Cognitive and Affective Empathy Disruption in Non-Fluent Primary Progressive Aphasia Syndromes

Clinical and cortical trajectories in non-fluent primary progressive aphasia and Alzheimer's disease: A role for emotion processing

OBJECTIVES

To examine the clinical trajectories and neural correlates of cognitive and emotion processing changes in the non-fluent/agrammatic (nfvPPA) and the logopenic (lvPPA) variants of primary progressive aphasia (PPA).

DESIGN

Observational case-control longitudinal cohort study.

SETTING

Research clinic of frontotemporal dementia.

PARTICIPANTS

This study recruited 29 non-semantic PPA patients (15 nfvPPA and 14 lvPPA) and compared them with 15 Alzheimer's disease (AD) patients and 14 healthy controls.

MEASUREMENTS

Participants completed an annual assessment (median = 2 years; range = 1-5 years) of general cognition, emotion processing and structural MRI. Linear mixed effects models investigated clinical and imaging trajectories between groups.

RESULTS

Over time, lvPPA showed the greatest cognitive deterioration. In contrast, nfvPPA showed significant decline in emotion recognition, whereas AD showed preserved emotion recognition, even with disease progression. Importantly, lvPPA also developed emotion processing impairments, with disease progression. Both nfvPPA and lvPPA showed continuing cortical atrophy in hallmark language-processing regions associated with these syndromes, together with progressive involvement of the right hemisphere regions, mirroring left hemisphere atrophy patterns at presentation. Decline in emotion processing was associated with bilateral frontal atrophy in nfvPPA and right temporal atrophy in lvPPA.

CONCLUSIONS

Our results show divergent clinical courses in nfvPPA and lvPPA, with rapid cognitive and neural deterioration in lvPPA and emotion processing decline in both groups and support the concurrent assessment of cognition and emotion processing in the clinic to inform diagnosis and monitoring in the non-semantic variants of PPA.

Differences and Similarities in Empathy Deficit and Its Neural Basis between Logopenic and Amnesic Alzheimer's Disease

The aims of the study were to assess empathy deficit and neuronal correlates in logopenic primary progressive aphasia (lv-PPA) and compare these data with those deriving from amnesic Alzheimer's disease (AD). Eighteen lv-PPA and thirty-eight amnesic AD patients were included. Empathy in both cognitive and affective domains was assessed by Informer-rated Interpersonal Reactivity Index (perspective taking, PT, and fantasy, FT, for cognitive empathy; empathic concern, EC, and personal distress, PD, for affective empathy) before (T0) and after (T1) cognitive symptoms' onset. Emotion recognition was explored through the Ekman 60 Faces Test. Cerebral FDG-PET was used to explore neural correlates underlying empathy deficits. From T0 to T1, PT scores decreased, and PD scores increased in both lv-PPA (PT z = -3.43, p = 0.001; PD z = -3.62, p < 0.001) and in amnesic AD (PT z = -4.57, p < 0.001; PD z = -5.20, p < 0.001). Delta PT (T0-T1) negatively correlated with metabolic disfunction of the right superior temporal gyrus, fusiform gyrus, and middle frontal gyrus (MFG) in amnesic AD and of the left inferior parietal lobule (IPL), insula, MFG, and bilateral superior frontal gyrus (SFG) in lv-PPA (p < 0.005). Delta PD (T0-T1) positively correlated with metabolic disfunction of the right inferior frontal gyrus in amnesic AD (p < 0.001) and of the left IPL, insula, and bilateral SFG in lv-PPA (p < 0.005). Lv-PPA and amnesic AD share the same empathic changes, with a damage of cognitive empathy and a heightening of personal distress over time. The differences in metabolic disfunctions correlated with empathy deficits might be due to a different vulnerability of specific brain regions in the two AD clinical presentations.

Neuropsychiatric outcomes and caregiver distress in primary progressive aphasia

BACKGROUND

In this study, we aimed to outline the neuropsychiatric consequences of primary progressive aphasia (PPA) and to understand how neuropsychiatric symptomatology affects distress in caregivers.

METHODS

The Neuropsychiatric Inventory (NPI) including the distress index (NPI-Distress) was used. Additional information about the caregiver burden was obtained using Zarit Burden Interview (ZBI). NPI, NPI-Distress, and ZBI data from 17 patients with a clinical diagnosis of PPA were compared with 10 stroke aphasia patients. Neuropsychiatric symptomatology was investigated based on three clusters; Mood, Frontal/Comportmental, and Psychotic/Disruptive. Additionally, the Activities of Daily Living Questionnaire (ADLQ) was used to outline the functional impairment. Twelve healthy controls were included to compare the neurocognitive test scores with PPA and stroke aphasia groups.

RESULTS

A greater number of neuropsychiatric symptoms were observed in the PPA group compared to the stroke aphasia group. The number of symptoms in Mood, and Frontal/Comportmental clusters were greater than the number of symptoms in Psychotic/Disruptive clusters in the PPA group, whereas no significant relationship between the number of symptoms and symptom clusters was found in the stroke aphasia group. In the PPA group, a strong correlation was found between the NPI-Frequency × Severity scores and the NPI-Distress scores. Moreover, the NPI-Distress scores in the PPA group strongly correlated with the ZBI scores. Scores for anxiety, irritability/lability, and apathy had a stronger correlation with the NPI-Distress scores compared to the other NPI symptoms. The Communication subscale was the most impaired domain in the PPA group. Travel, and Employment and Recreation subscales showed greater functional impairment in the stroke aphasia group compared to the PPA group.

CONCLUSIONS

Neuropsychiatric symptoms in PPA in our study were more frequent than previously reported. Furthermore, the distress index of the NPI was not only correlated with the severity of the neuropsychiatric symptoms but also reflected the overall burden on the caregivers in the PPA group.

Longitudinal changes in behaviour, mood and functional capacity in the primary progressive aphasia variants

Primary progressive aphasia (PPA) is a neurodegenerative clinical syndrome characterised by a progressive decline in speech and language functions. Deficits in behaviour, mood and functional capacity are reported in PPA but are less well understood. This study examined the PPA variants' profiles on these domains at initial presentation and over time and evaluated their relations to overall cognitive ability. Behaviour, mood and functional capacity were measured annually (over ~6 years) in 145 individuals diagnosed with PPA (41 logopenic [lv-PPA], 44 non-fluent [nfv-PPA] and 60 semantic variants [sv-PPA]) using the Cambridge Behavioural Inventory-Revised (CBI-R) carer questionnaire. Overall cognition was assessed annually with the Addenbrooke's Cognitive Examination-III. Distinct profiles were observed across PPA syndromes. Notably, sv-PPA carers reported greater behavioural, eating and motivational disturbances than the other PPA variants throughout the disease course. Reported memory problems were also greater in sv-PPA and lv-PPA than in nfv-PPA across all time points. These disturbances occurred in the context of the sv-PPA group demonstrating a slower rate of cognitive decline than the lv-PPA group and a parallel rate to that found in the nfv-PPA group. Associations between overall cognition and the CBI-R domains were trivial at baseline assessment; however, distinct profiles emerged when mapping each syndrome's overall cognitive decline with their behavioural, mood and functional trajectories. Our findings demonstrate that the evolving behaviour, mood and functional capacity profiles of the PPA variants are distinct and extend beyond the primary disorder of language. These findings have important implications for clinical management and caregiver education in PPA.

Understanding the multidimensional cognitive deficits of logopenic variant primary progressive aphasia

The logopenic variant of primary progressive aphasia is characterized by early deficits in language production and phonological short-term memory, attributed to left-lateralized temporoparietal, inferior parietal and posterior temporal neurodegeneration. Despite patients primarily complaining of language difficulties, emerging evidence points to performance deficits in non-linguistic domains. Temporoparietal cortex, and functional brain networks anchored to this region, are implicated as putative neural substrates of non-linguistic cognitive deficits in logopenic variant primary progressive aphasia, suggesting that degeneration of a shared set of brain regions may result in co-occurring linguistic and non-linguistic dysfunction early in the disease course. Here, we provide a Review aimed at broadening the understanding of logopenic variant primary progressive aphasia beyond the lens of an exclusive language disorder. By considering behavioural and neuroimaging research on non-linguistic dysfunction in logopenic variant primary progressive aphasia, we propose that a significant portion of multidimensional cognitive features can be explained by degeneration of temporal/inferior parietal cortices and connected regions. Drawing on insights from normative cognitive neuroscience, we propose that these regions underpin a combination of domain-general and domain-selective cognitive processes, whose disruption results in multifaceted cognitive deficits including aphasia. This account explains the common emergence of linguistic and non-linguistic cognitive difficulties in logopenic variant primary progressive aphasia, and predicts phenotypic diversification associated with progression of pathology in posterior neocortex.

Examining empathy deficits across familial forms of frontotemporal dementia within the GENFI cohort

BACKGROUND

Reduced empathy is a common symptom in frontotemporal dementia (FTD). Although empathy deficits have been extensively researched in sporadic cases, few studies have explored the differences in familial forms of FTD.

METHODS

Empathy was examined using a modified version of the Interpersonal Reactivity Index (mIRI) in 676 participants from the Genetic FTD Initiative: 216 mutation-negative controls, 192 C9orf72 expansion carriers, 193 GRN mutation carriers and 75 MAPT mutation carriers. Using global scores from the CDR® plus NACC FTLD, mutation carriers were divided into three groups, asymptomatic (0), very mildly symptomatic/prodromal (.5), or fully symptomatic (1 or more). The mIRI Total score, as well as the subscores of Empathic Concern (EC) and Perspective Taking (PT) were assessed. Linear regression models with bootstrapping were used to assess empathy ratings across genetic groups, as well as across phenotypes in the symptomatic carriers. Neural correlates of empathy deficits were examined using a voxel-based morphometry (VBM) analysis.

RESULTS

All fully symptomatic groups scored lower on the mIRI Total, EC, and PT when compared to controls and their asymptomatic or prodromal counterparts (all p < .001). Prodromal C9orf72 expansion carriers also scored significantly lower than controls on the mIRI Total score (p = .046). In the phenotype analysis, all groups (behavioural variant FTD, primary progressive aphasia and FTD with amyotrophic lateral sclerosis) scored significantly lower than controls (all p < .007). VBM revealed an overlapping neural correlate of the mIRI Total score across genetic groups in the orbitofrontal lobe but with additional involvement in the temporal lobe, insula and basal ganglia in both the GRN and MAPT groups, and uniquely more posterior regions such as the parietal lobe and thalamus in the GRN group, and medial temporal structures in the MAPT group.

CONCLUSIONS

Significant empathy deficits present in genetic FTD, particularly in symptomatic individuals and those with a bvFTD phenotype, while prodromal deficits are only seen using the mIRI in C9orf72 expansion carriers.

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.

Cognitive and Neural Mechanisms of Social Communication Dysfunction in Primary Progressive Aphasia

Mounting evidence suggests that, in parallel with well-defined changes in language, primary progressive aphasia (PPA) syndromes display co-occurring social cognitive impairments. Here, we explored multidimensional profiles of carer-rated social communication using the La Trobe Communication Questionnaire (LCQ) in 11 semantic dementia (SD), 12 logopenic progressive aphasia (LPA) and 9 progressive non-fluent aphasia (PNFA) cases and contrasted their performance with 19 Alzheimer’s disease (AD) cases, 26 behavioural variant frontotemporal dementia (bvFTD) cases and 31 healthy older controls. Relative to the controls, the majority of patient groups displayed significant overall social communication difficulties, with common and unique profiles of impairment evident on the LCQ subscales. Correlation analyses revealed a differential impact of social communication disturbances on functional outcomes in patient and carer well-being, most pronounced for SD and bvFTD. Finally, voxel-based morphometry analyses based on a structural brain MRI pointed to the degradation of a distributed brain network in mediating social communication dysfunction in dementia. Our findings suggest that social communication difficulties are an important feature of PPA, with significant implications for patient function and carer well-being. The origins of these changes are likely to be multifactorial, reflecting the breakdown of fronto-thalamic brain circuits specialised in the integration of complex information.

Measuring social cognition in frontotemporal lobar degeneration: a clinical approach

Alterations in social cognition, a broad term indicating our ability to understand others and adapt our behavior accordingly, have been the focus of growing attention in the past years. Some neurological conditions, such as those belonging to the frontotemporal lobar degeneration (FTLD) spectrum, are associated to varying degrees with social cognition deficits, encompassing problems with theory of mind (ToM), empathy, perception of social stimuli, and social behavior. In this review, we outline a clinical framework for the evaluation of social cognition and discuss its role in the assessment of patients affected by a range of FTLD conditions.

Social cognition in the FTLD spectrum: evidence from MRI

Over the past few years, there has been great interest in social cognition, a wide term referring to the human ability of understanding others' emotions, thoughts, and intentions, to empathize with them and to behave accordingly. While there is no agreement on the classification of social cognitive processes, they can broadly be categorized as consisting of theory of mind, empathy, social perception, and social behavior. The study of social cognition and its relative deficits is increasingly assuming clinical relevance. However, the clinical and neuroanatomical correlates of social cognitive alterations in neurodegenerative conditions, such as those belonging to the frontotemporal lobar (FTLD) spectrum, are not fully established. In this review, we describe the current understanding of social cognition impairments in different FTLD conditions with respect to MRI.

Laughter as a paradigm of socio-emotional signal processing in dementia

Laughter is a fundamental communicative signal in our relations with other people and is used to convey a diverse repertoire of social and emotional information. It is therefore potentially a useful probe of impaired socio-emotional signal processing in neurodegenerative diseases. Here we investigated the cognitive and affective processing of laughter in forty-seven patients representing all major syndromes of frontotemporal dementia, a disease spectrum characterised by severe socio-emotional dysfunction (twenty-two with behavioural variant frontotemporal dementia, twelve with semantic variant primary progressive aphasia, thirteen with nonfluent-agrammatic variant primary progressive aphasia), in relation to fifteen patients with typical amnestic Alzheimer's disease and twenty healthy age-matched individuals. We assessed cognitive labelling (identification) and valence rating (affective evaluation) of samples of spontaneous (mirthful and hostile) and volitional (posed) laughter versus two auditory control conditions (a synthetic laughter-like stimulus and spoken numbers). Neuroanatomical associations of laughter processing were assessed using voxel-based morphometry of patients' brain MR images. While all dementia syndromes were associated with impaired identification of laughter subtypes relative to healthy controls, this was significantly more severe overall in frontotemporal dementia than in Alzheimer's disease and particularly in the behavioural and semantic variants, which also showed abnormal affective evaluation of laughter. Over the patient cohort, laughter identification accuracy was correlated with measures of daily-life socio-emotional functioning. Certain striking syndromic signatures emerged, including enhanced liking for hostile laughter in behavioural variant frontotemporal dementia, impaired processing of synthetic laughter in the nonfluent-agrammatic variant (consistent with a generic complex auditory perceptual deficit) and enhanced liking for numbers ('numerophilia') in the semantic variant. Across the patient cohort, overall laughter identification accuracy correlated with regional grey matter in a core network encompassing inferior frontal and cingulo-insular cortices; and more specific correlates of laughter identification accuracy were delineated in cortical regions mediating affective disambiguation (identification of hostile and posed laughter in orbitofrontal cortex) and authenticity (social intent) decoding (identification of mirthful and posed laughter in anteromedial prefrontal cortex) (all p < .05 after correction for multiple voxel-wise comparisons over the whole brain). These findings reveal a rich diversity of cognitive and affective laughter phenotypes in canonical dementia syndromes and suggest that laughter is an informative probe of neural mechanisms underpinning socio-emotional dysfunction in neurodegenerative disease.

Social Cognition Deficits Are Pervasive across Both Classical and Overlap Frontotemporal Dementia Syndromes

Objectives

Frontotemporal dementia (FTD) syndromes are a complex group of disorders characterised by profound changes in behaviour and cognition. Many of the observed behavioural abnormalities are now recognised to be due to impaired social cognition. While deficits in emotion recognition and empathy are well-recognised in behavioural-variant (Bv)FTD, limited information exists about the nature of social cognitive impairment in the language variant primary progressive aphasia (PPA) that includes progressive non-fluent aphasia (PNFA) and semantic dementia (SD), and in the motor variants FTD amyotrophic lateral sclerosis (FTD-ALS) and FTD progressive supranuclear palsy (FTD-PSP). This prospective study sought to explore the nature and profile of social cognition deficits across the spectrum of FTD.

Methods

Sixty patients on the FTD spectrum, i.e., classical (16 with BvFTD and 20 with PPA) and overlap FTD syndromes (13 with FTD-ALS and 11 with FTD-PSP) were evaluated by means of the social cognition tasks, the Interpersonal Reactivity Index (IRI) for empathy, and pictures of facial affect (POFA) for emotion recognition. General cognition and behaviour were also assessed.

Results

A significant impairment in emotion recognition and empathy was detected in both the classical and overlap FTD syndromes. The recognition of positive emotions was relatively preserved compared to that of negative emotions. Among the FTD subtypes, maximal impairment of empathy was demonstrated in FTD-PSP.

Conclusion

Social cognition impairment is pervasive across the spectrum of FTD disorders, and tests of emotion recognition and empathy are clinically useful to identify the nature of behavioural problems in both classical and overlap FTD. Our findings also have implications for understanding the neural basis of social cognition in FTD.

Comparing two facets of emotion perception across multiple neurodegenerative diseases

Deficits in emotion perception (the ability to infer others' emotions accurately) can occur as a result of neurodegeneration. It remains unclear how different neurodegenerative diseases affect different forms of emotion perception. The present study compares performance on a dynamic tracking task of emotion perception (where participants track the changing valence of a film character's emotions) with performance on an emotion category labeling task (where participants label specific emotions portrayed by film characters) across seven diagnostic groups (N = 178) including Alzheimer's disease (AD), behavioral variant frontotemporal dementia (bvFTD), semantic variant primary progressive aphasia (svPPA), non-fluent variant primary progressive aphasia (nfvPPA), progressive supranuclear palsy (PSP), corticobasal syndrome and healthy controls. Consistent with hypotheses, compared to controls, the bvFTD group was impaired on both tasks. The svPPA group was impaired on the emotion labeling task, whereas the nfvPPA, PSP and AD groups were impaired on the dynamic tracking task. Smaller volumes in bilateral frontal and left insular regions were associated with worse labeling, whereas smaller volumes in bilateral medial frontal, temporal and right insular regions were associated with worse tracking. Findings suggest labeling and tracking facets of emotion perception are differentially affected across neurodegenerative diseases due to their unique neuroanatomical correlates.

The functional neuroanatomy of emotion processing in frontotemporal dementias

Impaired processing of emotional signals is a core feature of frontotemporal dementia syndromes, but the underlying neural mechanisms have proved challenging to characterize and measure. Progress in this field may depend on detecting functional changes in the working brain, and disentangling components of emotion processing that include sensory decoding, emotion categorization and emotional contagion. We addressed this using functional MRI of naturalistic, dynamic facial emotion processing with concurrent indices of autonomic arousal, in a cohort of patients representing all major frontotemporal dementia syndromes relative to healthy age-matched individuals. Seventeen patients with behavioural variant frontotemporal dementia [four female; mean (standard deviation) age 64.8 (6.8) years], 12 with semantic variant primary progressive aphasia [four female; 66.9 (7.0) years], nine with non-fluent variant primary progressive aphasia [five female; 67.4 (8.1) years] and 22 healthy controls [12 female; 68.6 (6.8) years] passively viewed videos of universal facial expressions during functional MRI acquisition, with simultaneous heart rate and pupillometric recordings; emotion identification accuracy was assessed in a post-scan behavioural task. Relative to healthy controls, patient groups showed significant impairments (analysis of variance models, all P < 0.05) of facial emotion identification (all syndromes) and cardiac (all syndromes) and pupillary (non-fluent variant only) reactivity. Group-level functional neuroanatomical changes were assessed using statistical parametric mapping, thresholded at P < 0.05 after correction for multiple comparisons over the whole brain or within pre-specified regions of interest. In response to viewing facial expressions, all participant groups showed comparable activation of primary visual cortex while patient groups showed differential hypo-activation of fusiform and posterior temporo-occipital junctional cortices. Bi-hemispheric, syndrome-specific activations predicting facial emotion identification performance were identified (behavioural variant, anterior insula and caudate; semantic variant, anterior temporal cortex; non-fluent variant, frontal operculum). The semantic and non-fluent variant groups additionally showed complex profiles of central parasympathetic and sympathetic autonomic involvement that overlapped signatures of emotional visual and categorization processing and extended (in the non-fluent group) to brainstem effector pathways. These findings open a window on the functional cerebral mechanisms underpinning complex socio-emotional phenotypes of frontotemporal dementia, with implications for novel physiological biomarker development.

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.

More than words: Social cognition across variants of primary progressive aphasia

Although primary progressive aphasia (PPA) is clinically typified by linguistic impairments, emerging evidence highlights the presence of early deficits in social cognition. This review systematically describes the latter patterns, specifying their relation to the characteristic linguistic dysfunctions and atrophy patterns of non-fluent, semantic, and logopenic variants of the disease (nfvPPA, svPPA, and lvPPA, respectively), relative to closely related dementia types. Whereas the evidence on lvPPA proves scant, studies on nfvPPA and svPPA patients show consistent deficits in emotion recognition, theory of mind, and empathy. Notably, these seem to be intertwined with language impairments in nfvPPA, but they prove primary and independent of language disturbances in svPPA. Also, only the profile of svPPA resembles that of behavioral variant frontotemporal dementia, probably reflecting the overlap of fronto-temporal disruptions in both conditions. In short, the neurocognitive relationship between linguistic and socio-cognitive deficits cannot be precisely predicated for PPA as a whole; instead, specific links must be acknowledged in each variant. These emergent patterns pave the way for fruitful dimensional research in the field.

Motor signatures of emotional reactivity in frontotemporal dementia

Automatic motor mimicry is essential to the normal processing of perceived emotion, and disrupted automatic imitation might underpin socio-emotional deficits in neurodegenerative diseases, particularly the frontotemporal dementias. However, the pathophysiology of emotional reactivity in these diseases has not been elucidated. We studied facial electromyographic responses during emotion identification on viewing videos of dynamic facial expressions in 37 patients representing canonical frontotemporal dementia syndromes versus 21 healthy older individuals. Neuroanatomical associations of emotional expression identification accuracy and facial muscle reactivity were assessed using voxel-based morphometry. Controls showed characteristic profiles of automatic imitation, and this response predicted correct emotion identification. Automatic imitation was reduced in the behavioural and right temporal variant groups, while the normal coupling between imitation and correct identification was lost in the right temporal and semantic variant groups. Grey matter correlates of emotion identification and imitation were delineated within a distributed network including primary visual and motor, prefrontal, insular, anterior temporal and temporo-occipital junctional areas, with common involvement of supplementary motor cortex across syndromes. Impaired emotional mimesis may be a core mechanism of disordered emotional signal understanding and reactivity in frontotemporal dementia, with implications for the development of novel physiological biomarkers of socio-emotional dysfunction in these diseases.

What's New in the Clinical Management of Disorders of Social Cognition?

Social cognition refers to the ability to use social cues to infer the meaning and intentions behind the behaviour of others in order to respond in a socially adaptive manner. It is increasingly recognised that disorders of social cognition, including problems with emotion perception, theory of mind, conversational inference, morality judgements, decision making and social inhibition, characterise many developmental and psychiatric disorders and are highly relevant to many with acquired brain injuries or diseases, especially the frontotemporal dementias. This review provides an introduction and overview of the papers in this special edition on social cognition and places these in the context of other recent research. In doing so, several current issues in the clinical management of social cognition are delineated. Given that social cognition seems to be a sensitive predictor of psychosocial function, the assessment of social cognition is seen by many clinicians to be important although which profession is responsible is yet to be resolved. Issues in how social cognition are assessed are discussed, including the importance of context to social cognition, its interactive nature and the need to recognise influences such as family upbringing, gender and emotional state on social cognitive performance. There also needs to be development of tests that address all aspects of social cognition, including decision making and inhibition. Finally, this review discusses intervention research. Interventions are especially well developed in relation to schizophrenia, and less well developed in brain injury. These appear to be generally effective although treatments for emotional self-awareness are yet to be developed.