Neuropsychological and Neuroanatomical Correlates of the Social Norms Questionnaire in Frontotemporal Dementia Versus Alzheimer's Disease

Semantic knowledge of social norms in frontotemporal dementia patients with either predominant frontal or temporal lobe atrophy

OBJECTIVE

Little is known about the relative contribution of frontal and anterior temporal lobes in semantic knowledge of social norms in frontotemporal dementia (FTD). Therefore, this study examined performance of FTD patients with either frontal (F-FTD, left temporal (LT-FTD) or bitemporal lobe atrophy (BT-FTD) on the Social Norms Questionnaire (SNQ) and explored what accounts for the variance in the SNQ-break norm subscale (i.e., endorsement of inappropriate behaviors).

METHODS

Using data from the National Alzheimer's Coordinating Center (NACC), groups were matched for age and education and included (a) 24 F-FTD patients, (b) 15 LT-FTD patients, (c) 17 BT-FTD patients, and (d) 188 older controls with normal cognition (NC).

RESULTS

The BT-FTD group had significantly higher SNQ break norm score than F-FTD and NC groups with a medium effect size, which was also positively associated with the severity personality changes in the real world. Interestingly, the F-FTD and LT-FTD groups performed similarly to the NC group. Regression analysis showed that approximately 21.2% of the variance in SNQ break norms subscale score performance was explained by performance on verb naming.

CONCLUSIONS

Social inappropriateness in FTD may partially arise from a deficit in knowledge of normative behavior.

Social norms in Korsakoff's syndrome and alcohol-related dementia

OBJECTIVE

Social cognition is essential for individuals to perceive, process, and interpret social information that enables them to function effectively in society. Korsakoff's syndrome (KS) and alcohol-related dementia (ARD) are alcohol-related cognitive disorders that are likely to impair social cognition. This study aimed to investigate the ability to judge social norms in KS and ARD in comparison to healthy subjects.

METHOD

The study included 30 patients with KS, 10 patients with ARD, and 74 age-, sex-, and education-matched control participants. The Social Norms Questionnaire - Dutch version (SNQ-NL) was used to measure social cognition, and standardized tests were used to examine the association between social cognition and executive functioning.

RESULTS

Both KS and ARD patients performed worse in judging social norms when compared to healthy controls, but there was no significant difference between KS and ARD. Both KS and ARD patients performed worse on the SNQ-NL, judging appropriate behavior as inappropriate (Overadhere errors), than controls. When compared to control participants, patients with KS demonstrated significantly more Break Errors, while the differences between the ARD group and the control group did not reach statistical significance. There were no significant correlations between the SNQ-NL variables and performances on standardized tests for executive functioning in both the KS and control group.

CONCLUSIONS

This study aimed to investigate the ability to judge social norms in KS and ARD in comparison to healthy subjects. The results show that compared to a control group, both KS and ARD patients performed worse in judging social norms. KS and ARD patients scored equally low on social norms identification. Overall, these findings can further help us understand the difficulties in social behavior as experienced by patients and care staff, since problems in accurately judging social norms could possibly contribute to the severe behavioral issues as observed in alcohol-related disorders.

Impairments in knowledge of social norms in presymptomatic, prodromal, and symptomatic frontotemporal dementia

INTRODUCTION

We aimed to assess the knowledge of social norms in patients with behavioral variant frontotemporal dementia (bvFTD) with the Dutch version of the Social Norms Questionnaire (SNQ-NL).

METHODS

The SNQ-NL was administered in 34 patients with bvFTD, 20 prodromal mutation carriers, 76 presymptomatic mutation carriers, and 56 controls. Group differences and correlations with other neuropsychological tests and gray matter volume were examined.

RESULTS

Patients with bvFTD had lower total SNQ-NL scores and more over-adherence errors than presymptomatic mutation carriers and controls (P < 0.001). SNQ-NL performance correlated with tests for executive functioning and social cognition, and with gray matter volume in bilateral frontal and unilateral temporal regions.

DISCUSSION

The SNQ-NL can identify impairments in knowledge of social norms in bvFTD, highlighting its significance in clinical diagnosis and upcoming clinical trials. The SNQ-NL currently fails to differentiate presymptomatic mutation carriers from controls; to this end, larger sample sizes from larger cohorts and longitudinal follow-up are warranted.

Highlights

The Dutch version of the Social Norms Questionnaire (SNQ-NL) is able to detect impairment in social cognition in symptomatic bvFTD patients.A trend towards a lower performance in prodromal mutation carriers was found.Performance on the SNQ-NL is related to other measures of social cognition, executive functioning, and language.Lower SNQ-NL performance is related to gray matter volume loss in bilateral frontal and temporal regions.The SNQ-NL provides insight into the underlying cause of deficits in social cognition in bvFTD.

A neuroanatomical and cognitive model of impaired social behaviour in frontotemporal dementia

Impaired social cognition is a core deficit in frontotemporal dementia (FTD). It is most commonly associated with the behavioural-variant of FTD, with atrophy of the orbitofrontal and ventromedial prefrontal cortex. Social cognitive changes are also common in semantic dementia, with atrophy centred on the anterior temporal lobes. The impairment of social behaviour in FTD has typically been attributed to damage to the orbitofrontal cortex and/or temporal poles and/or the uncinate fasciculus that connects them. However, the relative contributions of each region are unresolved. In this review, we present a unified neurocognitive model of controlled social behaviour that not only explains the observed impairment of social behaviours in FTD, but also assimilates both consistent and potentially contradictory findings from other patient groups, comparative neurology and normative cognitive neuroscience. We propose that impaired social behaviour results from damage to two cognitively- and anatomically-distinct components. The first component is social-semantic knowledge, a part of the general semantic-conceptual system supported by the anterior temporal lobes bilaterally. The second component is social control, supported by the orbitofrontal cortex, medial frontal cortex and ventrolateral frontal cortex, which interacts with social-semantic knowledge to guide and shape social behaviour.

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.

Italian adaptation of the Edinburgh Social Cognition Test (ESCoT): A new tool for the assessment of theory of mind and social norm understanding

The relevance of social cognition assessment has been formally described in the Diagnostic and Statistical Manual of Mental Disorders-5. However, social cognition tools evaluating different socio-cognitive components for Italian-speaking populations are lacking. The Edinburgh Social Cognition Test (ESCoT) is a new social cognition measure that uses animations of everyday social interactions to assess (i) cognitive theory of mind, (ii) affective theory of mind, (iii) interpersonal social norm understanding, and (iv) intrapersonal social norm understanding. Previous studies have shown that the ESCoT is a sensitive measure of social cognition in healthy and clinical populations in the United Kingdom. This work aimed to adapt and validate the ESCoT in an Italian population of healthy adults. A translation-back-translation procedure was followed to create and refine the Italian version. Then, 94 healthy adults (47 females, mean age  35 ± 15.9) completed the ESCoT, a battery of conventional social cognition tests (Yoni; Reading the Mind in the Eyes Strange Stories, and Social Norm Questionnaire, SNQ) and measures of intelligence and executive functions. Reliability, convergent validity, and predictors of performance on the ESCoT were examined. Results demonstrated good reliability of the ESCoT and an association between the ESCoT scores and some traditional social cognition tests (Yoni cognitive subscale, SNQ). Hierarchical regression results showed that the ESCoT total score was associated with age. Also, the ESCoT subscore (intrapersonal social norm understanding) was associated with education. These findings support the ESCoT as a valid tool testing social norm understanding, a reliable measure of social cognition for an adult Italian population, and provides further evidence that the ESCoT is sensitive to age- and education-related changes in social cognition, and it is a task not affected by general cognitive functioning.

Appreciation of Social Norms in Agenesis of the Corpus Callosum

OBJECTIVE

Anecdotal reports regarding high-functioning adults with agenesis of the corpus callosum (AgCC) suggest that they often lack psychosocial insight. We attempted to determine whether adults with AgCC are able to correctly identify appropriate behaviors within social contexts using the Social Norms Questionnaire.

METHOD

The Social Norms Questionnaire measures knowledge of norms and judgments of what is appropriate to do in particular contexts. It was administered online to individuals with AgCC and control participants.

RESULTS

Individuals with AgCC scored significantly lower in understanding social norms than controls, tending to over-adhere to social norms significantly more than controls. There was no significant difference regarding breaking of social norms.

CONCLUSION

Results suggest that adults with AgCC have deficient judgment regarding the nuances of appropriate behaviors in social contexts. They adhere to social norms concretely, lacking the ability to integrate context in social scenarios to make appropriately nuanced judgments.

The interplay of emotional and social conceptual processes during moral reasoning in frontotemporal dementia

Cooperative social behaviour in humans hinges upon our unique ability to make appropriate moral decisions in accordance with our ethical values. The complexity of the neurocognitive mechanisms underlying moral reasoning is revealed when this capacity breaks down. Patients with the behavioural variant of frontotemporal dementia (bvFTD) display striking moral transgressions in the context of atrophy to frontotemporal regions supporting affective and social conceptual processing. Developmental studies have highlighted the importance of social knowledge to moral decision making in children, yet the role of social knowledge in relation to moral reasoning impairments in neurodegeneration has largely been overlooked. Here, we sought to examine the role of affective and social conceptual processes in personal moral reasoning in bvFTD, and their relationship to the integrity and structural connectivity of frontotemporal brain regions. Personal moral reasoning across varying degrees of conflict was assessed in 26 bvFTD patients and compared with demographically matched Alzheimer's disease patients (n = 14), and healthy older adults (n = 22). Following each moral decision, we directly probed participants' subjective emotional experience as an index of their affective response, while social norm knowledge was assessed via an independent task. While groups did not differ significantly in terms of their moral decisions, bvFTD patients reported feeling 'better' about their decisions than healthy control subjects. In other words, although bvFTD patients could adjudicate between different courses of action in the moral scenarios, their affective responses to these decisions were highly irregular. This blunted emotional reaction was exclusive to the personal high-conflict condition, with 61.5% of bvFTD patients reporting feeling 'extremely good' about their decisions, and was correlated with reduced knowledge of socially acceptable behaviour. Voxel-based morphometry analyses revealed a distributed network of frontal, subcortical, and lateral temporal grey matter regions involved in the attenuated affective response to moral conflict in bvFTD. Crucially, diffusion-tensor imaging implicated the uncinate fasciculus as the pathway by which social conceptual knowledge may influence emotional reactions to personal high-conflict moral dilemmas in bvFTD. Our findings suggest that altered moral behaviour in bvFTD reflects the dynamic interplay between degraded social conceptual knowledge and blunted affective responsiveness, attributable to atrophy of, and impaired information transfer between, frontal and temporal cortices. Delineating the mechanisms of impaired morality in bvFTD provides crucial clinical information for understanding and treating this challenging symptom, which may help pave the way for targeted behavioural interventions.

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

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

Impaired Knowledge of Social Norms in Dementia and Psychiatric Disorders: Validation of the Social Norms Questionnaire-Dutch Version (SNQ-NL)

The Social Norms Questionnaire–Dutch version (SNQ-NL) measures the ability to understand and identify social boundaries. We examined the psychometric characteristics of the SNQ-NL and its ability to differentiate between patients with behavioral variant frontotemporal dementia (bvFTD; n = 23), Alzheimer’s dementia (AD; n = 26), chronic psychiatric disorders (n = 27), and control participants (n = 92). Between-group differences in the Total score, Break errors, and Overadhere errors were examined and associations with demographic variables and other cognitive functions were explored. Results showed that the SNQ-NL Total Score and Break errors differed between patients with AD and bvFTD, but not between patients with bvFTD and psychiatric disorders. Modest correlations with age, sex, and education were observed. The SNQ-NL Total score and Break errors correlated significantly with emotion recognition and verbal fluency but not with processing speed or mental flexibility. In conclusion, the SNQ-NL has sufficient construct validity and can be used to investigate knowledge of social norms in clinical populations.

More Than Words: Extra-Sylvian Neuroanatomic Networks Support Indirect Speech Act Comprehension and Discourse in Behavioral Variant Frontotemporal Dementia

Indirect speech acts—responding “I forgot to wear my watch today” to someone who asked for the time—are ubiquitous in daily conversation, but are understudied in current neurobiological models of language. To comprehend an indirect speech act like this one, listeners must not only decode the lexical-semantic content of the utterance, but also make a pragmatic, bridging inference. This inference allows listeners to derive the speaker’s true, intended meaning—in the above dialog, for example, that the speaker cannot provide the time. In the present work, we address this major gap by asking non-aphasic patients with behavioral variant frontotemporal dementia (bvFTD, n = 21) and brain-damaged controls with amnestic mild cognitive impairment (MCI, n = 17) to judge simple question-answer dialogs of the form: “Do you want some cake for dessert?” “I’m on a very strict diet right now,” and relate the results to structural and diffusion MRI. Accuracy and reaction time results demonstrate that subjects with bvFTD, but not MCI, are selectively impaired in indirect relative to direct speech act comprehension, due in part to their social and executive limitations, and performance is related to caregivers’ judgment of communication efficacy. MRI imaging associates the observed impairment in bvFTD to cortical thinning not only in traditional language-associated regions, but also in fronto-parietal regions implicated in social and executive cerebral networks. Finally, diffusion tensor imaging analyses implicate white matter tracts in both dorsal and ventral projection streams, including superior longitudinal fasciculus, frontal aslant, and uncinate fasciculus. These results have strong implications for updated neurobiological models of language, and emphasize a core, language-mediated social disorder in patients with bvFTD.

A Critical Review of Behavioral and Emotional Disinhibition

The theory of "disinhibition" has been very influential in psychiatry and neurology for over a century. Disinhibition has been used to explain clinical findings in many neurological and psychiatric disorders including dementia, traumatic brain injury, attention deficit hyperactive disorder, substance abuse, impulsivity in personality disorders, and neurodevelopmental disorders. In addition, disinhibition has been used as a unifying theory to link clinical observations with cognitive findings, and even cellular findings. This review discusses the origins and history of the theory of disinhibition and its strengths and weaknesses in four domains: face validity, consistency with other brain mechanisms, consistency with evolutionary mechanisms, and empiric support. I assert that the vagueness of the theory, inconsistency with other brain mechanisms, and lack of empiric support limit the usefulness of this theory. Alternative approaches, based on findings in other motor, language, and cognitive functions, are discussed.

Vicarious Embarrassment or "Fremdscham": Overendorsement in Frontotemporal Dementia

OBJECTIVE

The experience of embarrassment signals violations in social norms, and impairment in this social emotion may underlie much of the social dysfunction in behavioral variant frontotemporal dementia (bvFTD). The authors investigated whether impaired self-awareness of embarrassment may distinguish patients with bvFTD early in the course of disease from healthy control subjects (HCs).

METHODS

Self-reported embarrassment was examined among 18 patients with early bvFTD and 23 HCs by using the 36-item Embarrassability Scale, which includes items of situations eliciting embarrassment for oneself ("self-embarrassment") and embarrassment for others ("vicarious embarrassment"). The two study groups were also compared with the Social Norms Questionnaire (SNQ). The analyses included correlations of SNQ results (total score, violations or "break" errors, and overendorsement of social rules or "overadhere" errors) with Embarrassability Scale scores.

RESULTS

Patients with bvFTD did not differ from HCs on total or self-embarrassment scores but did have significantly higher vicarious embarrassment scores. Unlike in the HC group, reports of vicarious embarrassment did not differ from reports of self-embarrassment among patients in the bvFTD group. The Embarrassability Score further correlated with overadherence to norms on the SNQ.

CONCLUSIONS

In the presence of social dysfunction and emotional blunting, these findings suggest that patients with bvFTD rely on their own perspective for a rule-based application of social norms in reporting vicarious embarrassment. The assessment of reports of embarrassment for others may indicate an early and previously unrecognized clinical measure for detecting bvFTD.

Association Between Social Cognition Changes and Resting State Functional Connectivity in Frontotemporal Dementia, Alzheimer's Disease, Parkinson's Disease, and Healthy Controls

OBJECTIVE

To determine the relationship between alterations in resting state functional connectivity and social cognition dysfunction among patients with frontotemporal dementia (FTD), Alzheimer's disease (AD), Parkinson's disease (PD), and healthy controls (HC).

METHODS

Fifty-seven participants (FTD = 10, AD = 18, PD = 19, and HC = 10) underwent structural and functional imaging and completed the Awareness of Social Inference Test-Emotion Evaluation Test (TASIT-EET), Behavioral Inhibition System/Behavioral Activation System (BIS/BAS) scale, Revised Self-Monitoring Scale (RSMS), Interpersonal Reactivity Index (IRI), and Social Norms Questionnaire (SNQ). A multi-variate pattern analysis (MVPA) was carried out to determine activation differences between the groups. The clusters from the MVPA were used as seeds for the ROI-to-voxel analysis. Relationship between social cognition deficits and uncinate integrity was also investigated.

RESULTS

BOLD signal activation differed among the four groups of AD, PD, FTD, and HC in the left inferior temporal gyrus-anterior division [L-ITG (ant)], right central opercular cortex (R-COp), right supramarginal gyrus, posterior division (R-SMG, post), right angular gyrus (R-AG), and R-ITG. The BOLD co-activation of the L-ITG (ant) with bilateral frontal pole (FP) and paracingulate gyrus was positively associated with IRI-perspective taking (PT) (r = 0.38, p = 0.007), SNQ total (r = 0.37, p = 0.009), and TASIT-EET (r = 0.47, p < 0.001).

CONCLUSION

Patients with neurodegenerative diseases showed alterations in connectivity in brain regions important for social cognition compared with HCs. Functional connectivity correlated with performance on social cognition tasks and alterations could be responsible for some of the social cognition deficits observed in all neurodegenerative diseases.

Psychological and Cognitive Markers of Behavioral Variant Frontotemporal Dementia-A Clinical Neuropsychologist's View on Diagnostic Criteria and Beyond

Behavioral variant frontotemporal dementia (bvFTD) is the second leading cognitive disorder caused by neurodegeneration in patients under 65 years of age. Characterized by frontal, insular, and/or temporal brain atrophy, patients present with heterogeneous constellations of behavioral and psychological symptoms among which progressive changes in social conduct, lack of empathy, apathy, disinhibited behaviors, and cognitive impairments are frequently observed. Since the histopathology of the disease is heterogeneous and identified genetic mutations only account for ~30% of cases, there are no reliable biomarkers for the diagnosis of bvFTD available in clinical routine as yet. Early detection of bvFTD thus relies on correct application of clinical diagnostic criteria. Their evaluation however, requires expertise and in-depth assessments of cognitive functions, history taking, clinical observations as well as caregiver reports on behavioral and psychological symptoms and their respective changes. With this review, we aim for a critical appraisal of common methods to access the behavioral and psychological symptoms as well as the cognitive alterations presented in the diagnostic criteria for bvFTD. We highlight both, practical difficulties as well as current controversies regarding an overlap of symptoms and particularly cognitive impairments with other neurodegenerative and primary psychiatric diseases. We then review more recent developments and evidence on cognitive, behavioral and psychological symptoms of bvFTD beyond the diagnostic criteria which may prospectively enhance the early detection and differential diagnosis in clinical routine. In particular, evidence on specific impairments in social and emotional processing, praxis abilities as well as interoceptive processing in bvFTD is summarized and potential links with behavior and classic cognitive domains are discussed. We finally outline both, future opportunities and major challenges with regard to the role of clinical neuropsychology in detecting bvFTD and related neurocognitive disorders.

Frontotemporal asymmetry in socioemotional behavior: A pilot study in frontotemporal dementia

Clinical studies report abnormal socioemotional behavior in patients with right frontotemporal disease, but neuroimaging studies of socioemotional behavior usually show bilateral activations in normal subjects. This discrepancy suggests that impaired interhemispheric collaboration for socioemotional functions results from asymmetric frontotemporal disease. Behavioral variant frontotemporal dementia (bvFTD) can clarify the contribution of direction-independent frontotemporal asymmetry. In a two-part study, we evaluated bvFTD patients using socioemotional scales and magnetic and resonance imaging measures. Part A compared 18 patients on scales of social dysfunction and emotional intelligence with degree of asymmetry in frontal lobe volumes and analyzed differences between lower and higher asymmetry groups. Part B compared 24 patients on scales of social observation and emotional blunting with degree of asymmetry in frontotemporal cortical thickness using multiple linear regression. Both results showed that left or right hemispheric-specific contributions did not account for all socioemotional differences and that frontal lobe and frontotemporal differences in atrophy between the hemispheres accounted for significant variance in abnormalities in social and emotional behavior. These preliminary results indicate that the degree of frontal lobe and frontotemporal asymmetric involvement, regardless of direction or laterality, significantly contribute to socioemotional dysfunction and support the hypothesis that interhemispheric collaboration is important for complex socioemotional behavior.

Affective Empathy in Behavioral Variant Frontotemporal Dementia: A Meta-Analysis

Background: Empathy deficits are a widely recognized symptom in the behavioral variant frontotemporal dementia (bvFTD), and although several reviews have examined cognitive empathy deficits, there are no meta-analytic studies on affective empathy deficits. Objective: Identify salience of affective empathy in bvFTD. Method: A thorough review of affective empathy found 139 possible studies, but only 10 studies included measures of affective empathy and met standardized criteria. Results: BvFTD patients demonstrated a modest impairment compared to controls across all tasks (d = 0.98). Empathic concern as measured by the interpersonal reactivity index was particularly effected (d = 1.12). Conclusions: This study provides evidence for an increased commitment to observing affective empathy in bvFTD and capturing its role in the disorder.

Social Cognition in the Frontal Variant of Alzheimer's Disease: A Case Study

Although frontal presentations of Alzheimer's disease (fv-AD) have already been described in the literature, we still know little about patients' social cognitive abilities, especially their theory of mind (ToM). We report the case of FT, a 61-year-old woman who was diagnosed with fv-AD. Two assessments of social cognition, using a false-belief task, the Reading the Mind in the Eyes test, and a task probing knowledge of social norms, were performed one year apart. FT exhibited cognitive ToM and social knowledge deficits from the onset. Affective ToM was initially preserved, but deteriorated as the disease progressed.

The attribution of animacy and agency in frontotemporal dementia versus Alzheimer's disease

Impaired attribution of animacy (state of living or being sentient) and of agency (capability of intrinsically-driven action) may underlie social behavior disturbances in behavioral variant frontotemporal dementia (bvFTD). We presented the Heider and Simmel film of moving geometric shapes to 11 bvFTD patients, 11 Alzheimer's disease (AD) patients, and 12 healthy controls (HCs) and rated their recorded verbal responses for animacy attribution and agency attribution. All participants had skin conductance (SC) continuously recorded while viewing the film, and all dementia participants underwent magnetic resonance imaging (MRI) for regions of interest. The bvFTD patients, but not the AD patients, were impaired in animacy attribution, compared to the HCs. In contrast, both bvFTD and AD groups were impaired in agency attribution, compared to the HCs, and only the HCs had increasing SC responsiveness during viewing of the film. On MRI analysis of cortical thicknesses, animacy scores significantly correlated across groups with the right pars orbitalis and opercularis; agency scores with the left inferior and superior parietal cortices and the supramarginal gyrus; and both scores with the left cingulate isthmus involved in visuospatial context. These findings suggest that bvFTD is specifically associated with impaired animacy attribution from right inferior frontal atrophy. In contrast, both dementias may have impaired agency attribution from left parietal cortical atrophy and absent SC increases during the film, a sympathetic indicator of attribution of a social "story" to the moving shapes. These findings clarify disease-related changes in social attribution and corroborate the neuroanatomical origins of animacy and agency.