Distinguishing Frontotemporal Dementia From Alzheimer Disease Through Everyday Function Profiles: Trajectories of Change

Frontotemporal dementia. How to deal with its diagnostic complexity?

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

The graded multidimensional geometry of phenotypic variation and progression in neurodegenerative syndromes

Clinical variants of Alzheimer's disease and frontotemporal lobar degeneration display a spectrum of cognitive-behavioural changes varying between individuals and over time. Understanding the landscape of these graded individual/group level longitudinal variations is critical for precise phenotyping; however, this remains challenging to model. Addressing this challenge, we leverage the National Alzheimer's Coordinating Center database to derive a unified geometric framework of graded longitudinal phenotypic variation in Alzheimer's disease and frontotemporal lobar degeneration. We included three time point, cognitive-behavioural and clinical data from 390 typical, atypical and intermediate Alzheimer's disease and frontotemporal lobar degeneration variants (114 typical Alzheimer's disease; 107 behavioural variant frontotemporal dementia; 42 motor variants of frontotemporal lobar degeneration; and 103 primary progressive aphasia patients). On these data, we applied advanced data-science approaches to derive low-dimensional geometric spaces capturing core features underpinning clinical progression of Alzheimer's disease and frontotemporal lobar degeneration syndromes. To do so, we first used principal component analysis to derive six axes of graded longitudinal phenotypic variation capturing patient-specific movement along and across these axes. Then, we distilled these axes into a visualizable 2D manifold of longitudinal phenotypic variation using Uniform Manifold Approximation and Projection. Both geometries together enabled the assimilation and interrelation of paradigmatic and mixed cases, capturing dynamic individual trajectories and linking syndromic variability to neuropathology and key clinical end points, such as survival. Through these low-dimensional geometries, we show that (i) specific syndromes (Alzheimer's disease and primary progressive aphasia) converge over time into a de-differentiated pooled phenotype, while others (frontotemporal dementia variants) diverge to look different from this generic phenotype; (ii) phenotypic diversification is predicted by simultaneous progression along multiple axes, varying in a graded manner between individuals and syndromes; and (iii) movement along specific principal axes predicts survival at 36 months in a syndrome-specific manner and in individual pathological groupings. The resultant mapping of dynamics underlying cognitive-behavioural evolution potentially holds paradigm-changing implications to predicting phenotypic diversification and phenotype-neurobiological mapping in Alzheimer's disease and frontotemporal lobar degeneration.

Neurodegenerative Disorders in Criminal Offending and Cognitive Decline Among Aging Inmates

Dementia, including Alzheimer's disease (AD) and frontotemporal dementia (FTD), presents critical challenges for correctional systems, particularly as global populations age. AD, affecting 60-80% of dementia cases, primarily impairs memory and cognition in individuals over 65. In contrast, FTD, rarer than AD but not uncommon in those under 65, affects the frontal and temporal brain regions, leading to deficits in social behavior, language, and impulse control, often resulting in antisocial actions and legal consequences. Behavioral variant FTD is especially associated with socially inappropriate and impulsive behaviors due to frontal lobe degeneration. The prevalence of cognitive impairment in incarcerated populations is high, exacerbated by prison environments that compound distress and limited access to specialized healthcare. Studies indicate that up to 11% of United States state prison inmates over the age of 55 exhibit cognitive impairments, often undiagnosed, resulting in punitive rather than rehabilitative responses to symptoms like disinhibition and aggression. Ethical concerns around criminal responsibility for individuals with dementia are increasingly prominent, particularly regarding their ability to comprehend and engage in legal proceedings. The growing elderly prison population necessitates reform in correctional healthcare to include early cognitive assessment, targeted intervention, and tailored post-release programs. Addressing these needs is essential to ensure appropriate treatments, alleviate healthcare demands, and support reintegration for cognitively impaired inmates.

The Potential of Automated Assessment of Cognitive Function Using Non-Neuroimaging Data: A Systematic Review

Background/Objectives: The growing incidence of cognitive impairment among older adults has a significant impact on individuals, family members, caregivers, and society. Current conventional cognitive assessment tools are faced with some limitations. Recent evidence suggests that automating cognitive assessment holds promise, potentially resulting in earlier diagnosis, timely intervention, improved patient outcomes, and higher chances of response to treatment. Despite the advantages of automated assessment and technological advancements, automated cognitive assessment has yet to gain widespread use, especially in low and lower middle-income countries. This review highlights the potential of automated cognitive assessment tools and presents an overview of existing tools. Methods: This review includes 87 studies carried out with non-neuroimaging data alongside their performance metrics. Results: The identified articles automated the cognitive assessment process and were grouped into five categories either based on the tools' design or the data analysis approach. These categories include game-based, digital versions of conventional tools, original computerized tests and batteries, virtual reality/wearable sensors/smart home technologies, and artificial intelligence-based (AI-based) tools. These categories are further explained, and evaluation of their strengths and limitations is discussed to strengthen their adoption in clinical practice. Conclusions: The comparative metrics of both conventional and automated approaches of assessment suggest that the automated approach is a strong alternative to the conventional approach. Additionally, the results of the review show that the use of automated assessment tools is more prominent in countries ranked as high-income and upper middle-income countries. This trend merits further social and economic studies to understand the impact of this global reality.

Longitudinal changes in functional capacity in frontotemporal dementia and Alzheimer's disease

INTRODUCTION

This study investigated the changes in functional capacity with disease progression in a well-characterised cohort of patients diagnosed with frontotemporal dementia (FTD) and Alzheimer's disease (AD) presentations.

METHODS

We recruited 126 behavioural variant FTD (bvFTD), 40 progressive nonfluent aphasia (PNFA), 64 semantic dementia (SD), 45 logopenic progressive aphasia (LPA), and 115 AD patients. Functional capacity was measured annually over ∼7 years using the Disability Assessment for Dementia.

RESULTS

Linear mixed effects models revealed the bvFTD group demonstrated disproportionate functional impairment at baseline and over the study period. Functional capacity among the other syndromes showed a more uniform pattern of decline, with less severe functional impairment at baseline and ∼7%-10% mean annual decline. Baseline correlations indicated different mechanisms supporting basic and complex functional proficiency among the groups.

DISCUSSION

Our findings demonstrate distinct functional profiles across dementia syndromes with disease progression. Identifying progression milestones across syndromes will improve clinical management.

Highlights

bvFTD shows severe functional impairment at baseline and over time.PNFA, SD, LPA, AD: less severe baseline functional impairment; more uniform decline.General cognition is related to IADLs, but not BADLs, in all groups.Behavioural disturbances relate to IADLs and BADLs in bvFTD and SD.Behavioural-ADL relations are more mixed in PNFA, LPA, and AD.

The pursuit for markers of disease progression in behavioral variant frontotemporal dementia: a scoping review to optimize outcome measures for clinical trials

Behavioral variant frontotemporal dementia (bvFTD) is a neurodegenerative disorder characterized by diverse and prominent changes in behavior and personality. One of the greatest challenges in bvFTD is to capture, measure and predict its disease progression, due to clinical, pathological and genetic heterogeneity. Availability of reliable outcome measures is pivotal for future clinical trials and disease monitoring. Detection of change should be objective, clinically meaningful and easily assessed, preferably associated with a biological process. The purpose of this scoping review is to examine the status of longitudinal studies in bvFTD, evaluate current assessment tools and propose potential progression markers. A systematic literature search (in PubMed and Embase.com) was performed. Literature on disease trajectories and longitudinal validity of frequently-used measures was organized in five domains: global functioning, behavior, (social) cognition, neuroimaging and fluid biomarkers. Evaluating current longitudinal data, we propose an adaptive battery, combining a set of sensitive clinical, neuroimaging and fluid markers, adjusted for genetic and sporadic variants, for adequate detection of disease progression in bvFTD.

Gaps in clinical research in frontotemporal dementia: A call for diversity and disparities-focused research

Frontotemporal dementia (FTD) is one of the leading causes of dementia before age 65 and often manifests as abnormal behavior (in behavioral variant FTD) or language impairment (in primary progressive aphasia). FTD's exact clinical presentation varies by culture, language, education, social norms, and other socioeconomic factors; current research and clinical practice, however, is mainly based on studies conducted in North America and Western Europe. Changes in diagnostic criteria and procedures as well as new or adapted cognitive tests are likely needed to take into consideration global diversity. This perspective paper by two professional interest areas of the Alzheimer's Association International Society to Advance Alzheimer's Research and Treatment examines how increasing global diversity impacts the clinical presentation, screening, assessment, and diagnosis of FTD and its treatment and care. It subsequently provides recommendations to address immediate needs to advance global FTD research and clinical practice.

The cognitive and behavioral correlates of functional status in patients with frontotemporal dementia: A pilot study

Objective: Frontotemporal dementia (FTD) impinges significantly on cognition, behavior, and everyday functioning. Goal of the present study is the detailed description of behavioral disturbances and functional limitations, as well as the investigation of associations between cognition, behavior, and functional impairment among FTD patients. Given the importance of maintaining a satisfying functional status as long as possible, this study also aims to identify the cognitive correlates of compensatory strategy use in this clinical group. Methods: A total of 13 patients diagnosed with FTD (behavioral variant FTD = 9, non-fluent variant primary progressive aphasia = 3, semantic dementia = 1) were administrated a broad range of neuropsychological tests for the assessment of different cognitive abilities. Behavioral symptomatology and performance on everyday activities were rated with informant-based measures. Descriptive statistics were used for the delineation of behavioral and functional patterns, whereas stepwise multiple regression analyses were performed to identify associations between cognition, behavior, and functional status. Results: Negative symptoms, especially apathy, were found to predominate in the behavior of FTD patients. Instrumental tasks, such as housework and leisure activities, appeared to be the most impaired functional domains. Working memory was the strongest cognitive correlate of performance across various domains of everyday functioning, whereas working memory along with short-term verbal memory accounted for a great proportion of variance in compensatory strategy use. Behavioral disturbances and especially negative symptoms were also found to contribute significantly to functional impairment in FTD. Conclusions: Executive dysfunction, as well as behavioral disturbances contribute significantly to functional disability in FTD. Early interventions tailored at these domains may have the potential to improve functional outcomes and delay the rate of functional decline among FTD patients.