Promising therapies for the treatment of frontotemporal dementia clinical phenotypes: from symptomatic to disease-modifying drugs

Differential diagnosis of frontotemporal dementia subtypes with explainable deep learning on structural MRI

Background

Frontotemporal dementia (FTD) represents a collection of neurobehavioral and neurocognitive syndromes that are associated with a significant degree of clinical, pathological, and genetic heterogeneity. Such heterogeneity hinders the identification of effective biomarkers, preventing effective targeted recruitment of participants in clinical trials for developing potential interventions and treatments. In the present study, we aim to automatically differentiate patients with three clinical phenotypes of FTD, behavioral-variant FTD (bvFTD), semantic variant PPA (svPPA), and nonfluent variant PPA (nfvPPA), based on their structural MRI by training a deep neural network (DNN).

Methods

Data from 277 FTD patients (173 bvFTD, 63 nfvPPA, and 41 svPPA) recruited from two multi-site neuroimaging datasets: the Frontotemporal Lobar Degeneration Neuroimaging Initiative and the ARTFL-LEFFTDS Longitudinal Frontotemporal Lobar Degeneration databases. Raw T1-weighted MRI data were preprocessed and parcellated into patch-based ROIs, with cortical thickness and volume features extracted and harmonized to control the confounding effects of sex, age, total intracranial volume, cohort, and scanner difference. A multi-type parallel feature embedding framework was trained to classify three FTD subtypes with a weighted cross-entropy loss function used to account for unbalanced sample sizes. Feature visualization was achieved through post-hoc analysis using an integrated gradient approach.

Results

The proposed differential diagnosis framework achieved a mean balanced accuracy of 0.80 for bvFTD, 0.82 for nfvPPA, 0.89 for svPPA, and an overall balanced accuracy of 0.84. Feature importance maps showed more localized differential patterns among different FTD subtypes compared to groupwise statistical mapping.

Conclusion

In this study, we demonstrated the efficiency and effectiveness of using explainable deep-learning-based parallel feature embedding and visualization framework on MRI-derived multi-type structural patterns to differentiate three clinically defined subphenotypes of FTD: bvFTD, nfvPPA, and svPPA, which could help with the identification of at-risk populations for early and precise diagnosis for intervention planning.

A caregiver's perspective on clinically relevant symptoms in behavioural variant frontotemporal dementia: tools for disease management and trial design

BACKGROUND

Adequate detection of symptoms and disease progression in behavioural variant frontotemporal dementia (bvFTD) is complex. Dementia cohorts usually utilize cognitive and functional measures, which fail to detect dominant behavioural and social cognitive deficits in bvFTD. Moreover, since patients typically have a loss of insight, caregivers are important informants. This is the first qualitative study to investigate caregiver relevant symptoms during the disease course of bvFTD, aiming to improve tools for diagnosis, progression, and future clinical trials.

METHODS

Informal caregivers of patients in different disease stages of bvFTD (N = 20) were recruited from the neurology outpatient clinic of the Amsterdam UMC and a patient organization for peer support in the Netherlands. Their perspectives on clinical relevance were thoroughly explored during individual semi-structured interviews. Inductive content analysis with open coding was performed by two researchers independently to establish overarching themes and patterns.

RESULTS

Caregivers reported a variety of symptoms, in which (i) loss of emotional connection, (ii) preoccupation and restlessness, and (iii) apathy and dependency compose major themes of relevance for diagnosis and treatment. Within heterogeneous disease trajectories, symptom presence differed between stages and among individuals, which is relevant in the context of progression and outcome measures. Significant socio-emotional changes dominated in early stages, while severe cognitive, behavioural, and physical deterioration shifted focus from predominant personality change to quality of life in later stages.

CONCLUSIONS

Caregiver perspectives on target symptoms in bvFTD differ according to clinical stage and patient-caregiver characteristics, with significant socio-emotional changes characterizing early stages. These findings call for more appropriate tools and symptomatic treatments, as well as a personalized approach in treatment of bvFTD and a focus on early stage interventions in clinical trial design.

Functional Disabilities and Psychiatric Symptoms in Primary Progressive Aphasia

OBJECTIVE

The aims of this study are to describe the chronology of functional disabilities in primary progressive aphasia (PPA), and to examine associations between psychiatric comorbidities and functional disabilities.

METHODS

We conducted a retrospective data analysis using subjects enrolled at Alzheimer's Disease Research Centers between 2005 and 2019. Data were obtained from the National Alzheimer's Coordinating Center database. We included subjects whose primary diagnosis was PPA. Functional status was coded as a binary variable for the following functions: ambulation, transaction skills, verbal communication, meal preparation, and self-care. Behavioral data derived from the Neuropsychiatric Inventory Questionnaire. Descriptive statistics and cox proportional hazard analyses were used to characterize the emergence of disabilities and their association with psychiatric comorbidities.

RESULTS

Data included 91 subjects with a clinical dementia rating scale of zero at baseline. At the initial visit, no individuals had impairments in self-care, while 7% had impairments in transactions, 3% in ambulation, and 2% in meal preparation. Ninety-three percent had language impairments at the onset of the study, and all by visit 4. By visit 5, 41% of patients had impairments in ambulation and in self-care, 49% were impaired in meal preparation and 70% had impairment in transactions. The presence of anxiety, depression, sleep disturbance and psychosis were all significantly associated with an increased risk for multiple functional disabilities.

CONCLUSION

These findings provide clinicians with guidance for forecasting disabilities and targeting interventions in PPA.

New insights and therapeutic opportunities for progranulin-deficient frontotemporal dementia

Frontotemporal dementia (FTD) is the second most common form of dementia. It affects the frontal and temporal lobes of the brain and has a highly heterogeneous clinical representation with patients presenting with a wide range of behavioral, language, and executive dysfunctions. Etiology of FTD is complex and consists of both familial and sporadic cases. Heterozygous mutations in the GRN gene, resulting in GRN haploinsufficiency, cause progranulin (PGRN)-deficient FTD characterized with cytoplasmic mislocalization of TAR DNA-binding protein 43 kDa (TDP-43) aggregates. GRN codes for PGRN, a secreted protein that is also localized in the endolysosomes and plays a critical role in regulating lysosomal homeostasis. How PGRN deficiency modulates immunity and causes TDP-43 pathology and FTD-related neurodegeneration remains an active area of intense investigation. In the current review, we discuss some of the significant progress made in the past two years that links PGRN deficiency with microglial-associated neuroinflammation, TDP-43 pathology, and lysosomal dysfunction. We also review the opportunities and challenges toward developing therapies and biomarkers to treat PGRN-deficient FTD.

Treatment of the behavioral variant of frontotemporal dementia: a narrative review

Frontotemporal dementia (FTD) is a progressive neurodegenerative disorder accompanied by behavioral and personality changes and/or language deterioration. Its behavioral variant (bvFTD) is the main clinical presentation.

Objective

This study aims to investigate the treatment alternatives for bvFTD available so far.

Methods

We conducted a narrative review of bvFTD treatment options. We used PubMed and Lilacs databases with the terms "frontotemporal dementia" or "behavioral variant frontotemporal dementia" combined with "treatment," "pharmacological treatment," or "disease-modifying drugs."

Results

The articles retrieved and selected in the research pointed out that there is no specific treatment approved for bvFTD so far. The current proposals are limited to handle the cardinal behavioral symptoms of the disorder. Disease-modifying drugs are under development and may be promising, especially in the monogenic presentations of FTD.

Conclusions

There are numerous approaches to treat the core symptoms of bvFTD, most of them based on low-quality research. To date, there are no drugs with a disease-specific therapeutic recommendation for bvFTD. Treatments are often investigated guided by primary psychiatric disorders with similar symptoms and should be chosen by the predominant symptom profile.

Sensitivity of arterial Spin labeling for characterization of longitudinal perfusion changes in Frontotemporal dementia and related disorders

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This study demonstrates the value of ASL for longitudinal monitoring of perfusion in FTD patients.

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Good agreement was found in repeat measures of CBF in patients and controls.

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Transit times were not a significant source of error for the selected post labeling delay (2 s).

Background

Advances in the understanding of the pathophysiology of frontotemporal dementia (FTD) and related disorders, along with the development of novel candidate disease modifying treatments, have stimulated the need for tools to assess the efficacy of new therapies. While perfusion imaging by arterial spin labeling (ASL) is an attractive approach for longitudinal imaging biomarkers of neurodegeneration, sources of variability between sessions including arterial transit times (ATT) and fluctuations in resting perfusion can reduce its sensitivity. Establishing the magnitude of perfusion changes that can be reliably detected is necessary to delineate longitudinal perfusion changes related to disease processes from the effects of these sources of error.

Purpose

To assess the feasibility of ASL for longitudinal monitoring of patients with FTD by quantifying between-session variability of perfusion on a voxel-by-voxel basis.

Methods and materials

ASL data were collected in 13 healthy controls and 8 patients with FTD or progressive supra-nuclear palsy. Variability in cerebral blood flow (CBF) by single delay pseudo-continuous ASL (SD-pCASL) acquired one month apart were quantified by the coefficient of variation (CV) and intraclass correlation coefficient (ICC). Additionally, CBF by SD-pCASL and ATT by low-resolution multiple inversion time ASL (LowRes-pCASL) were compared to Hadamard encoded sequences which are able to simultaneously measure CBF and ATT with improved time-efficiency.

Results

Agreement of grey-matter perfusion between sessions was found for both patients and controls (CV = 10.8% and 8.3% respectively) with good reliability for both groups (ICC > 0.6). Intensity normalization to remove day-to-day fluctuations in resting perfusion reduced the CV by 28%. Less than 5% of voxels had ATTs above the chosen post labelling delay (2 s), indicating that the ATT was not a significant source of error. Hadamard-encoded perfusion imaging yielded systematically higher CBF compared to SD-pCASL, but produced similar transit-time measurements. Power analysis revealed that SD-pCASL has the sensitivity to detect longitudinal changes as low as 10% with as few as 10 patient participants.

Conclusion

With the appropriate labeling parameters, SD-pCASL is a promising approach for assessing longitudinal changes in CBF associated with FTD.

Agitation and Dementia: Prevention and Treatment Strategies in Acute and Chronic Conditions

Agitation is a behavioral syndrome characterized by increased, often undirected, motor activity, restlessness, aggressiveness, and emotional distress. According to several observations, agitation prevalence ranges from 30 to 50% in Alzheimer's disease, 30% in dementia with Lewy bodies, 40% in frontotemporal dementia, and 40% in vascular dementia (VaD). With an overall prevalence of about 30%, agitation is the third most common neuropsychiatric symptoms (NPS) in dementia, after apathy and depression, and it is even more frequent (80%) in residents of nursing homes. The pathophysiological mechanism underlying agitation is represented by a frontal lobe dysfunction, mostly involving the anterior cingulate cortex (ACC) and the orbitofrontal cortex (OFC), respectively, meaningful in selecting the salient stimuli and subsequent decision-making and behavioral reactions. Furthermore, increased sensitivity to noradrenergic signaling has been observed, possibly due to a frontal lobe up-regulation of adrenergic receptors, as a reaction to the depletion of noradrenergic neurons within the locus coeruleus (LC). Indeed, LC neurons mainly project toward the OFC and ACC. These observations may explain the abnormal reactivity to weak stimuli and the global arousal found in many patients who have dementia. Furthermore, agitation can be precipitated by several factors, e.g., the sunset or low lighted environments as in the sundown syndrome, hospitalization, the admission to nursing residencies, or changes in pharmacological regimens. In recent days, the global pandemic has increased agitation incidence among dementia patients and generated higher distress levels in patients and caregivers. Hence, given the increasing presence of this condition and its related burden on society and the health system, the present point of view aims at providing an extensive guide to facilitate the identification, prevention, and management of acute and chronic agitation in dementia patients.

Social and leisure activity are associated with attenuated cortical loss in behavioral variant frontotemporal degeneration

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Social and leisure activity may contribute to mitigation of cortical loss in bvFTD.

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This relationship was found in regions important for social cognition.

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Findings provide new evidence in burgeoning non-AD cognitive reserve literature.

Behavioral variant frontotemporal degeneration (bvFTD) is clinically characterized by progressive decline in social and executive domains. Previous work suggests that early lifestyle factors such as education and occupational attainment may relate to structural integrity and moderate the rate of cognitive decline in bvFTD, but the role of other cognitively stimulating activities is understudied. We sought to investigate the effect of such activities on cortical thickness (CT) in bvFTD. bvFTD patients (n = 31) completed a baseline MRI scan, and informants for the patients completed the Lifetime of Experiences Questionnaire (LEQ), which measures specific activities considered to be undertaken primarily within one particular life phase, such as education (young-life), occupation (mid-life), and social/leisure activity (late-life). At baseline, linear models assessed the effect of LEQ scores from each life phase on regional CT. A subset (n = 19) of patients completed longitudinal MRI, and to evaluate the association of LEQ with longitudinal rates of CT decline, we derived individualized slopes of decline using linear mixed effects models and these were related to LEQ scores from each life phase. At baseline, a higher late-life LEQ score was associated with less atrophy in left superior and inferior anterior temporal regions as well as right middle temporal gyrus. Longitudinally, we observed that higher late-life LEQ scores were associated with an attenuated rate of CT loss in insular cortex. Late-life LEQ score was positively associated with both relatively preserved CT early in bvFTD and a slower rate of cortical loss in regions important for social functioning. These findings suggest that social and leisure activities may contribute to a form of resilience against pathologic effects of disease.

A Clinicopathologic Study of Movement Disorders in Frontotemporal Lobar Degeneration

BACKGROUND

Despite the considerable overlap with atypical parkinsonism, a systematic characterization of the movement disorders associated with frontotemporal lobar degeneration (FTLD) is lacking.

OBJECTIVE

The aim of this study is to provide a detailed description of the phenomenology and neuropathologic correlations of movement disorders in FTLD.

METHODS

In this cohort study, movement disorder clinical data were retrospectively collected from medical records of consecutive patients with a postmortem diagnosis of FTLD from the Queen Square Brain Bank between January 2010 and December 2018. At postmortem, neurodegenerative pathologies were systematically evaluated following consensus criteria. Degeneration of the substantia nigra was assessed as a marker of presynaptic dopaminergic parkinsonism using semiquantitative methods.

RESULTS

A total of 55 patients (35 men [64%]) were included with median (interquartile range) age at diagnosis of 58.8 (52.6-63.9) years and a disease duration of 9.6 (6.2-12.9) years. Movement disorders were present in 19 (35%) patients without differences among disease subtypes. The most common syndromes were parkinsonism (9 patients [16%]), usually as an additional late feature, and corticobasal syndrome (CBS, 7 patients [13%]), commonly as a presenting feature. Substantia nigra degeneration was present in 37 (67%) patients although it did not show a good clinical correlation with movement disorders. Those with Pick's disease showed milder substantia nigra degeneration and better response to levodopa.

CONCLUSIONS

Movement disorders can present in all FTLD subtypes, more commonly as a late additional feature (parkinsonism) or as a presenting symptom (CBS). The underlying pathophysiology is complex and likely to involve structures outside the presynaptic striatonigral system. © 2020 International Parkinson and Movement Disorder Society.

[Speech disorders in neurodegenerative diseases as dysphasia manifestation]

OBJECTIVE

To develop the classification and methodology for assessment of speech disorders in neurodegenerative diseases, and to identify the characteristics of speech disorders for various forms.

MATERIALS AND METHODS

The study included 1016 patients with neurodegenerative diseases. Screening assessment identified 42.1% patients with speech disorders exceeding isolated dysarthria. Patients were assessed using the speech disorder test battery developed by the authors. Cluster, multifactor and contingency analyses were performed.

RESULTS

Nine subtypes of speech disorders were identified in neurodegenerative diseases that we denominated as dysphasia. Based on contingency analysis, the principal and the additional dysphasia variants were identified for each form of neurodegenerative pathology, which may contribute to better understanding of various phenotypes. Based on the general scheme of speech origination, the level of disorders typical for a given dysphasia subtype was identified.

CONCLUSION

The proposed classification enables identification of the subtypes of speech disorders for individual forms of neurodegenerative diseases. Introducing dysphasia concept to clinical practice will improve differential diagnosis and understanding of phenotypical heterogeneity of each nosological form as well as will facilitate therapy optimization.

Crossing Borders Between Frontotemporal Dementia and Psychiatric Disorders: An Updated Overview

Frontotemporal dementia (FTD) includes a group of neurocognitive syndromes, clinically characterized by altered behaviors, impairment of language proficiency, and altered executive functioning. FTD is one of the most frequently observed forms of dementia in the elderly population and the most common in presenile age. As for other subtypes of dementia, FTD incidence is constantly on the rise due to the steadily increasing age of the population, and its recognition is now becoming a determinant for clinicians. FTD and psychiatric disorders can overlap in terms of clinical presentations by sharing a common genetic predisposition and neuropathological mechanism in some cases. Nonetheless, this association is often unclear and underestimated. Since its first reports, research into FTD has constantly grown, with the identification of recent findings related to its neuropathology, genetic, clinical, and therapeutic issues. Literature is thriving on this topic, with numerous research articles published in recent years. In the present review, we aimed to provide an updated description of the clinical manifestations that link and potentially confound the diagnosis of FTD and psychiatric disorders in order to improve their differential diagnosis and early detection. In particular, we systematically reviewed the literature, considering articles specifically focused on the behavioral variant FTD, published after 2015 on the PubMed database.

Fronto-temporal dementia: a case study and strategies and support for caregivers

Fronto-temporal dementia, also known as fronto-temporal lobular degeneration, is the second most common form of early-onset dementia with a prevalence equal to Alzheimer's dementia. Behavioural variant fronto-temporal dementia primarily involves the frontal and temporal lobes of the brain. Myelination of nerve fibres in these areas allow for highly synchronized action potential timing. Diagnosis is often significantly delayed because symptoms are insidious and appear as personality and behavioural changes such as lack of inhibition, apathy, depression, and being socially inappropriate rather than exhibiting marked memory reductions. In this article, a case study illustrates care strategies and family education. Management of severe behavioural symptoms requires careful evaluation and monitoring. Support is especially important and beneficial in the early to middle stages of dementia when nursing home placement may not be required based on the individual's condition.