Social brain dysfunctions in patients with Parkinson's disease: a review of theory of mind studies

GBA moderates cognitive reserve's effect on cognitive function in patients with Parkinson's disease

BACKGROUND

Cognitive reserve (CR) involves an individual's ability to maintain cognitive vitality over their lifespan. Glucocerebrosidase (GBA) gene mutations contribute to additional effects on cognitive function in Parkinson's disease (PD) patients, but the interplay between GBA mutations and CR remains unclear. We investigated the interactions among CR, GBA, and diseases, aiming to examine whether the CR established at different stages interacts with specific genotypes to affect cognitive function.

METHODS

Three hundred and eighteen participants' CR indicators (i.e., education, occupation, and social function) and comprehensive neuropsychological function (i.e., tests for executive function, attention/working memory, visuospatial function, memory, and language) were evaluated.

RESULTS

We found that CR established in a specific life stage influences the individual's cognitive function, particularly in PD, based on their distinct GBA rs9628662 genotypes. Attention/working memory and memory performance are affected by occupational complexity in midlife in PD patients with the GG genotype (q < 0.0001; q < 0.0001) and healthy adults with the T genotype (q = 0.0440; q < 0.0001). Language is influenced by early education and occupation, and the effects of occupation are also observed in PD patients with the GG genotype (q = 0.0040) and in healthy adults carrying the T genotype (q = 0.0040).

CONCLUSIONS

CR, established at different life stages, can be influenced by the GBA rs9628662 genotype, impacting later-life cognition. Validating genotypes and incorporating genotype information when assessing cognitive reserve effects is crucial and can enhance targeted cognitive training.

Theory of Mind: A Brief Review of Candidate Genes

Deficits in theory of mind (ToM), known as the ability to understand the other's mind, have been associated with several psychopathological outcomes. The present systematic review aims to summarize the results of genetic studies that investigated gene polymorphisms associated with mentalization performance tasks in children and adults. The systematic review was carried out following PRISMA guidelines, and the literature search was conducted in PubMed and EBSCOhost using the following keywords: 'theory of mind, mentalizing, mindreading' and 'gene, genetic basis'. Nineteen studies met the eligibility criteria for inclusion. Most of the literature focused on the role of DRD4, DAT1, OXTR, OXT, COMT, ZNF804A, AVP, AVPR, SCL6A4, EFHC2, MAO-A, and the family of GTF2I genes in influencing ToM. However, controversial results emerged in sustaining the link between specific genetic polymorphisms and mentalization abilities in children and adults. Available data show heterogeneous outcomes, with studies reporting an association between the same family genes in subjects of the same age and other studies reporting no correlation. This does not allow us to draw any solid conclusions but paves the way for exploring genes involved in ToM tasks.

Neurocognitive Impairment and Social Cognition in Parkinson's Disease Patients

In addition to motor symptoms, neurocognitive impairment (NCI) affects patients with prodromal Parkinson's disease (PD). NCI in PD ranges from subjective cognitive complaints to dementia. The purpose of this review is to present the available evidence of NCI in PD and highlight the heterogeneity of NCI phenotypes as well as the range of factors that contribute to NCI onset and progression. A review of publications related to NCI in PD up to March 2023 was performed using PubMed/Medline. There is an interconnection between the neurocognitive and motor symptoms of the disease, suggesting a common underlying pathophysiology as well as an interconnection between NCI and non-motor symptoms, such as mood disorders, which may contribute to confounding NCI. Motor and non-motor symptom evaluation could be used prognostically for NCI onset and progression in combination with imaging, laboratory, and genetic data. Additionally, the implications of NCI on the social cognition of afflicted patients warrant its prompt management. The etiology of NCI onset and its progression in PD is multifactorial and its effects are equally grave as the motor effects. This review highlights the importance of the prompt identification of subjective cognitive complaints in PD patients and NCI management.

The Impact of Parkinson's Disease on Social Communication: An Exploratory Questionnaire Study

Individuals with Parkinson's disease (PD) often show breakdown in the production and interpretation of aspects of social communication. However, there is no current method of assessment for evaluating social communication dysfunction in individuals with PD. The aim of this study was to develop a self-report questionnaire for individuals with PD to identify their social communication skills, and further recognize the impact of PD on social communication. Fifty-one individuals with Parkinson's disease answered 28 survey questions. These questions pertained to emotional expression and perception, social communication, sarcasm/humor, and pragmatic skills. Exploratory factor analysis and reliability analysis were conducted to identify items loading onto the factors and to check the internal consistency of the items. Individuals with PD reported changes in emotional expression and perception, social communication, sarcasm and humor, and pragmatic skill domains post-PD diagnosis. No correlations were found between age or time since diagnosis and emotional expression, social communication, sarcasm, and humor. This study provides self-reported evidence that individuals with PD experience social communication challenges. Future research should further quantify these challenges, study their impact on daily communicative functioning, and use the results to develop social communication interventions that improve the quality of life for persons with PD.

Investigating the interaction between neuropsychiatry features and daily activities on social function in patients with Parkinson's disease with mild cognitive impairment

BACKGROUND

Social functioning is crucial for daily living and is an essential indicator of dementia in patients with Parkinson's disease. The pattern of social functioning in patients with Parkinson's disease without dementia (i.e. those who are cognitively intact or have mild cognitive impairment (PD-MCI)) and its determinants are unclear.

AIMS

In exploring the heterogeneity of social functioning among patients with Parkinson's disease-associated dementia, we determined the optimal cut-off score of the Parkinson's Disease Social Functioning Scale (PDSFS) for patients with PD-MCI, and the variables influencing patients' social functioning.

METHOD

A total of 302 participants underwent the Mini-Mental State Examination (MMSE) and PDSFS; 120 patients with Parkinson's disease completed the measurements (MMSE, Activities of Daily Living Scale and Neuropsychiatric Inventory). Group comparisons, receiver operating characteristic curves, Spearman correlation and multiple and hierarchical regression analyses were conducted.

RESULTS

The PD-MCI group scored the lowest on the PDSFS (F = 10.10, P < 0.001). The PDSFS cut-off score was 53 (area under the curve 0.700, sensitivity 0.800, specificity 0.534). The MMSE (β = 0.293, P = 0.002), Activities of Daily Living Scale (β = 0.189, P = 0.028) and Neuropsychiatric Inventory (β = -0.216, P = 0.005) scores predicted the PDSFS score. Further, there was an interaction effect between the Activities of Daily Living Scale and Neuropsychiatric Inventory scores on the PDSFS score (β = 0.305, P < 0.001).

CONCLUSIONS

We determined a PDSFS cut-off score for detecting PD-MCI and found that patients with PD-MCI have social dysfunction. Future research should focus on the effects of neuropsychiatry symptoms and activities of daily living on social functioning, and tailor the intervention programme for patients with Parkinson's disease.

Mild cognitive impairment in patients with Parkinson’s disease: An updated mini-review and future outlook

Mild cognitive impairment (MCI) is one of the common non-motor symptoms in patients with Parkinson’s disease (PD). MCI is the transition stage between normal aging and full-blown dementia and is also a powerful predictor of dementia. Although the concept of MCI has been used to describe some of the PD symptoms for many years, there is a lack of consistent diagnostic criteria. Moreover, because of the diverse patterns of the cognitive functions, each cognitive impairment will have a different progression. In this review, we overviewed the diagnostic criteria for PD-MCI, primarily focused on the heterogeneity of PD-MCI patients’ cognitive function, including various types of cognitive functions and their progression rates. A review of this topic is expected to be beneficial for clinical diagnosis, early intervention, and treatment. In addition, we also discussed the unmet needs and future vision in this field.

A New Instrument Combines Cognitive and Social Functioning Items for Detecting Mild Cognitive Impairment and Dementia in Parkinson’s Disease

Background

The commonly used screening tests for Parkinson’s disease (PD) are the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE), both of which only focus on cognitive function. A composite assessment that considers both cognitive and social dysfunction in PD would be helpful in detecting mild cognitive impairment (MCI) and PD dementia (PDD).

Objective

We aimed to simplify the commonly used tools and combine cognitive and social functioning tests to detect early MCI and PDD.

Materials and Methods

A total of 166 participants (84 PD patients and 82 healthy) were recruited who completed the MMSE, MoCA, PD social functioning scale (PDSFS), clock drawing test, activities of daily living, comprehensive neuropsychological assessment (e.g., executive, attention, language, memory, and visuospatial functions), and movement disorder society (MDS)-unified PD rating scale. According to the MDS diagnostic criteria, the patients were grouped into PD-nonMCI, PD-MCI, or PDD.

Results

To detect PD-MCI, the optimal cut-off scores for the simplified MoCA and the combined test were 9 and 35. The discrimination values measured by the area under the receiver operating characteristic curve (AUC) of the two tests were 0.767 (p < 0.001) and 0.790 (p < 0.001). When the simplified MoCA was 7 or the combined test 30, the patients would be classified as having PDD. The AUCs of the two tests were 0.846 (p < 0.001) and 0.794 (p = 0.003).

Conclusion

We suggest considering both cognitive and social functions when detecting PD-MCI and PDD.

The Neurobiological Correlates of Gaze Perception in Healthy Individuals and Neurologic Patients

The ability to adaptively follow conspecific eye movements is crucial for establishing shared attention and survival. Indeed, in humans, interacting with the gaze direction of others causes the reflexive orienting of attention and the faster object detection of the signaled spatial location. The behavioral evidence of this phenomenon is called gaze-cueing. Although this effect can be conceived as automatic and reflexive, gaze-cueing is often susceptible to context. In fact, gaze-cueing was shown to interact with other factors that characterize facial stimulus, such as the kind of cue that induces attention orienting (i.e., gaze or non-symbolic cues) or the emotional expression conveyed by the gaze cues. Here, we address neuroimaging evidence, investigating the neural bases of gaze-cueing and the perception of gaze direction and how contextual factors interact with the gaze shift of attention. Evidence from neuroimaging, as well as the fields of non-invasive brain stimulation and neurologic patients, highlights the involvement of the amygdala and the superior temporal lobe (especially the superior temporal sulcus (STS)) in gaze perception. However, in this review, we also emphasized the discrepancies of the attempts to characterize the distinct functional roles of the regions in the processing of gaze. Finally, we conclude by presenting the notion of invariant representation and underline its value as a conceptual framework for the future characterization of the perceptual processing of gaze within the STS.

Social Cognition and Cognitive Decline in Patients with Parkinson's Disease

Social cognition (SC) comprises an array of cognitive and affective abilities such as social perception, theory of mind, empathy, and social behavior. Previous studies have suggested the existence of deficits in several SC abilities in Parkinson disease (PD), although not unanimously.

OBJECTIVE

The aim of this study is to assess the SC construct and to explore its relationship with cognitive state in PD patients.

METHOD

We compare 19 PD patients with cognitive decline, 27 cognitively preserved PD patients, and 29 healthy control (HC) individuals in social perception (static and dynamic emotional facial recognition), theory of mind, empathy, and social behavior tasks. We also assess processing speed, executive functions, memory, language, and visuospatial ability.

RESULTS

PD patients with cognitive decline perform worse than the other groups in both facial expression recognition tasks and theory of mind. Cognitively preserved PD patients only score worse than HCs in the static facial expression recognition task. We find several significant correlations between each of the SC deficits and diverse cognitive processes.

CONCLUSIONS

The results indicate that some components of SC are impaired in PD patients. These problems seem to be related to a global cognitive decline rather than to specific deficits. Considering the importance of these abilities for social interaction, we suggest that SC be included in the assessment protocols in PD.

Social Cognition in Patients with Early-Onset Parkinson's Disease

Social cognition (SC) deficits have been linked to Parkinson's disease (PD) but have been less well researched than general cognitive processes, especially in early-onset PD (EOPD), despite this population often having greater social and family demands. Most studies focus on recognition of facial emotion, theory of mind (ToM), and decision-making domains, with limited research reporting on social reasoning. The main objective of this work was to compare SC ability across four domains: emotional processing, social reasoning, ToM, and decision-making between patients with EOPD and healthy controls. Twenty-five nondemented patients with EOPD and 25 controls matched for sex, age, and educational level were enrolled. A battery that included six SC tests was administered to all study participants; a decision-making scale was completed by participants' partners. Statistically significant differences were found between patients with EOPD and controls in all subtests across the four SC domains studied. The EOPD group demonstrated worse performance on all tasks, with large effect sizes. Differences remained significant after adjusting for Montreal Cognitive Assessment (MoCA) test scores for all SC subtests except the decision-making scale and the Iowa gambling task. No significant correlations between SC and other clinical PD variables were found. Our study shows that patients with EOPD perform significantly below controls in multiple SC domains affecting recognition of facial emotion, social reasoning, ToM, and decision-making. Only decision-making seems to be mediated by overall cognitive ability. The confounding or contributing effect of other clinical PD variables should be studied further.

Transcranial direct current stimulation enhances theory of mind in Parkinson's disease patients with mild cognitive impairment: a randomized, double-blind, sham-controlled study

Background

Parkinson’s Disease (PD) with mild cognitive impairment (MCI) (PD-MCI) represents one of the most dreaded complications for patients with PD and is associated with a higher risk of developing dementia. Although transcranial direct current stimulation (tDCS) has been demonstrated to improve motor and non-motor symptoms in PD, to date, no study has investigated the effects of tDCS on Theory of Mind (ToM), i.e., the ability to understand and predict other people’s behaviours, in PD-MCI.

Methods

In this randomized, double-blind, sham-controlled study, we applied active tDCS over the medial frontal cortex (MFC) to modulate ToM performance in twenty patients with PD-MCI. Twenty matched healthy controls (HC) were also enrolled and were asked to perform the ToM task without receiving tDCS.

Results

In the patients with PD-MCI, i) ToM performance was worse than that in the HC, ii) ToM abilities were poorer in those with fronto-executive difficulties, and iii) tDCS over the MFC led to significant shortening of latency for ToM tasks.

Conclusions

We show for the first time that active tDCS over the MFC enhances ToM in patients with PD-MCI, and suggest that non-invasive brain stimulation could be used to ameliorate ToM deficits observed in these patients.

Emotion-Specific Affective Theory of Mind Impairment in Parkinson's Disease

The neuropathology of Parkinson’s disease (PD) involves the frontal-subcortical circuit, an area responsible for processing affective theory of mind (ToM). Patients with PD are expected to experience deficits in the affective ToM. This study aims to investigate whether the ability to infer emotion in others is affected in either young-onset Parkinson’s disease (YOPD) or middle-onset PD (MOPD) patients and to test whether the impairments in affective ToM are associated with the motor symptoms. The affective ToM, global mental abilities, and clinical symptoms were assessed in a total of 107 MOPD, 30 YOPD, and 30 normal controls (NCs). The MOPD patients exhibited deficits in affective ToM to the negative and neutral valences, when compared to the participants in the NCs and YOPD group. By conducting gender-stratified analysis, the deficits in affective ToM was only found in female participants. After adjusting for demographic variables, the multiple linear regression model revealed that affective ToM predicted motor symptoms, especially in female MOPD patients. The present study may aid in the development of medical care programs by advocating for a more comprehensive therapeutic plan that includes continuous disease progression monitoring and social skills training for female MOPD patients or their caregivers.

Cognitive and Affective Theory of Mind in Mild Cognitive Impairment and Parkinson's Disease: Preliminary Evidence from the Italian Version of the Yoni Task

The aim of the study was to explore cognitive and affective dimensions of ToM using the computerized Yoni task in participants with amnestic Mild Cognitive Impairment (aMCI=16), early stage of Parkinson's Disease (PD=14), and healthy controls (HC=18) Results demonstrated that the Yoni task was effective in discriminating between groups in 1^th order cognitive dimension (MCI<PD=HC, p_corr<.05), and in 2^nd order cognitive and affective dimensions (MCI<HC, p_corr <.05), highlighting a reduced ToM performance also in people with PD (MCI<PD<HC, p_corr <.05). Thus, the Yoni task represents a sensitive tool for detecting different dimensions of ToM impairment, across different clinical conditions.

A novel framework for understanding reduced awareness of dyskinesias in Parkinson's Disease

BACKGROUND

Although dyskinesias-reduced-self-awareness (DRSA) in Parkinson's disease (PD) is related to deficit in metacognition, other factors, such as "Theory of Mind" (ToM), could operate.

METHODS

Forty-one PD patients were assessed using the Global Awareness of Movement Disorders (GAM) and the Dyskinesias Subtracted-Index (DS-I). To study whether GAM and DS-I scores could be influenced by second-type ToM or Reading the Mind in the Eyes (RME) tasks, we conducted two multiple logistic regression analyses.

RESULTS

The association between the GAM, the DS-I and RME task were highly significant. The association between DS-I and Trail Making Test B-A version was also verified.

CONCLUSION

DRSA was related with affective component of ToM and executive functions, thus caused by a complex interplay between specific neuropsychological and motor factors.

Nonmotor Symptoms in Parkinson Disease: A Descriptive Review on Social Cognition Ability

Parkinson disease (PD) is a neurodegenerative disorder characterized by motor and nonmotor symptoms. Nonmotor symptoms include cognitive deficits and impairment in emotions recognition ability associated with loss of dopaminergic neurons in the substantia nigra and with alteration in frontostriatal circuits. In this review, we analyzed the studies on social cognition ability in patients with PD. We searched on PubMed and Web of Science databases and screening references of included studied and review articles for additional citations. From initial 260 articles, only 18 met search criteria. A total of 496 patients were compared with 514 health controls, through 16 different tests that assessed some subcomponents of social cognition, such as theory of mind, decision-making, and emotional face recognition. Studies on cognitive function in patients with PD have focused on executive function. Patients with PD showed impairment in social cognition from the earliest stages of disease. This ability seems to not be significantly associated with other cognitive functions.

Parkinson Patients' Initial Trust in Avatars: Theory and Evidence

Parkinson's disease (PD) is a neurodegenerative disease that affects the motor system and cognitive and behavioral functions. Due to these impairments, PD patients also have problems in using the computer. However, using computers and the Internet could help these patients to overcome social isolation and enhance information search. Specifically, avatars (defined as virtual representations of humans) are increasingly used in online environments to enhance human-computer interaction by simulating face-to-face interaction. Our laboratory experiment investigated how PD patients behave in a trust game played with human and avatar counterparts, and we compared this behavior to the behavior of age, income, education and gender matched healthy controls. The results of our study show that PD patients trust avatar faces significantly more than human faces. Moreover, there was no significant difference between initial trust of PD patients and healthy controls in avatar faces, while PD patients trusted human faces significantly less than healthy controls. Our data suggests that PD patients' interaction with avatars may constitute an effective way of communication in situations in which trust is required (e.g., a physician recommends intake of medication). We discuss the implications of these results for several areas of human-computer interaction and neurological research.

Memory for gist and detail information in patients with Parkinson's disease

OBJECTIVE

Memory formation is proposed to be a dual process that involves the simultaneous memorisation of both detailed information (item-specific memory) and gist information (gist memory). Memory deficits have been reported in patients with Parkinson's disease (PD); however, few studies have explicitly addressed the nature of these deficits. To obtain a detailed understanding of memory dysfunction in patients with PD, it is of crucial importance to establish whether item-specific memory and gist memory performance are impaired. The aim of this study is to explore whether gist memory and item-specific memory performance are still intact in patients with PD, as well as to determine which psychological mechanisms are responsible for memory formation.

SETTING

Two hospitals in northern Taiwan.

PARTICIPANTS

Thirty-nine patients with PD and 28 normal controls were recruited. Each participant received a gist-based recognition test following the Deese-Roediger-McDermott paradigm, as well as neuropsychological tests and measures of clinical characteristics.

RESULTS

Gist memory was impaired in patients with advanced-stage disease (Hoehn and Yahr (H&Y) stage: III) (F2,64=3.58, p=0.033), whereas item-specific memory was preserved throughout all disease stages. Correlation analysis showed that item-specific memory was related to executive functions in normal controls and early-stage patients with PD (H&Y stage: I-II); however, item-specific memory was related to episodic memory, rather than to executive functions, in advanced-stage patients with PD. Moreover, gist memory was related to episodic memory, but only in early-stage patients with PD.

CONCLUSIONS

We discovered that impaired gist memory is found in advanced-stage, but not in early-stage, patients with PD. Our findings suggest that the techniques used to take advantage of the relatively preserved gist memory in early-stage patients with PD, as well as the preserved item-specific memory in patients with PD of all stages, could be useful for memory rehabilitation programmes.

Neuroanatomical Correlates of Theory of Mind Deficit in Parkinson's Disease: A Multimodal Imaging Study

BACKGROUND

Parkinson's disease (PD) patients show theory of mind (ToM) deficit since the early stages of the disease, and this deficit has been associated with working memory, executive functions and quality of life impairment. To date, neuroanatomical correlates of ToM have not been assessed with magnetic resonance imaging in PD. The main objective of this study was to assess cerebral correlates of ToM deficit in PD. The second objective was to explore the relationships between ToM, working memory and executive functions, and to analyse the neural correlates of ToM, controlling for both working memory and executive functions.

METHODS

Thirty-seven PD patients (Hoehn and Yahr median = 2.0) and 15 healthy controls underwent a neuropsychological assessment and magnetic resonance images in a 3T-scanner were acquired. T1-weighted images were analysed with voxel-based morphometry, and white matter integrity and diffusivity measures were obtained from diffusion weighted images and analysed using tract-based spatial statistics.

RESULTS

PD patients showed impairments in ToM, working memory and executive functions; grey matter loss and white matter reduction compared to healthy controls. Grey matter volume decrease in the precentral and postcentral gyrus, middle and inferior frontal gyrus correlated with ToM deficit in PD. White matter in the superior longitudinal fasciculus (adjacent to the parietal lobe) and white matter adjacent to the frontal lobe correlated with ToM impairment in PD. After controlling for executive functions, the relationship between ToM deficit and white matter remained significant for white matter areas adjacent to the precuneus and the parietal lobe.

CONCLUSIONS

Findings reinforce the existence of ToM impairment from the early Hoehn and Yahr stages in PD, and the findings suggest associations with white matter and grey matter volume decrease. This study contributes to better understand ToM deficit and its neural correlates in PD, which is a basic skill for development of healthy social relationships.

Cognitive neuroscience of human counterfactual reasoning

Counterfactual reasoning is a hallmark of human thought, enabling the capacity to shift from perceiving the immediate environment to an alternative, imagined perspective. Mental representations of counterfactual possibilities (e.g., imagined past events or future outcomes not yet at hand) provide the basis for learning from past experience, enable planning and prediction, support creativity and insight, and give rise to emotions and social attributions (e.g., regret and blame). Yet remarkably little is known about the psychological and neural foundations of counterfactual reasoning. In this review, we survey recent findings from psychology and neuroscience indicating that counterfactual thought depends on an integrative network of systems for affective processing, mental simulation, and cognitive control. We review evidence to elucidate how these mechanisms are systematically altered through psychiatric illness and neurological disease. We propose that counterfactual thinking depends on the coordination of multiple information processing systems that together enable adaptive behavior and goal-directed decision making and make recommendations for the study of counterfactual inference in health, aging, and disease.

The impact of nocturnal disturbances on daily quality of life in patients with Parkinson's disease

OBJECTIVES

The aims of this study were to explore nocturnal disturbances in patients with Parkinson's disease (PD) and to assess their impact on quality of life (QoL).

METHODS

A total of 211 patients with PD were recruited for this study, and each participant was evaluated using the mini-mental state examination, PD sleep scale - second version (PDSS-2), pittsburgh sleep quality index (PSQI), PD QoL questionnaire (PDQ), Epworth sleepiness scale, Hoehn and Yahr (H&Y) staging, and unified Parkinson's disease rating scale (UPDRS). Multiple regression analyses were performed to determine the contribution of the predictive variables on QoL.

RESULTS

There were 56.4% males (mean age: 64.08 years; disease duration: 6.02 years; H&Y stage: 2.25; and UPDRS: 33.01) in this study. Our patients' actual sleep time was 5.96±1.16 hours and the average sleep efficiency was 82.93%±12.79%. Up to 64.4% of patients were classified as "poor" sleepers and 23.8% suffered from daytime sleepiness. The final stepwise regression model revealed that UPDRS parts I and II, the sleep disturbance and daytime dysfunction components of the PSQI, the PD symptoms at night subscale of the PDSS-2, and the levodopa equivalent dose were significant predictors of the PDQ score (R (2)=53, F 7,165=28.746; P<0.001).

CONCLUSION

Most of the PD patients have sleep problems, and nearly one-quarter of them have abnormal daytime somnolence. The nocturnal disturbances were found to result in worse QoL in PD patients. Ethnicity-specific effects of susceptibility to sleep disturbances were discussed, and these results also highlighted the direction for further studies to explore when examining effective management programs toward these disturbances.