of disgust was reported in patients with focal dystonia several years ago, but the basic neural mechanisms remain largely unexplored. Therefore, we investigated whether dysfunction of the brain network involved in disgust recognition processing was related to this selective impairment in blepharospasm. Facial emotion recognition evaluations and resting-state functional magnetic resonance imaging were performed in 33 blepharospasm patients and 33 healthy controls (HCs). The disgust processing network was constructed, and modularity analyses were performed to identify sub-networks. Regional functional indexes and intra- and inter-functional connections were calculated and compared between the groups. Compared to HCs, blepharospasm patients demonstrated a worse performance in disgust recognition. In addition, functional connections within the sub-network involved in perception processing rather than recognition processing of disgust were significantly decreased in blepharospasm patients compared to HCs. Specifically, decreased functional connections were noted between the left fusiform gyrus (FG) and right middle occipital gyrus (MOG), the left FG and right FG, and the right FG and left MOG. We identified decreased functional activity in these regions, as indicated by a lower amplitude of low-frequency fluctuation in the left MOG, fractional amplitude of low-frequency fluctuation in the right FG, and regional homogeneity in the right FG and left MOG in blepharospasm patients versus HCs. Our results suggest that dysfunctions of the disgust processing network exist in blepharospasm. A deficit in disgust emotion recognition may be attributed to disturbances in the early perception of visual disgust stimuli in blepharospasm patients.

Facial Emotion Recognition in Older Adults With Cognitive Complaints

Background and Purpose

Facial emotion recognition deficits impact the daily life, particularly of Alzheimer's disease patients. We aimed to assess these deficits in the following three groups: subjective cognitive decline (SCD), mild cognitive impairment (MCI), and mild Alzheimer's dementia (AD). Additionally, we explored the associations between facial emotion recognition and cognitive performance.

Methods

We used the Korean version of the Florida Facial Affect Battery (K-FAB) in 72 SCD, 76 MCI, and 76 mild AD subjects. The comparison was conducted using the analysis of covariance (ANCOVA), with adjustments being made for age and sex. The Mini-Mental State Examination (MMSE) was utilized to gauge the overall cognitive status, while the Seoul Neuropsychological Screening Battery (SNSB) was employed to evaluate the performance in the following five cognitive domains: attention, language, visuospatial abilities, memory, and frontal executive functions.

Results

The ANCOVA results showed significant differences in K-FAB subtests 3, 4, and 5 (p=0.001, p=0.003, and p=0.004, respectively), especially for anger and fearful emotions. Recognition of 'anger' in the FAB subtest 5 declined from SCD to MCI to mild AD. Correlations were observed with age and education, and after controlling for these factors, MMSE and frontal executive function were associated with FAB tests, particularly in the FAB subtest 5 (r=0.507, p<0.001 and r=-0.288, p=0.026, respectively).

Conclusions

Emotion recognition deficits worsened from SCD to MCI to mild AD, especially for negative emotions. Complex tasks, such as matching, selection, and naming, showed greater deficits, with a connection to cognitive impairment, especially frontal executive dysfunction.

What does social cognition look like in everyday social functioning in Huntington's disease? A protocol for a scoping review to explore and synthesise knowledge about social cognition alongside day-to-day social functioning of people with Huntington's disease

INTRODUCTION

Social cognition is problematic in Huntington's disease (HD). Despite the observations of clinicians and families, there is minimal empirical literature about how it presents in daily life and the impact on social functioning. This protocol forms the basis of a scoping review to synthesise both the quantitative knowledge and qualitative experiences of the HD community so that a visual and narrative map can address what is known and what is not known for the benefit of the community and clinicians and academics alike.

METHODS AND ANALYSES

An umbrella scoping review of previous work and a scoping review of newer studies of social cognition and social functioning will be undertaken. The electronic databases PubMed, Medline, PsycINFO, Web of Science, Scopus, Embase and CINAHL will be searched to identify eligible studies from starting from 2003 to June 2023. A grey literature search and grey data search will also be undertaken. Quality appraisal of the included documents will use the Critical Appraisal Skills Programme and Authority, Accuracy, Coverage, Objectivity, Date, Significance checklists. A data charting table will be used for data extraction, with analysis of qualitative data using the framework method. The review findings will be presented in a visual form and in a narrative summary.

ETHICS AND DISSEMINATION

Ethical review is not usually required as scoping reviews are produced via secondary data analysis, however, this protocol includes the use of grey data from a charity web forum and so in line with best practice for internet mediated research ethical review was sought and approved (STEM Ethical Review Committee, University of Birmingham-ERN_21-1028A). Review findings will be shared with service users and disseminated through a peer-reviewed publications, conference presentations and hosted via the website of the patient association charity the HD Association.

Disgust as a transdiagnostic index of mental illness: A narrative review of clinical populations

Disgust is a basic emotion of rejection, providing an ancestral defensive mechanism against illness. Based on research that documents altered experiences of disgust across several psychopathological conditions, we conducted a narrative review to address the hypothesis that altered disgust may serve as a transdiagnostic index of mental illness. Our synthesis of the literature from past decades suggests that, compared to healthy populations, patients with mental disorders exhibit abnormal processing of disgust in at least one of the analyzed dimensions. We also outline evidence of alterations in brain areas relevant to disgust processing, such as the insula and the interconnected limbic network. Overall, we provide preliminary support for the hypothesis that altered disgust processing may serve as a transdiagnostic index of mental illness.

Sleep, Circadian Rhythms, and Cognitive Dysfunction in Huntington's Disease

BACKGROUND

In healthy people, sleep and circadian disruption are linked to cognitive deficits. People with Huntington's disease (HD), who have compromised brain function and sleep and circadian disturbances, may be even more susceptible to these cognitive effects.

OBJECTIVE

To conduct a comprehensive review and synthesis of the literature in HD on the associations of cognitive dysfunction with disturbed sleep and circadian rhythms.

METHODS

We searched MEDLINE via OVID, CINAHL Plus, EMBASE via OVID, and PubMed in May 2023. The first author then screened by title and abstract and conducted a full review of remaining articles.

RESULTS

Eight studies investigating the influence of sleep and/or circadian rhythms on cognitive function in HD were found. In manifest HD, poorer sleep was associated with worse cognitive function. For behavioral 24-hour (circadian) rhythms, two studies indicated that later wake times correlated with poorer cognitive function. No reported studies in HD examined altered physiological 24-hour (circadian) rhythms and cognitive impairment.

CONCLUSION

Some associations exist between poor sleep and cognitive dysfunction in manifest HD, yet whether these associations are present before clinical diagnosis is unknown. Whether circadian disturbances relate to cognitive impairment in HD also remains undetermined. To inform sleep and circadian interventions aimed at improving cognitive symptoms in HD, future research should include a range of disease stages, control for external factors, and utilize robust cognitive batteries targeted to the aspects of cognitive function known to be adversely affected in HD.

An Exploratory Study Investigating Autonomy in Huntington's Disease Gene Expansion Carriers

BACKGROUND

Autonomy describes a psychological state of self-regulation of motivation and action, which is a central characteristic of healthy functioning. In neurodegenerative diseases measures of self-perception have been found to be affected by the disease. However, it has never been investigated whether measures of self-perception, like autonomy, is affected in Huntington's disease.

OBJECTIVE

We investigated whether autonomy is affected in Huntington's disease and if the degree of autonomy is associated with motor function, neuropsychiatric symptoms, cognitive impairments, and apathy.

METHODS

We included 44 premanifest and motor-manifest Huntington's disease gene expansion carriers and 19 controls. Autonomy was examined using two self-report questionnaires, the Autonomy-Connectedness Scale-30 and the Index of Autonomous Functioning. All participants were examined according to motor function, cognitive impairments, and neuropsychiatric symptoms, including apathy.

RESULTS

Statistically significant differences were found between motor-manifest Huntington's disease gene expansion carriers and premanifest Huntington's disease gene expansion carriers or controls on two measures of autonomy. Between 25-38% of motor-manifest Huntington's disease gene expansion carriers scored significantly below the normal level on subscales of autonomy as compared to controls. One autonomy subscale was associated with apathy (r = -0.65), but not with other symptoms of Huntington's disease.

CONCLUSION

This study provides evidence for impaired autonomy in individuals with Huntington's disease and an association between autonomy and apathy. The results underline the importance of maintaining patient autonomy and involvement in care throughout the disease.

Association Between Insulin-Like Growth Factor-1 and Social Cognition in Huntington's Disease

Background

Insulin-like growth factor 1 (IGF-1) seems to be involved in the neural circuits associated with social cognition and brain structure.

Objectives

To investigate the association of IGF-1 levels with social cognition and brain structure in Huntington's disease (HD).

Methods

We evaluated social cognition using the Ekman test in 22 HD patients and 19 matched controls. Brain structure was assessed using standard volume-based voxel-based morphometry and surface-based cortical thickness pipeline. We analyzed the association of IGF-1 levels with social cognition and brain structure using adjusted regression analysis.

Results

Social cognition was worse in HD patients (P < 0.001), on antidopaminergic drugs (P = 0.02), and with lower IGF-1 levels (P = 0.04). In neuroimaging analyses, lower IGF-1 levels were associated with social cognition impairment and atrophy mainly in frontotemporal regions (P < 0.05 corrected).

Conclusions

In HD, abnormal IGF-1 function seems to be associated with brain atrophy leading to clinical deficits in social cognition.

On the association between apathy and deficits of social cognition and executive functions in Huntington's disease

OBJECTIVE

To investigate if executive and social cognitive dysfunction was associated with apathy in a large cohort of Huntington's disease gene expansion carriers.

METHOD

Eighty premanifest and motor-manifest Huntington's disease gene expansion carriers (Mini-Mental State Examination score ≥ 24 and Montreal Cognitive Assessment score ≥ 19) and thirty-two controls were examined with the Lille Apathy Rating Scale (LARS), a tailored and quantitative measure of apathy, and a comprehensive cognitive battery on executive functions and social cognition (emotion recognition, theory of mind and sarcasm detection), as well as general correlates like demographic variables, and neuropsychiatric and cognitive screening tests.

RESULTS

The motor-manifest Huntington's disease gene expansion carriers had significantly different scores on most measures of social cognition and executive functions, compared to premanifest and control participants. Apathy was significantly correlated with most executive test scores, but the Emotion Hexagon was the only social cognitive test score significantly correlated with apathy. We found that the motor score and the depression score were the only significant predictors of the apathy score, when the social cognitive and executive tests with the strongest association with the global LARS score were entered into a multiple stepwise regression model. No cognitive test score could significantly predict apathy. The model explained 21 % of the total variance.

CONCLUSION

Despite being significantly correlated with apathy neuropsychological variables did not have a significant impact on apathy when variables as depression and motor symptoms were taken into account. Apathy should be considered an independent symptom of Huntington's disease that requires specific examination.

Social cognition and empathy in adults with obsessive compulsive disorder: A meta-analysis

Obsessive-compulsive disorder (OCD) is characterized by intrusive thoughts (obsessions) and compulsions and has been associated with psychosocial impairment. Indeed, a number of studies have highlighted impairments in both social cognitive functions and empathic skills in OCD, despite several inconsistencies. This study aimed to investigate social cognitive dysfunction and empathy deficits in patients with OCD using a meta-analytic approach. A literature search was conducted using the databases Pubmed, PsycINFO, ProQuest and Scopus to identify the relevant studies (January 1980 to March 2020). Following the systematic review of relevant OCD studies, a random-effects meta-analysis was conducted. The current meta-analysis included 25 studies consisting of 1161 patients with OCD and 1329 healthy controls. OCD was associated with decreased performance in theory of mind (ToM). In the facial emotion recognition domain, patients with OCD significantly underperformed healthy controls only in their recognition of disgust. OCD was significantly related to reduced cognitive empathy. OCD was associated with medium-sized impairments in ToM and cognitive empathy, which can likely contribute to psychosocial impairment in this disorder. Further studies are needed to investigate state and trait-related factors using experimental measures of empathy.

The Hold me Tight Program for Couples Facing Huntington's Disease

BACKGROUND

A positive predictive genetic test for Huntington's disease (HD) can be a life-changing event for both carriers and their partners, leading to lower wellbeing and increasing the risk for separation and divorce. The 'Hold me Tight' program (HmT), based on emotionally focused couples' therapy, aims at strengthening the couple bond by targeting attachment needs.

OBJECTIVE

This study investigates whether the HmT program helps couples strengthen their relationship, as an investment in a future where the disease will affect life in many ways.

METHODS

In a multiple baseline design using three baselines of varying length, 15 couples of presymptomatic HD-carriers and their partners were included. In three consecutive groups, couples underwent the intervention (an adapted version of the 8-session HmT program) in four weekly sessions and completed self-report questionnaires throughout the study period of 19 weeks (17 measurements). Attachment style was assessed at baseline, resilience at baseline and at the end of the follow-up, while relationship satisfaction and wellbeing were measured weekly. A multi-level model was applied to the data.

RESULTS

Over the course of the study, wellbeing and relationship satisfaction significantly improved; resilience, however, did not. Furthermore, all three outcome measures were moderated by attachment style, with more securely attached individuals showing better outcomes.

CONCLUSION

HmT improved wellbeing and relationship satisfaction of couples facing HD. Due to these improvements and high patient acceptability rates, this program could become a standardized procedure in HD care. The program could be adapted for other populations, e.g., couples facing other genetic neurological disorders.

Decreased CSF oxytocin relates to measures of social cognitive impairment in Huntington's disease patients

OBJECTIVE

Huntington's disease (HD) is an inherited neurodegenerative disease with motor, cognitive and psychiatric symptoms. Non-motor symptoms like depression and altered social cognition are proposed to be caused by dysfunction of the hypothalamus. We measured the hypothalamic neuropeptide oxytocin in plasma and cerebrospinal fluid (CSF) in a cohort of HD gene expansion carriers (HDGECs), compared the levels to healthy HD family controls and correlated oxytocin levels to disease progression and social cognition.

METHODS

We recruited 113 HDGECs and 33 controls. Psychiatric and cognitive symptoms were evaluated, and social cognition was assessed with the Emotion Hexagon test, Reading the Mind in the Eyes and The Awareness of Social Inference Test. The levels of oxytocin in CSF and blood were analyzed by radioimmunoassay.

RESULTS

We found the level of oxytocin in CSF to be significantly lower by 33.5% in HDGECs compared to controls (p = 0.016). When dividing the HDGECs into groups with or without cognitive impairment, we found the oxytocin level to be significantly lower by 30.3% in the HDGECs with cognitive symptoms (p = 0.046). We found a statistically significant correlation between the level of oxytocin and scores on social cognition (Reading the Mind in the Eyes p = 0.0019; Emotion Hexagon test: p = 0.0062; The Awareness of Social Inference Test: p = 0.002).

CONCLUSIONS

This is the first study to measure oxytocin in the CSF of HDGECs. We find that HDGECs have a significantly lower level of oxytocin compared to controls, and that the level of oxytocin may represent an objective and comparable measure that could be used as a state biomarker for impairment of social cognition. We suggest treatment trials to evaluate a potential effect of oxytocin on social cognition in HD.

A qualitative examination of apathy and physical activity in Huntington's and Parkinson's disease

Aim: In Huntington's disease (HD) and Parkinson's disease (PD), apathy is a frequently cited barrier to participation in physical activity. Current diagnostic criteria emphasize dissociable variants of apathy that differentially affect goal-directed behavior. How these dimensions present and affect physical activity in HD and PD is unknown. Methods: Using a qualitative approach, we examined the experience of apathy and its impact on physical activity in 20 people with early-manifest HD or idiopathic PD. Results: Two major themes emerged: the multidimensionality of apathy, including initiation or goal-identification difficulties, and the interplay of apathy and fatigue; and facilitators of physical activity, including routines, safe environments and education. Conclusion: Physical activity interventions tailored to apathy phenotypes may maximize participant engagement.

Profiling Social Cognition in Premanifest Huntington's Disease

OBJECTIVE

Discrepancies exist in reports of social cognition deficits in individuals with premanifest Huntington's disease (HD); however, the reason for this variability has not been investigated. The aims of this study were to (1) evaluate group- and individual-level social cognitive performance and (2) examine intra-individual variability (dispersion) across social cognitive domains in individuals with premanifest HD.

METHOD

Theory of mind (ToM), social perception, empathy, and social connectedness were evaluated in 35 individuals with premanifest HD and 29 healthy controls. Cut-off values beneath the median and 1.5 × the interquartile range below the 25th percentile (P25 - 1.5 × IQR) of healthy controls for each variable were established for a profiling method. Dispersion between social cognitive domains was also calculated.

RESULTS

Compared to healthy controls, individuals with premanifest HD performed worse on all social cognitive domains except empathy. Application of the profiling method revealed a large proportion of people with premanifest HD fell below healthy control median values across ToM (>80%), social perception (>57%), empathy (>54%), and social behaviour (>40%), with a percentage of these individuals displaying more pronounced impairments in empathy (20%) and ToM (22%). Social cognition dispersion did not differ between groups. No significant correlations were found between social cognitive domains and mood, sleep, and neurocognitive outcomes.

CONCLUSIONS

Significant group-level social cognition deficits were observed in the premanifest HD cohort. However, our profiling method showed that only a small percentage of these individuals experienced marked difficulties in social cognition, indicating the importance of individual-level assessments, particularly regarding future personalised treatments.

Self-Reported Social Relationship Capacities Predict Motor, Functional and Cognitive Decline in Huntington’s Disease

Huntington’s Disease (HD) is an inherited neurodegenerative disease characterized by a combination of motor, cognitive, and behavioral disorders. The social and behavioral symptoms observed in HD patients impact their quality of life and probably explain their relational difficulties, conflicts, and social withdrawal. In this study, we described the development of the Social Relationship Self-Questionnaire (SRSQ), a self-reporting questionnaire that assesses how HD patients perceived their social relationships. The scale was proposed for 66 HD patients at an early stage of the disease, 32 PreHD patients (individuals carrying the mutant gene without motor symptoms), and 66 controls. The HD patients were included in a prospective longitudinal follow-up for an average of 1.07 years with motor, functional, cognitive, and behavioral assessments. Based on the HD patients’ answers at baseline, we identified two domains in the SRSQ. The first domain was related to social motivation and correlated with cognitive performance. The second domain was related to emotional insight and correlated with behavioral symptoms such as apathy, anxiety, and irritability. We discovered that both SRSQ domain scores at baseline predicted future motor, functional, and cognitive decline in HD.

Theory of mind and facial emotion recognition in adults with temporal lobe epilepsy: A meta-analysis

BACKGROUND

Mounting studies have investigated impairments in social cognitive domains (including theory of mind [ToM] and facial emotion recognition [FER] in adult patients with temporal lobe epilepsy (TLE). However, to date, inconsistent findings remain.

METHODS

A search of PubMed, Web of Science, and Embase databases was conducted until December 2021. Hedges g effect sizes were computed with a random-effects model. Meta-regressions were used to assess the potential confounding factors of between-study variability in effect sizes.

RESULTS

The meta-analysis included 41 studies, with a combined sample of 1,749 adult patients with TLE and 1,324 healthy controls (HCs). Relative to HCs, adult patients with TLE showed large impairments in ToM (g = -0.92) and cognitive ToM (g = -0.92), followed by medium impairments in affective ToM (g = -0.79) and FER (g = -0.77). Besides, no (statistically) significant differences were observed between the magnitude of social cognition impairment in adult with TLE who underwent and those who did not undergo epilepsy surgery. Meta-regressions exhibited that greater severity of executive functioning was associated with more severe ToM defects, and older age was associated with more severe FER defects.

CONCLUSIONS

Results of this meta-analysis suggest that adult patients with TLE show differential impairments in the core aspects of social cognitive domains (including ToM and FER), which may help in planning individualized treatment with appropriate cognitive and behavioral interventions.

Recent advances in stem cell therapy for neurodegenerative disease: Three dimensional tracing and its emerging use

Neurodegenerative disease is a brain disorder caused by the loss of structure and function of neurons that lowers the quality of human life. Apart from the limited potential for endogenous regeneration, stem cell-based therapies hold considerable promise for maintaining homeostatic tissue regeneration and enhancing plasticity. Despite many studies, there remains insufficient evidence for stem cell tracing and its correlation with endogenous neural cells in brain tissue with three-dimensional structures. Recent advancements in tissue optical clearing techniques have been developed to overcome the existing shortcomings of cross-sectional tissue analysis in thick and complex tissues. This review focuses on recent progress of stem cell treatments to improve neurodegenerative disease, and introduces tissue optical clearing techniques that can implement a three-dimensional image as a proof of concept. This review provides a more comprehensive understanding of stem cell tracing that will play an important role in evaluating therapeutic efficacy and cellular interrelationship for regeneration in neurodegenerative diseases.

Cognitive and Affective Empathy in Huntington's Disease

BACKGROUND

Empathy is a multidimensional construct and a key component of social cognition. In Huntington's disease (HD), little is known regarding the phenomenology and the neural correlates of cognitive and affective empathy, and regarding how empathic deficits interact with other behavioral and cognitive manifestations.

OBJECTIVE

To explore the cognitive and affective empathy disturbances and related behavioral and neural correlates in HD.

METHODS

Clinical and sociodemographic data were obtained from 36 healthy controls (HC) and 54 gene-mutation carriers (17 premanifest and 37 early-manifest HD). The Test of Cognitive and Affective Empathy (TECA) was used to characterize cognitive (CE) and affective empathy (AE), and to explore their associations with grey matter volume (GMV) and cortical thickness (Cth).

RESULTS

Compared to HC, premanifest participants performed significantly worse in perspective taking (CE) and empathic distress (AE). In symptomatic participants, scores were significantly lower in almost all the TECA subscales. Several empathy subscales were associated with the severity of apathy, irritability, and cognitive deficits. CE was associated with GMV in thalamic, temporal, and occipital regions, and with Cth in parietal and temporal areas. AE was associated with GMV in the basal ganglia, limbic, occipital, and medial orbitofrontal regions, and with Cth in parieto-occipital areas.

CONCLUSION

Cognitive and affective empathy deficits are detectable early, are more severe in symptomatic participants, and involve the disruption of several fronto-temporal, parieto-occipital, basal ganglia, and limbic regions. These deficits are associated with disease severity and contribute to several behavioral symptoms, facilitating the presentation of maladaptive patterns of social interaction.

Aberrant Striatal Value Representation in Huntington's Disease Gene Carriers 25 Years Before Onset

BACKGROUND

In this study, we asked whether differences in striatal activity during a reinforcement learning (RL) task with gain and loss domains could be one of the earliest functional imaging features associated with carrying the Huntington's disease (HD) gene. Based on previous work, we hypothesized that HD gene carriers would show either neural or behavioral asymmetry between gain and loss learning.

METHODS

We recruited 35 HD gene carriers, expected to demonstrate onset of motor symptoms in an average of 26 years, and 35 well-matched gene-negative control subjects. Participants were placed in a functional magnetic resonance imaging scanner, where they completed an RL task in which they were required to learn to choose between abstract stimuli with the aim of gaining rewards and avoiding losses. Task behavior was modeled using an RL model, and variables from this model were used to probe functional magnetic resonance imaging data.

RESULTS

In comparison with well-matched control subjects, gene carriers more than 25 years from motor onset showed exaggerated striatal responses to gain-predicting stimuli compared with loss-predicting stimuli (p = .002) in our RL task. Using computational analysis, we also found group differences in striatal representation of stimulus value (p = .0004). We found no group differences in behavior, cognitive scores, or caudate volumes.

CONCLUSIONS

Behaviorally, gene carriers 9 years from predicted onset have been shown to learn better from gains than from losses. Our data suggest that a window exists in which HD-related functional neural changes are detectable long before associated behavioral change and 25 years before predicted motor onset. These represent the earliest functional imaging differences between HD gene carriers and control subjects.

Social cognition in individuals born preterm

Faces hold a substantial value for effective social interactions and sharing. Covering faces with masks, due to COVID-19 regulations, may lead to difficulties in using social signals, in particular, in individuals with neurodevelopmental conditions. Daily-life social participation of individuals who were born preterm is of immense importance for their quality of life. Here we examined face tuning in individuals (aged 12.79 ± 1.89 years) who were born preterm and exhibited signs of periventricular leukomalacia (PVL), a dominant form of brain injury in preterm birth survivors. For assessing the face sensitivity in this population, we implemented a recently developed experimental tool, a set of Face-n-Food images bordering on the style of Giuseppe Arcimboldo. The key benefit of these images is that single components do not trigger face processing. Although a coarse face schema is thought to be hardwired in the brain, former preterms exhibit substantial shortages in the face tuning not only compared with typically developing controls but also with individuals with autistic spectrum disorders. The lack of correlations between the face sensitivity and other cognitive abilities indicates that these deficits are domain-specific. This underscores impact of preterm birth sequelae for social functioning at large. Comparison of the findings with data in individuals with other neurodevelopmental and neuropsychiatric conditions provides novel insights into the origins of deficient face processing.

Cognitive and behavioral associated changes in manifest Huntington disease: A retrospective cross-sectional study

INTRODUCTION

Behavioral and cognitive changes can be observed across all Huntington disease (HD) stages. Our multicenter and retrospective study investigated the association between cognitive and behavioral scale scores in manifest HD, at three different yearly timepoints.

METHODS

We analyzed cognitive and behavioral domains by the Unified Huntington's Disease Rating Scale (UHDRS) and by the Problem Behaviors Assessment Short Form (PBA-s), at three different yearly times of life (t0 or baseline, t1 after one year, t2 after two years), in 97 patients with manifest HD (mean age 48.62 ± 13.1), from three ENROLL-HD Centers. In order to test the disease progression, we also examined patients' motor and functional changes by the UHDRS, overtime.

RESULTS

The severity of apathy and of perseveration/obsession was associated with the severity of the cognitive decline (p < .0001), regardless of the yearly timepoint. The score of irritability significantly and positively correlated with perseveration errors in the verbal fluency test at t0 (r = .34; p = .001), while the psychosis significantly and negatively correlated with the information processing speed at t0 (r = -.21; p = .038) and significantly and positively correlated with perseveration errors in the verbal fluency test at t1 (r = .35; p < .0001). The disease progression was confirmed by the significant worsening of the UHDRS-Total Motor Score (TMS) and of the UHDRS-Total Functional Capacity (TFC) scale score after two-year follow-up (p < .0001).

CONCLUSION

Although the progression of abnormal behavioral manifestations cannot be predicted in HD, the severity of apathy and perseveration/obsessions are significantly associated with the severity of the cognitive function impairment, thus contributing, together, to the disease development and to patients' loss of independence, in addition to the neurological manifestations. This cognitive-behavior pattern determines a common underlying deficit depending on a dysexecutive syndrome.

Problems with Social Cognition and Decision-Making in Huntington's Disease: Why Is it Important?

Huntington’s disease starts slowly and progresses over a 15–20 year period. Motor changes begin subtly, often going unnoticed by patients although they are typically visible to those close to them. At this point, it is the early non-motor problems of HD that arguably cause the most functional impairment. Approximately 65% of gene carriers will experience a reduction in their occupational level, and just under half will feel unable to manage their finances independently before a clinical diagnosis is made. Understanding what drives this impairment in activities of daily living is the key to helping people with HD to live more independently for longer, especially in early disease. Early cognitive decline is likely to play a contributory factor although few studies have looked directly at this relationship. Recently, it has been shown that along with the well documented dysexecutive syndrome seen in HD, changes in social cognition and decision-making are more common than previously thought. Furthermore, some of the early neuropathological and neurochemical changes seen in HD disrupt networks known to be involved in social functioning. In this review, we explore how HD changes the way individuals interact in a social world. Specifically, we summarise the literature on both classical and social decision-making (value-based decision-making in a social context) along with studies of theory of mind, empathy, alexithymia, and emotion recognition in HD. The literature specific to HD is discussed and supported by evidence from similar neurodegenerative disorders and healthy individuals to propose future directions and potential therapeutic avenues to be explored.

The Relationship Between Plasma Oxytocin and Executive Functioning in Huntington's Disease: A Pilot Study

The role of oxytocin (OT) in social cognition of patients with Huntington's disease (HD) has been studied, but its impact on executive functioning has not been explored yet. Healthy controls, premanifest HD, and manifest HD participants underwent executive functioning assessment and OT plasma measurement. There were no significant group differences in plasma OT levels. Higher OT levels were associated with better executive functioning in premanifest HD participants. Our findings revealed an association between OT levels and depressive symptoms in premanifest and manifest HD participants. The potential role of OT in HD deserves further investigation.

Multidimensional Apathy: The Utility of the Dimensional Apathy Scale in Huntington's Disease

Background

Apathy is a disorder of motivation common to Huntington's disease (HD). Recent conceptual frameworks suggest that apathy is not unitary but consists of discrete subtypes ("dimensions"). Which of the proposed dimensions are preferentially affected in HD, and how these dimensions evolve with disease progression is unknown.

Objectives

The Dimensional Apathy Scale (DAS) separates apathy into Executive, Initiation and Emotional subscales. Using the DAS, we aimed to: 1) Determine the apathy subtypes prevalent in HD; 2) Compare the DAS against a unitary measure of apathy (Apathy Evaluation Scale, AES); 3) Assess the reliability of self- and observer-ratings; and 4) Determine the relationship between the DAS, and disease burden, total functional capacity (TFC) and the AES.

Method

Fifty pre-manifest, 51 manifest-HD, 87 controls, and 50 HD-observers completed the DAS, AES, and TFC.

Results

Manifest-HD participants had the highest levels of apathy across all dimensions (30.4% on Executive subscale, 34.8% on Initiation subscale, and 15.2% on Emotional subscale), relative to pre-manifest and control participants. Self- and observer-ratings on the DAS did not differ. Hierarchical regressions across the entire gene-expanded sample showed that scores on the Initiation subscale correlated with AES scores; higher Executive subscale scores were related to higher disease burden; and Emotional subscale scores with lower total functional capacity.

Conclusions

In this first study of the DAS in HD, manifest-HD participants were more apathetic than pre-manifest and control participants across all apathy subtypes. The DAS may be a useful tool for measuring different aspects of apathy in people with HD.

Altered third-party punishment in Huntington's disease: A study using neuroeconomic games

BACKGROUND

Huntington's disease (HD) is a heritable degenerative brain disease caused by a mutation in the huntingtin gene with excessive repeats of the base triplet cytosine-adenine-guanine (CAG), which codes for the aminoacid glutamine. HD is associated with a broad spectrum of neurocognitive dysfunction, including deficits in social cognition. The appreciation of fairness rules and reciprocity has not been studied in HD. Based on theoretical considerations suggesting that brain regions known to be affected from HD are involved in economic decision-making, the present study sought to examine HD patients' performance in two neuroeconomic games.

METHODS

Twenty-nine manifest HD mutation carriers (20 males, nine females) performed an Ultimatum Game (UG) and a Dictator Game (DG) where third-party punishment of observed unfairness was required. In addition, patients were tested for neurocognition and the ability to understand other people's mental states ("theory of mind"). For comparison, a clinical control group of 30 patients with chronic schizophrenia, and 30 unaffected healthy controls matched for age and verbal intelligence took part in the study.

RESULTS

Patients with HD had some appreciation of fairness rules, as they tended to reject unfair offers in the UG similar to controls. However, unlike the other two groups, individuals with HD did not punish observed unfairness from a third-party perspective. This lack of "altruistic punishment" was associated with deficits in executive functioning including working memory, inhibitory control and cognitive flexibility, and to a lesser degree with poor "theory of mind."

CONCLUSIONS

HD seems to be associated with impairments in understanding of more complex rules of social exchange. Aside from deficits in executive functioning, this behavior could, in part, be linked to an inability to experience third-party punishment as rewarding.

Mood and emotional disorders associated with parkinsonism, Huntington disease, and other movement disorders

This chapter provides a review of mood, emotional disorders, and emotion processing deficits associated with diseases that cause movement disorders, including Parkinson's disease, Lewy body dementia, multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, frontotemporal dementia with parkinsonism, Huntington's disease, essential tremor, dystonia, and tardive dyskinesia. For each disorder, a clinical description of the common signs and symptoms, disease progression, and epidemiology is provided. Then the mood and emotional disorders associated with each of these diseases are described and discussed in terms of clinical presentation, incidence, prevalence, and alterations in quality of life. Alterations of emotion communication, such as affective speech prosody and facial emotional expression, associated with these disorders are also discussed. In addition, if applicable, deficits in gestural and lexical/verbal emotion are reviewed. Throughout the chapter, the relationships among mood and emotional disorders, alterations of emotional experiences, social communication, and quality of life, as well as treatment, are emphasized.

Face pareidolia in the brain: Impact of gender and orientation

Research on face sensitivity is of particular relevance during the rapidly evolving Covid-19 pandemic leading to social isolation, but also calling for intact interaction and sharing. Humans possess high sensitivity even to a coarse face scheme, seeing faces in non-face images where real faces do not exist. The advantage of non-face images is that single components do not trigger face processing. Here by implementing a novel set of Face-n-Thing images, we examined (i) how face tuning alters with changing display orientation, and (ii) whether it is affected by observers’ gender. Young females and males were presented with a set of Face-n-Thing images either with canonical upright orientation or inverted 180° in the image plane. Face impression was substantially impeded by display inversion. Furthermore, whereas with upright display orientation, no gender differences were found, with inversion, Face-n-Thing images elicited face impression in females significantly more often. The outcome sheds light on the origins of the face inversion effect in general. Moreover, the findings open a way for examination of face sensitivity and underwriting brain networks in neuropsychiatric conditions related to the current pandemic (such as depression and anxiety), most of which are gender/sex-specific.

Abnormal visual scanning and impaired mental state recognition in pre-manifest Huntington disease

Huntington's disease (HD) is a genetic neurodegenerative disorder that affects not only the motor but also the cognitive and the neuropsychiatric domain. In particular, deficits in mental state recognition may emerge already at early pre-manifest stages of the disease. The aim of this research was to explore the relation between visual scanning behavior and complex mental state recognition in individuals with pre-manifest HD (preHD). Eighteen preHD and eighteen age- and gender-matched healthy controls took the revised "Reading the Mind in the Eyes" test while their eye-movements were tracked. In addition to the expected deficits in mental state recognition, preHD showed abnormalities concerning all three scanning variables we considered, namely the absolute number of fixations (FC), the average fixation duration (AFD), and the percentage of time spent fixating (FTR). In preHD, FC and FTR but not AFD predicted mental state recognition over and beyond general disease-related declines in cognition and motor functioning. Notably, preHD showed abnormal vertical and horizontal fixation patterns, and these patterns predicted mental state recognition, suggesting the involvement of mechanisms related to the embodied processing of emotional stimuli. Overall, our results suggest that impaired facial mental state recognition in pre-manifest HD is partly due to emotional-motivational factors affecting the visual scanning of facial expressions.

Social cognition and social functioning in patients with amnestic mild cognitive impairment or Alzheimer's dementia

The aim of the present study was to examine social cognition and social functioning in a group of amnestic mild cognitive impairment (aMCI) and Alzheimer’s dementia (AD) patients. Thirty one people with aMCI, 29 individuals with AD, and 45 healthy older adults participated in the study. Facial expressions of happiness, anger, fear, disgust, and surprise presented in different intensities had to be labelled. Mentalizing was assessed using first‐order belief theory of mind (ToM) stories and everyday social functioning by the Inventory of Interpersonal Situations (IIS), completed by an informant. aMCI patients were impaired in recognizing the emotions anger, disgust, and fear, while AD patients were impaired in recognizing the emotions anger, disgust, and surprise. More importantly, no significant differences between aMCI and AD patients were found on overall emotion recognition. Both the aMCI and AD patients were impaired on the ToM task, but no differences between the aMCI and AD patients were found. On everyday social functioning, only the AD patients showed impairments. No associations between the IIS and ToM were found, but the IIS and emotion perception were significantly correlated. Regression analysis taking all potentially confounding variables into account showed that only mood, but not the social‐cognitive task performance or any other cognitive variable, predicted social functioning. aMCI and AD patients demonstrated impairments in mentalizing and facial emotion perception, and showed decrements in everyday social functioning. Informing caregivers about these deficits may help them to understand deficits in social cognition that may be present already in the MCI stage of Alzheimer’s disease.

Mesenchymal stromal cells (MSCs) for neurodegenerative disease: A promising frontier

Neurodegenerative disorders are a variety of diseases including Alzheimer's (AD), Parkinson's (PD), and Huntington's diseases (HD), multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS) along with some other less common diseases generally described by the advanced deterioration of central or peripheral nervous system, structurally or functionally. In the last two decades, mesenchymal stromal cells (MSCs) due to their unique assets encompassing self-renewal, multipotency and accessibility in association with low ethical concern open new frontiers in the context of neurodegenerative diseases therapy. Interestingly, MSCs can be differentiated into endodermal and ectodermal lineages (e.g., neurons, oligodendrocyte, and astrocyte), and thus could be employed to advance cell-based therapeutic strategy. Additionally, as inflammation ordinarily ensues as a local response provoked by microglia in the neurodegenerative diseases, MSCs therapy because of their pronounced immunomodulatory properties is noticed as a rational approach for their treatment. Recently, varied types of studies have been mostly carried out in vitro and rodent models using MSCs upon their procurement from various sources and expansion. The promising results of the studies in rodent models have motivated researchers to design and perform several clinical trials, with a speedily rising number. In the current review, we aim to deliver a brief overview of MSCs sources, expansion strategies, and their immunosuppressive characteristics and discuss credible functional mechanisms exerted by MSCs to treat neurodegenerative disorders, covering AD, PD, ALS, MS, and HD.

Age-related alteration of emotional regulation in the BACHD rat model of Huntington disease

Huntington's disease (HD) is a genetic neurodegenerative disorder, caused by an expanded CAG repeat in the gene encoding the huntingtin protein. At the premanifest phase, before motor symptoms occur, psychiatric and emotional disorders are observed with high prevalence in HD patients. Agitation, anxiety and irritability are often described but also depression and/or apathy, associated with a lack of emotional control. The aim of the present study was to better circumscribe and understand the emotional symptoms and assess their evolution according to the progression of the disease using a transgenic HD model, BACHD rats, at the age of 4, 12 and 18 months. To achieve this goal, we confronted animals to two types of tests: first, tests assessing anxiety like the light/dark box and the conflict test, which are situations that did not involve an obvious threat and tests assessing the reactivity to a present threat using confrontation with an unknown conspecific (social behavior test) or with an aversive stimulus (fear conditioning test). In all animals, results show an age-dependent anxiety-like behavior, particularly marked in situation requiring passive responses (light/dark box and fear conditioning tests). BACHD rats exhibited a more profound alteration than WT animals in these tests from an early stage of the disease whereas, in tasks requiring some kind of motivation (for food or for social contacts), only old BACHD rats showed high anxiety-like behavior compared to WT, may be partly due to the other symptoms' occurrence at this stage: locomotor difficulties and/or apathy.

Induced pluripotent stem cells (iPSCs) as game-changing tools in the treatment of neurodegenerative disease: Mirage or reality?

Based on investigations, there exist tight correlations between neurodegenerative diseases' incidence and progression and aberrant protein aggregreferates in nervous tissue. However, the pathology of these diseases is not well known, leading to an inability to find an appropriate therapeutic approach to delay occurrence or slow many neurodegenerative diseases' development. The accessibility of induced pluripotent stem cells (iPSCs) in mimicking the phenotypes of various late-onset neurodegenerative diseases presents a novel strategy for in vitro disease modeling. The iPSCs provide a valuable and well-identified resource to clarify neurodegenerative disease mechanisms, as well as prepare a promising human stem cell platform for drug screening. Undoubtedly, neurodegenerative disease modeling using iPSCs has established innovative opportunities for both mechanistic types of research and recognition of novel disease treatments. Most important, the iPSCs have been considered as a novel autologous cell origin for cell-based therapy of neurodegenerative diseases following differentiation to varied types of neural lineage cells (e.g. GABAergic neurons, dopamine neurons, cortical neurons, and motor neurons). In this review, we summarize iPSC-based disease modeling in neurodegenerative diseases including Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, and Huntington's disease. Moreover, we discuss the efficacy of cell-replacement therapies for neurodegenerative disease.