Predicting Development of Amyotrophic Lateral Sclerosis in Frontotemporal Dementia

C9orf72 repeat expansions modify risk for secondary motor and cognitive-behavioral symptoms in behavioral-variant frontotemporal degeneration and amyotrophic lateral sclerosis

In behavioral-variant frontotemporal degeneration (bvFTD) and amyotrophic lateral sclerosis (ALS), the presence of secondary motor or cognitive-behavioral symptoms, respectively, is associated with shorter survival. However, factors influencing the risk and hazard of secondary symptom development remain largely unexplored. We performed a retrospective evaluation of the entire disease course of individuals with amyotrophic lateral sclerosis (n=172) and behavioral-variant frontotemporal degeneration (n=69). Only individuals who had neuropathological confirmation of a TDP-43 proteinopathy at autopsy or had a C9orf72 repeat expansion were included for analysis. We examined the odds and hazard of secondary symptom development and assessed whether they were modified by the presence of a C9orf72 repeat expansion or initial clinical syndrome. Binary logistic regression and Cox proportional hazard analyses revealed increased odds (OR=4.25 [1.97-9.14]; p<0.001) and an increased hazard (HR= 4.77 [2.33-9.79], p<0.001) for developing secondary symptoms in C9orf72 expansion carriers compared to noncarriers. Initial clinical syndrome (bvFTD or ALS), age at symptom onset, and sex were not associated with development of secondary motor or cognitive-behavioral symptoms. These findings highlight the need for clinician vigilance to detect the onset of secondary motor symptoms and cognitive-behavioral in patients carrying a C9orf72 repeat expansion, regardless of initial clinical syndrome, and may warrant dual referrals between cognitive and neuromuscular clinics in these cases.

Behavioural Variant Frontotemporal Dementia due to CCNF Gene Mutation: A Case Report

BACKGROUND

Frontal, temporal lobe dementia (FTD) and amyotrophic lateral sclerosis (ALS) are fatal neurodegenerative diseases. Studies have found that CCNF mutations have been found in patients with familial and sporadic ALS and FTD. Behavioural variant frontotemporal dementia (bvFTD) is a clinical syndrome characterized by progressive deterioration of personality, social behaviour, and cognitive function, which is most closely related to genetic factors. As the early symptoms of bvFTD are highly heterogeneous, the condition is often misdiagnosed as Alzheimer's disease or psychiatric disorders. In this study, a bvFTD patient had a CCNF gene mutation, which led to ubiquitinated protein accumulation and ultimately caused neurodegenerative disease. Genetic detection should be improved urgently for bvFTD patients and family members to provide a clinical reference for early diagnosis of frontotemporal dementia.

CASE PRESENTATION

In this case, the patient was 65 years old with an insidious onset, early-onset memory loss, a significant decline in the episodic memory, an early AD diagnosis, and oral treatment with donepezil hydrochloride for 3 years with poor efficacy, followed by a change to oral memantine hydrochloride tablets, which controlled the condition for several months. His medication was switched to sodium oligomannate capsules, and his condition was gradually controlled, but no significant improvement was observed. After spontaneous drug withdrawal, the patient's condition progressed rapidly; therefore, he visited our hospital and underwent neuropsychological tests for moderate to severe cognitive impairment. AD cerebrospinal fluid markers showed no significant abnormalities, and cranial MRI revealed frontotemporal lobe atrophy and decreased hippocampal volume. Genetic testing for the presence of the CCNF gene revealed a c.1532C > A (p. T511N) heterozygous variant, which might be a diagnostic criterion for bvFTD. Therefore, the patient's symptoms recurred after transient improvement with the combination of donepezil, oral memantine hydrochloride tablets, and sodium oligomannate, but his overall condition was improved compared to that before, and this treatment regimen was continued to observe changes during the follow-up.

CONCLUSION

The early clinical manifestations of bvFTD are complex and variable, and the condition is easily misdiagnosed, thus delaying treatment. Therefore, for patients with a high clinical suspicion of FTD, in addition to a detailed understanding of their medical history and family history and improvement of relevant examinations, genetic testing should be performed as early as possible to help confirm the diagnosis. For diseases closely related to genes, genetic testing of other family members should be optimised as much as possible to allow early diagnosis and intervention and guide fertility in the next generation.

Distinct disease trajectories in frontotemporal dementia-motor neuron disease and behavioural variant frontotemporal dementia: A longitudinal study

BACKGROUND AND PURPOSE

The heterogeneity of cognitive and behavioural disturbances in frontotemporal dementia-motor neuron disease (FTD-MND), and clinical differences between FTD-MND and FTD subtypes, have been illustrated cross-sectionally. This study aimed to examine the FTD-MND disease trajectory by comparing clinical features of FTD-MND and the behavioural variant FTD (bvFTD) longitudinally.

METHODS

Neuropsychological and disease severity assessments were conducted in a cohort of FTD-MND (baseline, n = 42; follow-up, n = 18) and bvFTD (baseline, n = 116; follow-up, n = 111) using a longitudinal, case-control design. Age-, sex-, and education-matched controls (n = 52) were recruited. Predictors of clinical progression were analyzed. Voxel-based morphometry analysis was undertaken to investigate the progression of brain atrophy.

RESULTS

At baseline, FTD-MND was characterized by semantic and general cognition deficits, whereas bvFTD had greater behavioural disturbances. General cognition and language deteriorated in FTD-MND when followed longitudinally. Language deficits at baseline predicted cognitive deterioration and disease progression and correlated with progressive atrophy of language regions. Further deterioration in behaviour was evident in bvFTD over time. The rate of disease progression (i.e., general cognition, semantic association, and disease severity) was significantly faster in FTD-MND than in bvFTD.

CONCLUSIONS

FTD-MND and bvFTD appear to have distinct disease trajectories, with more rapid progression in FTD-MND. Language impairments should be closely monitored in FTD-MND as potential predictors of cognitive deterioration and disease progression.

ANXA11 mutations are associated with amyotrophic lateral sclerosis–frontotemporal dementia

Background

The Annexin A11 (ANXA11) gene has been newly identified as a causative gene of amyotrophic lateral sclerosis (ALS) with or without frontotemporal dementia (FTD). The current study aimed to investigate the ANXA11 mutations in a Chinese ALS–FTD or FTD cohort.

Methods

We included ten probands/patients with suspected ALS–FTD or FTD. Mutational analysis of ANXA11 was performed through Next Generation Sequencing (NGS) and Sanger sequencing. We collected and reviewed clinical presentation, neuropsychology test results, brain-imaging findings, and electrophysiological examination findings.

Results

In total, six probands presented with ALS–FTD, and four with behavior variant FTD (bv-FTD). We identified a non-synonymous heterozygous mutation (c.119A>G, p.D40G) of ANXA11 in proband 1, which is associated with ALS. However, this is the first report of the mutation causing ALS–FTD. Proband 1 started with abnormal behavior and progressed to classic upper motor nervous disease. Magnetic resonance imaging (MRI) showed significant bilateral temporal lobe atrophy and bilateral hyperintensities along the corticospinal tracts.18F-AV45-PET imaging showed negative amyloid deposits.

Conclusion

ANXA11-related diseases have high clinical and genetic heterogeneity. Our study confirmed the contribution of ANXA11 mutations to ALS–FTD. The ANXA11 mutations established a complex genotype–phenotype correlation in ALS–FTD. Our research further elucidated the genetic mechanism of ALS–FTD and contributed to setting the foundation of future targeted therapy.

Primary progressive aphasia and motor neuron disease: A review

Background

This study aims at reviewing, within the framework of motor neuron disease-frontotemporal degeneration (MND-FTD)-spectrum disorders, evidence on the co-occurrence between primary progressive aphasia (PPA) and MND in order to profile such a complex at pathological, genetic and clinical levels.

Methods

This review was pre-registered (osf.io/ds8m4) and performed in accordance with the 2020 PRISMA guidelines. Case reports/series and group studies were included if addressing (1) progressive non-fluent aphasia (PNFA) or semantic dementia (SD) with MND or (2) MND patients with co-morbid PNFA/SD.

Results

Out of 546 initial records, 56 studies were included. As to case reports/series (N = 35), which included 61 PPA-MND patients, the following findings yielded: (1) PNFA is more frequent than SD in PPA-MND; (2) in PPA-MND, the most prevalent motor phenotypes are amyotrophic lateral sclerosis and predominant-upper MND, with bulbar involvement being ubiquitous; (3) extrapyramidal features are moderately frequent in PPA-MND; (4) PPA-MND patients usually display frontotemporal, left-greater-than-right involvement; (5) TDP-43-B is the typical pathological substrate of PPA-MND; (6) TBK1 mutations represent the most frequent genetic risk factors for PPA-MND.

As to group studies, including 121 patients, proportional meta-analytic procedures revealed that: (1) the lifetime prevalence of MND in PPA is 6%; (2) PPA occurs in 19% of patients with co-morbid MND and FTD; (3) MND is more frequent in PNFA (10%) than in SD patients (3%).

Discussion

Insights herewith delivered into the clinical, neuropathological and genetic features of PPA-MND patients prompt further investigations aimed at improving clinical practice within the MND-FTD spectrum.

Therapeutic Potential of Polyphenols in Amyotrophic Lateral Sclerosis and Frontotemporal Dementia

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are severe neurodegenerative disorders that belong to a common disease spectrum. The molecular and cellular aetiology of the spectrum is a highly complex encompassing dysfunction in many processes, including mitochondrial dysfunction and oxidative stress. There is a paucity of treatment options aside from therapies with subtle effects on the post diagnostic lifespan and symptom management. This presents great interest and necessity for the discovery and development of new compounds and therapies with beneficial effects on the disease. Polyphenols are secondary metabolites found in plant-based foods and are well known for their antioxidant activity. Recent research suggests that they also have a diverse array of neuroprotective functions that could lead to better treatments for neurodegenerative diseases. We present an overview of the effects of various polyphenols in cell line and animal models of ALS/FTD. Furthermore, possible mechanisms behind actions of the most researched compounds (resveratrol, curcumin and green tea catechins) are discussed.

The role of genetics in neurodegenerative dementia: a large cohort study in South China

Neurodegenerative dementias are a group of diseases with highly heterogeneous pathology and complicated etiology. There exist potential genetic component overlaps between different neurodegenerative dementias. Here, 1795 patients with neurodegenerative dementias from South China were enrolled, including 1592 with Alzheimer's disease (AD), 110 with frontotemporal dementia (FTD), and 93 with dementia with Lewy bodies (DLB). Genes targeted sequencing analysis were performed. According to the American College of Medical Genetics (ACMG) guidelines, 39 pathogenic/likely pathogenic (P/LP) variants were identified in 47 unrelated patients in 14 different genes, including PSEN1, PSEN2, APP, MAPT, GRN, CHCHD10, TBK1, VCP, HTRA1, OPTN, SQSTM1, SIGMAR1, and abnormal repeat expansions in C9orf72 and HTT. Overall, 33.3% (13/39) of the variants were novel, the identified P/LP variants were seen in 2.2% (35/1592) and 10.9% (12/110) of AD and FTD cases, respectively. The overall molecular diagnostic rate was 2.6%. Among them, PSEN1 was the most frequently mutated gene (46.8%, 22/47), followed by PSEN2 and APP. Additionally, the age at onset of patients with P/LP variants (51.4 years), ranging from 30 to 83 years, was ~10 years earlier than those without P/LP variants (p < 0.05). This study sheds insight into the genetic spectrum and clinical manifestations of neurodegenerative dementias in South China, further expands the existing repertoire of P/LP variants involved in known dementia-associated genes. It provides a new perspective for basic research on genetic pathogenesis and novel guiding for clinical practice of neurodegenerative dementia.

Motor neuron disease beginning with frontotemporal dementia: clinical features and progression

Objective: To study disease characteristics, progression and outcome in a group of motor neuron disease (MND) patients beginning with frontotemporal dementia (FTD) by comparing them with patients with the typical motor-onset. Methods: 849 patients recruited from tertiary centers were studied according to FTD-onset and motor-onset. We studied clinical data, functional decline and survival. Results: Twenty six patients (3.1%) had FTD-onset of whom seven (26.9%) had coincident motor dysfunction. In those with isolated FTD-onset, motor symptoms developed after a median of 12 months (IQR: 4-18). FTD-onset patients were older at presentation; the bulbar-region was more frequently first affected than in the motor-onset group; there was a predominant upper motor neuron (UMN) phenotype; fasciculations were less common than in motor onset disease but facial and upper limb apraxia was more frequent; as well as ALS and FTD familial history. No differences were observed for gender, frequency of C9orf72 hexanucleotide repeat expansion, family history of Alzheimer's and Parkinson's diseases, median delay from motor symptoms to diagnosis, median ALSFRS-R rate of change, handedness, emotional lability, depression, weight loss, resting tremor, bradykinesia, sensory changes or neuropathy. Clinical and demographic features were similar between FTD-onset patients developing bulbar MND and bulbar-onset ALS patients. Once bulbar symptoms manifested functional progression and survival were similar to those of bulbar-onset ALS patients. Conclusions: MND patients with FTD-onset have a distinctive phenotype characterized by predominant UMN presentation and rapid progression to bulbar involvement. The main factor impacting functional decline and survival is the onset of bulbar dysfunction.

Heterogeneity of behavioural and language deficits in FTD-MND

OBJECTIVE

To comprehensively examine the clinical presentation of patients diagnosed with frontotemporal dementia-motor neuron disease (FTD-MND) compared to FTD subtypes. To clarify the heterogeneity of behavioural and language deficits in FTD-MND using a data-driven approach.

METHODS

Patients with FTD-MND (n = 31), behavioural variant FTD (n = 119), non-fluent variant primary progressive aphasia (n = 47), semantic variant primary progressive aphasia (n = 42), and controls (n = 127) underwent comprehensive clinical, cognitive and behavioural assessments. Two-step cluster analysis examined patterns of behavioural and language impairment. Voxel-based morphometry and tract-based spatial statistics were used to investigate differences across the subgroups that emerged from cluster analysis.

RESULTS

More than half of FTD-MND patients initially presented with variable combinations of deficits (e.g., mixed behaviour/cognitive, mixed behaviour/cognitive/motor deficits), with 74% of them meeting criteria for FTD-MND within 24 months with a median of 12 months. The frequency and severity of behavioural and language abnormalities in FTD-MND lie between that seen in the three FTD phenotypes. Cluster analysis identified three patterns of behavioural and language impairment in FTD-MND. The three FTD-MND subgroups demonstrated different profiles of white matter tract disruption, but did not differ in age at onset, disease duration or patterns of cortical atrophy.

CONCLUSIONS

While highly heterogeneous, in terms of behavioural and language deficits, and disease severity, the presentation of FTD-MND may be distinct to that of FTD. Distinct white matter degeneration patterns may underpin heterogeneous clinical profiles in FTD-MND. FTD presenting with mixed behavioural-language disturbances should be monitored closely for at least 12-24 months for the emergence of MND symptoms/signs.

Cognition and behaviour in frontotemporal dementia with and without amyotrophic lateral sclerosis

OBJECTIVE

The precise relationship between frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) is incompletely understood. The association has been described as a continuum, yet data suggest that this may be an oversimplification. Direct comparisons between patients who have behavioural variant FTD (bvFTD) with and without ALS are rare. This prospective comparative study aimed to determine whether there are phenotypic differences in cognition and behaviour between patients with FTD-ALS and bvFTD alone.

METHODS

Patients with bvFTD or FTD-ALS and healthy controls underwent neuropsychological testing, focusing on language, executive functions and social cognition. Behavioural change was measured through caregiver interview. Blood samples were screened for known FTD genes.

RESULTS

23 bvFTD, 20 FTD-ALS and 30 controls participated. On cognitive tests, highly significant differences were elicited between patients and controls, confirming the tests' sensitivities to FTD. bvFTD and FTD-ALS groups performed similarly, although with slightly greater difficulty in patients with ALS-FTD on category fluency and a sentence-ordering task that assesses grammar production. Patients with bvFTD demonstrated more widespread behavioural change, with more frequent disinhibition, impulsivity, loss of empathy and repetitive behaviours. Behaviour in FTD-ALS was dominated by apathy. The C9ORF72 repeat expansion was associated with poorer performance on language-related tasks.

CONCLUSIONS

Differences were elicited in cognition and behaviour between bvFTD and FTD-ALS, and patients carrying the C9ORF72 repeat expansion. The findings, which raise the possibility of phenotypic variation between bvFTD and FTD-ALS, have clinical implications for early detection of FTD-ALS and theoretical implications for the nature of the relationship between FTD and ALS.

Functional characterization of a FUS mutant zebrafish line as a novel genetic model for ALS

Mutations in Fused in sarcoma (FUS), an RNA-binding protein, are known to cause Amyotrophic Lateral Sclerosis (ALS). However, molecular mechanisms due to loss of FUS function remain unclear and controversial. Here, we report the characterization and phenotypic analysis of a deletion mutant of the unique FUS orthologue in zebrafish where Fus protein levels are depleted. The homozygous mutants displayed a reduced lifespan as well as impaired motor abilities associated with specific cellular deficits, including decreased motor neurons length and neuromuscular junctions (NMJ) fragmentation. Furthermore, we demonstrate that these cellular impairments are linked to the misregulation of mRNA expression of acetylcholine receptor (AChR) subunits and histone deacetylase 4, markers of denervation and reinnervation processes observed in ALS patients. In addition, fus loss of function alters tau transcripts favoring the expression of small tau isoforms. Overall, this new animal model extends our knowledge on FUS and supports the relevance of FUS loss of function in ALS physiopathology.

Monoaminergic and Kynurenergic Characterization of Frontotemporal Dementia and Amyotrophic Lateral Sclerosis in Cerebrospinal Fluid and Serum

Exploring the neurochemical continuum between frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) with respect to monoamines and kynurenines in cerebrospinal fluid (CSF) and serum, may be useful to identify possible new research/therapeutic targets. Hence, we analysed monoamines and kynurenines in CSF and serum derived from patients with FTD (n = 39), ALS (n = 23), FTD-ALS (n = 4) and age-matched control subjects (n = 26), using reversed-phase ultra-high performance liquid chromatography (RP-UHPLC) with electrochemical detection (ECD) and liquid chromatography tandem mass spectrometry, respectively. We noted a shared dopaminergic disturbance in FTD and ALS when compared to CONTR, with significantly increased serum DA levels and decreased DOPAC concentrations, as well as decreased DOPAC/DA ratios in both disease groups. In CSF, significantly reduced DOPAC concentrations in FTD and ALS were observed as well. Here, a significant increase in DA levels and decrease in DOPAC/DA ratios was only found in FTD relative to CONTR. With respect to the kynurenine pathway (KP), we only found decreased HK/XA ratios, indicative for vitamin B6 status, in serum of ALS subjects compared to FTD. The dopaminergic commonalities observed in FTD and ALS might relate to a disturbance of dopaminergic nerve terminals in projection areas of the substantia nigra and/or ventral tegmental area, although these findings should first be confirmed in brain tissue. Lastly, based on the results of this work, the KP does not hold promise as a research/therapeutic target in FTD and ALS.

Pathomechanism Heterogeneity in the Amyotrophic Lateral Sclerosis and Frontotemporal Dementia Disease Spectrum: Providing Focus Through the Lens of Autophagy

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) constitute aggressive neurodegenerative pathologies that lead to the progressive degeneration of upper and lower motor neurons and of neocortical areas, respectively. In the past decade, the identification of several genes that cause these disorders indicated that the two diseases overlap in a multifaceted spectrum of conditions. The autophagy-lysosome system has been identified as a main intersection for the onset and progression of neurodegeneration in ALS/FTD. Genetic evidence has revealed that several genes with a mechanistic role at different stages of the autophagy process are mutated in patients with ALS/FTD. Moreover, the three main proteins aggregating in ALS/FTD, including in sporadic cases, are also targeted by autophagy and affect this process. Here, we examine the varied dysfunctions and degrees of involvement of the autophagy-lysosome system that have been discovered in ALS/FTD. We argue that these findings shed light on the pathological mechanisms in the ALS/FTD spectrum and conclude that they have important consequences both for treatment options and for the basic biomolecular understanding of how this process intersects with RNA metabolism, the other major cellular process reported to be dysfunctional in part of the ALS/FTD spectrum.

Cognitive impairment across ALS clinical stages in a population-based cohort

OBJECTIVE

To assess the association of the degree of severity of motor impairment to that of cognitive impairment in a large cohort of patients with amyotrophic lateral sclerosis (ALS).

METHODS

This is a population-based cross-sectional study on patients with ALS incident in Piemonte, Italy, between 2007 and 2015. Cognitive status was classified according to the revised ALS-FTD Consensus Criteria. The King system and the Milano Torino Staging system (MiToS) were used for defining the severity of motor impairment.

RESULTS

Of the 797 patients included in the study, 163 (20.5%) had ALS-frontotemporal dementia (FTD), 38 (4.8%) cognitive and behavioral impairment (ALScbi), 132 (16.6%) cognitive impairment (ALSci), 63 (7.9%) behavioral impairment (ALSbi), 16 (2.0%) nonexecutive impairment, and 385 (48.2%) were cognitively normal. According to King staging, the frequency of cases with ALS-FTD progressively increased from 16.5% in stage 1-44.4% in stage 4; conversely, the frequency of ALSci, ALSbi, and ALScbi increased from King stage 1 to King stage 3 and decreased thereafter. A similar pattern was observed with the MiToS staging. ALS-FTD was more frequent in patients with bulbar involvement at time of cognitive testing. Patients with C9ORF72 expansion (n = 61) showed more severe cognitive impairment with increasing King and MiToS stages.

CONCLUSION

Our findings suggest that ALS motor and cognitive components may worsen in parallel, and that cognitive impairment becomes more pronounced when bulbar function is involved. Our data support the hypothesis that ALS pathology disseminates in a regional ordered sequence, through a cortico-efferent spreading model.

Progress and Challenges in Frontotemporal Dementia Research: A 20-Year Review

The landscape of frontotemporal dementia (FTD) has evolved remarkably in recent years and is barely recognizable from two decades ago. Knowledge of the clinical phenomenology, cognition, neuroimaging, genetics, pathology of the different subtypes of FTD, and their relations to other neurodegenerative conditions, has increased rapidly, due in part, to the growing interests into these neurodegenerative brain conditions. This article reviews the major advances in the field of FTD over the past 20 years, focusing primarily on the work of Frontier, the frontotemporal dementia clinical research group, based in Sydney, Australia. Topics covered include clinical presentations (cognition, behavior, neuroimaging), pathology, genetics, and disease progression, as well as interventions and carer directed research. This review demonstrates the improvement in diagnostic accuracy and capacity to provide advice on genetic risks, prognosis, and outcome. The next major challenge will be to capitalize on these research findings to develop effective disease modifying drugs, which are currently lacking.

A case of progressive non-fluent aphasia as onset of amyotrophic lateral sclerosis with frontotemporal dementia

The association between Amyotrophic Lateral Sclerosis (ASL) and FrontoTemporal Dementia (FTD) is well known. Most of reports describing ASL-FTD cases show a strong association between ALS and the behavioural form of FTD. Conversely, the association between ALS and pure Semantic Dementia or Progressive Non-Fluent Aphasia (PNFA) is extremely rare, ranging from 1 to 3%. A clinical phenotype characterized by a rapidly progressive aphasic dementia and motoneuron disease (MND) has been described in few case reports; since the updating of PNFA diagnostic criteria in 2011, no clinical report has been related. We want to describe a case of patient presented, at the onset, as PNFA who developed, one year later, ALS with bulbar onset. The patient was screened for the main genes causing or associated with MND and/or dementia but no variants with a pathogenetic effect were observed.

ALS Genes in the Genomic Era and their Implications for FTD

Amyotrophic lateral sclerosis (ALS) is a complex neurodegenerative disease, characterized genetically by a disproportionately large contribution of rare genetic variation. Driven by advances in massive parallel sequencing and applied on large patient-control cohorts, systematic identification of these rare variants that make up the genetic architecture of ALS became feasible. In this review paper, we present a comprehensive overview of recently proposed ALS genes that were identified based on rare genetic variants (TBK1, CHCHD10, TUBA4A, CCNF, MATR3, NEK1, C21orf2, ANXA11, TIA1) and their potential relevance to frontotemporal dementia genetic etiology. As more causal and risk genes are identified, it has become apparent that affected individuals can carry multiple disease-associated variants. In light of this observation, we discuss the oligogenic architecture of ALS. To end, we highlight emerging key molecular processes and opportunities for therapy.