The functional neuroanatomy of emotion processing in frontotemporal dementias

Frontotemporal dementia. How to deal with its diagnostic complexity?

INTRODUCTION

Frontotemporal dementia (FTD) encompasses a group of heterogeneous neurodegenerative disorders. Aside from genetic cases, its diagnosis is challenging, particularly in the early stages when symptoms are ambiguous, and structural neuroimaging does not reveal characteristic patterns.

AREAS COVERED

The authors performed a comprehensive literature search through MEDLINE, Scopus, and Web of Science databases to gather evidence to aid the diagnostic process for suspected FTD patients, particularly in early phases, even in sporadic cases, ranging from established to promising tools. Blood-based biomarkers might help identify very early neuropathological stages and guide further evaluations. Subsequently, neurophysiological measures reflecting functional changes in cortical excitatory/inhibitory circuits, along with functional neuroimaging assessing brain network, connectivity, metabolism, and perfusion alterations, could detect specific changes associated to FTD even decades before symptom onset. As the neuropathological process advances, cognitive-behavioral profiles and atrophy patterns emerge, distinguishing specific FTD subtypes.

EXPERT OPINION

Emerging disease-modifying therapies require early patient enrollment. Therefore, a diagnostic paradigm shift is needed - from relying on typical cognitive and neuroimaging profiles of advanced cases to widely applicable biomarkers, primarily fluid biomarkers, and, subsequently, neurophysiological and functional neuroimaging biomarkers where appropriate. Additionally, exploring subjective complaints and behavioral changes detected by home-based technologies might be crucial for early diagnosis.

Comprehension of acoustically degraded emotional prosody in Alzheimer's disease and primary progressive aphasia

Previous research suggests that emotional prosody perception is impaired in neurodegenerative diseases like Alzheimer's disease (AD) and primary progressive aphasia (PPA). However, no previous research has investigated emotional prosody perception in these diseases under non-ideal listening conditions. We recruited 18 patients with AD, and 31 with PPA (nine logopenic (lvPPA); 11 nonfluent/agrammatic (nfvPPA) and 11 semantic (svPPA)), together with 24 healthy age-matched individuals. Participants listened to speech stimuli conveying three emotions in clear and noise-vocoded forms and had to identify the emotion being conveyed. We then conducted correlation analyses between task performance and measures of socio-emotional functioning. All patient groups showed significant impairments in identifying clear emotional prosody compared to healthy individuals. These deficits were exacerbated under noise-vocoded conditions, with all patient groups performing significantly worse than healthy individuals and patients with lvPPA performing significantly worse than those with svPPA. Significant correlations with social cognition measures were observed more consistently for noise-vocoded than clear emotional prosody comprehension. These findings open a window on a dimension of real-world emotional communication that has often been overlooked in dementia, with particular relevance to social cognition, and begin to suggest a novel candidate paradigm for investigating and quantifying this systematically.

Disgust-specific impairment of facial emotion recognition in Parkinson's disease patients with mild cognitive impairment

This study investigated the association between cognitive function and facial emotion recognition (FER) in patients with Parkinson's disease (PD) and mild cognitive impairment (PD-MCI). We enrolled 126 participants from Taiwan, including 63 patients with idiopathic PD and 63 matched healthy controls. The PD group was divided into two groups: those with normal cognitive function (PD-NC) and those with MCI (PD-MCI). Participants underwent a modality emotion recognition test and comprehensive cognitive assessment. Our findings reveal that patients with PD-MCI exhibit significantly impaired FER, especially in recognizing "disgust," compared with patients with PD-NC and healthy adults (P = .001). This deficit correlates with executive function, attention, memory, and visuospatial abilities. Attention mediates the relationship between executive function and "disgust" FER. The findings highlight how patients with PD-MCI are specifically challenged when recognizing "disgust" and suggest that cognitive training focusing on cognitive flexibility and attention may improve their FER abilities. This study contributes to our understanding of the nuanced relationship between cognitive dysfunction and FER in patients with PD-MCI, emphasizing the need for targeted interventions.

Abnormal activation patterns in MT+ during visual motion perception in major depressive disorder

Objective

Previous studies have found that patients with Major Depressive Disorder (MDD) exhibit impaired visual motion perception capabilities, and multi-level abnormalities in the human middle temporal complex (MT+), a key brain area for processing visual motion information. However, the brain activity pattern of MDD patients during the perception of visual motion information is currently unclear. In order to study the effect of depression on the activity and functional connectivity (FC) of MT+ during the perception of visual motion information, we conducted a study combining task-state fMRI and psychophysical paradigm to compare MDD patients and healthy control (HC).

Methods

Duration threshold was examined through a visual motion perception psychophysical experiment. In addition, a classic block-design grating motion task was utilized for fMRI scanning of 24 MDD patients and 25 HC. The grating moved randomly in one of eight directions. We examined the neural activation under visual stimulation conditions compared to the baseline and FC.

Results

Compared to HC group, MDD patients exhibited increased duration threshold. During the task, MDD patients showed decreased beta value and percent signal change in left and right MT+. In the sample comprising MDD and HC, there was a significant negative correlation between beta value in right MT+ and duration threshold. And in MDD group, activation in MT+ were significantly correlated with retardation score. Notably, no such differences in activation were observed in primary visual cortex (V1). Furthermore, when left MT+ served as the seed region, compared to the HC, MDD group showed increased FC with right calcarine fissure and surrounding cortex and decreased FC with left precuneus.

Conclusion

Overall, the findings of this study highlight that the visual motion perception function impairment in MDD patients relates to abnormal activation patterns in MT+, and task-related activity are significantly connected to the retardation symptoms of the disease. This not only provides insights into the potential neurobiological mechanisms behind visual motion perception disorder in MDD patients from the aspect of task-related brain activity, but also supports the importance of MT+ as a candidate biomarker region for MDD.

Basal parasympathetic deficits in C9orf72 hexanucleotide repeat expansion carriers relate to smaller frontoinsula and thalamus volume and lower empathy

Diminished basal parasympathetic nervous system activity is a feature of frontotemporal dementia that relates to left frontoinsula dysfunction and empathy impairment. Individuals with a pathogenic expansion of the hexanucleotide repeat in chromosome 9 open reading frame 72 (C9orf72), the most common genetic cause of frontotemporal dementia and amyotrophic lateral sclerosis, provide a unique opportunity to examine whether parasympathetic activity is disrupted in genetic forms of frontotemporal dementia and to investigate when parasympathetic deficits manifest in the pathophysiological cascade. We measured baseline respiratory sinus arrhythmia, a parasympathetic measure of heart rate variability, over two minutes in a sample of 102 participants that included 19 asymptomatic expansion carriers (C9+ asymp), 14 expansion carriers with mild cognitive impairment (C9+ MCI), 16 symptomatic expansion carriers with frontotemporal dementia (C9+ FTD), and 53 expansion-negative healthy controls (C9- HC) who also underwent structural magnetic resonance imaging. In follow-up analyses, we compared baseline respiratory sinus arrhythmia in the C9+ FTD group with an independent age-, sex-, and clinical severity-matched group of 26 people with sporadic behavioral variant frontotemporal dementia. The Frontotemporal Lobar Degeneration-modified Clinical Dementia Rating-Sum of Boxes score was used to quantify behavioral symptom severity, and informant ratings on the Interpersonal Reactivity Index provided measures of participants' current emotional (empathic concern) and cognitive (perspective-taking) empathy. Results indicated that the C9+ FTD group had lower baseline respiratory sinus arrhythmia than the C9+ MCI, C9+ asymp, and C9- HC groups, a deficit that was comparable to that of sporadic behavioral variant frontotemporal dementia. Linear regression analyses indicated that lower baseline respiratory sinus arrhythmia was associated with worse behavioral symptom severity and lower empathic concern and perspective-taking across the C9orf72 expansion carrier clinical spectrum. Whole-brain voxel-based morphometry analyses in participants with C9orf72 pathogenic expansions found that lower baseline respiratory sinus arrhythmia correlated with smaller gray matter volume in the left frontoinsula and bilateral thalamus, key structures that support parasympathetic function, and in the bilateral parietal lobes, occipital lobes, and cerebellum, regions that are also vulnerable in individuals with C9orf72 expansions. This study provides novel evidence that basal parasympathetic functioning is diminished in FTD due to C9orf72 expansions and suggests that baseline respiratory sinus arrhythmia may be a potential non-invasive biomarker that is sensitive to behavioral symptoms in the early stages of disease.

Error profiles of facial emotion recognition in frontotemporal dementia and Alzheimer's disease

OBJECTIVES

To identify the patterns of errors in facial emotion recognition in frontotemporal dementia (FTD) subtypes compared with Alzheimer's disease (AD) and healthy controls.

DESIGN

Retrospective analysis.

SETTING

Participants were recruited from FRONTIER, the frontotemporal dementia research group at the University of Sydney, Australia.

PARTICIPANTS

A total of 356 participants (behavioral-variant FTD (bvFTD): 62, semantic dementia (SD)-left: 29, SD-right: 14, progressive non-fluent aphasia (PNFA): 21, AD: 76, controls: 90) were included.

MEASUREMENTS

Facial emotion recognition was assessed using the Facial Affect Selection Task, a word-face matching task measuring recognition of the six basic emotions (anger, disgust, fear, happiness, sadness, and surprise), as well as neutral emotion, portrayed by black and white faces.

RESULTS

Overall, all clinical groups performed significantly worse than controls with the exception of the PNFA subgroup (p = .051). The SD-right group scored worse than all other clinical groups (all p values < .027) and the bvFTD subgroup performed worse than the PNFA group (p < .001). The most frequent errors were in response to the facial emotions disgust (26.1%) and fear (22.9%). The primary error response to each target emotion was identified; patterns of errors were similar across all clinical groups.

CONCLUSIONS

Facial emotion recognition is impaired in FTD and AD compared to healthy controls. Within FTD, bvFTD and SD-right are particularly impaired. Dementia groups cannot be distinguished based on error responses alone. Implications for future clinical diagnosis and research are discussed.

Emerging Theories of Allostatic-Interoceptive Overload in Neurodegeneration

Recent integrative multilevel models offer novel insights into the etiology and course of neurodegenerative conditions. The predictive coding of allostatic-interoception theory posits that the brain adapts to environmental demands by modulating internal bodily signals through the allostatic-interoceptive system. Specifically, a domain-general allostatic-interoceptive network exerts adaptive physiological control by fine-tuning initial top-down predictions and bottom-up peripheral signaling. In this context, adequate adaptation implies the minimization of prediction errors thereby optimizing energy expenditure. Abnormalities in top-down interoceptive predictions or peripheral signaling can trigger allostatic overload states, ultimately leading to dysregulated interoceptive and bodily systems (endocrine, immunological, circulatory, etc.). In this context, environmental stress, social determinants of health, and harmful exposomes (i.e., the cumulative life-course exposition to different environmental stressors) may interact with physiological and genetic factors, dysregulating allostatic interoception and precipitating neurodegenerative processes. We review the allostatic-interoceptive overload framework across different neurodegenerative diseases, particularly in the behavioral variant frontotemporal dementia (bvFTD). We describe how concepts of allostasis and interoception could be integrated with principles of predictive coding to explain how the brain optimizes adaptive responses, while maintaining physiological stability through feedback loops with multiple organismic systems. Then, we introduce the model of allostatic-interoceptive overload of bvFTD and discuss its implications for the understanding of pathophysiological and neurocognitive abnormalities in multiple neurodegenerative conditions.

Disrupted social perception in frontotemporal dementia and Alzheimer's disease - Associated cognitive processes and clinical implications

BACKGROUND

Social perception refers to the ability to adapt and update one's behaviour in accordance with the current context and provides the foundation for many complex social and emotional interactions. Alterations in social cognition are a hallmark of the behavioural variant of frontotemporal dementia (bvFTD), yet the capacity for social perception in this syndrome remains unclear.

METHODS

We examined social perception in 18 bvFTD and 13 Alzheimer's disease (AD) patients, in comparison with 17 healthy older controls, using a social perception task derived from the Dewey Story Test. Participants also completed a comprehensive neuropsychological battery and carers provided ratings of behavioural and neuropsychiatric changes.

RESULTS

Overall, bvFTD and AD performance diverged significantly from control ratings on the social perception task, however, no significant difference was found between patient groups. Standardised values relative to the mean control rating revealed considerable variability within the patient groups in terms of the direction of deviation, i.e., over- or under-rating the vignettes relative to healthy controls (range z-scores = -1.79 to +1.63). Greater deviation from control ratings was associated with more pronounced memory (p = .007) and behavioural (p = .009) disturbances in bvFTD; whilst social perception performance correlated exclusively with verbal fluency in AD (p = .003).

CONCLUSIONS

Social perception is comparably disrupted in bvFTD and AD, yet likely reflects the differential breakdown of distinct cognitive processes in each dementia syndrome. Our findings have important clinical implications for the development of targeted interventions to manage disease-specific changes in social perception in dementia.

Frequency specific alterations of the degree centrality in patients with acute basal ganglia ischemic stroke: a resting-state fMRI study

This study intended to investigate the frequency specific brain oscillation activity in patients with acute basal ganglia ischemic stroke (BGIS) by using the degree centrality (DC) method. A total of 34 acute BGIS patients and 44 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging (rs-fMRI) scanning. The DC values in three frequency bands (conventional band: 0.01-0.08 Hz, slow‑4 band: 0.027-0.073 Hz, slow‑5 band: 0.01-0.027 Hz) were calculated. A two-sample t-test was used to explore the between-group differences in the conventional frequency band. A two-way repeated-measures analysis of variance (ANOVA) was used to analyze the DC differences between groups (BGIS patients, HCs) and bands (slow‑4, slow‑5). Moreover, correlations between DC values and clinical indicators were performed. In conventional band, the DC value in the right middle temporal gyrus was decreased in BGIS patients compared with HCs. Significant differences of DC were observed between the two bands mainly in the bilateral cortical brain regions. Compared with the HCs, the BGIS patients showed increased DC in the right superior temporal gyrus and the left precuneus, but decreased mainly in the right inferior temporal gyrus, right inferior occipital gyrus, right precentral, and right supplementary motor area. Furthermore, the decreased DC in the right rolandic operculum in slow-4 band and the right superior temporal gyrus in slow-5 band were found by post hoc two-sample t-test of main effect of group. There was no significant correlation between DC values and clinical scales after Bonferroni correction. Our findings showed that the DC changes in BGIS patients were frequency specific. Functional abnormalities in local brain regions may help us to understand the underlying pathogenesis mechanism of brain functional reorganization of BGIS patients.

Primary progressive aphasia: six questions in search of an answer

Here, we review recent progress in the diagnosis and management of primary progressive aphasia-the language-led dementias. We pose six key unanswered questions that challenge current assumptions and highlight the unresolved difficulties that surround these diseases. How many syndromes of primary progressive aphasia are there-and is syndromic diagnosis even useful? Are these truly 'language-led' dementias? How can we diagnose (and track) primary progressive aphasia better? Can brain pathology be predicted in these diseases? What is their core pathophysiology? In addition, how can primary progressive aphasia best be treated? We propose that pathophysiological mechanisms linking proteinopathies to phenotypes may help resolve the clinical complexity of primary progressive aphasia, and may suggest novel diagnostic tools and markers and guide the deployment of effective therapies.

Facial expression recognition deficits in frontotemporal dementia and Alzheimer's disease: a meta-analytic investigation of effects of phenotypic variant, task modality, geographical region and symptomatic specificity

Deficits in social cognition may be present in frontotemporal dementia (FTD) and Alzheimer's disease (AD). Here, we conduct a qualitative synthesis and meta-analysis of facial expression recognition studies in which we compare the deficits between both disorders. Furthermore, we investigate the specificity of the deficit regarding phenotypic variant, domain-specificity, emotion category, task modality, and geographical region. The results reveal that both FTD and AD are associated with facial expression recognition deficits, that this deficit is more pronounced in FTD compared to AD and that this applies for the behavioral as well as for language FTD-variants, with no difference between the latter two. In both disorders, overall emotion recognition was most frequently impaired, followed by recognition of anger in FTD and by fear in AD. Verbal categorization was the most frequently used task, although matching or intensity rating tasks may be more specific. Studies from Oceania revealed larger deficits. On the other hand, non-emotional control tasks were more impacted by AD than by FTD. The present findings sharpen the social cognitive phenotype of FTD and AD, and support the use of social cognition assessment in late-life neuropsychiatric disorders.

Diminished baseline autonomic outflow in semantic dementia relates to left-lateralized insula atrophy

In semantic dementia (SD), asymmetric degeneration of the anterior temporal lobes is associated with loss of semantic knowledge and alterations in socioemotional behavior. There are two clinical variants of SD: semantic variant primary progressive aphasia (svPPA), which is characterized by predominant atrophy in the anterior temporal lobe and insula in the left hemisphere, and semantic behavioral variant frontotemporal dementia (sbvFTD), which is characterized by predominant atrophy in those structures in the right hemisphere. Previous studies of behavioral variant frontotemporal dementia, an associated clinical syndrome that targets the frontal lobes and anterior insula, have found impairments in baseline autonomic nervous system activity that correlate with left-lateralized frontotemporal atrophy patterns and disruptions in socioemotional functioning. Here, we evaluated whether there are similar impairments in resting autonomic nervous system activity in SD that also reflect left-lateralized atrophy and relate to diminished affiliative behavior. A total of 82 participants including 33 people with SD (20 svPPA and 13 sbvFTD) and 49 healthy older controls completed a laboratory-based assessment of respiratory sinus arrhythmia (RSA; a parasympathetic measure) and skin conductance level (SCL; a sympathetic measure) during a two-minute resting baseline period. Participants also underwent structural magnetic resonance imaging, and informants rated their current affiliative behavior on the Interpersonal Adjective Scale. Results indicated that baseline RSA and SCL were lower in SD than in healthy controls, with significant impairments present in both svPPA and sbvFTD. Voxel-based morphometry analyses revealed left-greater-than-right atrophy related to diminished parasympathetic and sympathetic outflow in SD. While left-lateralized atrophy in the mid-to-posterior insula correlated with lower RSA, left-lateralized atrophy in the ventral anterior insula correlated with lower SCL. In SD, lower baseline RSA, but not lower SCL, was associated with lower gregariousness/extraversion. Neither autonomic measure related to warmth/agreeableness, however. Through the assessment of baseline autonomic nervous system physiology, the present study contributes to expanding conceptualizations of the biological basis of socioemotional alterations in svPPA and sbvFTD.

Broadening and deepening the understanding of agency in dementia

Agency has become an essential component of discussions concerning selfhood, well-being, and care in dementia studies but the concept itself is rarely clearly defined and the use of this term can be confusing and conflicting. This paper outlines some of the key ways in which agency has been conceptualised in relation to dementia, highlighting the complexities surrounding this concept and focusing on agency in a way that is tied to our ideas about citizenship, legal and human rights. Seven key dimensions of agency are examined: embodiment, emotions, sense of agency, intentional conscious action, the social context of agency, decision-making and moral responsibility. Using a critical realist approach, this paper brings together the diverse ways in which agency has been understood into an interdisciplinary, laminated understanding of agency. This model is then used in an applied example demonstrating that this model can be used to identify the ways in which an arts intervention can support the agency of people living with dementia. This paper proposes that agency is layered, multidimensional and exists on a continuum.

The architecture of abnormal reward behaviour in dementia: multimodal hedonic phenotypes and brain substrate

Abnormal reward processing is a hallmark of neurodegenerative diseases, most strikingly in frontotemporal dementia. However, the phenotypic repertoire and neuroanatomical substrates of abnormal reward behaviour in these diseases remain incompletely characterized and poorly understood. Here we addressed these issues in a large, intensively phenotyped patient cohort representing all major syndromes of sporadic frontotemporal dementia and Alzheimer's disease. We studied 27 patients with behavioural variant frontotemporal dementia, 58 with primary progressive aphasia (22 semantic variant, 24 non-fluent/agrammatic variant and 12 logopenic) and 34 with typical amnestic Alzheimer's disease, in relation to 42 healthy older individuals. Changes in behavioural responsiveness were assessed for canonical primary rewards (appetite, sweet tooth, sexual activity) and non-primary rewards (music, religion, art, colours), using a semi-structured survey completed by patients' primary caregivers. Changes in more general socio-emotional behaviours were also recorded. We applied multiple correspondence analysis and k-means clustering to map relationships between hedonic domains and extract core factors defining aberrant hedonic phenotypes. Neuroanatomical associations were assessed using voxel-based morphometry of brain MRI images across the combined patient cohort. Altered (increased and/or decreased) reward responsiveness was exhibited by most patients in the behavioural and semantic variants of frontotemporal dementia and around two-thirds of patients in other dementia groups, significantly (P < 0.05) more frequently than in healthy controls. While food-directed changes were most prevalent across the patient cohort, behavioural changes directed toward non-primary rewards occurred significantly more frequently (P < 0.05) in the behavioural and semantic variants of frontotemporal dementia than in other patient groups. Hedonic behavioural changes across the patient cohort were underpinned by two principal factors: a 'gating' factor determining the emergence of altered reward behaviour and a 'modulatory' factor determining how that behaviour is directed. These factors were expressed jointly in a set of four core, trans-diagnostic and multimodal hedonic phenotypes: 'reward-seeking', 'reward-restricted', 'eating-predominant' and 'control-like'-variably represented across the cohort and associated with more pervasive socio-emotional behavioural abnormalities. The principal gating factor was associated (P < 0.05 after correction for multiple voxel-wise comparisons over the whole brain) with a common profile of grey matter atrophy in anterior cingulate, bilateral temporal poles, right middle frontal and fusiform gyri: the cortical circuitry that mediates behavioural salience and semantic and affective appraisal of sensory stimuli. Our findings define a multi-domain phenotypic architecture for aberrant reward behaviours in major dementias, with novel implications for the neurobiological understanding and clinical management of these diseases.

Altered brain activities in mesocorticolimbic pathway in primary dysmenorrhea patients of long-term menstrual pain

Background

Patients with primary dysmenorrhea (PDM) often present with abnormalities other than dysmenorrhea including co-occurrence with other chronic pain conditions and central sensitization. Changes in brain activity in PDM have been demonstrated; however, the results are not consistent. Herein, this study probed into altered intraregional and interregional brain activity in patients with PDM and expounded more findings.

Methods

A total of 33 patients with PDM and 36 healthy controls (HCs) were recruited and underwent a resting-state functional magnetic resonance imaging scan. Regional homogeneity (ReHo) and mean amplitude of low-frequency fluctuation (mALFF) analysis were applied to compare the difference in intraregional brain activity between the two groups, and the regions with ReHo and mALFF group differences were used as seeds for functional connectivity (FC) analysis to explore the difference of interregional activity. Pearson's correlation analysis was conducted between rs-fMRI data and clinical symptoms in patients with PDM.

Results

Compared with HCs, patients with PDM showed altered intraregional activity in a series of brain regions, including the hippocampus, the temporal pole superior temporal gyrus, the nucleus accumbens, the pregenual anterior cingulate cortex, the cerebellum_8, the middle temporal gyrus, the inferior temporal gyrus, the rolandic operculum, the postcentral gyrus and the middle frontal gyrus (MFG), and altered interregional FC mainly between regions of the mesocorticolimbic pathway and regions associated with sensation and movement. The anxiety symptoms are correlated with the intraregional activity of the right temporal pole superior temporal gyrus and FC between MFG and superior frontal gyrus.

Conclusion

Our study showed a more comprehensive method to explore changes in brain activity in PDM. We found that the mesocorticolimbic pathway might play a key role in the chronic transformation of pain in PDM. We, therefore, speculate that the modulation of the mesocorticolimbic pathway may be a potential novel therapeutic mechanism for PDM.

Neural compensation in manifest neurodegeneration: systems neuroscience evidence from social cognition in frontotemporal dementia

BACKGROUND

It has been argued that symptom onset in neurodegeneration reflects the overload of compensatory mechanisms. The present study aimed to investigate whether neural functional compensation can be observed in the manifest neurodegenerative disease stage, by focusing on a core deficit in frontotemporal dementia, i.e. social cognition, and by combining psychophysical assessment, structural MRI and functional MRI with multidimensional neural markers that allow quantification of neural computations.

METHODS

Nineteen patients with clinically manifest behavioral variant frontotemporal dementia (bvFTD) and 20 controls performed facial expression recognition tasks in the MRI-scanner and offline. Group differences in grey matter volume, neural response amplitude and neural patterns were assessed via a combination of voxel-wise whole-brain, searchlight, and ROI-analyses and these measures were correlated with psychophysical measures of emotion, valence and arousal ratings.

RESULTS

Significant group effects were observed only outside task-relevant regions, converging in the caudate nucleus. This area showed a diagnostic neural pattern as well as hyperactivation and stronger neural representation of facial expressions in the bvFTD sample. Furthermore, response amplitude was associated with behavioral arousal ratings.

CONCLUSIONS

The combined findings reveal converging support for compensatory processes in clinically manifest neurodegeneration, complementing accounts that clinical onset synchronizes with the breakdown of compensatory processes. Furthermore, active compensation may proceed along nodes in intrinsically connected networks, rather than along the more task-specific networks. The findings underscore the potential of distributed multidimensional functional neural characteristics that may provide a novel class of biomarkers with both diagnostic and therapeutic implications, including biomarkers for clinical trials.

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.

A predictive coding framework of allostatic-interoceptive overload in frontotemporal dementia

Recent allostatic-interoceptive explanations using predictive coding models propose that efficient regulation of the body's internal milieu is necessary to correctly anticipate environmental needs. We review this framework applied to understanding behavioral variant frontotemporal dementia (bvFTD) considering both allostatic overload and interoceptive deficits. First, we show how this framework could explain divergent deficits in bvFTD (cognitive impairments, behavioral maladjustment, brain atrophy, fronto-insular-temporal network atypicality, aberrant interoceptive electrophysiological activity, and autonomic disbalance). We develop a set of theory-driven predictions based on levels of allostatic interoception associated with bvFTD phenomenology and related physiopathological mechanisms. This approach may help further understand the disparate behavioral and physiopathological dysregulations of bvFTD, suggesting targeted interventions and strengthening clinical models of neurological and psychiatric disorders.

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.

Authors' Reply: Why a Connectionist Perspective on Emotion is Helpful

To make progress related to long-standing questions related to the nature of emotion, we offer the Interactive Activation and Competition framework for Emotion (IAC-E). The IAC-E is not another conventional theory of emotion. Rather, it offers a neural-network-based, algorithmic account of how emotion instances and categories arise. Our approach suggests that there need not be a contradiction between instances of the same emotion being sometimes consistent and sometimes variable. Similarly, there need not be a contradiction between observations of homogeneity (common in the basic emotion approach) and heterogeneity (common in the constructed emotion approach) within emotion categories

Resting state functional brain networks associated with emotion processing in frontotemporal lobar degeneration

This study investigated the relationship between emotion processing and resting-state functional connectivity (rs-FC) of the brain networks in frontotemporal lobar degeneration (FTLD). Eighty FTLD patients (including cases with behavioral variant of frontotemporal dementia, primary progressive aphasia, progressive supranuclear palsy syndrome, motor neuron disease) and 65 healthy controls underwent rs-functional MRI. Emotion processing was tested using the Comprehensive Affect Testing System (CATS). In patients and controls, correlations were investigated between each emotion construct and rs-FC changes within critical networks. Mean rs-FC of the clusters significantly associated with CATS scoring were compared among FTLD groups. FTLD patients had pathological CATS scores compared with controls. In controls, increased rs-FC of the cerebellar and visuo-associative networks correlated with better scores in emotion-matching and discrimination tasks, respectively; while decreased rs-FC of the visuo-spatial network was related with better performance in the affect-matching and naming. In FTLD, the associations between rs-FC and CATS scores involved more brain regions, such as orbitofrontal and middle frontal gyri within anterior networks (i.e., salience and default-mode), parietal and somatosensory regions within visuo-spatial and sensorimotor networks, caudate and thalamus within basal-ganglia network. Rs-FC changes associated with CATS were similar among all FTLD groups. In FTLD compared to controls, the pattern of rs-FC associated with emotional processing involves a larger number of brain regions, likely due to functional specificity loss and compensatory attempts. These associations were similar across all FTLD groups, suggesting a common physiopathological mechanism of emotion processing breakdown, regardless the clinical presentation and pattern of atrophy.

Test-retest reliability of dynamic functional connectivity in naturalistic paradigm functional magnetic resonance imaging

Dynamic functional connectivity (dFC) has been increasingly used to characterize the brain transient temporal functional patterns and their alterations in diseased brains. Meanwhile, naturalistic neuroimaging paradigms have been an emerging approach for cognitive neuroscience with high ecological validity. However, the test–retest reliability of dFC in naturalistic paradigm neuroimaging is largely unknown. To address this issue, we examined the test–retest reliability of dFC in functional magnetic resonance imaging (fMRI) under natural viewing condition. The intraclass correlation coefficients (ICC) of four dFC statistics including standard deviation (Std), coefficient of variation (COV), amplitude of low frequency fluctuation (ALFF), and excursion (Excursion) were used to measure the test–retest reliability. The test–retest reliability of dFC in naturalistic viewing condition was then compared with that under resting state. Our experimental results showed that: (a) Global test–retest reliability of dFC was much lower than that of static functional connectivity (sFC) in both resting‐state and naturalistic viewing conditions; (b) Both global and local (including visual, limbic and default mode networks) test–retest reliability of dFC could be significantly improved in naturalistic viewing condition compared to that in resting state; (c) There existed strong negative correlation between sFC and dFC, weak negative correlation between dFC and dFC‐ICC (i.e., ICC of dFC), as well as weak positive correlation between dFC‐ICC and sFC‐ICC (i.e., ICC of sFC). The present study provides novel evidence for the promotion of naturalistic paradigm fMRI in functional brain network studies.

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.

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.

Classification of Complex Emotions Using EEG and Virtual Environment: Proof of Concept and Therapeutic Implication

During the last decades, neurofeedback training for emotional self-regulation has received significant attention from scientific and clinical communities. Most studies have investigated emotions using functional magnetic resonance imaging (fMRI), including the real-time application in neurofeedback training. However, the electroencephalogram (EEG) is a more suitable tool for therapeutic application. Our study aims at establishing a method to classify discrete complex emotions (e.g., tenderness and anguish) elicited through a near-immersive scenario that can be later used for EEG-neurofeedback. EEG-based affective computing studies have mainly focused on emotion classification based on dimensions, commonly using passive elicitation through single-modality stimuli. Here, we integrated both passive and active elicitation methods. We recorded electrophysiological data during emotion-evoking trials, combining emotional self-induction with a multimodal virtual environment. We extracted correlational and time-frequency features, including frontal-alpha asymmetry (FAA), using Complex Morlet Wavelet convolution. Thinking about future real-time applications, we performed within-subject classification using 1-s windows as samples and we applied trial-specific cross-validation. We opted for a traditional machine-learning classifier with low computational complexity and sufficient validation in online settings, the Support Vector Machine. Results of individual-based cross-validation using the whole feature sets showed considerable between-subject variability. The individual accuracies ranged from 59.2 to 92.9% using time-frequency/FAA and 62.4 to 92.4% using correlational features. We found that features of the temporal, occipital, and left-frontal channels were the most discriminative between the two emotions. Our results show that the suggested pipeline is suitable for individual-based classification of discrete emotions, paving the way for future personalized EEG-neurofeedback training.

Decoding expectation and surprise in dementia: the paradigm of music

Making predictions about the world and responding appropriately to unexpected events are essential functions of the healthy brain. In neurodegenerative disorders, such as frontotemporal dementia and Alzheimer's disease, impaired processing of 'surprise' may underpin a diverse array of symptoms, particularly abnormalities of social and emotional behaviour, but is challenging to characterize. Here, we addressed this issue using a novel paradigm: music. We studied 62 patients (24 female; aged 53-88) representing major syndromes of frontotemporal dementia (behavioural variant, semantic variant primary progressive aphasia, non-fluent-agrammatic variant primary progressive aphasia) and typical amnestic Alzheimer's disease, in relation to 33 healthy controls (18 female; aged 54-78). Participants heard famous melodies containing no deviants or one of three types of deviant note-acoustic (white-noise burst), syntactic (key-violating pitch change) or semantic (key-preserving pitch change). Using a regression model that took elementary perceptual, executive and musical competence into account, we assessed accuracy detecting melodic deviants and simultaneously recorded pupillary responses and related these to deviant surprise value (information-content) and carrier melody predictability (entropy), calculated using an unsupervised machine learning model of music. Neuroanatomical associations of deviant detection accuracy and coupling of detection to deviant surprise value were assessed using voxel-based morphometry of patients' brain MRI. Whereas Alzheimer's disease was associated with normal deviant detection accuracy, behavioural and semantic variant frontotemporal dementia syndromes were associated with strikingly similar profiles of impaired syntactic and semantic deviant detection accuracy and impaired behavioural and autonomic sensitivity to deviant information-content (all P < 0.05). On the other hand, non-fluent-agrammatic primary progressive aphasia was associated with generalized impairment of deviant discriminability (P < 0.05) due to excessive false-alarms, despite retained behavioural and autonomic sensitivity to deviant information-content and melody predictability. Across the patient cohort, grey matter correlates of acoustic deviant detection accuracy were identified in precuneus, mid and mesial temporal regions; correlates of syntactic deviant detection accuracy and information-content processing, in inferior frontal and anterior temporal cortices, putamen and nucleus accumbens; and a common correlate of musical salience coding in supplementary motor area (all P < 0.05, corrected for multiple comparisons in pre-specified regions of interest). Our findings suggest that major dementias have distinct profiles of sensory 'surprise' processing, as instantiated in music. Music may be a useful and informative paradigm for probing the predictive decoding of complex sensory environments in neurodegenerative proteinopathies, with implications for understanding and measuring the core pathophysiology of these diseases.

Resting functional connectivity in the semantic appraisal network predicts accuracy of emotion identification

OBJECTIVE

Structural and task-based functional studies associate emotion reading with frontotemporal brain networks, though it remains unclear whether functional connectivity (FC) alone predicts emotion reading ability. The predominantly frontotemporal salience and semantic appraisal (SAN) networks are selectively impacted in neurodegenerative disease syndromes like behavioral-variant frontotemporal dementia (bvFTD) and semantic-variant primary progressive aphasia (svPPA). Accurate emotion identification diminishes in some of these patients, but studies investigating the source of this symptom in patients have predominantly examined structural rather than functional brain changes. Thus, we investigated the impact of altered connectivity on their emotion reading.

METHODS

One-hundred-eighty-five participants (26 bvFTD, 21 svPPA, 24 non-fluent variant PPA, 24 progressive supranuclear palsy, 49 Alzheimer's disease, 41 neurologically healthy older controls) underwent task-free fMRI, and completed the Emotion Evaluation subtest of The Awareness of Social Inference Test (TASIT-EET), watching videos and selecting labels for actors' emotions.

RESULTS

As expected, patients averaged significantly worse on emotion reading, but with wide inter-individual variability. Across all groups, lower mean FC in the SAN, but not other ICNs, predicted worse TASIT-EET performance. Node-pair analysis revealed that emotion identification was predicted by FC between 1) right anterior temporal lobe (RaTL) and right anterior orbitofrontal (OFC), 2) RaTL and right posterior OFC, and 3) left basolateral amygdala and left posterior OFC.

CONCLUSION

Emotion reading test performance predicts FC in specific SAN regions mediating socioemotional semantics, personalized evaluations, and salience-driven attention, highlighting the value of emotion testing in clinical and research settings to index neural circuit dysfunction in patients with neurodegeneration and other neurologic disorders.

Primary Progressive Aphasia: Toward a Pathophysiological Synthesis

PURPOSE OF REVIEW

The term primary progressive aphasia (PPA) refers to a diverse group of dementias that present with prominent and early problems with speech and language. They present considerable challenges to clinicians and researchers.

RECENT FINDINGS

Here, we review critical issues around diagnosis of the three major PPA variants (semantic variant PPA, nonfluent/agrammatic variant PPA, logopenic variant PPA), as well as considering 'fragmentary' syndromes. We next consider issues around assessing disease stage, before discussing physiological phenotyping of proteinopathies across the PPA spectrum. We also review evidence for core central auditory impairments in PPA, outline critical challenges associated with treatment, discuss pathophysiological features of each major PPA variant, and conclude with thoughts on key challenges that remain to be addressed. New findings elucidating the pathophysiology of PPA represent a major step forward in our understanding of these diseases, with implications for diagnosis, care, management, and therapies.

Frontotemporal Dementia: A Window to Alexithymia

Alexithymia is pervasive among psychiatric patients, but its neurobiological mechanism is unclear. Patients with alexithymia cannot "read emotions," a process involving interoception, or the perception of the body's internal state, primarily in the insulae. The frontotemporal dementias are also associated with inability to correctly read emotions; hence, these dementias can provide a window into the mechanism of alexithymia. Patients with behavioral variant frontotemporal dementia (bvFTD) have a weak emotional signal with impaired emotional recognition, hypoemotionality, and decreased physiological arousal. bvFTD affects the insulae, and the weak emotional signal facilitates impaired interoceptive accuracy, resulting in an overreliance on cognitive appraisal rather than on internal sensations. In contrast, patients with semantic dementia, another frontotemporal dementia syndrome, can have intact interoception, but they have disturbed cognitive appraisal of the meaning of their bodily sensations. This "alexisomia" in semantic dementia can lead to misinterpreted somatic symptoms. Together, the findings in alexithymic patients and frontotemporal dementia syndromes support the model of impaired interoceptive accuracy as the mechanism of alexithymia, possibly from dysfunction in the insulae.

Disorders of facial emotional expression and comprehension

One of the most important means of communicating emotions is by facial expressions. About 30-40 years ago, several studies examined patients with right and left hemisphere strokes for deficits in expressing and comprehending emotional facial expressions. The participants with right- or left-hemispheric strokes attempted to determine if two different actors were displaying the same or different emotions, to name the different emotions being displayed, and to select the face displaying an emotion named by the examiner. Investigators found that the right hemisphere-damaged group was impaired on all these emotional facial tests and that this deficit was not solely related to visuoperceptual processing defects. Further studies revealed that the patients who were impaired at recognizing emotional facial expressions and who had lost these visual representations of emotional faces often had damage to their right parietal lobe and their right somatosensory cortex. Injury to the cerebellum has been reported to impair emotional facial recognition, as have dementing diseases such as Alzheimer's disease and frontotemporal dementia, movement disorders such as Parkinson's disease and Huntington's disease, traumatic brain injuries, and temporal lobe epilepsy. Patients with right hemisphere injury are also more impaired than left-hemisphere-damaged patients when attempting to voluntarily produce facial emotional expressions and in their spontaneous expression of emotions in response to stimuli. This impairment does not appear to be induced by emotional conceptual deficits or an inability to experience emotions. Many of the disorders that cause impairments of comprehension of affective facial expressions also impair facial emotional expression. Treating the underlying disease may help patients with impairments of facial emotion recognition and expression, but unfortunately, there have not been many studies of rehabilitation.

Degenerative dementias: Alterations of emotions and mood disorders

Degenerative dementias such as Alzheimer's disease and frontotemporal dementia result in distinct alterations in emotional processing, emotional experiences, and mood. The neuropathology of these dementias extends to structures involved in emotional processing, including the basolateral limbic network (orbitofrontal cortex, anterior temporal lobe, amygdala, and thalamus), the insula, and ventromedial frontal lobe. Depression is the most common emotion and mood disorder affecting patients with Alzheimer's disease. The onset of depression can be a prodromal sign of this dementia. Anxiety can also be present early in the course of Alzheimer's disease and especially among patients with early-onset forms of the disease. In contrast, patients with behavioral variant frontotemporal dementia demonstrate hypoemotionality, deficits in the recognition of emotion, and decreased psychophysiological reactivity to emotional stimuli. They typically have a disproportionate impairment in emotional and cognitive empathy. One other unique feature of behavioral variant frontotemporal dementia is the frequent occurrence of bipolar disorder. The management strategies for these alterations of emotion and mood in degenerative dementias primarily involve the judicious use of the psychiatric armamentarium of medications.

rTMS modulates precuneus-hippocampal subregion circuit in patients with subjective cognitive decline

Hippocampal subregions (HIPsub) and their network connectivities are generally aberrant in patients with subjective cognitive decline (SCD). This study aimed to investigate whether repetitive transcranial magnetic stimulation (rTMS) could ameliorate HIPsub network connectivity by modulating one node of HIPsub network in SCD. In the first cohort, the functional connectivity (FC) of three HIPsub (i.e., hippocampal emotional, cognitive, and perceptual regions: HIPe, HIPc, and HIPp) were analyzed so as to identify alterations in HIPsub connectivity associated with SCD. Afterwards, a support vector machine (SVM) approach was applied using the alterations in order to evaluate to what extent we could distinguish SCD from healthy controls (CN). In the second cohort, a 2-week rTMS course of 5-day, once-daily, was used to activate the altered HIPsub network connectivity in a sham-controlled design. SCD subjects exhibited distinct patterns alterations of HIPsub network connectivity compared to CN in the first cohort. SVM classifier indicated that the abnormalities had a high power to discriminate SCD from CN, with 92.9% area under the receiver operating characteristic curve (AUC), 86.0% accuracy, 83.8% sensitivity and 89.1% specificity. In the second cohort, changes of HIPc connectivity with the left parahippocampal gyrus and HIPp connectivity with the left middle temporal gyrus demonstrated an amelioration of episodic memory in SCD after rTMS. In addition, SCD exhibited improved episodic memory after the rTMS course. rTMS therapy could improve the posterior hippocampus connectivity by modulating the precuneus in SCD. Simultaneous correction of the breakdown in HIPc and HIPp could ameliorate episodic memory in SCD. Thus, these findings suggested that rTMS manipulation of precuneus-hippocampal circuit might prevent disease progression by improving memory as the earliest at-risk state of Alzheimer’s disease in clinical trials and in practice.

Lesions in the right Rolandic operculum are associated with self-rating affective and apathetic depressive symptoms for post-stroke patients

Stroke survivors majorly suffered from post-stroke depression (PSD). The PSD diagnosis is commonly performed based on the clinical cut-off for psychometric inventories. However, we hypothesized that PSD involves spectrum symptoms (e.g., apathy, depression, anxiety, and stress domains) and severity levels. Therefore, instead of using the clinical cut-off, we suggested a data-driven analysis to interpret patient spectrum conditions. The patients’ psychological conditions were categorized in an unsupervised manner using the k-means clustering method, and the relationships between psychological conditions and quantitative lesion degrees were evaluated. This study involved one hundred sixty-five patient data; all patients were able to understand and perform self-rating psychological conditions (i.e., no aphasia). Four severity levels—low, low-to-moderate, moderate-to-high, and high—were observed for each combination of two psychological domains. Patients with worse conditions showed the significantly greater lesion degree at the right Rolandic operculum (part of Brodmann area 43). The dissimilarities between stress and other domains were also suggested. Patients with high stress were specifically associated with lesions in the left thalamus. Impaired emotion processing and stress-affected functions have been frequently related to those lesion regions. Those lesions were also robust and localized, suggesting the possibility of an objective for predicting psychological conditions from brain lesions.

The interplay among education, brain metabolism, and cognitive impairment suggests a role of cognitive reserve in Amyotrophic Lateral Sclerosis

We tested the Cognitive Reserve (CR) hypothesis in Amyotrophic Lateral Sclerosis (ALS), enrolling 111 patients, using education as CR proxy, ¹⁸F-FDG-PET to assess brain damage, and ECAS to measure cognition. Education was regressed out against brain metabolism, including age, sex, spinal/bulbar onset, ALSFRS-R, and ECAS as covariates. Clusters showing a significant correlation were used as seed regions in an interregional correlation analysis (IRCA) in the ALS group and in 40 controls. In the ALS group, we found a negative correlation between brain metabolism and education in the right anterior cingulate and bilateral medial frontal gyrus. In the IRCA in the ALS group, the medial frontal cluster metabolism positively correlated with that of frontotemporal regions (right > left), bilateral caudate nuclei, and right insula, and negatively correlated with that of corticospinal tracts, cerebellum, and pons. In controls, the IRCA showed significant positive correlations in the same regions but less extended. Our results agree with the CR hypothesis. The negative correlation between the medial frontal cluster and the cerebellum found only in ALS patients might reflect cerebellar compensation.

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.

Neural effects of oxytocin and mimicry in frontotemporal dementia: A randomized crossover study

OBJECTIVE

To determine whether intranasal oxytocin, alone or in combination with instructed mimicry of facial expressions, would augment neural activity in patients with frontotemporal dementia (FTD) in brain regions associated with empathy, emotion processing, and the simulation network, as indexed by blood oxygen-level dependent (BOLD) signal during fMRI.

METHODS

In a placebo-controlled, randomized crossover design, 28 patients with FTD received 72 IU intranasal oxytocin or placebo and then completed an fMRI facial expression mimicry task.

RESULTS

Oxytocin alone and in combination with instructed mimicry increased activity in regions of the simulation network and in limbic regions associated with emotional expression processing.

CONCLUSIONS

The findings demonstrate latent capacity to augment neural activity in affected limbic and other frontal and temporal regions during social cognition in patients with FTD, and support the promise and need for further investigation of these interventions as therapeutics in FTD.

CLINICALTRIALSGOV IDENTIFIER

NCT01937013.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that a single dose of 72 IU intranasal oxytocin augments BOLD signal in patients with FTD during viewing of emotional facial expressions.

Altered phobic reactions in frontotemporal dementia: A behavioural and neuroanatomical analysis

INTRODUCTION

Abnormal behavioural and physiological reactivity to emotional stimuli is a hallmark of frontotemporal dementia (FTD), particularly the behavioural variant (bvFTD). As part of this repertoire, altered phobic responses have been reported in some patients with FTD but are poorly characterised.

METHODS

We collected data (based on caregiver reports) concerning the prevalence and nature of any behavioural changes related to specific phobias in a cohort of patients representing canonical syndromes of FTD and Alzheimer's disease (AD), relative to healthy older controls. Neuroanatomical correlates of altered phobic reactivity were assessed using voxel-based morphometry.

RESULTS

46 patients with bvFTD, 20 with semantic variant primary progressive aphasia, 25 with non-fluent variant primary progressive aphasia, 29 with AD and 55 healthy age-matched individuals participated. Changes in specific phobia were significantly more prevalent in the combined FTD cohort (15.4% of cases) and in the bvFTD group (17.4%) compared both to healthy controls (3.6%) and patients with AD (3.5%). Attenuation of phobic reactivity was reported for individuals in all participant groups, however new phobias developed only in the FTD cohort. Altered phobic reactivity was significantly associated with relative preservation of grey matter in left posterior middle temporal gyrus, right temporo-occipital junction and right anterior cingulate gyrus, brain regions previously implicated in contextual decoding, salience processing and reward valuation.

CONCLUSION

Altered phobic reactivity is a relatively common issue in patients with FTD, particularly bvFTD. This novel paradigm of strong fear experience has broad implications: clinically, for diagnosis and patient well-being; and neurobiologically, for our understanding of the pathophysiology of aversive sensory signal processing in FTD and the neural mechanisms of fear more generally.

Physiological, behavioral and subjective sadness reactivity in frontotemporal dementia subtypes

Frontotemporal dementia (FTD), a neurodegenerative disease broadly characterized by socioemotional impairments, includes three clinical subtypes: behavioral variant FTD (bvFTD), semantic variant primary progressive aphasia (svPPA) and non-fluent variant primary progressive aphasia (nfvPPA). Emerging evidence has shown emotional reactivity impairments in bvFTD and svPPA, whereas emotional reactivity in nfvPPA is far less studied. In 105 patients with FTD (49 bvFTD, 31 svPPA and 25 nfvPPA) and 27 healthy controls, we examined three aspects of emotional reactivity (physiology, facial behavior and subjective experience) in response to a sad film. In a subset of the sample, we also examined the neural correlates of diminished aspects of reactivity using voxel-based morphometry. Results indicated that all three subtypes of FTD showed diminished physiological responding in respiration rate and diastolic blood pressure; patients with bvFTD and svPPA also showed diminished subjective experience, and no subtypes showed diminished facial behavior. Moreover, there were differences among the clinical subtypes in brain regions where smaller volumes were associated with diminished sadness reactivity. These results show that emotion impairments extend to sadness reactivity in FTD and underscore the importance of considering different aspects of sadness reactivity in multiple clinical subtypes for characterizing emotional deficits and associated neurodegeneration in FTD.

Correlation Between Thalamus-Related Functional Connectivity and Serum BDNF Levels During the Periovulatory Phase of Primary Dysmenorrhea

The thalamus is a key region for the transmission of nociceptive information in the central modulation of pain and has been studied in the setting of numerous chronic pain conditions. Brain-derived neurotrophic factor (BDNF) is considered an important modulator for mediating nociceptive pathways in chronic pain. The present study aimed to investigate whether there was thalamus-related abnormal functional connectivity or relevant serum BDNF level alterations during periovulation in long-term primary dysmenorrhea (PDM). Thalamic subregions were defined according to the Human Brainnetome Atlas. Functional connectivity analyses were performed in 36 patients in the periovulatory phase and 29 age-, education-, and gender-matched healthy controls. Serum BDNF levels were evaluated by enzyme-linked immunosorbent assay and a significantly higher BDNF level was detected in PDM patients. Compared with HCs, PDM patients had abnormal functional connectivity of thalamic-subregions, mainly involving with prefrontal cortex, sensorimotor cortex, and temporal cortex. In addition, the functional connectivity of thalamic-subregions showed significant interactive effect correlated with serum BDNF level between PDM and HCs. It has been suggested that there were maladaptive or adoptive alteration associated with chronic menstrual pain even without the ongoing menstrual pain. BDNF might play a role in the development and chronicity of central nervous system dysfunction. These findings provided more accurate information about the involvement of the thalamus in the pathophysiology of PDM.