Through your eyes or mine? The neural correlates of mental state recognition in Huntington's disease

Basal ganglia contributions to social cognition: evidence from movement disorders

Introduction and method: Over the last few decades many studies have demonstrated that various populations with movement disorder exhibit a variety of difficulties with social cognition. This brief review paper summarises the major findings of social cognitive research conducted in various hypo- and hyper-kinetic movement disorders (Parkinson's disease, Huntington's disease and Tourette syndrome), with a focus on findings that may shed new light on the functions of the basal ganglia.Results: Task impairments include more predictable difficulties with embodied processes involving the motor system, such as problems with facial expressions and other non-verbal gestures. The cognitive and emotional changes associated with broader frontostriatal dysfunction may also explain some deficits, particularly difficulties with verbal tasks or perspective taking, with impacts varying according to the type of disorder and disease stage. Most intriguingly, transdiagnostic comparisons reveal patterns implying that the role of the basal ganglia in social cognition may be more important than previously recognised.Conclusions: Movement disorders show remarkable overlap in terms of atypical intention attribution across various tasks, as well as relationships between social cognition and behavioural or motivational symptoms (e.g., apathy; anhedonia; impulsivity). The possible mechanisms underlying these similarities are explored with a view to guiding future research.

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.

Assessing social cognition in patients with schizophrenia and healthy controls using the reading the mind in the eyes test (RMET): a systematic review and meta-regression

The reading the mind in the eyes test (RMET) - which assesses the theory of mind component of social cognition - is often used to compare social cognition between patients with schizophrenia and healthy controls. There is, however, no systematic review integrating the results of these studies. We identified 198 studies published before July 2020 that administered RMET to patients with schizophrenia or healthy controls from three English-language and two Chinese-language databases. These studies included 41 separate samples of patients with schizophrenia (total n = 1836) and 197 separate samples of healthy controls (total n = 23 675). The pooled RMET score was 19.76 (95% CI 18.91-20.60) in patients and 25.53 (95% CI 25.19-25.87) in controls (z = 12.41, p < 0.001). After excluding small-sample outlier studies, this difference in RMET performance was greater in studies using non-English v. English versions of RMET (Chi [Q] = 8.54, p < 0.001). Meta-regression analyses found a negative association of age with RMET score and a positive association of years of schooling with RMET score in both patients and controls. A secondary meta-analysis using a spline construction of 180 healthy control samples identified a non-monotonic relationship between age and RMET score - RMET scores increased with age before 31 and decreased with age after 31. These results indicate that patients with schizophrenia have substantial deficits in theory of mind compared with healthy controls, supporting the construct validity of RMET as a measure of social cognition. The different results for English versus non-English versions of RMET and the non-monotonic relationship between age and RMET score highlight the importance of the language of administration of RMET and the possibility that the relationship of aging with theory of mind is different from the relationship of aging with other types of cognitive functioning.

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.

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.

The non-human animal reading the mind in the eyes test (NARMET): A new measure for the assessment of social cognition

The Reading the Mind in the Eyes test (RMET) is a widely applied test of social cognition, based on mental state judgments in response to photographs of human eyes, which can elicit impairment in patients with numerous psychiatric and neurological disorders. However, interpretation of task performance is limited without the use of appropriate control tasks. In addition to a matched task requiring age judgments of the RMET stimuli, it was recently shown that a mental state judgment task of comparable difficulty, could be developed using photographs of domestic cat eyes. The current study aimed to further develop a Non-human Animal RMET (NARMET) by testing additional stimuli in the form of photographs of domestic dog eyes. A variety of additional tasks were used alongside the eyes test stimuli in a large sample of healthy young adults, to explore how alexithymia, schizotypal features, and autistic tendencies may differentially influence mental state attribution in response to cat, dog, and human eyes test stimuli. The resulting NARMET features both cat and dog trials, depicting a similar range of complex mental states to the human RMET. It shows favorable psychometric properties as well as being well matched to the RMET in terms of linguistic variables, length and difficulty. However, reading measures predicted performance on the RMET, but not on the NARMET. Although further testing is required in samples with a higher proportion of males, future application of the NARMET in neuropsychiatric populations exhibiting cognitive and behavioral difficulties could offer enhanced assessment of social cognitive skills.

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 quality of life in Huntington's disease

Individuals with Huntington's disease (HD) and their close others report difficulties with social interaction, and previous studies have shown that the areas of quality of life detrimentally impacted by HD include social and emotional domains. However, despite the finding that people with HD often exhibit difficulties on standard tests of social cognition, the relationship between such impairments and patients' everyday life has remained largely unexplored. We used a range of tasks assessing empathy, emotion recognition and Theory of Mind, to investigate whether patients' performance may predict quality of life within the social and emotional domains, while also accounting for broader cognitive function, behavioural changes, motor symptoms, disease stage and functional capacity. Poorer social functioning was predicted specifically by a reduced tendency to attribute intentionality while viewing social animations, in addition to emotional blunting and apathy, while role limitations due to emotional problems were predicted by personal distress, irritability and aspects of executive function. These findings highlight the potential impact of Theory of Mind impairment on quality of life in HD, and suggest that enhanced assessment of social cognition will offer unique insight into patients' social function and related wellbeing.

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.

Patterns of CAG repeat instability in the central nervous system and periphery in Huntington's disease and in spinocerebellar ataxia type 1

The expanded HTT CAG repeat causing Huntington’s disease (HD) exhibits somatic expansion proposed to drive the rate of disease onset by eliciting a pathological process that ultimately claims vulnerable cells. To gain insight into somatic expansion in humans, we performed comprehensive quantitative analyses of CAG expansion in ~50 central nervous system (CNS) and peripheral postmortem tissues from seven adult-onset and one juvenile-onset HD individual. We also assessed ATXN1 CAG repeat expansion in brain regions of an individual with a neurologically and pathologically distinct repeat expansion disorder, spinocerebellar ataxia type 1 (SCA1). Our findings reveal similar profiles of tissue instability in all HD individuals, which, notably, were also apparent in the SCA1 individual. CAG expansion was observed in all tissues, but to different degrees, with multiple cortical regions and neostriatum tending to have the greatest instability in the CNS, and liver in the periphery. These patterns indicate different propensities for CAG expansion contributed by disease locus-independent trans-factors and demonstrate that expansion per se is not sufficient to cause cell type or disease-specific pathology. Rather, pathology may reflect distinct toxic processes triggered by different repeat lengths across cell types and diseases. We also find that the HTT CAG length-dependent expansion propensity of an individual is reflected in all tissues and in cerebrospinal fluid. Our data indicate that peripheral cells may be a useful source to measure CAG expansion in biomarker assays for therapeutic efforts, prompting efforts to dissect underlying mechanisms of expansion that may differ between the brain and periphery.

What Do You Have in Mind? Measures to Assess Mental State Reasoning in Neuropsychiatric Populations

Social interaction is closely associated with both functional capacity and well-being. Previous research has not only revealed evidence of social dysfunction in individuals with a wide range of psychiatric and neurological disorders but also generated an abundance of potential measures for assessing social cognition. This review explores the most popular measures used within neuropsychiatric populations to investigate the ability to recognize or reason about the mental states of others. Measures are also critically analyzed in terms of strengths and limitations to aid task selection in future clinical studies. The most frequently applied assessment tools use verbal, visual or audiovisual forms of presentation and assess recognition of mental states from facial features, self-rated empathy, the understanding of other's cognitive mental states such as beliefs and intentions, or the ability to combine knowledge of other's thoughts and emotions in order to understand subtle communications or socially inappropriate behavior. Key weaknesses of previous research include limited investigation of relationships with clinical symptoms, and underutilization of measures of everyday social functioning that offer a useful counterpart to traditional "lab" tasks. Future studies should aim to carefully select measures not only based on the range of skills to be assessed but also taking into account potential difficulties with interpretation and the need to gain insight into the application of social cognitive skills as well as ability per se. Some of the best measures include those with well-matched control trials (e.g., Yoni Task) or those that restrict the influence of verbal deficits (e.g., intentions comic strip task), elicit spontaneous mentalizing (e.g., Animations Task), and possess greater ecological validity (e.g., Movie for the Assessment of Social Cognition). Social cognitive research within psychiatric populations will be further enhanced through the development of more closely matched control tasks, and the exploration of relationships between task performance, medication, strategy use, and broader emotional and motor functions.

Effects of stimulus-related variables on mental states recognition in Huntington's disease

BACKGROUND

Cognitive abnormalities in Huntington's Disease (HD) can involve the specific impairment of the social perspective taking as well as difficulties in recognizing others' mental state many years before the onset of motor symptoms.

AIMS

At the scope of assessing how the difficulties in mental state recognition might be an HD early sign before motor symptoms appear, our study was aimed to investigate how the recognition of others' mental states in HD subjects is moderated by different stimulus related features (gender, difficulty (low, medium, high), and valence (positive, negative, neutral) of the mental states that are to be recognized).

METHODS

Subjects with premanifest (n = 20) and manifest (n = 40) HD performed the revised 'Reading the Mind in the Eyes Test' and were compared with age-matched healthy controls (HC, 40 subjects per cohort).

RESULTS

Our results highlight an early impairment in mental state recognition preceding manifest HD symptoms and a deterioration of these abilities with HD progression. Moreover, we found in HD premanifest subjects an impairment concerning the recognition of negative and neutral mental states, as well as of mental states with moderate recognition difficulty. Finally, we found that participant gender did not influence the performance in recognizing others' mental states, while all participants recognized mental states displayed by females more accurately than those displayed by males.

CONCLUSIONS

We conclude that difficulties in the recognition of complex mental states can be considered as an early sign of HD, before evident behavioral manifestations, and peculiar features of the stimulus influence it.

Through your eyes or mine? The neural correlates of mental state recognition in Huntington's disease

Huntington's disease (HD) can impair social cognition. This study investigated whether patients with HD exhibit neural differences to healthy controls when they are considering mental and physical states relating to the static expressions of human eyes. Thirty-two patients with HD and 28 age-matched controls were scanned with fMRI during two versions of the Reading the Mind in the Eyes Task: The standard version requiring mental state judgments, and a comparison version requiring judgments about age. HD was associated with behavioral deficits on only the mental state eyes task. Contrasting the two versions of the eyes task (mental state > age judgment) revealed hypoactivation within left middle frontal gyrus and supramarginal gyrus in HD. Subgroup analyses comparing premanifest HD patients to age-matched controls revealed reduced activity in right supramarginal gyrus and increased activity in anterior cingulate during mental state recognition in these patients, while manifest HD was associated with hypoactivity in left insula and left supramarginal gyrus. When controlling for the effects of healthy aging, manifest patients exhibited declining activation within areas including right temporal pole. Our findings provide compelling evidence for a selective impairment of internal emotional status when patients with HD appraise facial features in order to make social judgements. Differential activity in temporal and anterior cingulate cortices may suggest that poor emotion regulation and emotional egocentricity underlie impaired mental state recognition in premanifest patients, while more extensive mental state recognition impairments in manifest disease reflect dysfunction in neural substrates underlying executive functions, and the experience and interpretation of emotion.