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

BACKGROUND: Social perception refers to the ability to adapt and update one's behaviour in accordance with the current context and provides the foundation for many complex social and emotional interactions. Alterations in social cognition are a hallmark of the behavioural variant of frontotemporal dementia (bvFTD), yet the capacity for social perception in this syndrome remains unclear. METHODS: We examined social perception in 18 bvFTD and 13 Alzheimer's disease (AD) patients, in comparison with 17 healthy older controls, using a social perception task derived from the Dewey Story Test. Participants also completed a comprehensive neuropsychological battery and carers provided ratings of behavioural and neuropsychiatric changes. RESULTS: Overall, bvFTD and AD performance diverged significantly from control ratings on the social perception task, however, no significant difference was found between patient groups. Standardised values relative to the mean control rating revealed considerable variability within the patient groups in terms of the direction of deviation, i.e., over- or under-rating the vignettes relative to healthy controls (range z-scores = -1.79 to +1.63). Greater deviation from control ratings was associated with more pronounced memory (p = .007) and behavioural (p = .009) disturbances in bvFTD; whilst social perception performance correlated exclusively with verbal fluency in AD (p = .003). CONCLUSIONS: Social perception is comparably disrupted in bvFTD and AD, yet likely reflects the differential breakdown of distinct cognitive processes in each dementia syndrome. Our findings have important clinical implications for the development of targeted interventions to manage disease-specific changes in social perception in dementia.

Dementia Prevention and Individual and Socioeconomic Barriers: Avoiding "Lifestyle" Stigma.

Recent decades have seen exponential growth in research on modifiable risk factors for dementia across the lifespan, which has considerably advanced our understanding of brain health. Not all modifiable risk factors are equal, however, in the ease with which they can be addressed. Some individuals and populations face significant barriers to engaging in dementia risk-reduction behaviors. With the evolution of the dementia prevention field, there is a need to broaden our approach from identifying individual risk factors toward addressing inclusive and globally effective intervention strategies. Here, we argue for a greater awareness of individual and socioeconomic barriers to behavior change-oriented dementia risk reduction. We caution against inadvertently increasing health inequities through "lifestyle" stigma and call for an approach that both harnesses current dementia risk-reduction knowledge and effectively addresses barriers to change. A greater focus on more positive aspects of reducing dementia risk, such as enhancing mental well-being, may also be beneficial. Evidence for the negative ramifications of stigma in dementia is discussed as well as overly simplistic media representations of dementia as a disease, which one can "stave off" through lifestyle. Further, we explore potential negative implications for research funding and policy resulting from stigma. More research regarding the experience of stigma in dementia is needed, across diverse cultural and socioeconomic groups.

Testing times for dementia: a community survey identifying contemporary barriers to risk reduction and screening.

BACKGROUND: Advances in pharmacological and non-pharmacological dementia interventions may mean future dementia prevention incorporates a combination of targeted screening and lifestyle modifications. Elucidating potential barriers which may prevent community engagement with dementia prevention initiatives is important to maximise the accessibility and feasibility of these initiatives across the lifespan. METHODS: Six hundred seven adults aged over 18 years completed a 54-item, multiple-choice survey exploring contemporary attitudes towards, and barriers to, dementia risk reduction and screening relative to other common health conditions. Participants were sourced from Australia's largest, paid, data analytics service (ORIMA). RESULTS: Finances (p = .009), poor motivation (p = .043), and time (p ≤ .0001) emerged as significant perceived barriers to dementia risk reduction behaviours. Lack of time was more likely to be reported by younger, relative to older, participants (p ≤ .0001), while females were more likely than males to report financial (p = .019) and motivational (p = .043) factors. Binary logistic regression revealed willingness to undertake dementia testing modalities was significantly influenced by gender (genetic testing, p = .012; saliva, p = .038, modifiable risk factors p = .003), age (cognitive testing, p ≤ .0001; blood, p = .010), and socio-economic group (retinal imaging, p = .042; modifiable risk-factor screening, p = .019). Over 65% of respondents felt adequately informed about risk reduction for at least one non-dementia health condition, compared to 30.5% for dementia. CONCLUSIONS: This study found perceived barriers to dementia risk reduction behaviours, and the willingness to engage in various dementia testing modalities, was significantly associated with socio-demographic factors across the lifespan. These findings provide valuable insight regarding the accessibility and feasibility of potential methods for identifying those most at risk of developing dementia, as well as the need to better promote and support wide-scale engagement in dementia risk reduction behaviours across the lifespan.

What would a population-level approach to dementia risk reduction look like, and how would it work?

Dementia is a leading global public health challenge. Prevention approaches have traditionally focused on individual-level strategies. However, such approaches have limited potential, particularly for resource-constrained populations in which exposure to risk factors is greatest, and exposure to protective factors is lowest. A population-level approach to dementia risk reduction is therefore essential to meet the scale of the challenge and to tackle global inequalities in risk and incidence of disease. Such approaches can be highly cost effective. In this viewpoint article, we describe what such an approach should look like, barriers and facilitators to success, and how we should go about achieving it. We include 10 strategic goals to achieve population-level dementia risk reduction and protection enhancement, targeted at researchers, professionals, funders, science communicators, governments, businesses, and policy makers. If we are to significantly reduce the prevalence of dementia there must be increased emphasis on population-level approaches. HIGHLIGHTS: Dementia risk reduction is a global public health priority Population-level approaches change societal conditions to make them less conducive to dementia's modifiable risk factors, and increase exposure to protective factors. Urgent development of population-level approaches is required to reduce the prevalence of, and inequalities in, dementia Action is required from researchers, governments and business, funders, public health professionals, and science communicators.

Putting the Pieces Together: Mental Construction of Semantically Congruent and Incongruent Scenes in Dementia.

Scene construction refers to the process by which humans generate richly detailed and spatially cohesive scenes in the mind's eye. The cognitive processes that underwrite this capacity remain unclear, particularly when the envisaged scene calls for the integration of various types of contextual information. Here, we explored social and non-social forms of scene construction in Alzheimer's disease (AD; n = 11) and the behavioural variant of frontotemporal dementia (bvFTD; n = 15) relative to healthy older control participants (n = 16) using a novel adaptation of the scene construction task. Participants mentally constructed detailed scenes in response to scene-object cues that varied in terms of their sociality (social; non-social) and congruence (congruent; incongruent). A significant group × sociality × congruence interaction was found whereby performance on the incongruent social scene condition was significantly disrupted in both patient groups relative to controls. Moreover, bvFTD patients produced significantly less contextual detail in social relative to non-social incongruent scenes. Construction of social and non-social incongruent scenes in the patient groups combined was significantly associated with independent measures of semantic processing and visuospatial memory. Our findings demonstrate the influence of schema-incongruency on scene construction performance and reinforce the importance of episodic-semantic interactions during novel event construction.

Constructing the social world: Impaired capacity for social simulation in dementia.

Scene construction refers to the capacity to imagine richly detailed scenes in one's mind's eye and has been demonstrated to be compromised across a range of clinical disorders in which episodic memory processes are also affected. It remains unclear however, how task demands modulate the content of the to-be-simulated scenes. Here, we sought to investigate the capacity for social forms of scene construction in the behavioural-variant of frontotemporal dementia (bvFTD), a progressive neurodegenerative disorder characterised by pronounced social cognitive and executive dysfunction, alongside episodic memory impairments. Twenty bvFTD patients, 14 Alzheimer's disease (AD) patients, and 20 healthy controls completed a scene construction task involving imagining social (e.g., busy restaurant, crowded train), and non-social (e.g., forest, abandoned warehouse) scenes, as well as a comprehensive neuropsychological battery. Relative to Controls, patient groups provided significantly fewer contextual details during scene construction, irrespective of condition, with no difference between the patient groups. A significant group by condition interaction reflected the fact that bvFTD patients were disproportionately impaired on social relative to non-social scenes, whereas performance was comparable across conditions within Control and AD groups. Social construction impairments correlated with response inhibition and verbal episodic memory in bvFTD, with no such associations emerging in the AD group. A multiple regression confirmed that response inhibition and verbal episodic memory were significant predictors of social construction capacity, accounting for ~54% of the overall variance on the task. Our findings suggest that the capacity to simulate social scenes represents a special class of mental construction that relies upon a number of interacting cognitive processes, including aspects of executive function and episodic memory. How the process of social construction relates to acts of prosocial behaviour or empathy will be important for future studies to address.

Scene construction impairments in frontotemporal dementia: Evidence for a primary hippocampal contribution.

The capacity to generate naturalistic three-dimensional and spatially coherent representations of the world, i.e., scene construction, is posited to lie at the heart of a wide range of complex cognitive endeavours. Clinical populations with selective damage to key nodes of a putative scene construction network of the brain have provided important insights regarding the contribution of medial temporal and prefrontal regions in this regard. Here, we explored the capacity for atemporal scene construction, and its associated neural substrates, in the behavioural-variant of frontotemporal dementia (bvFTD); a neurodegenerative brain disorder in which atrophy systematically erodes medial and lateral prefrontal cortices with variable medial temporal lobe involvement. Nineteen bvFTD patients were compared to 18 typical Alzheimer's Disease (AD), and 25 healthy older Control participants on a scene construction task. Relative to Controls, both patient groups displayed marked impairments in generating contextually detailed and spatially coherent scenes, with bvFTD indistinguishable from AD patients across the majority of task metrics. Voxel-based morphometry, based on structural brain MRI, revealed divergent neural substrates of scene construction performance in each patient group. Despite widespread medial and lateral prefrontal atrophy, the capacity to generate richly detailed and spatially coherent scenes in bvFTD was found to rely predominantly upon the integrity of right medial temporal structures, including the hippocampus and parahippocampal gyrus. Scene construction impairments in AD, by contrast, hinged upon the integrity of posterior parietal brain regions. Our findings in bvFTD resonate with a large body of work implicating the right hippocampus in the construction of spatially integrated scene imagery. How these impairments relate to changes in autobiographical memory and prospection in bvFTD will be an important question for future studies to address.

Damage to right medial temporal structures disrupts the capacity for scene construction-a case study.

The medial temporal lobes (MTLs) are widely held to support a range of constructive endeavors including remembering the past, envisaging the future, and imagining hypothetical scenarios. While right MTL structures have been ascribed a prominent role in the construction of spatial contexts, lesion evidence to directly test this hypothesis is lacking. To this end, we assessed scene construction performance in two cases, GC and DF, who presented with left- and right-lateralized presentations of semantic dementia, respectively. GC displayed characteristic semantic processing difficulties in the context of marked left anterior and medial temporal lobe atrophy. Despite significant volume loss across the entire length of the left hippocampus, GC was capable of generating richly detailed, spatially coherent scenes, most likely reflecting the preservation of his right anterior MTL. In contrast, DF's cognitive profile was one of dense prosopagnosia, with subjectively reported gaps in autobiographical memory and wayfinding difficulties. Formal testing on the scene construction task revealed striking deficits, with DF producing impoverished descriptions of spatially fragmented scenes. We attribute DF's inability to construct spatially contiguous scenes to the degeneration of right-sided MTL structures, most prominently the right anterior hippocampus (19% volume loss) and right parahippocampal cortex (23% volume loss). Our findings complement the extant fMRI literature to suggest a fundamental role for right medial temporal regions in the construction of rich detailed spatial arrays.

Examining Rey Complex Figure Test organization in healthy adults.

INTRODUCTION: The Rey Complex Figure Test (RCFT) is a popular measure of visuospatial and executive functioning. Clinical interpretations of RCFT performance are partly based on how an individual approaches the task with piecemeal organization often considered indicative of impairment. This is despite little previous research examining RCFT organizational variability in healthy adults and considerable individual differences previously shown in processing the global and local features of visual stimuli. METHOD: Fifty-seven undergraduate university students (44 females, 13 males), aged 18 to 34 years (M = 20.14, SD = 3.29) participated in the study. Participants completed the RCFT copy trial followed by a hierarchical shape task. RCFT organization was measured using the qualitative score (Q-score). RESULTS: Extensive variation was demonstrated in the distribution of RCFT organization and global processing scores with largely nonsignificant deviation from a normal distribution (p ≤ .05). Only 53% of participants commenced the RCFT copy by completing the base rectangle using four consecutively drawn lines. The diagonals were completed using two consecutive lines by 40% of participants with only 11% doing so immediately following completion of the base rectangle. Only 32% completed the bisectors as two consecutive lines, and only 18% did so immediately following completion of the base rectangle. Global processing scores significantly predicted RCFT organization (b = 0.63, p = .006) with individuals demonstrating higher global processing on average exhibiting more organized RCFT copies than those demonstrating lower global processing. CONCLUSIONS: A sample of healthy individuals demonstrated a wide range of RCFT organizational strategies with the variation partly explained by individual differences in global/local processing.