Frontotemporal dementia

Antisense RNA C9orf72 hexanucleotide repeat associated with amyotrophic lateral sclerosis and frontotemporal dementia forms a triplex-like structure and binds small synthetic ligand

The abnormal expansion of GGGGCC/GGCCCC hexanucleotide repeats (HR) in C9orf72 is associated with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Structural polymorphisms of HR result in the multifactorial pathomechanism of ALS/FTD. Consequently, many ongoing studies are focused at developing therapies targeting pathogenic HR RNA. One of them involves small molecules blocking sequestration of important proteins, preventing formation of toxic nuclear foci. However, rational design of potential therapeutics is hindered by limited number of structural studies of RNA-ligand complexes. We determined the crystal structure of antisense HR RNA in complex with ANP77 ligand (1.1 Å resolution) and in the free form (0.92 and 1.5 Å resolution). HR RNA folds into a triplex structure composed of four RNA chains. ANP77 interacted with two neighboring single-stranded cytosines to form pseudo-canonical base pairs by adopting sandwich-like conformation and adjusting the position of its naphthyridine units to the helical twist of the RNA. In the unliganded structure, the cytosines formed a peculiar triplex i-motif, assembled by trans C•C+ pair and a third cytosine located at the Hoogsteen edge of the C•C+ pair. These results extend our knowledge of the structural polymorphisms of HR and can be used for rational design of small molecules targeting disease-related RNAs.

Behavioral variant frontotemporal dementia associated with GRN and ErbB4 gene mutations: a case report and literature review

OBJECTIVE

To report the clinical manifestation and genetic characteristics of a patient having frontotemporal dementia (FTD) with abnormal behavior and unstable walking.

METHODS

The clinical and imaging features of a patient who was eventually diagnosed with FTD were analyzed. The patient's neuropsychological, PET-CT, electromyography, and genetic data were collected. Furthermore, the patient's blood samples were examined for FTD-related genes.

RESULTS

The patient was a 52-year-old man with hidden onset. The symptoms progressed gradually, presenting with abnormal behaviors, including repeated shopping, taking away other people's things, constantly eating snacks, and frequently calling friends at night. The patient also exhibited executive dysfunction, such as the inability to cook and multiple driving problems, e.g., constantly deviates from his lane while driving. In addition, the patient showed personality changes such as irritability, indifference, and withdrawal, as well as motor symptoms, including unstable walking and frequent falls when walking. Brain magnetic resonance imaging revealed hippocampal sclerosis along with widening and deepening of the bilateral temporal lobe sulcus. Brain metabolic imaging via PET-CT demonstrated decreased metabolism in the bilateral prefrontal lobe, with the abnormal energy metabolism indicating FTD. Lastly, blood sample analysis detected mutations in the amyotrophic lateral sclerosis (ALS)-related GRN gene c.1352C > T (p.P451L) and ErbB4 gene c.256 T > C (p.Y86H).

CONCLUSION

This is the first case of heterozygous mutations in the GRN and ErbB4 genes in FTD alone. The GRN and ErbB4 genes are likely to be important in the pathogenesis of FTD, expanding the common genetic profile of ALS and FTD.

Neuronal dysfunction caused by FUSR521G promotes ALS-associated phenotypes that are attenuated by NF-κB inhibition

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are related neurodegenerative diseases that belong to a common disease spectrum based on overlapping clinical, pathological and genetic evidence. Early pathological changes to the morphology and synapses of affected neuron populations in ALS/FTD suggest a common underlying mechanism of disease that requires further investigation. Fused in sarcoma (FUS) is a DNA/RNA-binding protein with known genetic and pathological links to ALS/FTD. Expression of ALS-linked FUS mutants in mice causes cognitive and motor defects, which correlate with loss of motor neuron dendritic branching and synapses, in addition to other pathological features of ALS/FTD. The role of ALS-linked FUS mutants in causing ALS/FTD-associated disease phenotypes is well established, but there are significant gaps in our understanding of the cell-autonomous role of FUS in promoting structural changes to motor neurons, and how these changes relate to disease progression. Here we generated a neuron-specific FUS-transgenic mouse model expressing the ALS-linked human FUSR521G variant, hFUSR521G/Syn1, to investigate the cell-autonomous role of FUSR521G in causing loss of dendritic branching and synapses of motor neurons, and to understand how these changes relate to ALS-associated phenotypes. Longitudinal analysis of mice revealed that cognitive impairments in juvenile hFUSR521G/Syn1 mice coincide with reduced dendritic branching of cortical motor neurons in the absence of motor impairments or changes in the neuromorphology of spinal motor neurons. Motor impairments and dendritic attrition of spinal motor neurons developed later in aged hFUSR521G/Syn1 mice, along with FUS cytoplasmic mislocalisation, mitochondrial abnormalities and glial activation. Neuroinflammation promotes neuronal dysfunction and drives disease progression in ALS/FTD. The therapeutic effects of inhibiting the pro-inflammatory nuclear factor kappa B (NF-κB) pathway with an analog of Withaferin A, IMS-088, were assessed in symptomatic hFUSR521G/Syn1 mice and were found to improve cognitive and motor function, increase dendritic branches and synapses of motor neurons, and attenuate other ALS/FTD-associated pathological features. Treatment of primary cortical neurons expressing FUSR521G with IMS-088 promoted the restoration of dendritic mitochondrial numbers and mitochondrial activity to wild-type levels, suggesting that inhibition of NF-κB permits the restoration of mitochondrial stasis in our models. Collectively, this work demonstrates that FUSR521G has a cell-autonomous role in causing early pathological changes to dendritic and synaptic structures of motor neurons, and that these changes precede motor defects and other well-known pathological features of ALS/FTD. Finally, these findings provide further support that modulation of the NF-κB pathway in ALS/FTD is an important therapeutic approach to attenuate disease.

Analysis of Potential Biomarkers in Frontal Temporal Dementia: A Bioinformatics Approach

Frontal temporal dementia (FTD) is a neurological disorder known to have fewer therapeutic options. So far, only a few biomarkers are available for FTD that can be used as potential comorbidity targets. For example, genes such as VCP, which has a role in breast cancer, and WFS1, which has a role in COVID-19, are known to show a role in FTD as well. To this end, in the present study, we aim to identify potential biomarkers or susceptible genes for FTD that show comorbidities with diseases such as COVID-19 and breast cancer. A dataset from Gene Expression Omnibus containing FTD expression profiles from African American and white ethnicity backgrounds was included in our study. In FTD samples of the GSE193391 dataset, we identified 305 DEGs, with 168 genes being up-regulated and 137 genes being down-regulated. We conducted a comorbidity analysis for COVID-19 and breast cancer, followed by an analysis of potential drug interactions, pathogenicity, analysis of genetic variants, and functional enrichment analysis. Our results showed that the genes AKT3, GFAP, ADCYAP1R1, VDAC1, and C4A have significant transcriptomic alterations in FTD along with the comorbidity status with COVID-19 and breast cancer. Functional pathway analysis revealed that these comorbid genes were significantly enriched in the pathways such as glioma, JAK/STAT signaling, systematic lupus erythematosus, neurodegeneration-multiple diseases, and neuroactive ligand-receptor interaction. Overall, from these results, we concluded that these genes could be recommended as potential therapeutic targets for the treatment of comorbidities (breast cancer and COVID-19) in patients with FTD.

Current clinical and research practices on frontotemporal dementia in Brazil: a national survey

BACKGROUND

Frontotemporal dementia (FTD) is a frequent cause of young-onset dementia and represents a major challenge for the diagnosis and clinical management. It is essential to evaluate the difficulties faced by physicians on the diagnostic workup and on patient care.

OBJECTIVE

The aim of this study was to investigate the current practices and the local limits on the diagnosis and management of FTD in Brazil.

METHODS

We elaborated an online survey, composed of 29 questions and divided in four parts, comprising questions about existing health facilities, clinical practices related to FTD, and suggestions to increment the national research on FTD. The invitation to participate was sent by email to all neurologists affiliated to the Brazilian Academy of Neurology (n = 3658), and to all physicians who attended the XII Meeting of Researchers on Alzheimer's disease, in 2019 (n = 187). The invitation was also diffused through social media.

RESULTS

256 Brazilian physicians answered the questionnaire. The three most relevant disorders for the differential diagnosis of FTD were Alzheimer's disease (AD) (n = 211), bipolar disorder (n = 117) and dementia with Lewy bodies (n = 92). Most respondents (125/256) reported the difficulty in performing genetic testing as the main limit in the diagnostic of FTD. 93% and 63% of participants considered that the assessment of social cognition and AD CSF biomarkers are useful for the diagnosis of FTD, respectively.

CONCLUSIONS

The present study may provide valuable insights for the medical education and clinical training of physicians, and to foster future research on FTD in Brazil.

Frontotemporal dementia: Addressing the scattered harbingers of genetics and its relationship with glucose metabolism, bipolar disorder, and amyotrophic lateral sclerosis

Frontotemporal Dementia, also known by the name Pick's disease, is a rare form of dementia that can run for several generations. The two key characteristics are argyrophilic, spherical intraneuronal inclusions, which most frequently impact the frontal and temporal poles, and localized cortical atrophy (Pick bodies). Although personality decline and memory loss are frequently more severe than the visuospatial and apraxia disorders that are common in Alzheimer's disease, clinical overlap with other non-Alzheimer degenerative disorders is being increasingly recognized. The limbic system, which includes the hippocampus, entorhinal cortex, and amygdala, typically experiences the greatest levels of neuronal loss and degeneration. In the hippocampus's dentate fascia, several Pick bodies are frequently seen. Leukoencephalopathy and inflated cortical neurons are less specific symptoms (Pick cells). In this paper, we review the factors leading to Picks disease along with its pathophysiology, clinical manifestations, diagnosis, imaging, treatment, prognosis, and a comprehensive discussion on the same. We have also discussed the relationship of frontotemporal dementia with glucose metabolism, bipolar disorder, and amyotrophic lateral sclerosis, all of which are emerging fields of interest and need more studies.

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.

Blood Biomarkers for the Diagnosis of Neurodegenerative Dementia: A Systematic Review

IMPORTANCE

Accurately diagnosing neurodegenerative dementia is often challenging due to overlapping clinical features. Disease specific biomarkers could enhance diagnostic accuracy. However, CSF analysis procedures and advanced imaging modalities are either invasive or high-priced, and routinely unavailable. Easily accessible disease biomarkers would be of utmost value for accurate differential diagnosis of dementia subtypes.

OBJECTIVE

To assess the diagnostic accuracy of blood-based biomarkers for the differential diagnosis of AD from Frontotemporal Lobar Degeneration (FTLD), or AD from Dementia with Lewy Bodies (DLB).

METHODS

Systematic review. Three databases (PubMed, Scopus, and Web of Science) were searched. Studies assessing blood-based biomarkers levels in AD versus FTLD, or AD versus DLB, and its diagnostic accuracy, were selected. When the same biomarker was assessed in three or more studies, a meta-analysis was performed. QUADAS-2 criteria were used for quality assessment.

RESULTS

Twenty studies were included in this analysis. Collectively, 905 AD patients were compared to 1262 FTLD patients, and 209 AD patients were compared to 246 DLB patients. Regarding biomarkers for AD versus FTLD, excellent discriminative accuracy (AUC >0.9) was found for p-tau181, p-tau217, synaptophysin, synaptopodin, GAP43 and calmodulin. Other biomarkers also demonstrated good accuracy (AUC = 0.8-0.9). For AD versus DLB distinction, only miR-21-5p and miR-451a achieved excellent accuracy (AUC >0.9).

CONCLUSION

Encouraging results were found for several biomarkers, alone or in combination. Prospective longitudinal designs and consensual protocols, comprising larger cohorts and homogeneous testing modalities across centres, are essential to validate the clinical value of blood biomarkers for the precise etiological diagnosis of dementia.

The Advance on Frontotemporal Dementia (FTD)’s Neuropathology and Molecular Genetics

The morbidity of frontotemporal dementia (FTD), one of the most prevalent dementias praccox, is second to Alzheimer disease (AD). It is different with AD that FTD has a rapider course and a higher mortality. FTD has not yet been fully understood in terms of etiology or pathogenesis, but genetic factors are believed to be involved. In this paper, we were committed to providing a comprehensive overview to FTD in aspects of the neuropathology features and the relevant molecular genetics advances, so that there would be insights to those researchers in search of novel approaches in FTD diagnosis and treatment.

Synaptic dysfunction in ALS and FTD: anatomical and molecular changes provide insights into mechanisms of disease

Synaptic loss is a pathological feature of all neurodegenerative diseases including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). ALS is a disease of the cortical and spinal motor neurons resulting in fatal paralysis due to denervation of muscles. FTD is a form of dementia that primarily affects brain regions controlling cognition, language and behavior. Once classified as two distinct diseases, ALS and FTD are now considered as part of a common disease spectrum based on overlapping clinical, pathological and genetic evidence. At the cellular level, aggregation of common proteins and overlapping gene susceptibilities are shared in both ALS and FTD. Despite the convergence of these two fields of research, the underlying disease mechanisms remain elusive. However, recent discovers from ALS and FTD patient studies and models of ALS/FTD strongly suggests that synaptic dysfunction is an early event in the disease process and a unifying hallmark of these diseases. This review provides a summary of the reported anatomical and cellular changes that occur in cortical and spinal motor neurons in ALS and FTD tissues and models of disease. We also highlight studies that identify changes in the proteome and transcriptome of ALS and FTD models and provide a conceptual overview of the processes that contribute to synaptic dysfunction in these diseases. Due to space limitations and the vast number of publications in the ALS and FTD fields, many articles have not been discussed in this review. As such, this review focuses on the three most common shared mutations in ALS and FTD, the hexanucleuotide repeat expansion within intron 1 of chromosome 9 open reading frame 72 (C9ORF72), transactive response DNA binding protein 43 (TARDBP or TDP-43) and fused in sarcoma (FUS), with the intention of highlighting common pathways that promote synaptic dysfunction in the ALS-FTD disease spectrum.

Protein synthesis modulation as a therapeutic approach for amyotrophic lateral sclerosis and frontotemporal dementia

Protein synthesis is essential for cells to perform life metabolic processes. Pathological alterations of protein content can lead to particular diseases. Cells have an intrinsic array of mechanisms and pathways that are activated when protein misfolding, accumulation, aggregation or mislocalization occur. Some of them (like the unfolded protein response) represent complex interactions between endoplasmic reticulum sensors and elongation factors that tend to increase expression of chaperone proteins and/or repress translation in order to restore protein homeostasis (also known as proteostasis). This is even more important in neurons, as they are very susceptible to harmful effects associated with protein overload and proteostatic mechanisms are less effective with age. Several neurodegenerative pathologies such as Alzheimer's, Parkinson's, and Huntington's diseases, amyotrophic lateral sclerosis and frontotemporal dementia exhibit a particular molecular signature of distinct, unbalanced protein overload. In amyotrophic lateral sclerosis and frontotemporal dementia, the majority of cases present intracellular inclusions of ubiquitinated transactive response DNA-binding protein of 43 kDa (TDP-43). TDP-43 is an RNA binding protein that participates in RNA metabolism, among other functions. Dysregulation of TDP-43 (e.g. aggregation and mislocalization) can dramatically affect neurons, and this has been linked to disease development. Expression of amyotrophic lateral sclerosis/frontotemporal dementia TDP-43-related mutations in cellular and animal models has been shown to recapitulate key features of the amyotrophic lateral sclerosis/frontotemporal dementia disease spectrum. These variants can be causative of degeneration onset and progression. Most neurodegenerative diseases (including amyotrophic lateral sclerosis and frontotemporal dementia) have no cure at the moment; however, modulating translation has recently emerged as an attractive approach that can be performed at several steps (i.e. regulating activation of initiation and elongation factors, inhibiting unfolded protein response activation or inducing chaperone expression and activity). This review focuses on the features of protein imbalance in neurodegenerative disorders and the relevance of developing therapeutical compounds aiming at restoring proteostasis. We strive to highlight the importance of research on drugs that, not only restore protein imbalance without compromising translational activity of cells, but are also as safe as possible for the patients.

A Systematic Review of Expressive and Receptive Prosody in People With Dementia

Purpose This review was designed to provide a systematic overview of prosody in people with a primary diagnosis of dementia (PwD) and evaluate the potential use of prosodic features for diagnosis of dementia. Method A systematic search of five databases was conducted using Medical Subject Headings and keywords. Studies included in the review were evaluated for their methodological quality using the modified Joanna Briggs Institute checklist. Results A total of 14 articles were identified as being relevant for this review. Among the 14 articles, the methodological quality ranged, with eight rated as weak, four rated as moderate, and two rated as strong. Ten of the 14 articles had people with Alzheimer's disease (AD) as participants, and the remaining four had people with frontotemporal dementia as participants. Four articles focused on receptive prosody, another six focused on expressive prosody, and the remaining four articles were investigations into both. The 14 articles presented inconsistent findings, and various tasks were used to measure prosodic features in PwD in the articles. Prosody was studied as a diagnostic tool for dementia in four of the articles, all of which were based on expressive prosody in individuals with AD. Among the four articles, three proposed the use of automatic speech analysis for diagnosis of AD. Conclusions This review demonstrates that prosody in PwD is an underinvestigated area. In particular, it was concerning that most articles were of weak methodological quality. Nevertheless, it was found that prosody may be a potential diagnostic tool for assessing dementia. More studies that replicate the existing studies and those with stronger methodology are needed to confirm that receptive and/or expressive prosody can be used for dementia diagnosis.

Tau and MAPT genetics in tauopathies and synucleinopathies

MAPT encodes the microtubule-associated protein tau, which is the main component of neurofibrillary tangles (NFTs) and found in other protein aggregates. These aggregates are among the pathological hallmarks of primary tauopathies such as frontotemporal dementia (FTD). Abnormal tau can also be observed in secondary tauopathies such as Alzheimer's disease (AD) and synucleinopathies such as Parkinson's disease (PD). On top of pathological findings, genetic data also links MAPT to these disorders. MAPT variations are a cause or risk factors for many tauopathies and synucleinopathies and are associated with certain clinical and pathological features in affected individuals. In addition to clinical, pathological, and genetic overlap, evidence also suggests that tau and alpha-synuclein may interact on the molecular level, and thus might collaborate in the neurodegenerative process. Understanding the role of MAPT variations in tauopathies and synucleinopathies is therefore essential to elucidate the role of tau in the pathogenesis and phenotype of those disorders, and ultimately to develop targeted therapies. In this review, we describe the role of MAPT genetic variations in tauopathies and synucleinopathies, several genotype-phenotype and pathological features, and discuss their implications for the classification and treatment of those disorders.

Update on Major Neurocognitive Disorders

Dementia is a syndrome characterized by a gradually progressive course that spans a continuum from preclinical symptoms to major impairment in two or more cognitive domains with functional decline. In this review, the author examines some of the more common dementia syndromes from among dozens of different diseases. Findings show that as the U.S. population continues to age, the number of Americans with dementia is expected to rise drastically over the next several decades. This upsurge will contribute to increased health care costs and will have a significant public health impact. Neurodegenerative disorders such as Alzheimer's disease, frontotemporal degeneration, and alpha-synucleinopathies (e.g., Lewy body disease and Parkinson's disease) are some of the more prevalent causes for dementia. In recent years, advancements in neuroimaging, understanding of genetic contributions and pathological changes, and the development of novel biomarkers have fueled clinical understanding of these disorders. However, substantial disease-modifying therapies are still lagging. The advent of future interventions hinges on the ability to discern the distinct clinico-pathologic profiles of the various dementia syndromes and to identify reliable biomarkers for utilization in clinical trials.

Tumor necrosis factor superfamily molecules are increased in behavioral variant frontotemporal dementia and correlate with cortical atrophy: An exploratory investigation

Frontotemporal dementia (FTD) is the second most frequent cause of young-onset dementia. Even though immune-mediated and neuroinflammatory factors have been recognized as potential pathophysiological mechanisms, the role of specific immune molecules, such as the tumor necrosis factor (TNF) superfamily, remains elusive. The aim of this study was to investigate TNF Superfamily Molecules (TNF, TNF-related weak inducer of apoptosis [TWEAK], soluble TNF receptor type 1 [sTNFRI] and soluble TNF receptor type 2 [sTNFRII]) in patients with behavioral variant FTD (bvFTD) and controls, and to explore potential associations with clinical parameters and brain atrophy. This study included two groups of participants matched for age, sex and schooling years: patients with probable bvFTD (n = 17, mean age = 64.9 years, 6 women/11 men) and healthy controls (HC, n = 17; mean age = 63.9 years, 10 women/7 men). All participants underwent comprehensive cognitive assessment and structural brain imaging with 3 T magnetic resonance imaging. Plasma levels of TNF, TWEAK, sTNFRI and sTNFRII were determined by ELISA. We conducted voxel-based morphometry analyses to investigate correlations between grey matter (GM) atrophy and plasma levels of TNF, TWEAK, sTNFRI and sTNFRII within bvFTD group. Compared to HC, bvFTD patients had lower cognitive scores and marked frontotemporal atrophy. Patients with bvFTD had significantly higher plasma levels of TNF (p < 0.0001), sTNFRI (p < 0.001), and sTNFRII (p < 0.0001), and similar levels of TWEAK in comparison with controls. The levels of sTNFRII were positively correlated with GM atrophy involving temporal poles, precuneus and cerebellum in bvFTD patients, while the levels of TWEAK positively correlated with right superior temporal gyrus. Our results implicate TNF superfamily in the pathophysiology of FTD.