Which neuropsychiatric and behavioural features distinguish frontal and temporal variants of frontotemporal dementia from Alzheimer's disease?

Development of the Flexibility in Daily Life scale to measure multidimensional cognitive and behavioural flexibility in health and disease

OBJECTIVES

Inflexibility of thought and behaviour is a transdiagnostic feature of many neuropsychiatric disorders and presents several empirical measurement challenges. Here, we developed and validated the Flexibility in Daily Life scale (FIDL); a novel, self-report questionnaire, which captures expressions of cognitive and behavioural flexibility in daily life and is sensitive to natural shifts in these processes across the adult lifespan.

METHODS

The FIDL was developed using a deductive scale development approach, which aimed to capture common themes within the flexibility literature and across diagnoses (e.g. insistence on sameness, preference for routines). Following multidisciplinary consensus, an initial 37-item questionnaire was submitted for validation in an online sample of 295 healthy adult participants (19-78 years).

RESULTS

Exploratory factor analysis produced a revised 21-item version comprising five factors, labelled: Repetition, Switching, Predictability/Control, Routine, and Thoughts/Beliefs. Internal consistency reliability was good-to-strong for the total FIDL score and moderate-to-strong for individual subscales. Convergent validity was established between the FIDL and an existing measure of cognitive flexibility. Critically, the FIDL total score evinced a U-shaped relationship with age, whereby flexibility was lower at the younger and older tails of the lifespan and greater in middle age. The same U-shaped trajectory emerged for the Repetition, Routine, and Thoughts/Beliefs factors.

CONCLUSIONS

Overall, the FIDL is a valid and reliable multidimensional measure of flexibility, which upholds a clearly defined factor structure and good psychometric properties. It promises to be a valuable clinical and research tool to assess the natural fluctuations in flexibility across the lifespan and departures thereof.

Social interaction as a unique form of reward - Insights from healthy ageing and frontotemporal dementia

The drive for positive social interactions, or "social rewards", is an important motivator of human behaviour, conferring several adaptive benefits. Social motivation fluctuates across the lifespan, reflecting changes in goals and priorities at different developmental stages. In older adulthood, for instance, priorities tend to shift toward maintaining emotional wellbeing and resources over seeking novel gains. Contemporary theories of social interaction must account for such motivational shifts, addressing the enhancement of social processing in ageing and its decline in dementia. Here, we propose a framework to track the evolution of social motivation across the lifespan, focusing on three mechanisms: (i) social interactions as rewards, (ii) learning from social interactions, and (iii) the effort required for social interactions. We posit that social rewards hold equivalent or increased value later in life, enhancing older adults' social connections. Conversely, social rewards become devalued in neurodegenerative disorders such as frontotemporal dementia (FTD), resulting in social withdrawal. This integrative framework serves as a foundation for understanding adaptive and maladaptive trajectories of social motivation throughout the adult lifespan.

Hyperorality in Frontotemporal Dementia: How Psychiatric and Neural Correlates Change During the Disease Course

OBJECTIVE

Hyperorality is a core feature of behavioral variant frontotemporal dementia (bvFTD); however, the cognitive, psychiatric, and neuroanatomical correlates of hyperorality across the bvFTD stages remain unclear. The authors explored these associations in early- and advanced-stage bvFTD.

METHODS

Participants with sporadic or genetic bvFTD were enrolled in the ARTFL LEFFTDS Longitudinal Frontotemporal Lobar Degeneration (ALLFTD) consortium study. Baseline cognitive and psychiatric symptoms of participants with or without hyperorality were compared after stratification by disease severity. Linear multivariable regressions adjusted for age and total intracranial volume were used to examine associations between regional gray matter volume (GMV) and hyperorality status. Five anatomical regions of interest were preselected for analysis on the basis of previously identified neuroanatomical correlates of hyperorality in bvFTD.

RESULTS

Hyperorality was present in 50% of early-stage bvFTD participants (N=136) and was associated with higher rates of ritualistic-compulsive behavior and difficulty detecting social-emotional expressions. Hyperorality was present in 63% of advanced-stage participants (N=208) and was associated with higher rates of apathy, ritualistic-compulsive behavior, and socially aberrant behavior. Regional GMV was similar for those with or without hyperorality among early-stage participants. Among advanced-stage participants, hyperorality was associated with lower GMV in the right dorsal and ventral striatum.

CONCLUSIONS

Hyperorality emerged early in bvFTD and was accompanied by deficits in social cognition and complex-ritualistic behavior before clinically significant GMV loss. These findings suggest that early identification and management of hyperorality could improve neuropsychiatric trajectories in bvFTD.

Correlation between mild cognitive impairment and flourishing among Chinese residents: a cross-sectional study

Objective

This study aimed to investigate the correlation between mild cognitive impairment and flourishing among Chinese residents.

Methods

A total of 527 community residents aged ≥18 years were recruited from December 2023 to April 2024. Based on the results of the Ascertain Dementia 8-Item Informant Questionnaire (AD8), participants were classified into a healthy group (n = 356) and a mild cognitive impairment (MCI) group (n = 171). General demographic data, including age, gender, height, weight, place of residence, education level, marital status, household composition, personal income, occupation, and the flourishing scale (FS) were collected for statistical analysis. The analysis was performed using Statistical Product and Service Solutions software. Chi-square test was used to compare differences between the groups, while Kendall's correlation analysis and multivariate logistic regression were applied to assess the relationship between flourishing and MCI.

Results

Comparisons between the healthy and MCI groups showed that the FS scores in the healthy group were significantly higher than those in the MCI group (p < 0.01). Kendall's correlation analysis revealed that the score of AD8 was negatively correlated with FS (r = -0.237, p < 0.01). Multivariate analysis indicated that age [odds ratio (OR) = 1.451, 95% confidence interval (CI; 1.107-1.902), p = 0.007], place of residence [OR = 5.523, 95% CI (3.572-8.539), p < 0.001], and FS [OR = 0.421, 95%CI (0.311-0.569), p < 0.001] were correlated with MCI.

Conclusion

Flourishing levels are negatively correlated with MCI, and higher levels of flourishing associated with a lower risk of MCI. This suggests that flourishing may serve as a protective factor against cognitive decline. Additionally, age and place of residence are identified as risk factors for MCI.

Beyond group classification: Probabilistic differential diagnosis of frontotemporal dementia and Alzheimer's disease with MRI and CSF biomarkers

Neuroimaging and fluid biomarkers are used to differentiate frontotemporal dementia (FTD) from Alzheimer's disease (AD). We implemented a machine learning algorithm that provides individual probabilistic scores based on magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) data. We investigated whether combining MRI and CSF levels could improve the diagnosis confidence. 215 AD patients, 103 FTD patients, and 173 healthy controls (CTR) were studied. With MRI data, we obtained an accuracy of 82 % for AD vs. FTD. A total of 74 % of FTD and 73 % of AD participants have a high probability of accurate diagnosis. Adding CSF-NfL and 14-3-3 levels improved the accuracy and the number of patients in the confidence group for differentiating FTD from AD. We obtain individual diagnostic probabilities with high precision to address the problem of confidence in the diagnosis. We suggest when MRI, CSF, or the combination are necessary to improve the FTD and AD diagnosis. This algorithm holds promise towards clinical applications as support to clinical findings or in settings with limited access to expert diagnoses.

Social-semantic knowledge in frontotemporal dementia and after anterior temporal lobe resection

Degraded semantic memory is a prominent feature of frontotemporal dementia (FTD). It is classically associated with semantic dementia and anterior temporal lobe (ATL) atrophy, but semantic knowledge can also be compromised in behavioural variant FTD. Motivated by understanding behavioural change in FTD, recent research has focused selectively on social-semantic knowledge, with proposals that the right ATL is specialized for social concepts. Previous studies have assessed very different types of social concepts and have not compared performance with that of matched non-social concepts. Consequently, it remains unclear to what extent various social concepts are (i) concurrently impaired in FTD, (ii) distinct from general semantic memory and (iii) differentially supported by the left and right ATL. This study assessed multiple aspects of social-semantic knowledge and general conceptual knowledge across cohorts with ATL damage arising from either neurodegeneration or resection. We assembled a test battery measuring knowledge of multiple types of social concept. Performance was compared with non-social general conceptual knowledge, measured using the Cambridge Semantic Memory Test Battery and other matched non-social-semantic tests. Our trans-diagnostic approach included behavioural variant FTD, semantic dementia and 'mixed' intermediate cases to capture the FTD clinical spectrum, as well as age-matched healthy controls. People with unilateral left or right ATL resection for temporal lobe epilepsy were also recruited to assess how selective damage to the left or right ATL impacts social- and non-social-semantic knowledge. Social- and non-social-semantic deficits were severe and highly correlated in FTD. Much milder impairments were found after unilateral ATL resection, with no left versus right differences in social-semantic knowledge or general semantic processing and with only naming showing a greater deficit following left versus right damage. A principal component analysis of all behavioural measures in the FTD cohort extracted three components, interpreted as capturing (i) FTD severity, (ii) semantic memory and (iii) executive function. Social and non-social measures both loaded heavily on the same semantic memory component, and scores on this factor were uniquely associated with bilateral ATL grey matter volume but not with the degree of ATL asymmetry. Together, these findings demonstrate that both social- and non-social-semantic knowledge degrade in FTD (semantic dementia and behavioural variant FTD) following bilateral ATL atrophy. We propose that social-semantic knowledge is part of a broader conceptual system underpinned by a bilaterally implemented, functionally unitary semantic hub in the ATLs. Our results also highlight the value of a trans-diagnostic approach for investigating the neuroanatomical underpinnings of cognitive deficits in FTD.

Social cognition differentiates phenocopy syndrome of behavioural variant frontotemporal dementia from behavioural variant frontotemporal dementia

BACKGROUND

Patients displaying clinical features of behavioural variant of frontotemporal dementia (bvFTD) but lacking both neuroimaging abnormalities and clinical progression are considered to represent the phenocopy syndrome of bvFTD (phFTD). Extensive clinical overlap between early phase bvFTD and phFTD hampers diagnostic distinction. We aimed to assess the diagnostic value of clinician-rated, self-reported and caregiver-reported symptoms for clinical distinction between phFTD and bvFTD.

METHODS

There were 33 phFTD and 95 probable bvFTD patients included in the study (total N = 128). Clinician-rated, self-reported tests and caregiver-reported symptoms were compared between phFTD and bvFTD on social cognition, behaviour, mood and activities of daily living (ADL). Scores were compared between groups, followed by multiple logistic regression analysis, adjusted for age and sex. Receiver operating characteristic curves were plotted to assess diagnostic value.

RESULTS

Using clinician-rated and self-reported tests, phFTD patients performed better on facial emotion recognition and reported more depressive symptoms. Caregiver-reported behavioural symptoms indicated higher behavioural and ADL impairment in phFTD compared to bvFTD. Facial emotion recognition provided highest diagnostic accuracy for distinction of phFTD from bvFTD (area under the curve (AUC) 0.813 95% CI 0.735-0.892, P < 0.001, sensitivity 81%, specificity 74%) followed by depressive symptoms (AUC 0.769 95% 0.674-0.864, P < 0.001 sensitivity 81%, specificity of 63%).

CONCLUSION

Social cognition tests are most suitable for distinction of phFTD from bvFTD. Caregiver-reported questionnaires and phFTD diagnosis seemed inversely correlated, showing more symptoms in phFTD. Further research is needed on phFTD aetiology and in caregivers taking into account disease burden to assess what explains this discrepancy between clinician-rated and caregiver-based tools.

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.

The quality of the relationship perceived by spouses of people with young-onset dementia

BACKGROUND

Young-onset dementia (YOD) has a profound impact on spouses. However, little is known on how the quality of the relationship changes over time in YOD. This study aims to determine how the quality of the relationship changes over time and identify predictors of this change.

METHODS

This study used data from the NEEDs in Young onset Dementia (NeedYD) study. The primary outcome measure was the quality of the relationship perceived by spouses measured throughout 24 months. Baseline characteristics of persons with YOD and spouses were also measured to assess their predictive value.

RESULTS

Totally, 178 dyads were included. The perceived quality of the relationship deteriorated over time. A longer symptom duration, a diagnosis of frontotemporal dementia, lower levels of awareness of deficits, lower levels of initiative toward daily living activities, and higher levels of apathy, hyperactivity, depression, and anxiety in the person with YOD were associated with a lower perceived quality of the relationship by spouses. A coping style characterized by palliative and passive reacting patterns and higher levels of neuroticism in spouses was also associated with a lower quality of the relationship.

CONCLUSION

The quality of the relationship as perceived by spouses deteriorated over time and was influenced by characteristics of the person with YOD as well as their spouse. Helping spouses to come to terms with factors that threaten their sense of couplehood might help them to develop a more positive attitude toward their spousal relationship and improve the quality of the relationship and care.

A systematic review of cognitive and behavioral tools to differentiate behavioral variant frontotemporal dementia from other conditions

The behavioral variant of frontotemporal dementia (bvFTD) is thought to be the commonest clinical presentation of frontotemporal lobar degeneration and is predominantly characterized by changes in behavior. In patients lacking unequivocal biomarker evidence of frontotemporal neurodegeneration, the clinical diagnosis of bvFTD is often unstable. In response, we conducted a systematic review and critical appraisal of cognitive and behavioral tools that have sought to differentiate bvFTD from other conditions. A systematic literature review of PubMed, Scopus, and Web of Science was conducted on December 31, 2023 for cognitive and behavioral tools that differentiated bvFTD from other cohorts. Ninety-six studies were included. The quality appraisal of almost all studies was low and introduced a high risk of bias. The few studies that were of high quality had a prospective study design and recruited patients suspected (but not yet confirmed) to have bvFTD. These studies reported that behavioral tools (e.g., the Frontal Behavioral Inventory) and social cognition tests (e.g., the Ekman's Faces Test) had good test performance in differentiating bvFTD from a broad range of psychiatric and neurological conditions. Importantly, the review highlighted the extreme paucity of studies that have evaluated methods where, in Bayesian terms, there is genuine clinical uncertainty regarding a diagnosis of bvFTD. Most studies used healthy controls of typical Alzheimer's disease as comparators-groups that often have negligible pretest probability of bvFTD. In response, we propose a study design checklist for studies seeking to develop diagnostic algorithms in bvFTD research.

Longitudinal volumetric changes in amygdala subregions in frontotemporal dementia

Amygdala atrophy has been found in frontotemporal dementia (FTD), yet the specific changes of its subregions across different FTD phenotypes remain unclear. The aim of this study was to investigate the volumetric alterations of the amygdala subregions in FTD phenotypes and how they evolve with disease progression. Patients clinically diagnosed with behavioral variant FTD (bvFTD) (n = 20), semantic dementia (SD) (n = 20), primary nonfluent aphasia (PNFA) (n = 20), Alzheimer's disease (AD) (n = 20), and 20 matched healthy controls underwent whole brain structural MRI. The patient groups were followed up annually for up to 3.5 years. Amygdala nuclei were segmented using FreeSurfer, corrected by total intracranial volumes, and grouped into the basolateral, superficial, and centromedial subregions. Linear mixed effects models were applied to identify changes in amygdala subregional volumes over time. At baseline, bvFTD, SD, and AD displayed global amygdala volume reduction, whereas amygdala volume appeared to be preserved in PNFA. Asymmetrical amygdala atrophy (left > right) was most pronounced in SD. Longitudinally, SD and PNFA showed greater rates of annual decline in the right basolateral and superficial subregions compared to bvFTD and AD. The findings provide comprehensive insights into the differential impact of FTD pathology on amygdala subregions, revealing distinct atrophy patterns that evolve over disease progression. The characterization of amygdala subregional involvement in FTD and their potential role as biomarkers carry substantial clinical implications.

Subjective clustering in patients with fronto-temporal dementia

In the behavioral variant of frontotemporal dementia (bvFTD) memory deficits have been traditionally considered as due to difficulties in encoding/retrieval frontal strategies. However, the frontal origin of memory deficits in bvFTD has been questioned and hippocampal dysfunction has been also proposed. Here we analyzed bvFTD patients' proficiency in subjectively organizing memories without an external criterion. Twenty bvFTD patients and 20 healthy individuals were assessed with memory and executive tasks. The ability to subjectively organize memories in the immediate recall of a 15 unrelated word list was measured by calculating the index of subjective clustering (ISC) based on the constancies in response order across the five consecutive free recall trials. Results revealed reduced ISC in bvFTD patients with respect to normal controls. In the bvFTD group, the ISC score correlated with the Corsi span backward score and the number of categories achieved on the Modified Card Sorting Test. The bvFTD patients' reduced ISC and its correlation with executive performance suggest that executive deficits underlie their defective strategic organization of memories. However, as ISC did not predict memory accuracy in these patients, the memory deficit may not be the mere expression of their executive difficulties.

Establishing the link between motivational disturbances and behavioural rigidity in frontotemporal dementia

BACKGROUND

Rigid and inflexible behaviours are common in frontotemporal dementia (FTD), manifesting in compulsive pursuit of specific interests, routines, and rituals. Paradoxically, these changes occur alongside profound motivational disturbances including apathy and anhedonia. While posited to be related, no study to date has explored the link between motivational changes and behavioural rigidity in FTD.

METHODS

Carer ratings for 71 FTD participants (26 semantic dementia [SD], 45 behavioural variant [bvFTD]) were obtained on the Dimensional Apathy Scale (apathy), the Snaith-Hamilton Pleasure Scale (hedonic tone) and the Cambridge Behavioural Inventory-Revised (CBI-R; behavioural changes). A rigidity index was created from existing items on the CBI-R. Whole-brain voxel-based morphometry was used to explore associations between rigidity and grey matter intensity in the combined FTD group.

RESULTS

Behavioural rigidity was significantly related to apathy severity (r = 0.57) and decreased hedonic tone (r = -0.36) in the combined FTD group. Multiple linear regression revealed a significant diagnosis × hedonic tone interaction (β = -1.40), whereby lower hedonic tone predicted rigidity in SD (r = -0.65) but not in bvFTD (r = -0.18). In contrast, the relationship between rigidity and apathy did not differ between the groups (β = -0.42). At the neural level, rigidity correlated with degeneration of predominantly right-sided frontostriatal structures including, notably, the nucleus accumbens.

CONCLUSIONS

As the first study to demonstrate a link between motivational changes and behavioural rigidity in FTD, our findings have important clinical implications. By identifying candidate mechanisms of behavioural rigidity, our findings can inform targeted interventions to manage inflexible patterns of thought and behaviour in daily life.

Attention Circuits Mediate the Connection between Emotional Experience and Expression within the Emotional Circuit

Objective

: Most affective neuroscience studies use pictures from the International Affective Picture System or standard facial expressions to elicit emotional experiences. The attention system, including the prefrontal cortex, can mediate emotional regulation in response to stimulation with emotional faces. We hypothesized that emotional experience is associated with brain activity within the neocortex. In addition, modification within the neocortex may be associated with brain activity within the attention system.

Methods

: Thirty-one healthy adult participants were recruited to be assessed for emotional expression using clinical scales of happiness, sadness, anxiety, and anger as and for emotional experience using brain activity in response to pictures of facial emotional expressions. The attention system was assessed using brain activity in response to the go-no-go task.

Results

: We found that emotional experience was associated with brain activity within the frontotemporal cortices, while emotional expression was associated with brain activity within the temporal and insular cortices. In addition, the association of brain activity between emotional experiences and expressions of sadness and anxiety was affected by brain activity within the anterior cingulate gyrus in response to the go-no-go task.

Conclusion

: Emotional expression may be associated with brain activity within the temporal cortex, whereas emotional experience may be associated with brain activity within the frontotemporal cortices. In addition, the attention system may interfere with the connection between emotional expression and experience.

Relationship between eating problems and the risk of dementia: A retrospective study

BACKGROUND

Older adults and individuals with decreased cognition often experience appetite changes and weight loss. As weight loss can result in cognitive decline, change in appetite may be an important contributor to the onset of dementia. However, there is a lack of relevant studies on this topic. This study aimed to determine the relationship between appetite changes, weight loss, and dementia onset.

METHODS

A total of 135 patients with normal cognitive function, subjective cognitive impairment, and mild cognitive impairment who were assessed using the Neuropsychiatric Inventory 12 item version (NPI-12) and followed up for at least 1 month were enrolled in the study. All patients underwent a Mini-Mental State Examination (MMSE). Eating problems were assessed using the NPI Eating Problems Score. Appetite and weight loss were assessed at the first visit by caregivers. Kaplan-Meier survival analyses with a log-rank test were used to compare the time to the onset of dementia between the presence or absence of the NPI eating problems, appetite loss, weight loss, or NPI depression scores. Cox proportional hazards regression models using the forced entry method were employed to estimate the hazard ratio (HR) for dementia.

RESULTS

Weight loss was significantly related to dementia onset (P = 0.027) in the Kaplan-Meier survival analyses, while eating problems, appetite loss, and depression showed no significant association (P = 0.519, P = 0.326, and P = 0.317, respectively). In the Cox proportional hazards regression models, the MMSE score was found to be a significant factor (P = 0.021, HR = 0.871); moreover, weight loss tended to increase the risk of dementia onset (P = 0.057, HR = 1.694).

CONCLUSIONS

Weight loss experienced by older adults could contribute to an increased risk of developing dementia.

A systematic review of the prevalence of depression, anxiety, and apathy in frontotemporal dementia, atypical and young-onset Alzheimer's disease, and inherited dementia

OBJECTIVES

Depression, anxiety, and apathy are the most commonly reported neuropsychiatric symptoms (NPS) in Alzheimer's disease (AD). Understanding their prevalence in rarer dementias such as frontotemporal dementia (FTD), primary progressive aphasia (PPA), posterior cortical atrophy (PCA), young-onset AD (YOAD), and inherited dementias has implications for both clinical practice and research. In this study, we aimed to examine the current state of knowledge of the prevalence of these three NPS in less prevalent dementias.

DESIGN

We conducted a systematic review based on searches of EMBASE, PsycINFO, and PubMed up to September 2019.

RESULTS

47 articles meeting inclusion criteria were identified. Depression, anxiety, and apathy were commonly reported across the phenotypes studied but their prevalence showed large variation between studies. Apathy showed the highest reported frequency in FTD (50-100% across studies), behavioral variant frontotemporal dementia (bvFTD) (73-100%), and YOAD (44-100%). Anxiety was frequently reported in FTD (0-100%) and bvFTD (19-63%). Depression showed the highest prevalence in FTD (7-69%) and YOAD (11-55%). Among the three variants of PPA, sv-PPA is the one most investigated (seven articles). Three or fewer articles were identified examining NPS in the remaining PPA variants, PCA, familial AD, and familial FTD. Inconsistency in the tools used to measure symptoms and small sample sizes were common methodological limitations.

CONCLUSIONS

Future studies should consider the inclusion of larger sample sizes (e.g. through multicenter collaborations) and the use of harmonized protocols that include the combination of caregiver and patient-derived measures and symptom-specific questionnaires. More research is needed on the phenotype-specific barriers and facilitators for people living with dementia to successfully engage in self-reports of NPS.

A 20-Year Systematic Review of the 'Reading the Mind in the Eyes' Test across Neurodegenerative Conditions

Social cognition has a broad theoretical definition, which includes the ability to mentalise, i.e., recognise and infer mental states to explain and predict another's behaviour. There is growing recognition of the clinical, diagnostic, and prognostic value of assessing a person's ability to perform social cognitive tasks, particularly aspects of theory of mind, such as mentalising. One such measure of mentalising is the 'Reading the Mind in the Eyes' test (RMET). This systematic review and meta-analysis consider performance on the RMET, applied to people with neurodegenerative conditions in matched control studies, since its publication in 2001. Overall, this review includes 22 papers with data from N = 800 participants with neurodegenerative conditions: Alzheimer's disease, n = 31; Parkinson's disease, n = 221; Lewy body dementia, n = 33; motor neuron disease, n = 218; Huntington's disease n = 80; multiple sclerosis, n = 217; and N = 601 matched typical controls. Our meta-analyses show that deficits in mentalising, as measured by the RMET, are consistently reported across neurodegenerative conditions, with participants in both early and late disease stages being affected. Social cognition is an emerging field of cognitive neuroscience requiring specific and sensitive measurement across each subdomain. Adult-based meta-normative data feature, for which future groups or individuals could be compared against, and hypotheses relating to the source of these mentalising deficits are further discussed. This review was registered with PROSPERO (CRD42020182874).

Awareness impairment in Alzheimer's disease and frontotemporal dementia: a systematic MRI review

This review aims to define awareness impairment and related disturbances in neurodegenerative diseases, including Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD) spectrum of disorders. An update of the available scientific literature on the use of magnetic resonance imaging (MRI) in the study of awareness in these disorders is also offered. MRI plays an important role in the characterization of neurodegenerative signatures and can increase our knowledge on brain structural and functional correlates of awareness. In the reviewing process, we established a-priori criteria and we searched the scientific literature for relevant articles on this topic. In summary, we selected 36 articles out of 1340 publications retrieved from PubMed. Based on this selection, this review discusses the multiple terms used to define different or overlapping aspects of awareness impairment, and specifically summarizes recent application of MRI for investigating anosognosia, social cognition, including theory of mind and emotional processing, free will, and autonoetic awareness alterations in different neurodegenerative disorders, with most of these studies focused on AD and FTLD. This systematic review highlights the importance of awareness impairment and related domains in neurodegenerative disorders, especially in AD and FTLD, and it outlines MRI structural and functional correlates in these populations.

Addition of the FTD Module to the Neuropsychiatric Inventory improves classification of frontotemporal dementia spectrum disorders

Most neuropsychiatric symptoms (NPS) common in frontotemporal dementia (FTD) are currently not part of the Neuropsychiatric Inventory (NPI). We piloted an FTD Module that included eight extra items to be used in conjunction with the NPI. Caregivers of patients with behavioural variant FTD (n = 49), primary progressive aphasia (PPA; n = 52), Alzheimer's dementia (AD; n = 41), psychiatric disorders (n = 18), presymptomatic mutation carriers (n = 58) and controls (n = 58) completed the NPI and FTD Module. We investigated (concurrent and construct) validity, factor structure and internal consistency of the NPI and FTD Module. We performed group comparisons on item prevalence, mean item and total NPI and NPI with FTD Module scores, and multinomial logistic regression to determine its classification abilities. We extracted four components, together explaining 64.1% of the total variance, of which the largest indicated the underlying dimension 'frontal-behavioural symptoms'. Whilst apathy (original NPI) occurred most frequently in AD, logopenic and non-fluent variant PPA, the most common NPS in behavioural variant FTD and semantic variant PPA were loss of sympathy/empathy and poor response to social/emotional cues (part of FTD Module). Patients with primary psychiatric disorders and behavioural variant FTD showed the most severe behavioural problems on both the NPI as well as the NPI with FTD Module. The NPI with FTD Module correctly classified more FTD patients than the NPI alone. By quantifying common NPS in FTD the NPI with FTD Module has large diagnostic potential. Future studies should investigate whether it can also prove a useful addition to the NPI in therapeutic trials.

Emotion recognition and baseline cortisol levels relationship in early Alzheimer disease

BACKGROUND

Emotion recognition is often impaired in early Alzheimer's disease (AD) and can be evaluated using the Reading the Mind in the Eyes Test (RMET). Similarly, cortisol levels can affect cognition and could be considered a biomarker of AD.

OBJECTIVES

The aim of this study was to analyse the relationship between the emotion recognition task and cortisol levels in participants with early Alzheimer Disease (AD).

METHODS

Complex emotion recognition was assessed with RMET, and plasma cortisol levels were determined by mass spectrometry in participants classified into mild cognitive impairment (MCI) due to AD (n = 25), mild dementia (MD) due to AD (n = 20), MCI non-AD (n = 34), MD non-AD (n = 13) and healthy controls (HC) (n = 16) groups.

RESULTS

Significantly lower positive emotion recognition was found in the MCI non-AD group (p = 0.02) and lower emotion recognition in MD (AD and non-AD) groups (p < 0.01) compared to the healthy group. In addition, significant differences were observed between cortisol and all RMET scores among the MCI and MD groups (p < 0.01). A significant correlation was also obtained between total and neutral RMET scores and cortisol levels in MD groups (p = 0.01).

CONCLUSIONS

These outcomes suggest that detection of positive emotion dysfunction could help to identify MCI non-AD patients. Furthermore, general impaired emotion recognition and high cortisol levels may be associated with cognitive impairment at mild dementia level.

Repetitive Behaviors in Alzheimer's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Repetitive behaviors (RBs) are a well-known symptom of Alzheimer's disease (AD); however, they have been little studied and have not been the subject of any specific literature review.

OBJECTIVE

To conduct a systematic review of all studies to document RBs in AD.

METHODS

An extensive literature search combining five databases and a meta-analysis were conducted to investigate the frequency, nature, and cognitive correlates of RBs in AD.

RESULTS

Ten studies were included in the review. Seven studies out of ten investigated the frequency of RBs in patients with AD, which ranged from 52.3% to 87%. A meta-analysis showed an overall frequency of 66.3% (95% CI: 55.5; 77.1) of patients exhibiting RBs in AD, but important heterogeneity was observed between studies. Three studies investigated the predominant nature of RBs in AD. Verbal RBs, complex behavioral stereotypies, and simple motor stereotypies have been identified to different degrees depending on the level of dementia. Most verbal RBs are underpinned by episodic memory impairment, while simple motor stereotypies and complex behavioral stereotypies are mostly underpinned by executive dysfunction.

CONCLUSIONS

The current review seems to suggest that there are two types of mechanisms underpinning RBs involved in AD. The first is observed especially in the mild stages of the disease and is mediated by episodic memory impairment. The second occurs later and is mediated by executive impairment. Additional studies should be conducted to improve the knowledge about RBs in AD and thus improve their management.Systematic review registration number: PROSPERO 2022: CRD42022310027.

Primary Progressive Aphasia Presenting With Neuropsychiatric Symptoms

We describe a case of primary progressive aphasia (PPA) with an underlying neurodegenerative motor disorder (possible ALS or PSP), presenting with symptoms of irritability and frustration, that were misdiagnosed and treated as a primary psychiatric disorder, i.e. depression. PPA is a rare neurodegenerative disorder characterized by insidious onset and gradual progression of speech and language impairment. We emphasize that PPA can initially masquerade as or be accompanied by neuropsychiatric symptoms potentially leading to misdiagnosis. Most prevalent neuropsychiatric symptoms reported in the PPA literature are agitation, depression, anxiety, apathy, irritability, abnormal appetite and disinhibition. To ensure early diagnosis of PPA, if a patient presents with new psychiatric symptoms accompanied by new onset speech and/or language impairment, referral to a specialist (i.e., neurologist and/or speech-language pathologist) is recommended.

Network analysis of impulse dyscontrol in mild cognitive impairment and subjective cognitive decline

OBJECTIVES

To investigate conditional dependence relationships of impulse dyscontrol symptoms in mild cognitive impairment (MCI) and subjective cognitive decline (SCD).

DESIGN

A prospective, observational study.

PARTICIPANTS

Two hundred and thirty-five patients with MCI (n = 159) or SCD (n = 76) from the Prospective Study for Persons with Memory Symptoms dataset.

MEASUREMENTS

Items of the Mild Behavioral Impairment Checklist impulse dyscontrol subscale.

RESULTS

Stubbornness/rigidity, agitation/aggressiveness, and argumentativeness were frequent and the most central symptoms in the network. Impulsivity, the fourth most central symptom in the network, served as the bridge between these common symptoms and less central and rare symptoms.

CONCLUSIONS

Impulse dyscontrol in at-risk states for dementia is characterized by closely connected symptoms of irritability, agitation, and rigidity. Compulsions and difficulties in regulating rewarding behaviors are relatively isolated symptoms.

Proposed research criteria for prodromal behavioural variant frontotemporal dementia

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

Behavioral and Psychological Symptoms of Dementia in Different Dementia Disorders: A Large-Scale Study of 10,000 Individuals

Background:

The majority of individuals with dementia will suffer from behavioral and psychological symptoms of dementia (BPSD). These symptoms contribute to functional impairment and caregiver burden.

Objective:

To characterize BPSD in Alzheimer’s disease (AD), vascular dementia (VaD), mixed (Mixed) dementia, Parkinson’s disease dementia (PDD), dementia with Lewy bodies (DLB), frontotemporal dementia (FTD), and unspecified dementia in individuals residing in long-term care facilities.

Methods:

We included 10,405 individuals with dementia living in long-term care facilities from the Swedish registry for cognitive/dementia disorders (SveDem) and the Swedish BPSD registry. BPSD was assessed with the Neuropsychiatric Inventory - Nursing Home Version (NPI-NH). Multivariate logistic regression models were used to evaluate the associations between dementia diagnoses and different BPSDs.

Results:

The most common symptoms were aberrant motor behavior, agitation, and irritability. Compared to AD, we found a lower risk of delusions (in FTD, unspecified dementia), hallucinations (FTD), agitation (VaD, PDD, unspecified dementia), elation/euphoria (DLB), anxiety (Mixed, VaD, unspecified dementia), disinhibition (in PDD), irritability (in DLB, FTD, unspecified dementia), aberrant motor behavior (Mixed, VaD, unspecified dementia), and sleep and night-time behavior changes (unspecified dementia). Higher risk of delusions (DLB), hallucinations (DLB, PDD), apathy (VaD, FTD), disinhibition (FTD), and appetite and eating abnormalities (FTD) were also found in comparison to AD.

Conclusion:

Although individuals in our sample were diagnosed with different dementia disorders, they all exhibited aberrant motor behavior, agitation, and irritability. This suggests common underlying psychosocial or biological mechanisms. We recommend prioritizing these symptoms while planning interventions in long-term care facilities.

Multidimensional Clinical Assessment in Frontotemporal Dementia and Its Spectrum in Latin America and the Caribbean: A Narrative Review and a Glance at Future Challenges

Frontotemporal dementia (FTD) is the third most common form of dementia across all age groups and is a leading cause of early-onset dementia. The Frontotemporal dementia (FTD) includes a spectrum of diseases that are classified according to their clinical presentation and patterns of neurodegeneration. There are two main types of FTD: behavioral FTD variant (bvFTD), characterized by a deterioration in social function, behavior, and personality; and primary progressive aphasias (PPA), characterized by a deficit in language skills. There are other types of FTD-related disorders that present motor impairment and/or parkinsonism, including FTD with motor neuron disease (FTD-MND), progressive supranuclear palsy (PSP), and corticobasal syndrome (CBS). The FTD and its associated disorders present great clinical heterogeneity. The diagnosis of FTD is based on the identification through clinical assessments of a specific clinical phenotype of impairments in different domains, complemented by an evaluation through instruments, i.e., tests and questionnaires, validated for the population under study, thus, achieving timely detection and treatment. While the prevalence of dementia in Latin America and the Caribbean (LAC) is increasing rapidly, there is still a lack of standardized instruments and consensus for FTD diagnosis. In this context, it is important to review the published tests and questionnaires adapted and/or validated in LAC for the assessment of cognition, behavior, functionality, and gait in FTD and its spectrum. Therefore, our paper has three main goals. First, to present a narrative review of the main tests and questionnaires published in LAC for the assessment of FTD and its spectrum in six dimensions: (i) Cognitive screening; (ii) Neuropsychological assessment divided by cognitive domain; (iii) Gait assessment; (iv) Behavioral and neuropsychiatric symptoms; (v) Functional assessment; and (vi) Global Rating Scale. Second, to propose a multidimensional clinical assessment of FTD in LAC identifying the main gaps. Lastly, it is proposed to create a LAC consortium that will discuss strategies to address the current challenges in the field.

Pronoun Use among Caregivers of People Living with Dementia: Associations with Dementia Severity Using Text Analysis of a Natural Language Sample

Introduction

Family caregivers of persons living with dementia (PLWDs) have extensive social, physical, emotional, and financial responsibilities. However, less is known about the relationship and interpersonal connection between caregivers and PLWDs. We examined caregiver pronoun use, as an index of the connection between the caregiver and PLWD and its associations with the caregiver's and PLWD's health and well-being.

Methods

Caregivers of PLWDs (N = 320) were asked to describe a recent time they felt connected to the PLWD in their care. Responses were transcribed and coded to quantify pronoun use by category (we-pronouns, I-pronouns, and they-pronouns). Caregivers also reported on their depression, burden, and the PLWD's dementia severity and marital satisfaction. Sixty-eight caregivers repeated the same survey 24 months after the initial survey.

Results

Caregivers used less we-pronouns when the PLWD's dementia was more severe, at both timepoints. Spousal caregivers used more we-pronouns and less I- and they-pronouns than nonspousal caregivers. There was an interaction between spousal relationship and dementia severity, such that spousal caregivers exhibited a stronger negative association between dementia severity and we-pronoun use. There were no associations between pronoun category and caregiver burden or depression.

Discussion

Caregivers may feel increasingly disconnected from the PLWD as their dementia becomes more severe, as reflected by less we-pronoun usage. This study highlights the opportunity to explore relationship connection through text analysis.

Depression Is Associated With Preserved Cortical Thickness Relative to Apathy in Frontotemporal Dementia

OBJECTIVES

To understand the differential neuroanatomical substrates underlying apathy and depression in Frontotemporal dementia (FTD).

METHODS

T1-MRIs and clinical data of patients with behavioral and aphasic variants of FTD were obtained from an open database. Cortical thickness was derived, its association with apathy severity and difference between the depressed and not depressed were examined with appropriate covariates.

RESULTS

Apathy severity was significantly associated with cortical thinning of the lateral parts of the right sided frontal, temporal and parietal lobes. The right sided orbitofrontal, parsorbitalis and rostral anterior cingulate cortex were thicker in depressed compared to patients not depressed.

CONCLUSIONS

Greater thickness of right sided ventromedial and inferior frontal cortex in depression compared to patients without depression suggests a possible requisite of gray matter in this particular area for the manifestation of depression in FTD. This study demonstrates a method for deriving neuroanatomical patterns across non-harmonized neuroimaging data in a neurodegenerative disease.

In vivo hypothalamic regional volumetry across the frontotemporal dementia spectrum

BACKGROUND

Frontotemporal dementia (FTD) is a spectrum of diseases characterised by language, behavioural and motor symptoms. Among the different subcortical regions implicated in the FTD symptomatology, the hypothalamus regulates various bodily functions, including eating behaviours which are commonly present across the FTD spectrum. The pattern of specific hypothalamic involvement across the clinical, pathological, and genetic forms of FTD has yet to be fully investigated, and its possible associations with abnormal eating behaviours have yet to be fully explored.

METHODS

Using an automated segmentation tool for volumetric T1-weighted MR images, we measured hypothalamic regional volumes in a cohort of 439 patients with FTD (197 behavioural variant FTD [bvFTD]; 7 FTD with associated motor neurone disease [FTD-MND]; 99 semantic variant primary progressive aphasia [svPPA]; 117 non-fluent variant PPA [nfvPPA]; 19 PPA not otherwise specified [PPA-NOS]) and 118 age-matched controls. We compared volumes across the clinical, genetic (29 MAPT, 32 C9orf72, 23 GRN), and pathological diagnoses (61 tauopathy, 40 TDP-43opathy, 4 FUSopathy). We correlated the volumes with presence of abnormal eating behaviours assessed with the revised version of the Cambridge Behavioural Inventory (CBI-R).

RESULTS

On average, FTD patients showed 14% smaller hypothalamic volumes than controls. The groups with the smallest hypothalamic regions were FTD-MND (20%), MAPT (25%) and FUS (33%), with differences mainly localised in the anterior and posterior regions. The inferior tuberal region was only significantly smaller in tauopathies (MAPT and Pick's disease) and in TDP-43 type C compared to controls and was the only regions that did not correlate with eating symptoms. PPA-NOS and nfvPPA were the groups with the least frequent eating behaviours and the least hypothalamic involvement.

CONCLUSIONS

Abnormal hypothalamic volumes are present in all the FTD forms, but different hypothalamic regions might play a different role in the development of abnormal eating behavioural and metabolic symptoms. These findings might therefore help in the identification of different underlying pathological mechanisms, suggesting the potential use of hypothalamic imaging biomarkers and the research of potential therapeutic targets within the hypothalamic neuropeptides.

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

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

Impaired emotion perception and categorization in semantic aphasia

According to a constructionist model of emotion, conceptual knowledge plays a foundational role in emotion perception; reduced availability of relevant conceptual knowledge should therefore impair emotion perception. Conceptual deficits can follow both degradation of semantic knowledge (e.g., semantic 'storage' deficits in semantic dementia) and deregulation of retrieval (e.g., semantic 'access' deficits in semantic aphasia). While emotion recognition deficits are known to accompany degraded conceptual knowledge, less is known about the impact of semantic access deficits. Here, we examined emotion perception and categorization tasks in patients with semantic aphasia, who have difficulty accessing semantic information in a flexible and controlled fashion following left hemisphere stroke. In Study 1, participants were asked to sort faces according to the emotion they portrayed - with numbers, written labels and picture examples each provided as category anchors across tasks. Semantic aphasia patients made more errors and showed a larger benefit from word anchors that reduced the need to internally constrain categorization than comparison participants. They successfully sorted portrayals that differed in valence (positive vs. negative) but had difficulty categorizing different negative emotions. They were unimpaired on a control task that involved sorting faces by identity. In Study 2, participants matched facial emotion portrayals to written labels following vocal emotion prosody cues, miscues, or no cues. Patients presented with overall poorer performance and benefited from cue trials relative to within-valence miscue trials. This same effect was seen in comparison participants, who also showed deleterious effects of within-valence miscue relative to no cue trials. Overall, we found that patients with deregulated semantic retrieval have deficits in emotional perception but that word anchors and cue conditions can facilitate emotion perception by increasing access to relevant emotion concepts and reducing reliance on semantic control. Semantic control may be of particular importance in emotion perception when it is necessary to interpret ambiguous inputs, or when there is interference between conceptually similar emotional states. These findings extend constructionist accounts of emotion to encompass difficulties in controlled semantic retrieval.

Selective expression of the neurexin substrate for presenilin in the adult forebrain causes deficits in associative memory and presynaptic plasticity

Presenilins (PS) form the active subunit of the gamma-secretase complex, which mediates the proteolytic clearance of a broad variety of type-I plasma membrane proteins. Loss-of-function mutations in PSEN1/2 genes are the leading cause of familial Alzheimer's disease (fAD). However, the PS/gamma-secretase substrates relevant for the neuronal deficits associated with a loss of PS function are not completely known. The members of the neurexin (Nrxn) family of presynaptic plasma membrane proteins are candidates to mediate aspects of the synaptic and memory deficits associated with a loss of PS function. Previous work has shown that fAD-linked PS mutants or inactivation of PS by genetic and pharmacological approaches failed to clear Nrxn C-terminal fragments (NrxnCTF), leading to its abnormal accumulation at presynaptic terminals. Here, we generated transgenic mice that selectively recreate the presynaptic accumulation of NrxnCTF in adult forebrain neurons, leaving unaltered the function of PS/gamma-secretase complex towards other substrates. Behavioral characterization identified selective impairments in NrxnCTF mice, including decreased fear-conditioning memory. Electrophysiological recordings in medial prefrontal cortex-basolateral amygdala (mPFC-BLA) of behaving mice showed normal synaptic transmission and uncovered specific defects in synaptic facilitation. These data functionally link the accumulation of NrxnCTF with defects in associative memory and short-term synaptic plasticity, pointing at impaired clearance of NrxnCTF as a new mediator in AD.

Characteristics of behavioral symptoms in right-sided predominant semantic dementia and their impact on caregiver burden: a cross-sectional study

Background

This study aimed to clarify the neuropsychiatric symptoms of right-sided predominant semantic dementia (SD-R) by comparing them with those of behavioral variant frontotemporal dementia (bvFTD), left-sided predominant SD (SD-L), and Alzheimer’s disease (AD). This study also aimed to identify clinical factors related to caregiver burden for bvFTD, SD-R, and SD-L.

Methods

The neuropsychiatric symptoms of 28 patients with bvFTD, 14 patients with SD-R, 24 patients with SD-L, and 43 patients with AD were evaluated using the Neuropsychiatric Inventory (NPI) and the Stereotypy Rating Inventory (SRI). Cognitive function was assessed using the Mini-Mental State Examination (MMSE). Dementia severity was assessed using the Clinical Dementia Rating. Activities of daily living were assessed using the Lawton Instrument Activities of Daily Living (IADL) scale and the Physical Self-Maintenance Scale. We compared the NPI and SRI scores among the four groups using the Kruskal-Wallis test. In addition, clinical factors related to caregiver burden, represented by the Japanese version of the Zarit Burden Interview (J-ZBI), were analyzed using multiple regression analysis in the bvFTD, SD-R, and SD-L groups.

Results

The NPI total score and the NPI subscale scores of apathy and disinhibition were significantly higher in the bvFTD group than in the SD-L and AD groups. The SD-R group scores were closer to those of the bvFTD group than the SD-L group. The SRI total score and SRI subscale scores for eating and cooking and speaking were significantly higher in the bvFTD, SD-R, and SD-L groups than in the AD group. The NPI total score was significantly associated with the J-ZBI score in the bvFTD group. The NPI total score and Lawton IADL scale score were independently associated with the J-ZBI score in the SD-R group. Furthermore, the NPI total score and MMSE score were independently associated with the J-ZBI score in the SD-L group.

Conclusions

SD-R seemed to be a similar condition to bvFTD rather than SD-L regarding behavioral symptoms. Our results suggest that each frontotemporal dementia subgroup requires different approaches to reduce the caregiver burden.

Pharmacotherapy for Neuropsychiatric Symptoms in Frontotemporal Dementia

Despite significant progress in the understanding of the frontotemporal dementias (FTDs), there remains no disease-modifying treatment for these conditions, and limited effective symptomatic treatment. Behavioural variant frontotemporal dementia (bvFTD) is the most common FTD syndrome, and is characterized by severe impairments in behaviour, personality and cognition. Neuropsychiatric symptoms are common features of bvFTD but are present in the other FTD syndromes. Current treatment strategies therefore focus on ameliorating the neuropsychiatric features. Here we review the rationale for current treatments related to each of the main neuropsychiatric symptoms forming the diagnostic criteria for bvFTD relevant to all FTD subtypes, and two additional symptoms not currently part of the diagnostic criteria: lack of insight and psychosis. Given the paucity of effective treatments for these symptoms, we highlight how contributing mechanisms delineated in cognitive neuroscience may inform future approaches to clinical trials and more precise symptomatic treatments for FTDs.

Validation of The Edinburgh cognitive and behavioural ALS screen (ECAS) in behavioural variant frontotemporal dementia and Alzheimer's disease

The Edinburgh Cognitive and Behavioural ALS Screen (ECAS) was developed to assess cognitive and behavioural changes in an anterior frontotemporal syndrome (executive functions, language, fluency and behaviour), common in Amyotrophic Lateral Sclerosis (ALS) and also assesses posterior cerebral dysfunction (memory and visuospatial abilities).

OBJECTIVES

To validate the ECAS in behavioural variant Frontotemporal Dementia (bvFTD) without ALS, as compared with Alzheimer's disease (AD), against comprehensive neuropsychological assessment. Compare its sensitivity to that of the Addenbrooke's Cognitive Examination (ACE-III) and investigate behavioural changes in both types of dementia.

METHODS

Retrospective study of 16 people with bvFTD (without ALS), 32 with AD, and 48 healthy controls completed the ECAS, ACE-III and extensive neuropsychological assessment.

RESULTS

The ECAS showed higher sensitivity (94%) and marginally lower specificity (96%) than the ACE-III for both the bvFTD and AD groups. The anterior composite subscore was sensitive for bvFTD (94%), and slightly less so for AD (84%), while the posterior composite subscore was sensitive for AD (97%), and less so for bvFTD (75%). All people with bvFTD that were impaired on the ECAS total and anterior composite scores were also impaired on the anterior function's tests of the neuropsychological assessment. A cut-off of four or more behavioural domains affected differentiated well between the bvFTD and AD groups, while a qualitative analysis of the behavioural interview found different themes between groups.

CONCLUSIONS

The ECAS is a valid and sensitive assessment for bvFTD without ALS and for AD. The carer behavioural interview makes it particularly suitable to detect behavioural abnormalities related to frontal lobe disorders.

The neuroscience of social feelings: mechanisms of adaptive social functioning

Social feelings have conceptual and empirical connections with affect and emotion. In this review, we discuss how they relate to cognition, emotion, behavior and well-being. We examine the functional neuroanatomy and neurobiology of social feelings and their role in adaptive social functioning. Existing neuroscience literature is reviewed to identify concepts, methods and challenges that might be addressed by social feelings research. Specific topic areas highlight the influence and modulation of social feelings on interpersonal affiliation, parent-child attachments, moral sentiments, interpersonal stressors, and emotional communication. Brain regions involved in social feelings were confirmed by meta-analysis using the Neurosynth platform for large-scale, automated synthesis of functional magnetic resonance imaging data. Words that relate specifically to social feelings were identfied as potential research variables. Topical inquiries into social media behaviors, loneliness, trauma, and social sensitivity, especially with recent physical distancing for guarding public and personal health, underscored the increasing importance of social feelings for affective and second person neuroscience research with implications for brain development, physical and mental health, and lifelong adaptive functioning.

The role of semantic memory in prospective memory and episodic future thinking: new insights from a case of semantic dementia

Prospective memory (PM), the ability to remember to execute planned actions, and episodic future thinking (EFT), the ability to imagine future personal events, are two core aspects of future-oriented cognition. The present study aimed for the first time at examining the role of semantic memory loss in PM and EFT in a single case patient (SL) at the early stage of semantic dementia.First, we investigated various types of PM as well as episodic memory of new events using a validated ecological assessment via virtual reality. Second, we examined EFT using a temporally extended version of the TEMPau task, which measures episodic aspects of remembering the past and imagining the future taking temporal distance into account.Patient SL was deficient in semantically linked event-based PM and was unable to provide any EFT for the most distant period but was preserved in other types of PM and near and intermediate EFT.These findings provide new evidence on the role of semantic memory in PM depending on the type of intention and in EFT depending on the temporal distance mirroring autobiographical memory. Finally, they point out a specific link between PM and near EFT in future-oriented cognition.

Anhedonia in Semantic Dementia-Exploring Right Hemispheric Contributions to the Loss of Pleasure

Semantic dementia (SD) is a younger-onset neurodegenerative disease characterised by progressive deterioration of the semantic knowledge base in the context of predominantly left-lateralised anterior temporal lobe (ATL) atrophy. Mounting evidence indicates the emergence of florid socioemotional changes in SD as atrophy encroaches into right temporal regions. How lateralisation of temporal lobe pathology impacts the hedonic experience in SD remains largely unknown yet has important implications for understanding socioemotional and functional impairments in this syndrome. Here, we explored how lateralisation of temporal lobe atrophy impacts anhedonia severity on the Snaith–Hamilton Pleasure Scale in 28 SD patients presenting with variable right- (SD-R) and left-predominant (SD-L) profiles of temporal lobe atrophy compared to that of 30 participants with Alzheimer’s disease and 30 healthy older Control participants. Relative to Controls, SD-R but not SD-L or Alzheimer’s patients showed clinically significant anhedonia, representing a clear departure from premorbid levels. Overall, anhedonia was more strongly associated with functional impairment on the Frontotemporal Dementia Functional Rating Scale and motivational changes on the Cambridge Behavioural Inventory in SD than in Alzheimer’s disease patients. Voxel-based morphometry analyses revealed that anhedonia severity correlated with reduced grey matter intensity in a restricted set of regions centred on right orbitofrontal and temporopolar cortices, bilateral posterior temporal cortices, as well as the anterior cingulate gyrus and parahippocampal gyrus, bilaterally. Finally, regression and mediation analysis indicated a unique role for right temporal lobe structures in modulating anhedonia in SD. Our findings suggest that degeneration of predominantly right-hemisphere structures deleteriously impacts the capacity to experience pleasure in SD. These findings offer important insights into hemispheric lateralisation of motivational disturbances in dementia and suggest that anhedonia may emerge at different timescales in the SD disease trajectory depending on the integrity of the right hemisphere.

Neural correlates of reversal learning in frontotemporal dementia

OBJECTIVE

Frontotemporal Dementia (FTD) is a neurodegenerative disorder that results in disinhibition and difficulty with flexible responding when provided feedback. Inflexible responding is observed early in the course of the illness and contributes to the financial and social morbidities of FTD. Reversal learning is an established cognitive paradigm that indexes flexible responding in the face of feedback signaling a change in reinforcement contingencies, with components of reversal learning associated with specific neurotransmitter systems. The objective of the study was to evaluate the neural mechanisms underlying impaired flexible behavioural responding in FTD using a reversal learning paradigm combined with fMRI.

METHODS

Twenty-two patients meeting the diagnostic criteria for FTD and twenty-one healthy controls completed the study. Participants completed an fMRI-adapted reversal learning task that indexes behavioural flexibility when provided positive and negative feedback.

RESULTS

Patients with FTD demonstrated poorer behavioural flexibility relative to controls and abnormal BOLD responses within the left ventrolateral prefrontal cortex to incorrect responses made during the learning phase, and during correct responses when reward contingencies were reversed. As well, patients showed decreased activity within the left dorsal lateral prefrontal cortex to incorrect responses compared to controls.

CONCLUSIONS

These findings suggest that reversal learning impairments in patients with FTD, in particular those with frontal predominant atrophy, may be related to impaired flexible motor responding when selecting among several choices and deficient attention to relevant stimuli during instances of conflict (i.e., receiving negative feedback). These results and the associated neurotransmitter systems mediating these regions may provide targets for future pharmacological or behavioural interventions mediating these cognitive deficits.

PS1 FAD mutants decrease ephrinB2-regulated angiogenic functions, ischemia-induced brain neovascularization and neuronal survival

Microvascular pathology and ischemic lesions contribute substantially to neuronal dysfunction and loss that lead to Alzheimer disease (AD). To facilitate recovery, the brain stimulates neovascularization of damaged tissue via sprouting angiogenesis, a process regulated by endothelial cell (EC) sprouting and the EphB4/ephrinB2 system. Here, we show that in cultures of brain ECs, EphB4 stimulates the VE-cadherin/Rok-α angiogenic complexes known to mediate sprouting angiogenesis. Importantly, brain EC cultures expressing PS1 FAD mutants decrease the EphB4-stimulated γ-secretase cleavage of ephrinB2 and reduce production of the angiogenic peptide ephrinB2/CTF2, the VE-cadherin angiogenic complexes and EC sprouting and tube formation. These data suggest that FAD mutants may attenuate ischemia-induced brain angiogenesis. Supporting this hypothesis, ischemia-induced VE-cadherin angiogenic complexes, levels of neoangiogenesis marker Endoglin, vascular density, and cerebral blood flow recovery, are all decreased in brains of mouse models expressing PS1 FAD mutants. Ischemia-induced brain neuronal death and cognitive deficits also increase in these mice. Furthermore, a small peptide comprising the C-terminal sequence of peptide ephrinB2/CTF2 rescues angiogenic functions of brain ECs expressing PS1 FAD mutants. Together, our data show that PS1 FAD mutations impede the EphB4/ephrinB2-mediated angiogenic functions of ECs and impair brain neovascularization, neuronal survival and cognitive recovery following ischemia. Furthermore, our data reveal a novel brain angiogenic mechanism targeted by PS1 FAD mutants and a potential therapeutic target for ischemia-induced neurodegeneration. Importantly, FAD mutant effects occur in absence of neuropathological hallmarks of AD, supporting that such hallmarks may form downstream of mutant effects on neoangiogenesis and neuronal survival.

Uncovering the prevalence and neural substrates of anhedonia in frontotemporal dementia

Much of human behaviour is motivated by the drive to experience pleasure. The capacity to envisage pleasurable outcomes and to engage in goal-directed behaviour to secure these outcomes depends upon the integrity of frontostriatal circuits in the brain. Anhedonia refers to the diminished ability to experience, and to pursue, pleasurable outcomes, and represents a prominent motivational disturbance in neuropsychiatric disorders. Despite increasing evidence of motivational disturbances in frontotemporal dementia (FTD), no study to date has explored the hedonic experience in these syndromes. Here, we present the first study to document the prevalence and neural correlates of anhedonia in FTD in comparison with Alzheimer's disease, and its potential overlap with related motivational symptoms including apathy and depression. A total of 172 participants were recruited, including 87 FTD, 34 Alzheimer's disease, and 51 healthy older control participants. Within the FTD group, 55 cases were diagnosed with clinically probable behavioural variant FTD, 24 presented with semantic dementia, and eight cases had progressive non-fluent aphasia (PNFA). Premorbid and current anhedonia was measured using the Snaith-Hamilton Pleasure Scale, while apathy was assessed using the Dimensional Apathy Scale, and depression was indexed via the Depression, Anxiety and Stress Scale. Whole-brain voxel-based morphometry analysis was used to examine associations between grey matter atrophy and levels of anhedonia, apathy, and depression in patients. Relative to controls, behavioural variant FTD and semantic dementia, but not PNFA or Alzheimer's disease, patients showed clinically significant anhedonia, representing a clear departure from pre-morbid levels. Voxel-based morphometry analyses revealed that anhedonia was associated with atrophy in an extended frontostriatal network including orbitofrontal and medial prefrontal, paracingulate and insular cortices, as well as the putamen. Although correlated on the behavioural level, the neural correlates of anhedonia were largely dissociable from that of apathy, with only a small region of overlap detected in the right orbitofrontal cortices whilst no overlapping regions were found between anhedonia and depression. This is the first study, to our knowledge, to demonstrate profound anhedonia in FTD syndromes, reflecting atrophy of predominantly frontostriatal brain regions specialized for hedonic tone. Our findings point to the importance of considering anhedonia as a primary presenting feature of behavioural variant FTD and semantic dementia, with distinct neural drivers to that of apathy or depression. Future studies will be essential to address the impact of anhedonia on everyday activities, and to inform the development of targeted interventions to improve quality of life in patients and their families.

Clinical features of behavioral symptoms in patients with semantic dementia: Does semantic dementia cause autistic traits?

Objective

To investigate the behavioral characteristics of semantic dementia (SD) using an instrument originally developed for patients with autism spectrum disorder.

Methods

The behavioral symptoms of 20 patients with SD and 20 patients with Alzheimer’s disease (AD) in both the preclinical state and the dementia state were evaluated using the Pervasive Developmental Disorders Autism Society Japan Rating Scale (PARS).

Results

The SD group showed high prevalence in four behaviors related to stereotypy and social impairment: eating very few food items, selfishness, difficulty in recognizing others’ feeling and thoughts, and interpreting language literally. Scores on the PARS short version, which is sensitive for diagnosis of autism spectrum disorder, were significantly higher in the dementia state than in the preclinical state in both the SD (11.5 ± 6.0 and 1.7 ± 2.5, respectively; t (19) = 6.7, p < 0.001) and AD (6.9 ± 4.6 and 1.7 ± 2.0, respectively; t (19) = 5.1, p < 0.001) groups. PARS short version scores after dementia onset increased in both the SD and AD groups, although the increase was significantly larger in the SD group (F = 5.6, p = 0.023). Additionally, a significantly higher rate of patients exceeded the cutoff score for autism diagnosis in the dementia state in the SD group (75%) than in the AD group (40%; χ² = 5.0, p = 0.025). PARS scores in the dementia state were significantly correlated with illness duration (r = 0.46, p = 0.04) and Mini-Mental State Examination scores (r = −0.75, p < 0.001) in the SD group only.

Conclusions

Although SD and autism spectrum disorder are etiologically distinct diseases, patients with semantic dementia behave like those with autism spectrum disorder. Our findings suggest the symptomatic similarity of the two disorders.

Effect of Instrumental Activities of Daily Living habituation due to routinising therapy in patients with frontotemporal dementia

We examined whether Instrumental Activities of Daily Living (IADL) improves with routinising therapy for a patient with frontotemporal dementia (FTD) living in a group home. The patient exhibited symptoms of agitation, apathy, disinhibition, irritability and stereotyped behaviour. The care staff experienced long-term care burden and the patient was spending time idly. An occupational therapist, in collaboration with care staff, evaluated the patient and routinised the household chores included in IADL. Consequently, a routine of household chores was established, reducing behavioural and psychological symptoms of dementia and long-term care burden, and the quality of life (QOL) of the patient improved. The results suggested that routinising IADL of the patient with FTD reduced long-term care burden and improved QOL of the patient.

Evaluating the distinction between semantic knowledge and semantic access: Evidence from semantic dementia and comprehension-impaired stroke aphasia

Theories of semantic memory based on neuropsychological findings have posited a distinction between stored semantic representations and the mechanisms used to access and manipulate them (e.g., Lambon Ralph, Jefferies, Patterson, & Rogers, 2017; Warrington & Cipolotti, 1996). The most recent instantiation of this view, the controlled semantic cognition theory (Lambon Ralph et al., 2017), is supported by findings suggesting that multimodal (i.e., both verbal and nonverbal) semantic deficits may result from qualitatively different impairments: on the one hand, damage to a semantic access mechanism related to executive control, which is observed in semantic aphasia (SA), and on the other, damage to semantic representations, which is observed in semantic dementia (SD) (Jefferies & Lambon Ralph, 2006). In this study we compared SA and SD patients on several phenomena previously used to support these distinctions. Contrary to the prior results, we found that (1) overall, cross-task consistency was equivalent for the two groups; (2) neither patient group showed consistency driven by item identity across different semantic tasks; (3) correlations among task performance were not obviously driven by the semantic control demands of different tasks; (4) both groups showed executive function deficits; and (5) both groups showed strong effects of distractor interference in a synonym judgment task. Furthermore, we investigated the components of executive ability that could underlie semantic control deficits by correlating performance on updating, shifting, and inhibition tasks with performance on tasks testing semantic abilities. We found that updating was related to semantic processing generally, whereas shifting and inhibition were not. These results also suggest that complex executive function tasks relate to semantic tasks through their shared relationship with language abilities. Overall, evidence from SA and SD patients does not differentiate representations and access mechanisms in the semantic system, as has previously been suggested. Implications for the storage-access distinction are discussed.

Progression of Behavioral Disturbances and Neuropsychiatric Symptoms in Patients With Genetic Frontotemporal Dementia

IMPORTANCE

Behavioral disturbances are core features of frontotemporal dementia (FTD); however, symptom progression across the course of disease is not well characterized in genetic FTD.

OBJECTIVE

To investigate behavioral symptom frequency and severity and their evolution and progression in different forms of genetic FTD.

DESIGN, SETTING, AND PARTICIPANTS

This longitudinal cohort study, the international Genetic FTD Initiative (GENFI), was conducted from January 30, 2012, to May 31, 2019, at 23 multicenter specialist tertiary FTD research clinics in the United Kingdom, the Netherlands, Belgium, France, Spain, Portugal, Italy, Germany, Sweden, Finland, and Canada. Participants included a consecutive sample of 232 symptomatic FTD gene variation carriers comprising 115 with variations in C9orf72, 78 in GRN, and 39 in MAPT. A total of 101 carriers had at least 1 follow-up evaluation (for a total of 400 assessments). Gene variations were included only if considered pathogenetic.

MAIN OUTCOMES AND MEASURES

Behavioral and neuropsychiatric symptoms were assessed across disease duration and evaluated from symptom onset. Hierarchical generalized linear mixed models were used to model behavioral and neuropsychiatric measures as a function of disease duration and variation.

RESULTS

Of 232 patients with FTD, 115 (49.6%) had a C9orf72 expansion (median [interquartile range (IQR)] age at evaluation, 64.3 [57.5-69.7] years; 72 men [62.6%]; 115 White patients [100%]), 78 (33.6%) had a GRN variant (median [IQR] age, 63.4 [58.3-68.8] years; 40 women [51.3%]; 77 White patients [98.7%]), and 39 (16.8%) had a MAPT variant (median [IQR] age, 56.3 [49.9-62.4] years; 25 men [64.1%]; 37 White patients [94.9%]). All core behavioral symptoms, including disinhibition, apathy, loss of empathy, perseverative behavior, and hyperorality, were highly expressed in all gene variant carriers (>50% patients), with apathy being one of the most common and severe symptoms throughout the disease course (51.7%-100% of patients). Patients with MAPT variants showed the highest frequency and severity of most behavioral symptoms, particularly disinhibition (79.3%-100% of patients) and compulsive behavior (64.3%-100% of patients), compared with C9orf72 carriers (51.7%-95.8% of patients with disinhibition and 34.5%-75.0% with compulsive behavior) and GRN carriers (38.2%-100% with disinhibition and 20.6%-100% with compulsive behavior). Alongside behavioral symptoms, neuropsychiatric symptoms were very frequently reported in patients with genetic FTD: anxiety and depression were most common in GRN carriers (23.8%-100% of patients) and MAPT carriers (26.1%-77.8% of patients); hallucinations, particularly auditory and visual, were most common in C9orf72 carriers (10.3%-54.5% of patients). Most behavioral and neuropsychiatric symptoms increased in the early-intermediate phases and plateaued in the late stages of disease, except for depression, which steadily declined in C9orf72 carriers, and depression and anxiety, which surged only in the late stages in GRN carriers.

CONCLUSIONS AND RELEVANCE

This cohort study suggests that behavioral and neuropsychiatric disturbances differ between the common FTD gene variants and have different trajectories throughout the course of disease. These findings have crucial implications for counseling patients and caregivers and for the design of disease-modifying treatment trials in genetic FTD.

Eating Behavior in Aging and Dementia: The Need for a Comprehensive Assessment

Eating behavior can change during aging due to physiological, psychological, and social changes. Modifications can occur at different levels: (1) in food choice, (2) in eating habits, and (3) in dietary intake. A good dietary behavior, like the Mediterranean dietary pattern, can be a protective factor for some aging related pathologies, such as dementia, while a worse eating behavior can lead to pathological conditions such as malnutrition. Changes in eating behavior can also be linked to the onset of dementia: for some types of dementia, such as frontotemporal dementia, dietary changes are one of the key clinical diagnostic feature, for others, like Alzheimer's disease, weight loss is a clinical reported feature. For these reasons, it is important to be able to assess eating behavior in a proper way, considering that there are normal age-related changes. An adequate assessment of dietary behavior can help to plan preventive intervention strategies for heathy aging or can help to identify abnormal behaviors that underline aging related-diseases. In this review, we have analyzed normal age-related and dementia-related changes and the tools that can be used to assess eating behavior. Thus, we make recommendations to screening and monitoring eating behavior in aging and dementia, and to adopt these tools in clinical practice.

Cognitive and Behavioral Profiles of Left and Right Semantic Dementia: Differential Diagnosis with Behavioral Variant Frontotemporal Dementia and Alzheimer's Disease

BACKGROUND

Semantic dementia (SD) is a subtype of frontotemporal dementia (FTD) characterized by semantic memory loss and preserved abilities of other cognitive functions. The clinical manifestations of SD require a differential diagnosis with Alzheimer's disease (AD), especially those with early onset, and behavioral variant FTD (bvFTD).

OBJECTIVE

The present study aimed to compare cognitive performances and neuropsychiatric symptoms in a population of AD, bvFTD, and left and right SD defined with the support of molecular imaging (amyloid and 2-[18F] fluoro-2-deoxy-D-glucose positron emission tomography) and assessed the accuracy of different neuropsychological markers in distinguishing these neurodegenerative diseases.

METHODS

Eighty-seven participants (32 AD, 20 bvFTD, and 35 SD (17 Left-SD and 18 Right-SD) completed a comprehensive neuropsychological battery that included memory, language, attention and executive functions, visuospatial function, visuoconstructional skills, and tasks designed specifically to evaluate prosopagnosia and facial emotions recognition. The Neuropsychiatric Inventory was administered to assess neuropsychiatric symptoms.

RESULTS

An episodic memory test that included semantic cues, a visuospatial test (both impaired in AD), a naming test and a prosopagnosia task (both impaired in SD) were the four most valuable cognitive metrics for the differential diagnosis between groups. Several behavioral abnormalities were differentially present, of which aggression, self-care (both more frequent in bvFTD), and eating habits, specifically overeating and altered dietary preference (more frequent in SD), were the most valuable in group discrimination.

CONCLUSION

Our study highlights the value of a comprehensive neuropsychological and neuropsychiatric evaluation for the differential diagnosis between FTD syndromes and AD.

A case study investigating the role of the anterior temporal lobes in general semantics and semantics specific to persons, emotions and social conceptual knowledge

The role of the anterior temporal lobes (ATLs) in semantic representation remains still much debated. Long thought to support domain-general semantic processing, recent accounts have alternatively suggested that they may be preferentially involved in the processing of person-related semantic knowledge. Several studies have supported such a distinction, but few have either examined both types of semantic processing together, or considered the role of potentially important confounding variables. Here, we address these issues by investigating both domain-general and person-specific semantic processing in a patient with focal ATL damage. The patient presents with dense anterograde and retrograde amnesia. Performance was impaired on tests of general semantic knowledge, but most striking deficits were for person-related semantics, including recognition and identification, knowledge of emotions and social conceptual knowledge. This unique case provides compelling evidence that, in addition to the role in general semantic knowledge, the ATLs are critical for person-related semantics.

Using a second-person approach to identify disease-specific profiles of social behavior in frontotemporal dementia and Alzheimer's disease

Changes in social behavior are recognized as potential symptoms of behavioral-variant frontotemporal dementia (bvFTD) and semantic dementia (SD), yet objective ways to assess these behaviors in natural social situations are lacking. This study takes a truly social (or second-person) approach and examines changes in real-world social behavior in different dementia syndromes, by analyzing non-scripted social interactions in bvFTD patients (n = 20) and SD patients (n = 20), compared to patients with Alzheimer's disease (AD) (n = 20). Video recordings of 10-min conversations between patients and behavioral neurologists were analyzed for the presence of socially engaging (e.g., nodding, smiling, gesturing) and disengaging behavior (e.g., avoiding eye contact, self-grooming, interrupting). Results demonstrated disease-specific profiles, with bvFTD patients showing less nodding and more looking away than AD, and SD patients showing more gesturing than AD. A principal components analysis revealed the presence of four unobserved components, showing atypical disengaging patterns of behavior. Whole-brain voxel-based morphometry analyses revealed distinct neurobiological bases for each of these components, with the brain regions identified previously associated with behavior selection, abstract mentalization and processing of multi-sensory and socially-relevant information, in mediating socially engaging and disengaging behavior. This study demonstrates the utility of systematic behavioral observation of social interactions in the differential diagnosis of dementia.

Cognitive and behavioural inhibition deficits in neurodegenerative dementias

Disinhibition, mainly caused by damage in frontotemporal brain regions, is one of the major causes of caregiver distress in neurodegenerative dementias. Behavioural inhibition deficits are usually described as a loss of social conduct and impulsivity, whereas cognitive inhibition deficits refer to impairments in the suppression of prepotent verbal responses and resistance to distractor interference. In this review, we aim to discuss inhibition deficits in neurodegenerative dementias through behavioural, cognitive, neuroanatomical and neurophysiological exploration. We also discuss impulsivity and compulsivity behaviours as related to disinhibition. We will therefore describe different tests available to assess both behavioural and cognitive disinhibition and summarise different manifestations of disinhibition across several neurodegenerative diseases (behavioural variant of frontotemporal dementia, Alzheimer's disease, Parkinson's disease, progressive supranuclear palsy, Huntington's disease). Finally, we will present the latest findings about structural, metabolic, functional, neurophysiological and also neuropathological correlates of inhibition impairments. We will briefly conclude by mentioning some of the latest pharmacological and non pharmacological treatment options available for disinhibition. Within this framework, we aim to highlight i) the current interests and limits of tests and questionnaires available to assess behavioural and cognitive inhibition in clinical practice and in clinical research; ii) the interpretation of impulsivity and compulsivity within the spectrum of inhibition deficits; and iii) the brain regions and networks involved in such behaviours.