Assessing the “social brain” in dementia: Applying TASIT-S

Dissecting neural correlates of theory of mind and executive functions in behavioral variant frontotemporal dementia

Behavioral variant frontotemporal dementia (bvFTD) is characterized by profound and early deficits in social cognition (SC) and executive functions (EF). To date it remains unclear whether deficits of the respective cognitive domains are based on the degeneration of distinct brain regions. In 103 patients with a diagnosis of bvFTD (possible/probable/definite: N = 40/58/5) from the frontotemporal lobar degeneration (FTLD) consortium Germany cohort (age 62.5±9.4 years, gender 38 female/65 male) we applied multimodal structural imaging, i.e. voxel-based morphometry, cortical thickness (CTH) and networks of structural covariance via source based morphometry. We cross-sectionally investigated associations with performance in a modified Reading the Mind in the Eyes Test (RMET; reflective of theory of mind - ToM) and five different tests reflective of EF (i.e. Hamasch-Five-Point Test, semantic and phonemic Fluency, Trail Making Test, Stroop interference). Finally, we investigated the conjunction of RMET correlates with functional networks commonly associated with SC respectively ToM and EF as extracted meta-analytically within the Neurosynth database. RMET performance was mainly associated with gray matter volume (GMV) and CTH within temporal and insular cortical regions and less within the prefrontal cortex (PFC), whereas EF performance was mainly associated with prefrontal regions (GMV and CTH). Overlap of RMET and EF associations was primarily located within the insula, adjacent subcortical structures (i.e. putamen) and the dorsolateral PFC (dlPFC). These patterns were more pronounced after adjustment for the respective other cognitive domain. Corroborative results were obtained in analyses of structural covariance networks. Overlap of RMET with meta-analytically extracted functional networks commonly associated with SC, ToM and EF was again primarily located within the temporal and insular region and the dlPFC. In addition, on a meta-analytical level, strong associations were found for temporal cortical RMET correlates with SC and ToM in particular. These data indicate a temporo-frontal dissociation of bvFTD related disturbances of ToM and EF, with atrophy of the anterior temporal lobe being critically involved in ToM deficits. The consistent overlap within the insular cortex may be attributable to the multimodal and integrative role of this region in socioemotional and cognitive processing.

Neuroimaging meta-analyses reveal convergence of interoception, emotion, and social cognition across neurodegenerative diseases

INTRODUCTION

Simultaneous interoceptive, emotional, and social cognition deficits are observed across neurodegenerative diseases. Indirect evidence suggests shared neurobiological bases underlying these impairments, termed the allostatic-interoceptive network (AIN). However, no study has yet explored the convergence of these deficits in neurodegenerative diseases or examined how structural and functional changes contribute to cross-domain impairments.

METHODS

A PRISMA Activated Likelihood Estimate (ALE) metanalyses encompassed studies meeting inclusion criteria: interoception, emotion, or social cognition tasks; neurodegenerative diseases (behavioral variant frontotemporal dementia (bvFTD), primary progressive aphasias (PPAs) Alzheimer's disease (AD), Parkinson's Disease (PD), multiple sclerosis (MS)); and neuroimaging (structural: MRI voxel-based morphometry; functional: fMRI and FDG-PET).

RESULTS

From 20,593 studies, 170 met inclusion criteria (58 interoception, 65 emotion, and 47 social cognition) involving 7032 participants (4963 patients and 2069 healthy controls). In all participants combined, conjunction analyses revealed AIN involvement of the insula, amygdala, orbitofrontal cortex, anterior cingulate, striatum, thalamus, and hippocampus across domains. In bvFTD this conjunction was replicated across domains, with further involvement of the temporal pole, temporal fusiform cortex, and angular gyrus. A convergence of interoception and emotion in the striatum, thalamus, and hippocampus in PD and the posterior insula in PPAs was also observed. In AD and MS, disruptions in the AIN were observed during interoception, but no convergence with emotion was identified.

INTERPRETATION

Neurodegeneration induces dysfunctional AIN across atrophy, connectivity, and metabolism, more accentuated in bvFTD. Findings bolster the predictive coding theories of large-scale AIN, calling for more synergistic approaches to understanding interoception, emotion, and social cognition impairments in neurodegeneration.

Understanding the Psychosis Spectrum Using a Hierarchical Model of Social Cognition

BACKGROUND AND HYPOTHESIS

Social cognitive impairments are central to psychosis, including lower severity psychosis-like experiences (PLEs). Nonetheless, progress has been hindered by social cognition's poorly defined factor structure, as well as limited work examining the specificity of social cognitive impairment to psychosis. The present study examined how PLEs relate to social cognition in the context of other psychopathology dimensions, using a hierarchical factors approach to social cognition.

STUDY DESIGN

Online community participants (N = 1026) completed psychosis, autism, and personality disorder questionnaires, as well as 3 social cognitive tasks that varied in methodology (vignette vs video) and construct (higher- vs lower-level social cognition). Exploratory (EFA) and confirmatory factor analyses (CFA) were used to model social cognition, with the best models being examined in association with PLEs and psychopathology dimensions.

STUDY RESULTS

EFA and CFA supported a hierarchical model of social cognition, with 2 higher-order factors emerging: verbal/vignette task methodology and a multimethod general social cognition factor. These higher-order factors accounted for task-level associations to psychopathology, with relations to positive symptoms (r = .23) and antagonism (r = .28). After controlling for other psychopathology, positive symptoms were most clearly related to tasks with verbal methodology (β = -0.34).

CONCLUSIONS

These results suggest that broad social cognitive processes and method effects may account for many previous findings in psychosis and psychopathology research. Additionally, accounting for broad social cognitive impairment may yield insights into more specific social cognitive processes as well.

Overlapping neural correlates underpin theory of mind and semantic cognition: Evidence from a meta-analysis of 344 functional neuroimaging studies

Key unanswered questions for cognitive neuroscience include whether social cognition is underpinned by specialised brain regions and to what extent it simultaneously depends on more domain-general systems. Until we glean a better understanding of the full set of contributions made by various systems, theories of social cognition will remain fundamentally limited. In the present study, we evaluate a recent proposal that semantic cognition plays a crucial role in supporting social cognition. While previous brain-based investigations have focused on dissociating these two systems, our primary aim was to assess the degree to which the neural correlates are overlapping, particularly within two key regions, the anterior temporal lobe (ATL) and the temporoparietal junction (TPJ). We focus on activation associated with theory of mind (ToM) and adopt a meta-analytic activation likelihood approach to synthesise a large set of functional neuroimaging studies and compare their results with studies of semantic cognition. As a key consideration, we sought to account for methodological differences across the two sets of studies, including the fact that ToM studies tend to use nonverbal stimuli while the semantics literature is dominated by language-based tasks. Overall, we observed consistent overlap between the two sets of brain regions, especially in the ATL and TPJ. This supports the claim that tasks involving ToM draw upon more general semantic retrieval processes. We also identified activation specific to ToM in the right TPJ, bilateral anterior mPFC, and right precuneus. This is consistent with the view that, nested amongst more domain-general systems, there is specialised circuitry that is tuned to social processes.

Beyond memory: exploring the value of social cognition for older adults with neurocognitive disorders

Neurocognitive disorders involves progressive decline in cognition, function, behavior and needs. Recent developments have identified the need to characterize social cognition in individuals with neurocognitive impairments to support uncertainty in clinical decision making, treatment plans and monitoring individual change. Routine social cognition assessments have thus been more recently used and adopted in persons with dementia or mild cognitive impairment. This work serves to summarize current assessments and provide a discourse on the practicality of available social cognition tools, its implication in clinical practice and key future directions. We highlight advantages in establishing validated, multicomponent measures of social cognition for people with neurocognitive disorders.

Frontotemporal Dementia, Where Do We Stand? A Narrative Review

Frontotemporal dementia (FTD) is a neurodegenerative disease of growing interest, since it accounts for up to 10% of middle-age-onset dementias and entails a social, economic, and emotional burden for the patients and caregivers. It is characterised by a (at least initially) selective degeneration of the frontal and/or temporal lobe, generally leading to behavioural alterations, speech disorders, and psychiatric symptoms. Despite the recent advances, given its extreme heterogeneity, an overview that can bring together all the data currently available is still lacking. Here, we aim to provide a state of the art on the pathogenesis of this disease, starting with established findings and integrating them with more recent ones. In particular, advances in the genetics field will be examined, assessing them in relation to both the clinical manifestations and histopathological findings, as well as considering the link with other diseases, such as amyotrophic lateral sclerosis (ALS). Furthermore, the current diagnostic criteria will be explored, including neuroimaging methods, nuclear medicine investigations, and biomarkers on biological fluids. Of note, the promising information provided by neurophysiological investigations, i.e., electroencephalography and non-invasive brain stimulation techniques, concerning the alterations in brain networks and neurotransmitter systems will be reviewed. Finally, current and experimental therapies will be considered.

Social and non-social working memory in neurodegeneration

Although social functioning relies on working memory, whether a social-specific mechanism exists remains unclear. This undermines the characterization of neurodegenerative conditions with both working memory and social deficits. We assessed working memory domain-specificity across behavioral, electrophysiological, and neuroimaging dimensions in 245 participants. A novel working memory task involving social and non-social stimuli with three load levels was assessed across controls and different neurodegenerative conditions with recognized impairments in: working memory and social cognition (behavioral-variant frontotemporal dementia); general cognition (Alzheimer's disease); and unspecific patterns (Parkinson's disease). We also examined resting-state theta oscillations and functional connectivity correlates of working memory domain-specificity. Results in controls and all groups together evidenced increased working memory demands for social stimuli associated with frontocinguloparietal theta oscillations and salience network connectivity. Canonical frontal theta oscillations and executive-default mode network anticorrelation indexed non-social stimuli. Behavioral-variant frontotemporal dementia presented generalized working memory deficits related to posterior theta oscillations, with social stimuli linked to salience network connectivity. In Alzheimer's disease, generalized working memory impairments were related to temporoparietal theta oscillations, with non-social stimuli linked to the executive network. Parkinson's disease showed spared working memory performance and canonical brain correlates. Findings support a social-specific working memory and related disease-selective pathophysiological mechanisms.

Development of the Basel Version of the Awareness of Social Inference Test - Theory of Mind (BASIT-ToM) in healthy adults

Impairments of Theory of Mind (ToM) abilities occur in a wide range of brain disorders. Therefore, reliable and ecologically valid examination of these abilities is a crucial part of any comprehensive neuropsychological assessment. An established and ecologically valid, English-language test identifying deficits in ToM abilities is "The Awareness of Social Inference Test - Social Inference Minimal (TASIT-SIM)". However, no comparable German-language ToM test currently exists. In this study, we aimed to develop the first German-language adaption of TASIT-SIM in healthy adults. We selected 13 scenes [four scenes per message type (i.e., honesty, simple sarcasm, paradoxical sarcasm) and one practice scene] out of the 30 TASIT-SIM scenes. In collaboration with a film institute, we filmed each scene at three different intensities. These intensity version scenes were then administered to 240 healthy adults, equally distributed in sex and age, ranging from 35 to 92 years. By applying Rasch analysis, we selected intensity versions that showed neither floor nor ceiling effects in the majority of ToM questions in participants whose ToM abilities were in the medium range. In conclusion, we have developed the first German-language adaption of TASIT-SIM, i.e., the "Basel Version of the Awareness of Social Inference Test - Theory of Mind (BASIT-ToM)". The BASIT-ToM incorporates the strengths of TASIT-SIM, while overcoming its limitations such as inconsistencies in cinematic realization and ceiling effects in healthy participants. Next, the BASIT-ToM needs to be validated in healthy people and clinical populations.

Social Cognition in Behavioral Variant Frontotemporal Dementia and Pathological Subtypes: A Narrative Review

Behavioral variant frontotemporal dementia (bvFTD) belongs to the spectrum of frontotemporal lobar degeneration (FTLD) and is characterized by frontal dysfunction with executive deficits and prominent socioemotional impairments. Social cognition, such as emotion processing, theory of mind, and empathy may significantly impact daily behavior in bvFTD. Abnormal protein accumulation of tau or TDP-43 are the main causes of neurodegeneration and cognitive decline. Differential diagnosis is difficult due to the heterogeneous pathology in bvFTD and the high clinicopathological overlap with other FTLD syndromes, especially in late disease stages. Despite recent advances, social cognition in bvFTD has not yet received sufficient attention, nor has its association with underlying pathology. This narrative review evaluates social behavior and social cognition in bvFTD, by relating these symptoms to neural correlates and underlying molecular pathology or genetic subtypes. Negative and positive behavioral symptoms, such as apathy and disinhibition, share similar brain atrophy and reflect social cognition. More complex social cognitive impairments are probably caused by the interference of executive impairments due to increasing neurodegeneration. Evidence suggests that underlying TDP-43 is associated with neuropsychiatric and early social cognitive dysfunction, while patients with underlying tau pathology are marked by strong cognitive dysfunction with increasing social impairments in later stages. Despite many current research gaps and controversies, finding distinct social cognitive markers in association to underlying pathology in bvFTD is essential for validating biomarkers, for clinical trials of novel therapies, and for clinical practice.

Behavioral Variant Frontotemporal Dementia and Social and Criminal Transgressions

OBJECTIVE

Behavioral variant frontotemporal dementia (bvFTD) is associated with social and criminal transgressions; studies from countries around the world have documented such behavior in persons with this condition. An overview and analysis of social and criminal transgressions in bvFTD and their potential neurobiological mechanisms can provide a window for understanding the relationship of antisocial behavior and the brain.

METHODS

This review evaluated the literature on the frequency of social and criminal transgressions in bvFTD and the neurobiological disturbances that underlie them.

RESULTS

There is a high frequency of transgressions among patients with bvFTD due to impairments in neurocognition, such as social perception, behavioral regulation, and theory of mind, and impairments in social emotions, such as self-conscious emotions and empathy. Additionally, there is significant evidence for a specific impairment in an innate sense of morality. Alterations in these neurobiological processes result from predominantly right-hemisphere pathology in frontal (ventromedial, orbitofrontal, inferolateral frontal), anterior temporal (amygdala, temporal pole), limbic (anterior cingulate, amygdala), and insular regions.

CONCLUSIONS

Overlapping disturbances in neurocognition, social emotions, and moral reasoning result from disease in the mostly mesial and right-sided frontotemporal network necessary for responding emotionally to others and for behavioral control. With increased sophistication in neurobiological interventions, future goals may be the routine evaluation of these processes among individuals with bvFTD who engage in social and criminal transgressions and the targeting of these neurobiological mechanisms with behavioral, pharmacological, and other interventions.

The role of the ventrolateral anterior temporal lobes in social cognition

A key challenge for neurobiological models of social cognition is to elucidate whether brain regions are specialised for that domain. In recent years, discussion surrounding the role of anterior temporal regions epitomises such debates; some argue the anterior temporal lobe (ATL) is part of a domain‐specific network for social processing, while others claim it comprises a domain‐general hub for semantic representation. In the present study, we used ATL‐optimised fMRI to map the contribution of different ATL structures to a variety of paradigms frequently used to probe a crucial social ability, namely ‘theory of mind’ (ToM). Using multiple tasks enables a clearer attribution of activation to ToM as opposed to idiosyncratic features of stimuli. Further, we directly explored whether these same structures are also activated by a non‐social task probing semantic representations. We revealed that common to all of the tasks was activation of a key ventrolateral ATL region that is often invisible to standard fMRI. This constitutes novel evidence in support of the view that the ventrolateral ATL contributes to social cognition via a domain‐general role in semantic processing and against claims of a specialised social function.

Behavioral Variant Frontotemporal Dementia

PURPOSE OF REVIEW

This article reviews many of the complex facets of behavioral variant frontotemporal dementia (bvFTD) and frontotemporal lobar degeneration (FTLD). A particular focus is on improving diagnostic accuracy to reduce the arduous diagnostic odyssey that so many patients and families endure. Strategies to promote diagnostic accuracy and approach the management of problematic symptoms are also discussed.

RECENT FINDINGS

Although the International Consensus Criteria for bvFTD were published more than a decade ago and clinicopathologic studies have confirmed their utility, diagnostic confusion continues. This article presents updated data along with illustrative cases to emphasize the clinical pearls that are most useful for clinicians. Although accurate prediction of the underlying proteinopathy remains a challenge, the ability to differentiate bvFTD from atypical Alzheimer disease, psychiatric disorders, and other mimickers has improved. Knowledge about the genetic underpinnings in a significant minority of individuals with familial FTLD is enabling early and accurate diagnosis. Therapeutic optimism has also increased, particularly in familial FTLD, with a few clinical trials in progress and several more planned, some of which are designed to slow progression or delay the onset of symptoms, or both.

SUMMARY

The diagnosis and management of bvFTD is challenging for clinicians and particularly for patients and their families. Although much progress has been gained over recent years, several key research questions persist. Treatments that significantly improve symptoms or alter the course of FTLD remain elusive, but optimism is increasing as pathobiology is better understood and novel therapies are being developed.

Proposed research criteria for prodromal behavioural variant frontotemporal dementia

At present, no research criteria exist for the diagnosis of prodromal behavioural variant frontotemporal dementia (bvFTD), though early detection is of high research importance. Thus, we sought to develop and validate a proposed set of research criteria for prodromal bvFTD, termed 'mild behavioural and/or cognitive impairment in bvFTD' (MBCI-FTD). Participants included 72 participants deemed to have prodromal bvFTD; this comprised 55 carriers of a pathogenic mutation known to cause frontotemporal lobar degeneration, and 17 individuals with autopsy-confirmed frontotemporal lobar degeneration. All had mild behavioural and/or cognitive changes, as judged by an evaluating clinician. Based on extensive clinical workup, the prodromal bvFTD group was divided into a Development Group (n = 22) and a Validation Group (n = 50). The Development Group was selected to be the subset of the prodromal bvFTD group for whom we had the strongest longitudinal evidence of conversion to bvFTD, and was used to develop the MBCI-FTD criteria. The Validation Group was the remainder of the prodromal bvFTD group and was used as a separate sample on which to validate the criteria. Familial non-carriers were included as healthy controls (n = 165). The frequencies of behavioural and neuropsychiatric features, neuropsychological deficits, and social cognitive dysfunction in the prodromal bvFTD Development Group and healthy controls were assessed. Based on sensitivity and specificity analyses, seven core features were identified: apathy without moderate-severe dysphoria, behavioural disinhibition, irritability/agitation, reduced empathy/sympathy, repetitive behaviours (simple and/or complex), joviality/gregariousness, and appetite changes/hyperorality. Supportive features include a neuropsychological profile of impaired executive function or naming with intact orientation and visuospatial skills, reduced insight for cognitive or behavioural changes, and poor social cognition. Three core features or two core features plus one supportive feature are required for the diagnosis of possible MBCI-FTD; probable MBCI-FTD requires imaging or biomarker evidence, or a pathogenic genetic mutation. The proposed MBCI-FTD criteria correctly classified 95% of the prodromal bvFTD Development Group, and 74% of the prodromal bvFTD Validation Group, with a false positive rate of <10% in healthy controls. Finally, the MBCI-FTD criteria were tested on a cohort of individuals with prodromal Alzheimer's disease, and the false positive rate of diagnosis was 11-16%. Future research will need to refine the sensitivity and specificity of these criteria, and incorporate emerging biomarker evidence.

Exploring the Relationship Between Deficits in Social Cognition and Neurodegenerative Dementia: A Systematic Review

Background

Neurodegenerative diseases might affect social cognition in various ways depending on their components (theory of mind, emotional processing, attribution bias, and social perception) and the subtype of dementia they cause. This review aims to explore this difference in cognitive function among individuals with different aetiologies of dementia.

Methods

The following databases were explored: MEDLINE via PubMed, Cochrane Library, Lilacs, Web of Science, and PsycINFO. We selected studies examining social cognition in individuals with neurodegenerative diseases in which dementia was the primary symptom that was studied. The neurodegenerative diseases included Alzheimer's disease, Lewy body disease and frontotemporal lobar degeneration. The search yielded 2,803 articles.

Results

One hundred twenty-two articles were included in the present review. The summarised results indicate that people with neurodegenerative diseases indeed have deficits in social cognitive performance. Both in populations with Alzheimer's disease and in populations with frontotemporal dementia, we found that emotional processing was strongly affected. However, although theory of mind impairment could also be observed in the initial stages of frontotemporal dementia, in Alzheimer's disease it was only appreciated when performing highly complex task or in advanced stages of the disease.

Conclusions

Each type of dementia has a differential profile of social cognition deterioration. This review could provide a useful reference for clinicians to improve detection and diagnosis, which would undoubtedly guarantee better interventions.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020152562, PROSPERO, identifier: CRD42020152562.

A transdiagnostic review of neuroimaging studies of apathy and disinhibition in dementia

Apathy and disinhibition are common and highly distressing neuropsychiatric symptoms associated with negative outcomes in persons with dementia. This paper is a critical review of functional and structural neuroimaging studies of these symptoms transdiagnostically in dementia of the Alzheimer type, which is characterized by prominent amnesia early in the disease course, and behavioural variant frontotemporal dementia, characterized by early social-comportmental deficits. We describe the prevalence and clinical correlates of these symptoms and describe methodological issues, including difficulties with symptom definition and different measurement instruments. We highlight the heterogeneity of findings, noting however, a striking similarity of the set of brain regions implicated across clinical diagnoses and symptoms. These regions involve several key nodes of the salience network, and we describe the functions and anatomical connectivity of these brain areas, as well as present a new theoretical account of disinhibition in dementia. Future avenues for research are discussed, including the importance of transdiagnostic studies, measuring subdomains of apathy and disinhibition, and examining different units of analysis for deepening our understanding of the networks and mechanisms underlying these extremely distressing symptoms.

Apathy, Executive Function, and Emotion Recognition Are the Main Drivers of Functional Impairment in Behavioral Variant of Frontotemporal Dementia

Background: The cognitive and neuropsychiatric deficits present in patients with behavioral variant frontotemporal dementia (bvFTD) are associated with loss of functionality in the activities of daily living (ADLs). The main purpose of this study was to examine and explore the association between the cognitive and neuropsychiatric features that might prompt functional impairment of basic, instrumental, and advanced ADL domains in patients with bvFTD. Methods: A retrospective cross-sectional study was conducted with 27 patients with bvFTD in its early stage (<2 years of evolution) and 32 healthy control subjects. A neuropsychological assessment was carried out wherein measures of cognitive function and neuropsychiatric symptoms were obtained. The informant-report Technology-Activities of Daily Living Questionnaire was used to assess the percentage of functional impairment in the different ADL domains. To identify the best determinants, three separate multiple regression analyses were performed, considering each functional impairment as the dependent variable and executive function, emotion recognition, disinhibition, and apathy as independent variables. Results: For the basic ADLs, a model that explains 28.2% of the variability was found, in which the presence of apathy (β = 0.33, p = 0.02) and disinhibition (β = 0.29, p = 0.04) were significant factors. Concerning instrumental ADLs, the model produced accounted for 63.7% of the functional variability, with the presence of apathy (β = 0.71, p < 0.001), deficits in executive function (β = -0.36, p = 0.002), and lack of emotion recognition (β = 0.28, p = 0.017) as the main contributors. Finally, in terms of advanced ADLs, the model found explained 52.6% of the variance, wherein only the presence of apathy acted as a significant factor (β = 0.59, p < 0.001). Conclusions: The results of this study show the prominent and transverse effect of apathy in the loss of functionality throughout all the ADL domains. Apart from that, this is the first study that shows that the factors associated with loss of functionality differ according to the functional domain in patients with bvFTD in its early stage. Finally, no other study has analyzed the impact of the lack of emotion recognition in the functionality of ADLs. These results could guide the planning of tailored interventions that might enhance everyday activities and the improvement of quality of life.

Emotion Processing Dysfunction in Alzheimer's Disease: An Overview of Behavioral Findings, Systems Neural Correlates, and Underlying Neural Biology

We described behavioral studies to highlight emotional processing deficits in Alzheimer's disease (AD). The findings suggest prominent deficit in recognizing negative emotions, pronounced effect of positive emotion on enhancing memory, and a critical role of cognitive deficits in manifesting emotional processing dysfunction in AD. We reviewed imaging studies to highlight morphometric and functional markers of hippocampal circuit dysfunction in emotional processing deficits. Despite amygdala reactivity to emotional stimuli, hippocampal dysfunction conduces to deficits in emotional memory. Finally, the reviewed studies implicating major neurotransmitter systems in anxiety and depression in AD supported altered cholinergic and noradrenergic signaling in AD emotional disorders. Overall, the studies showed altered emotions early in the course of illness and suggest the need of multimodal imaging for further investigations. Particularly, longitudinal studies with multiple behavioral paradigms translatable between preclinical and clinical models would provide data to elucidate the time course and underlying neurobiology of emotion processing dysfunction in AD.

Large-Scale Functional Networks, Cognition and Brain Structures Supporting Social Cognition and Theory of Mind Performance in Prodromal to Mild Alzheimer's Disease

Impairment of social cognition (SC) skills such as recognition and attribution of intentions and affective states of others (Theory of Mind, ToM) has been evidenced in Alzheimer’s Disease (AD). This study investigated the neuropsychological, neuroanatomical and brain-functional underpinnings of SC processing to obtain an understanding of the social neurophenotype in early probable AD. Forty-six patients with mild cognitive impairment and mild probable AD underwent SC assessment including emotion recognition (Ekman-60-faces task) and cognitive and affective ToM (Reading-the-Mind-in-the-Eyes test and Story-based Empathy task). Linear models tested the association between SC scores and neuropsychological measures, grey matter maps and large-scale functional networks activity. The executive domain had the most predominant association with SC scores in the cognitive profile. Grey matter volume of the anterior cingulate, orbitofrontal, temporoparietal junction (TPJ), superior temporal, and cerebellar cortices were associated with ToM. Social cognition scores were associated with lower connectivity of the default-mode network with the prefrontal cortex. The right fronto-parietal network displayed higher inter-network connectivity in the right TPJ and insula while the salience network showed lower inter-network connectivity with the left TPJ and insula. Connectivity coupling alterations of executive-attentional networks may support default mode social-cognitive-associated decline through the recruitment of frontal executive mechanisms.

Speech and language impairments in behavioral variant frontotemporal dementia: A systematic review

Although behavioral variant frontotemporal dementia (bvFTD) is classically defined by behavioral and socio-emotional changes, impairments often extend to other cognitive functions. These include early speech and language deficits related to the disease's core neural disruptions. Yet, their scope and clinical relevance remains poorly understood. This systematic review characterizes such disturbances in bvFTD, considering clinically, neuroanatomically, genetically, and neuropathologically defined subgroups. We included 181 experimental studies, with at least 5 bvFTD patients diagnosed using accepted criteria, comparing speech and language outcomes between bvFTD patients and healthy controls or between bvFTD subgroups. Results reveal extensive and heterogeneous deficits across cohorts, with (a) consistent lexico-semantic, reading & writing, and prosodic impairments; (b) inconsistent deficits in motor speech and grammar; and (c) relative preservation of phonological skills. Also, preliminary findings suggest that the severity of speech and language deficits might be associated with global cognitive impairment, predominantly temporal or fronto-temporal atrophy and MAPT mutations (vs C9orf72). Although under-recognized, these impairments contribute to patient characterization and phenotyping, while potentially informing diagnosis and management.

Medicolegal Implications of Mild Neurocognitive Disorder

INTRODUCTION

The syndromes of mild cognitive impairment (MCI) or mild neurocognitive disorder (MiND), often prodromal to dementia (Major Neurocognitive Disorder), are characterized by acquired clinically significant changes in one or more cognitive domains despite preserved independence. Mild impairment has significant medicolegal consequences for an affected person and their care system. We review the more common etiologies of MiND and provide a systematic review of its medicolegal implications.

METHODS

We conducted a systematic review of the peer-reviewed English literature on medicolegal aspects of MCI or MiND using comprehensive search terms and expanding our review to include sources cited by these reports.

RESULTS

Impairment of memory, executive function, social cognition, judgment, insight or abstraction can alter an individual's abilities in a variety of areas that include decision making, informed consent, designation of a surrogate decision-maker such as a health care proxy, understanding and management of financial affairs, execution of a will, or safe driving.

CONCLUSION

Even mild cognitive impairment can have significant behavioral consequences. Clinicians can assist care partners and persons with MCI or MiND by alerting them to the medicolegal concerns that often accompany cognitive decline. Early recognition and discussion can help a care system manage medicolegal risk more effectively and promote thoughtful advance planning.

Emotion recognition and theory of mind after temporal lobe epilepsy surgery: A systematic review

In order to navigate in our complex social world successfully, it is crucial to maintain and practice cognitive skills that are dedicated to adaptive social functioning. Emerging evidence suggests that besides deficits in declarative memory, executive functions, and language, impairments in social cognition (SC, e.g., emotion recognition, theory of mind) are also present in temporal lobe epilepsy (TLE). The organic and psycho-social consequences of epilepsy surgery might have additional implications regarding this deficit. Here we qualitatively synthesize longitudinal and cross-sectional findings on SC after TLE surgery. A literature search using PubMed and Scopus identified 275 potential articles. Studies were eligible if they (1) included patients with a diagnosis of TLE, (2) included a healthy comparison group, (3) reported original research, (4) were published in peer-reviewed journals and in English language, (5) reported the intervention of epilepsy surgery. Articles that (1) were case studies, (2) did not focus on SC abilities, (3) used interviews or self-report questionnaires to examine SC functions were excluded. A total of 16 original studies assessing emotion recognition (ER) and/or theory of mind (ToM) matched our criteria. The literature suggests that neither ER nor ToM abilities change after surgery: post-surgery patients show similar impairment patterns to pre-surgery patients. Nevertheless, individual improvement or decline could be masked by group comparisons and results should be considered in light of methodological heterogeneity among studies.

Alzheimer's Disease or Behavioral Variant Frontotemporal Dementia? Review of Key Points Toward an Accurate Clinical and Neuropsychological Diagnosis

Alzheimer's disease (AD) and frontotemporal dementia (FTD) are the most common neurodegenerative early-onset dementias. Despite the fact that both conditions have a very distinctive clinical pattern, they present with an overlap in their cognitive and behavioral features that may lead to misdiagnosis or delay in diagnosis. The current review intends to summarize briefly the main differences at the clinical, neuropsychological, and behavioral levels, in an attempt to suggest which aspects would facilitate an adequate diagnosis in a clinical setting, especially in Latin American and low- and middle-income countries, where the resources needed for a differential diagnosis (such as MRI or biomarkers) are not always available. A timely diagnosis of AD and FTD have significant implications for the medical management and quality of life of patients and careers.

Can Social Cognition Measurements Differentiate Behavioral Variant Frontotemporal Dementia from Alzheimer's Disease Regardless of Apathy?

BACKGROUND

Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) share cognitive and behavioral symptoms, such as apathy. Social cognition measurements are useful in distinguishing bvFTD from AD, but their accuracies may be affected by apathy.

OBJECTIVE

To investigate whether social cognition measurements can distinguish bvFTD from either apathetic or non-apathetic AD patients.

METHODS

Three groups of participants were enrolled in the present study: bvFTD (n = 22), AD (n = 20), and healthy controls (HC, n = 23). The AD group was divided into apathetic (n = 10) and non-apathetic (n = 10). All subjects underwent comprehensive neuropsychological examination, including the short version of the Social and Emotional Assessment (Mini-SEA), which comprises the facial emotion recognition test and the faux-pas recognition test (Faux-Pas Test). Apathy was assessed according to the Starkstein's Apathy (SA) Scale.

RESULTS

The bvFTD and AD groups did not differ on global cognitive efficiency and on executive functions. In comparison to the whole AD group, bvFTD displayed lower Faux-Pas Test and Mini-SEA scores. Both AD subgroups, apathetic or non-apathetic, exhibited similar performance on all social cognition measurements. In comparison to either apathetic AD or non-apathetic AD, bvFTD patients underperformed on the Faux-Pas Test and on the Mini-SEA. The area under the curve values for the Mini-SEA total score were 0.87 (bvFTD versus AD), 0.90 (bvFTD versus apathetic AD), and 0.83 (bvFTD versus non-apathetic AD).

CONCLUSION

Social cognition tests provide accurate distinction between bvFTD against either apathetic AD or non-apathetic AD. Social cognition measurements did not correlate with apathy severity.

Understanding Alzheimer's disease as a disorder of consciousness

People with Alzheimer's disease (AD) demonstrate a range of alterations in consciousness. Changes in awareness of cognitive deficit, self-awareness, and introspection are seen early in AD, and dysfunction of awareness and arousal progresses with increasing disease severity. However, heterogeneity of deficits between individuals and a lack of empirical studies in people with severe dementia highlight the importance of identifying and applying biomarkers of awareness in AD. Impairments of awareness in AD are associated with neuropathology in regions that overlap with proposed neural correlates of consciousness. Recent developments in consciousness science provide theoretical frameworks and experimental approaches to help further understand the conscious experience of people with AD. Recognition of AD as a disorder of consciousness is overdue, and important to both understand the lived experience of people with AD and to improve care.

Predicting and Characterizing Neurodegenerative Subtypes with Multimodal Neurocognitive Signatures of Social and Cognitive Processes

BACKGROUND

Social cognition is critically compromised across neurodegenerative diseases, including the behavioral variant frontotemporal dementia (bvFTD), Alzheimer's disease (AD), and Parkinson's disease (PD). However, no previous study has used social cognition and other cognitive tasks to predict diagnoses of these conditions, let alone reporting the brain correlates of prediction outcomes.

OBJECTIVE

We performed a diagnostic classification analysis using social cognition, cognitive screening (CS), and executive function (EF) measures, and explored which anatomical and functional networks were associated with main predictors.

METHODS

Multiple group discriminant function analyses (MDAs) and ROC analyses of social cognition (facial emotional recognition, theory of mind), CS, and EF were implemented in 223 participants (bvFTD, AD, PD, controls). Gray matter volume and functional connectivity correlates of top discriminant scores were investigated.

RESULTS

Although all patient groups revealed deficits in social cognition, CS, and EF, our classification approach provided robust discriminatory characterizations. Regarding controls, probabilistic social cognition outcomes provided the best characterization for bvFTD (together with CS) and PD, but not AD (for which CS alone was the best predictor). Within patient groups, the best MDA probabilities scores yielded high classification rates for bvFTD versus PD (98.3%, social cognition), AD versus PD (98.6%, social cognition + CS), and bvFTD versus AD (71.7%, social cognition + CS). Top MDA scores were associated with specific patterns of atrophy and functional networks across neurodegenerative conditions.

CONCLUSION

Standardized validated measures of social cognition, in combination with CS, can provide a dimensional classification with specific pathophysiological markers of neurodegeneration diagnoses.

Empathy and Theory of Mind in Alzheimer's Disease: A Meta-analysis

OBJECTIVE

A large literature now shows that Alzheimer's disease (AD) disrupts a number of social cognitive abilities, including social perceptual function and theory of mind (ToM). However, less well understood is how the specific subcomponents of ToM as well as both the broader and specific subcomponents of empathic processing are affected.

METHOD

The current study provides the first meta-analytic review of AD that focuses on both empathy and ToM as broad constructs, as well as their overlapping (cognitive empathy and affective ToM) and distinct (affective empathy and cognitive ToM) subcomponents.

RESULTS

Aggregated across 31 studies, the results revealed that, relative to controls, AD is associated with large-sized deficits in both cognitive ToM (g = 1.09) and affective ToM/cognitive empathy (g = 0.76). However, no statistical differences were found between the AD participants and controls on affective empathic abilities (g = 0.36).

CONCLUSIONS

These data point to a potentially important disconnect between core aspects of social cognitive processing in people with AD. The practical and theoretical implications of these findings are discussed.

Evaluation of Discriminative Detection Abilities of Social Cognition Measures for the Diagnosis of the Behavioral Variant of Frontotemporal Dementia: a Systematic Review

The use of social tasks in the neuropsychological assessment of the behavioral variant of frontotemporal dementia (bvFTD) is at present not required by diagnostic guidelines, despite extensive literature shows relevant social cognitive dysfunctions in such patients. In this systematic review, we explored the clinical maturity of social cognition measures in the diagnosis of bvFTD. Papers were selected according to the PRISMA guidelines by searching the PubMed and Medline databases. Only papers reporting indices of diagnostic accuracy and/or sensitivity/specificity in classifying bvFTD from controls or from other relevant diseases were considered. Quality of evidence was assessed through QUADAS-2. Among the 663 articles entered in the paper selection only 14 papers were eligible for the scope of the present review and showed an overall moderate-to-low quality. The major risk of bias was the lack of pathological confirmation. The evaluation of the accuracy of social cognition tasks in bvFTD detection compared to normal controls, as well as in the discrimination with Alzheimer's disease and psychiatric patients, is mainly focused on emotion recognition and theory of mind. However, the use of different cognitive measures, variable task formats and the limited normative data hamper study comparability. Although literature seems to suggest that emotion recognition and ToM tasks could be the best choice to ensure a high diagnostic accuracy in clinical settings, further comparative studies are required and no recommendation concerning the use of a specific social task in bvFTD diagnosis can be currently provided.

The complex audio visual emotion assessment task (CAVEAT): development of a shorter version for clinical use

PURPOSE

The Complex Audio Visual Emotion Assessment Task (CAVEAT) is a measure of emotion recognition using dynamic, naturalistic videos to assess recognition of 22 different emotional states (11 positive, 11 negative). It has established construct validity and demonstrated sensitivity to emotion perception impairments in those with moderate-severe traumatic brain injury (TBI). Despite this, its lengthy administration has limited its use in clinical practice and rehabilitation. The current paper aimed to develop shortened versions of the CAVEAT and examine their psychometric properties.

METHODS

The CAVEAT-S A and CAVEAT-S B (22 items each) and the CAVEAT-S AB (44 items) were developed using the original data. Comparability, reliability, construct and predictive validity were examined in the original sample (Study 1: 32 people with TBI and 32 demographically matched control participants) and a replication sample (Study 2: 18 adults with TBI and 21 demographically matched controls).

RESULTS

All short forms produced comparable accuracy ratings to the full measure, as well as discriminating between people with or without a TBI. Shortened forms all correlated with other measures of emotion perception and social cognition and also predicted psychosocial outcomes in terms of self-reported interpersonal relationships. Internal reliability of the short forms was low relative to the longer forms, especially for the two very short measures.

CONCLUSIONS

The new shortened forms of the CAVEAT are promising tools that are sensitive and valid for assessing emotion perception in people with TBI for clinical purposes. Their application in other clinical disorders is yet to be examined.Implications for rehabilitationEmotion perception deficits are present in many clinical populations and an important target for rehabilitation.CAVEAT Short provides ecologically valid emotional stimuli. Such stimuli are important for assessing real world function and to set rehabilitation targets.By having parallel versions of CAVEAT, there is the opportunity to test pre and post intervention while minimising practice effects.Alternatively, one version of CAVEAT-S can be used for assessment, while the other is used for training purposes during remediation.

Recommendations to distinguish behavioural variant frontotemporal dementia from psychiatric disorders

The behavioural variant of frontotemporal dementia (bvFTD) is a frequent cause of early-onset dementia. The diagnosis of bvFTD remains challenging because of the limited accuracy of neuroimaging in the early disease stages and the absence of molecular biomarkers, and therefore relies predominantly on clinical assessment. BvFTD shows significant symptomatic overlap with non-degenerative primary psychiatric disorders including major depressive disorder, bipolar disorder, schizophrenia, obsessive-compulsive disorder, autism spectrum disorders and even personality disorders. To date, ∼50% of patients with bvFTD receive a prior psychiatric diagnosis, and average diagnostic delay is up to 5-6 years from symptom onset. It is also not uncommon for patients with primary psychiatric disorders to be wrongly diagnosed with bvFTD. The Neuropsychiatric International Consortium for Frontotemporal Dementia was recently established to determine the current best clinical practice and set up an international collaboration to share a common dataset for future research. The goal of the present paper was to review the existing literature on the diagnosis of bvFTD and its differential diagnosis with primary psychiatric disorders to provide consensus recommendations on the clinical assessment. A systematic literature search with a narrative review was performed to determine all bvFTD-related diagnostic evidence for the following topics: bvFTD history taking, psychiatric assessment, clinical scales, physical and neurological examination, bedside cognitive tests, neuropsychological assessment, social cognition, structural neuroimaging, functional neuroimaging, CSF and genetic testing. For each topic, responsible team members proposed a set of minimal requirements, optimal clinical recommendations, and tools requiring further research or those that should be developed. Recommendations were listed if they reached a ≥ 85% expert consensus based on an online survey among all consortium participants. New recommendations include performing at least one formal social cognition test in the standard neuropsychological battery for bvFTD. We emphasize the importance of 3D-T1 brain MRI with a standardized review protocol including validated visual atrophy rating scales, and to consider volumetric analyses if available. We clarify the role of 18F-fluorodeoxyglucose PET for the exclusion of bvFTD when normal, whereas non-specific regional metabolism abnormalities should not be over-interpreted in the case of a psychiatric differential diagnosis. We highlight the potential role of serum or CSF neurofilament light chain to differentiate bvFTD from primary psychiatric disorders. Finally, based on the increasing literature and clinical experience, the consortium determined that screening for C9orf72 mutation should be performed in all possible/probable bvFTD cases or suspected cases with strong psychiatric features.

The Cerebellum in Frontotemporal Dementia: a Meta-Analysis of Neuroimaging Studies

Frontotemporal dementia (FTD) is a neurodegenerative brain disorder primarily affecting the frontal and/or temporal lobes. Three main subtypes have been recognized: behavioural-variant FTD (bvFTD), semantic dementia (SD), and progressive nonfluent aphasia (PNFA), each of which has a distinct clinical and cognitive profile. Although the role of the cerebellum in cognition is increasingly accepted, knowledge of cerebellar changes across neuroimaging modalities and their contribution to behavioural and cognitive changes in FTD syndromes is currently scant. We conducted an anatomical/activation likelihood estimation (ALE) meta-analysis in 53 neuroimaging studies (structural MRI: 42; positron emission tomography: 6; functional MRI: 4; single-photon emission computed tomography: 1) to identify the patterns of cerebellar changes and their relations to profiles of behavioural and cognitive deficits in FTD syndromes. Overall, widespread bilateral cerebellar changes were found in FTD and notably the patterns were subtype specific. In bvFTD, ALE peaks were identified in the bilateral Crus, left lobule VI, right lobules VIIb and VIIIb. In SD, focal cerebellar changes were located in the left Crus I and lobule VI. A separate ALE meta-analysis on PNFA studies was not performed due to the limited number of studies available. In addition, the ALE analysis indicated that bilateral Crus I and Crus II were associated with behavioural disruption and cognitive dysfunction. This ALE meta-analysis provides the quantification of the location and extent of cerebellar changes across the main FTD syndromes, which in turn provides evidence of cerebellar contributions to behavioural and cognitive changes in FTD. These results bring new insights into the mechanisms mediating FTD symptomatology.

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.

Progress and Challenges in Frontotemporal Dementia Research: A 20-Year Review

The landscape of frontotemporal dementia (FTD) has evolved remarkably in recent years and is barely recognizable from two decades ago. Knowledge of the clinical phenomenology, cognition, neuroimaging, genetics, pathology of the different subtypes of FTD, and their relations to other neurodegenerative conditions, has increased rapidly, due in part, to the growing interests into these neurodegenerative brain conditions. This article reviews the major advances in the field of FTD over the past 20 years, focusing primarily on the work of Frontier, the frontotemporal dementia clinical research group, based in Sydney, Australia. Topics covered include clinical presentations (cognition, behavior, neuroimaging), pathology, genetics, and disease progression, as well as interventions and carer directed research. This review demonstrates the improvement in diagnostic accuracy and capacity to provide advice on genetic risks, prognosis, and outcome. The next major challenge will be to capitalize on these research findings to develop effective disease modifying drugs, which are currently lacking.

Lower- and Higher-Level Social Cognitive Factors Across Individuals With Schizophrenia Spectrum Disorders and Healthy Controls: Relationship With Neurocognition and Functional Outcome

BACKGROUND

Schizophrenia spectrum disorders (SSDs) often feature social cognitive deficits. However, little work has focused on the factor structure of social cognition, and results have been inconsistent in schizophrenia. This study aimed to elucidate the factor structure of social cognition across people with SSDs and healthy controls. It was hypothesized that a 2-factor model, including lower-level "simulation" and higher-level "mentalizing" factors, would demonstrate the best fit across participants.

METHODS

Participants with SSDs (N = 164) and healthy controls (N = 102) completed social cognitive tasks ranging from emotion recognition to complex mental state inference, as well as clinical and functional outcome, and neurocognitive measures. Structural equation modeling was used to test social cognitive models, models of social cognition and neurocognition, measurement invariance between cases and controls, and relationships with outcome measures.

RESULTS

A 2-factor (simulation and mentalizing) model fit the social cognitive data best across participants and showed adequate measurement invariance in both SSD and control groups. Patients showed lower simulation and mentalizing scores than controls, but only mentalizing was significantly associated with negative symptoms and functional outcome. Social cognition also mediated the relationship between neurocognition and both negative symptoms and functional outcome.

CONCLUSIONS

These results uniquely indicate that distinct lower- and higher-level aspects of social cognition exist across SSDs and healthy controls. Further, mentalizing may be particularly linked to negative symptoms and functional outcome. This informs future studies of the neural circuitry underlying social cognition and the development of targeted treatment options for improving functional outcome.

Reduced tendency to attribute mental states to abstract shapes in behavioral variant frontotemporal dementia links with cerebellar structural integrity

Theory of mind (ToM) refers to the ability to attribute mental states to others. Behavioral variant frontotemporal dementia (bvFTD) is a neurodegenerative disorder characterized by profound deficits in social cognition, including ToM. We investigate whether bvFTD affects intention attribution tendency while viewing abstract animations and whether this might represent a primary deficit. A sample of 15 bvFTD patients and 19 matched controls were assessed on cognition and performed an implicit ToM task. They were instructed to describe what they observed in movement patterns displayed by geometrical shapes (triangles). These movement patterns either represented animacy, goal-directed actions or manipulation of mental state (ToM). The responses were scored for both accuracy and intentionality attribution. Using Voxel-Based Morphometry, we investigated the structural neuroanatomy associated with intention attribution tendency. The behavioral results revealed deficits in the bvFTD group on intentionality attribution that were specific for the ToM condition after controlling for global cognitive functioning (MMSE-score), visual attention (TMT B-score), fluid intelligence (RCPMT-score) and confrontation naming (BNT-score). In the bvFTD sample, the intention attribution tendency on the ToM-condition was associated with grey matter volume of a cluster in the cerebellum, spanning the right Crus I, Crus II, VIIIb, IX, left VIIb, IX and vermal IX and X. The results reveal a specific, primary, implicit domain-general ToM deficit in bvFTD that cannot be explained by cognitive dysfunction. Furthermore, the findings point to a contribution of the cerebellum in the social-cognitive phenotype of bvFTD.

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We show a reduction in intention attribution tendency to abstract shapes in bvFTD.

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Cognitive or subordinate processes did not explain the reduction.

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The reduction was associated with structural integrity of a cerebellar cluster.

Frontal variant of Alzheimer's disease masquerading as behavioural-variant frontotemporal dementia: a case study comparison

The current clinical diagnostic criteria for Alzheimer's disease (AD) recognize an atypical, non-amnestic presentation of AD, characterized by prominent executive dysfunction. Increasing evidence, however, indicates that the clinical phenotype of this so-called "frontal-variant" of AD (fv-AD) includes behavioral symptoms and deficits in social cognition, together with disproportionate frontal lobe atrophy. As these features resemble those characteristic of behavioral-variant frontotemporal dementia (bvFTD), differential diagnosis can be challenging. Here, we report a case of fv-AD who met clinical diagnostic criteria bvFTD, but had in vivo amyloid neuroimaging evidence of AD pathology. We compare this case against two individuals who were clinically diagnosed with bvFTD and early-onset AD, with in vivo amyloid neuroimaging confirmation of pathology. We highlight the challenges in differential diagnosis by contrasting their behavioral, cognitive and structural neuroimaging findings.

Social Cognition Dysfunctions in Neurodegenerative Diseases: Neuroanatomical Correlates and Clinical Implications

Social cognitive function, involved in the perception, processing, and interpretation of social information, has been shown to be crucial for successful communication and interpersonal relationships, thereby significantly impacting mental health, well-being, and quality of life. In this regard, assessment of social cognition, mainly focusing on four key domains, such as theory of mind (ToM), emotional empathy, and social perception and behavior, has been increasingly evaluated in clinical settings, given the potential implications of impairments of these skills for therapeutic decision-making. With regard to neurodegenerative diseases (NDs), most disorders, characterized by variable disease phenotypes and progression, although similar for the unfavorable prognosis, are associated to impairments of social cognitive function, with consequent negative effects on patients' management. Specifically, in some NDs these deficits may represent core diagnostic criteria, such as for behavioral variant frontotemporal dementia (bvFTD), or may emerge during the disease course as critical aspects, such as for Parkinson's and Alzheimer's diseases. On this background, we aimed to revise the most updated evidence on the neurobiological hypotheses derived from network-based approaches, clinical manifestations, and assessment tools of social cognitive dysfunctions in NDs, also prospecting potential benefits on patients' well-being, quality of life, and outcome derived from potential therapeutic perspectives of these deficits.