Features Of Frontotemporal Lobar Degeneration Research Articles

Presymptomatic and early pathological features of MAPT-associated frontotemporal lobar degeneration

Early pathological features of frontotemporal lobar degeneration (FTLD) due to MAPT pathogenic variants (FTLD-MAPT) are understudied, since early-stage tissue is rarely available. Here, we report unique pathological data from three presymptomatic/early-stage MAPT variant carriers (FTLD Clinical Dementia Rating [FTLD-CDR] = 0–1). We examined neuronal degeneration semi-quantitatively and digitally quantified tau burden in 18 grey matter (9 cortical, 9 subcortical) and 13 white matter (9 cortical, 4 subcortical) regions. We compared presymptomatic/early-stage pathology to an intermediate/end-stage cohort (FTLD-CDR = 2–3) with the same variants (2 L315R, 10 P301L, 6 G272V), and developed a clinicopathological staging model for P301L and G272V variants. The 68-year-old presymptomatic L315R carrier (FTLD-CDR = 0) had limited tau burden morphologically similar to L315R end-stage carriers in middle frontal, antero-inferior temporal, amygdala, (para-)hippocampus and striatum, along with age-related Alzheimer’s disease neuropathological change. The 59-year-old prodromal P301L carrier (FTLD-CDR = 0.5) had highest tau burden in anterior cingulate, anterior temporal, middle/superior frontal, and fronto-insular cortex, and amygdala. The 45-year-old early-stage G272V carrier (FTLD-CDR = 1) had highest tau burden in superior frontal and anterior cingulate cortex, subiculum and CA1. The severity and distribution of tau burden showed some regional variability between variants at presymptomatic/early-stage, while neuronal degeneration, mild-to-moderate, was similarly distributed in frontotemporal regions. Early-stage tau burden and neuronal degeneration were both less severe than in intermediate-/end-stage cases. In a subset of regions (10 GM, 8 WM) used for clinicopathological staging, clinical severity correlated strongly with neuronal degeneration (rho = 0.72, p < 0.001), less strongly with GM tau burden (rho = 0.57, p = 0.006), and did not with WM tau burden (p = 0.9). Clinicopathological staging showed variant-specific patterns of early tau pathology and progression across stages. These unique data demonstrate that tau pathology and neuronal degeneration are present already at the presymptomatic/early-stage of FTLD-MAPT, though less severely compared to intermediate/end-stage disease. Moreover, early pathological patterns, especially of tau burden, differ partly between specific MAPT variants.

Molecular fragment characteristics and distribution of tangle associated TDP-43 (TATs) and other TDP-43 lesions in Alzheimer's disease.

TAR DNA binding protein 43 (TDP-43) pathology is a defining feature of frontotemporal lobar degeneration (FTLD). In FTLD-TDP there is a moderate-to-high burden of morphologically distinctive TDP-43 immunoreactive inclusions distributed throughout the brain. In Alzheimer's disease (AD), similar TDP-43 immunoreactive inclusions are observed. In AD, however, there is a unique phenomenon of neurofibrillary tangle-associated TDP-43 (TATs) whereby TDP-43 intermingles with neurofibrillary tangles. Little is known about the characteristics and distribution of TATs, or how burden and distribution of TATs compares to burden and distribution of other FTLD-TDP-like lesions observed in AD. Here we characterize molecular fragment characteristics, burden and distribution of TATs and assess how these features compare to features of other TDP-43 lesions. We performed TDP-43 immunohistochemistry with anti-phosphorylated, C- and N-terminal TDP-43 antibodies in 20 high-probability AD cases and semi-quantitative burden of seven inclusion types within five brain regions (entorhinal cortex, subiculum, CA1 and dentate gyrus of hippocampus, occipitotemporal cortex). Hierarchical cluster analysis was used to analyze the dataset that consisted of 75 different combinations of neuropathological features. TATs were nonspherical with heterogeneous staining patterns and present in all regions except hippocampal dentate. All three antibodies detected TATs although N-terminal antibody sensitivity was low. Three clusters were identified: Cluster-1 had mild-moderate TATs, moderate-frequent neuronal cytoplasmic inclusions, dystrophic neurites, neuronal intranuclear inclusions and fine neurites, and perivascular and granular inclusions identified only with the N-terminal antibody throughout the brain; Cluster-2 had scant TATs in limbic regions and Cluster-3 mild-moderate TATs and mild-moderate neuronal cytoplasmic inclusions and dystrophic neurites throughout the brain and moderate fine neurites. Only 17% of cluster 1 cases had the TMEM106b GG (protective) haplotype and 83% had hippocampal sclerosis. Both features differed across clusters (p=0.03 & p=0.01). TATs have molecular characteristics, distribution and burden, and genetic and pathologic associations like FTLD-TDP lesions.

Portuguese version of the CDR plus NACC FTLD: Validation studies

The CDR Dementia Staging Instrument PLUS National Alzheimer's Coordinating Center (CDR plus NACC FTLD) was developed by adding to the standard CDR two extra domains focused on the main features of frontotemporal lobar degeneration (FTLD): language and behavior/personality. We intended to perform the validation studies for the European-Portuguese population. A total of 105 participants matched for age, education, and disease staging (35 bvFTD, 35 AD, and 35 controls) were included. A translated-version of the CDR and the two added domains was administered by a neuropsychologist who was blinded to the diagnosis. The bvFTD group had higher baseline CDR plus NACC FTLD scores compared to the AD and controls. Only the sum-of-boxes (SB) score, the behavior/personality, and language domains were able to distinguish between clinical groups. Logistic regression analyses showed that adding the behavior/personality domain with or without language significantly enhanced the discriminating ability. Results show that the CDR plus NACC FTLD is a reliable tool in the diagnostic process of bvFTD patients and has an added value in distinguishing them from patients with AD.

Cognitive decline in amyotrophic lateral sclerosis: Neuropathological substrate and genetic determinants.

Cognitive impairment and behavioral changes in amyotrophic lateral sclerosis (ALS) are now recognized as part of the disease. Whether it is solely related to the extent of TDP‐43 pathology is currently unclear. We aim to evaluate the influence of age, genetics, neuropathological features, and concomitant pathologies on cognitive impairment in ALS patients. We analyzed a postmortem series of 104 ALS patients and retrospectively reviewed clinical and neuropathological data. We assessed the burden and extent of concomitant pathologies, the role of APOE ε4 and mutations, and correlated these findings with cognitive status. We performed a logistic regression model to identify which pathologies are related to cognitive impairment. Cognitive decline was recorded in 38.5% of the subjects. Neuropathological features of frontotemporal lobar degeneration (FTLD) were found in 32.7%, explaining most, but not all, cases with cognitive impairment. Extent of TDP‐43 pathology and the presence of hippocampal sclerosis were associated with cognitive impairment. Mutation carriers presented a higher burden of TDP‐43 pathology and FTLD more frequently than sporadic cases. Most cases (89.4%) presented some degree of concomitant pathologies. The presence of concomitant pathologies was associated with older age at death. FTLD, but also Alzheimer’s disease, were the predominant underlying pathologies explaining the cognitive impairment in ALS patients. In sum, FTLD explained the presence of cognitive decline in most but not all ALS cases, while other non‐FTLD related findings can influence the cognitive status, particularly in older age groups.

Behavioural impairments in mice of a novel FUS transgenic line recapitulate features of frontotemporal lobar degeneration.

Multiple clinical and experimental evidences suggest that amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are members of a disease continuum. Pathological inclusions of fused in sarcoma (FUS) protein have been observed in subsets of patients with these diseases but their anatomical distribution is different for two diseases. These structures are present in motor neurons in ALS cases but in cortical neurons in FTLD cases. Expression of a C-terminally truncated form of human FUS causes an early onset and progressive motor neuron pathology in transgenic mice but only when these neurons express a certain level of this protein. Severe motor dysfunction and early lethality of mice with expression above this level prevent their use for studies of FTLD-related pathology caused by expression of this form of FUS. In the present study, we used another line of mice expressing the same protein but not developing any signs of motor system dysfunction due to substantially lower level of transgene expression in motor neurons. In a set of tests 5-month old mice displayed certain behavioural abnormalities, including increased impulsivity, decreased anxiety and compromised social interaction, which recapitulate behaviour characteristics typically seen in FTLD patients.

Cognitive Impairment Involving Social Cognition in SPG4 Hereditary Spastic Paraplegia.

Objectives. To describe cognitive assessment including social cognition in SPG4 patients. Methods. We reported a series of nine patients with SPG4 mutation with an extensive neuropsychological examination including social cognition assessment. Results. None of our patients presented with mental retardation or dementia. All presented with mild cognitive impairment with a high frequency of attention deficit (100%), executive disorders (89%), and social cognition impairment (78%). An asymptomatic patient for motor skills presented with the same cognitive profile. No correlation was found in this small sample between cognitive impairment and motor impairment, age at disease onset, or disease duration. Conclusions. SPG4 phenotypes share some cognitive features of frontotemporal lobar degeneration and amyotrophic lateral sclerosis. Cognitive disorders including executive disorders and social cognition impairment are frequent in SPG4 patients and might sometimes occur before motor disorders. Therefore, cognitive functions including social cognition should be systematically assessed in order to improve the clinical management of this population.

Pathological features of FTLD-FUS in a Japanese population: Analyses of nine cases

We investigated the pathological features of frontotemporal lobar degeneration (FTLD) with fused in sarcoma protein (FUS) accumulation (FTLD-FUS) in the Japanese population. Only one out of nine FTLD-FUS cases showed pathology that corresponds to atypical FTLD with ubiquitin-positive inclusions (aFTLD-U). Five were basophilic inclusion body disease (BIBD) and two were neuronal intermediate filament inclusion disease. The last case was unclassifiable and was associated with dystrophic neurites (DNs) as the predominant FUS pathology. The results of this study indicate an ethnic difference from western countries. In Japan, BIBD is the most common subtype of FTLD-FUS and aFTLD-U is rare, a finding which contrasts with aFTLD-U being the most common form in western countries. Immunohistochemical analyses of these FTLD-FUS cases reveal that FUS abnormally accumulated in neuronal cytoplasmic inclusions (NCIs) and DNs has an immunohistochemical profile distinct from that of normal, nuclear FUS. NCIs and DNs are more readily stained than the nuclei by antibodies to the middle portion of FUS. Antibodies to the carboxyl terminal portion, on the other hand, stain the nuclei more readily than NCIs and DNs. Such an immunohistochemical profile of NCIs and DNs was similar to that of cytoplasmic granular FUS staining which we previously reported to be associated with dendrites and synapses. Redistribution of FUS from the nucleus to the cytoplasm could be associated with the formation of abnormal FUS aggregates in FTLD-FUS.

Cognitive decline and reduced survival in C9orf72 expansion frontotemporal degeneration and amyotrophic lateral sclerosis

BackgroundSignificant heterogeneity in clinical features of frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) cases with the pathogenic C9orf72 expansion (C9P) have been described. To clarify this issue, we...

Neuronal sensitivity to TDP-43 overexpression is dependent on timing of induction

Ubiquitin-immunoreactive neuronal inclusions composed of TAR DNA binding protein of 43 kDa (TDP-43) are a major pathological feature of frontotemporal lobar degeneration (FTLD-TDP). In vivo studies with TDP-43 knockout mice have suggested that TDP-43 plays a critical, although undefined role in development. In the current report, we generated transgenic mice that conditionally express wild-type human TDP-43 (hTDP-43) in the forebrain and established a paradigm to examine the sensitivity of neurons to TDP-43 overexpression at different developmental stages. Continuous TDP-43 expression during early neuronal development produced a complex phenotype, including aggregation of phospho-TDP-43, increased ubiquitin immunoreactivity, mitochondrial abnormalities, neurodegeneration and early lethality. In contrast, later induction of hTDP-43 in the forebrain of weaned mice prevented early death and mitochondrial abnormalities while yielding salient features of FTLD-TDP, including progressive neurodegeneration and ubiquitinated, phospho-TDP-43 neuronal cytoplasmic inclusions. These results suggest that neurons in the developing forebrain are extremely sensitive to TDP-43 overexpression and that timing of TDP-43 overexpression in transgenic mice must be considered when distinguishing normal roles of TDP-43, particularly as they relate to development, from its pathogenic role in FTLD-TDP and other TDP-43 proteinopathies. Finally, our adult induction of hTDP-43 strategy provides a mouse model that develops critical pathological features that are directly relevant for human TDP-43 proteinopathies.Electronic supplementary materialThe online version of this article (doi:10.1007/s00401-012-0979-3) contains supplementary material, which is available to authorized users.

Molecular basis of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal disorder of motor neuron degeneration with unclear etiology and no effective treatment to date. ALS is, however, increasingly recognized as a multisystem disorder associated with impaired cognition. The overlap between ALS and dementia at clinical, genetic and neuropathologic levels indicates a spectrum of clinical phenotypes that may include features of frontotemporal lobar degeneration (FTLD). Most cases of ALS are sporadic (SALS), but approximately 10% of all ALS cases are familial ALS (FALS). Mutations in the Cu/Zn superoxide dismutase-1 gene (SOD-1) occur in about 20% of FALS cases. Mutations in the TAR DNA-binding protein 43 gene (TARDBP or TDP-43) may occur in 3-4% of FALS cases, and less frequently, in FTLD. Recently, mutations in the fused in sarcoma/translation in liposarcoma gene (FUS/TLS) were identified as causing about 4-5% of FALS, SALS, and FTLD cases, but not SOD-1 ALS cases, indicating a pathogenic role of FUS, together with TDP-43, in possibly all types of ALS, except for SOD-1 linked ALS. TDP-43 and FUS have striking structural and functional similarities, most likely implicating altered RNA processing as a major event in ALS pathogenesis. Thus, TARDBP and FUS/TLS mutations define a novel class of neurodegenerative diseases called TDP-43- and FUS-proteinopathies, in which both misfolded proteins are novel targets for the development of therapeutics in this spectrum of diseases. However, SOD-1 linked ALS may have a pathogenic pathway distinct from other types of ALS.

Clinical and pathological features of frontotemporal lobar degeneration with FUS-positive inclusions

Clinical and pathological features of frontotemporal lobar degeneration with FUS-positive inclusions

Aberrant cleavage of TDP-43 enhances aggregation and cellular toxicity

Inclusions of TAR DNA-binding protein-43 (TDP-43), a nuclear protein that regulates transcription and RNA splicing, are the defining histopathological feature of frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-Us) and sporadic and familial forms of amyotrophic lateral sclerosis (ALS). In ALS and FTLD-U, aggregated, ubiquitinated, and N-terminally truncated TDP-43 can be isolated from brain tissue rich in neuronal and glial cytoplasmic inclusions. The loss of TDP-43 function resulting from inappropriate cleavage, translocation from the nucleus, or its sequestration into inclusions could play important roles in neurodegeneration. However, it is not known whether TDP-43 fragments directly mediate toxicity and, more specifically, whether their abnormal aggregation is a cause or consequence of pathogenesis. We report that the ectopic expression of a approximately 25-kDa TDP-43 fragment corresponding to the C-terminal truncation product of caspase-cleaved TDP-43 leads to the formation of toxic, insoluble, and ubiquitin- and phospho-positive cytoplasmic inclusions within cells. The 25-kDa C-terminal fragment is more prone to phosphorylation at S409/S410 than full-length TDP-43, but phosphorylation at these sites is not required for inclusion formation or toxicity. Although this fragment shows no biological activity, its exogenous expression neither inhibits the function nor causes the sequestration of full-length nuclear TDP-43, suggesting that the 25-kDa fragment can induce cell death through a toxic gain-of-function. Finally, by generating a conformation-dependent antibody that detects C-terminal fragments, we show that this toxic cleavage product is specific for pathologic inclusions in human TDP-43 proteinopathies.

Dual pathologies: Utility of TAR DNA‐binding Protein 43 (TDP‐43) Staining in Patients with Frontal and Temporal Lobe Abnormalities and Alzheimer disease

Prominent behavioral changes and language dysfunction are features of frontotemporal lobar degeneration (FTLD) but can also occur in AD. Recently, application of TAR DNA-binding protein 43 (TDP-43) antibody has been shown to be useful for demonstrating the pathologic lesions of FTLD-U and FTLD-MND. Since these cases might represent combined disorders (FTD and AD), we studied the utility of TDP-43 staining to demonstrate inclusion bodies in brains of patients with clinical features of frontal or temporal lobe dysfunction but with autopsy features of AD. METHODS: Eight patients from 1998 to 2005 were identified, including 1 with combined pathologic features of FTLD-U (previously identified with anti-ubiquitin staining) and mild AD (Braak stage IV). Sections of hippocampus and frontal and temporal lobes were stained with anti-TDP-43 antibody (Proteintech Group). RESULTS: Of the 8 patients, 1 had advanced AD (Braak stage VI) and scattered TDP-43 positive cytoplasmic inclusions in hippocampal dentate granular cells and frontal and temporal neocortical neurons. The previously identified patient with combined FTLD-U and mild AD also had TDP-43 positive cytoplasmic and nuclear inclusions. CONCLUSION: TDP-43 aids in the identification of case with dual pathologies, particularly in advanced AD where inclusion may be masked by overwhelming AD pathology.

Neuropathologic Features of Frontotemporal Lobar Degeneration With Ubiquitin-Positive Inclusions With Progranulin Gene (PGRN) Mutations

Frontotemporal lobar degeneration is heterogeneous; cases with tau- and synuclein-negative, ubiquitin-positive neuronal inclusions are the most common, and some have mutations in the gene for progranulin (PGRN). The purpose of this study was to determine whether there were distinctive clinical and neuropathologic features of frontotemporal lobar degeneration with ubiquitin-positive inclusions with PGRN mutations. A retrospective review of medical records and semiquantitative neuropathologic analysis was performed on 18 PGRN(+) and 24 PGRN(-) cases. Clinically, PGRN(+) cases had more frequent language impairment and parkinsonism. Pathologically, PGRN(+) cases had smaller brains, more marked global atrophy, and more frontal atrophy. There was no difference in the frequency of hippocampal sclerosis. The pathology of PGRN(+) cases was relatively homogeneous, whereas PGRN(-) cases were more heterogenous. PGRN(+) cases had greater density of cortical ubiquitin-immunoreactive lesions, especially dystrophic neurites in layer II. Intranuclear inclusions were present in all PGRN(+) and 42% of PGRN(-) cases. The results suggest that frontotemporal lobar degeneration with ubiquitin-positive inclusions due to PGRN mutations has several characteristic features, including ubiquitin-immunoreactive neuritic pathology in superficial cortical layers and neuronal intranuclear inclusions. On the other hand, there is no histopathologic feature or combination of features that is pathognomonic. Neuronal intranuclear inclusions are virtually always present, but they can be detected in PGRN(-) cases.

Recognition of Facial Expressions of Different Emotional Intensities in Patients with Frontotemporal Lobar Degeneration

Behavioural problems are a key feature of frontotemporal lobar degeneration (FTLD). Also, FTLD patients show impairments in emotion processing. Specifically, the perception of negative emotional facial expressions is affected. Generally, however, negative emotional expressions are regarded as more difficult to recognize than positive ones, which thus may have been a confounding factor in previous studies. Also, ceiling effects are often present on emotion recognition tasks using full-blown emotional facial expressions. In the present study with FTLD patients, we examined the perception of sadness, anger, fear, happiness, surprise and disgust at different emotional intensities on morphed facial expressions to take task difficulty into account. Results showed that our FTLD patients were specifically impaired at the recognition of the emotion anger. Also, the patients performed worse than the controls on recognition of surprise, but performed at control levels on disgust, happiness, sadness and fear. These findings corroborate and extend previous results showing deficits in emotion perception in FTLD.

Frontotemporal lobar degeneration through loss of progranulin function

The striking clinical and pathological features of frontotemporal lobar degeneration (FTLD) have attracted much attention ever since Arnold Pick reported the first disease cases and Alois Alzheimer described the characteristic nerve cell inclusions of Pick's disease. We now know that FTLD is a common cause of dementia, especially in the population below the age of 65 (Neary et al ., 2005). Clinically, it encompasses cases of frontotemporal dementia (FTD), semantic dementia (SD) and primary progressive aphasia (PPA). Of these, FTD is the most common. It is characterized by progressive behavioural and personality disturbances, which evolve gradually into cognitive impairment and dementia. SD is characterized by a loss of conceptual knowledge, whereas in PPA progressive language impairment usually precedes the behavioural symptoms. In some patients, behavioural symptoms are also associated with a parkinsonian syndrome or with motor neuron disease (MND). Pathologically, FTLD is characterized by the severe degeneration of frontal and/or temporal regions of the cerebral cortex. It can be divided into three broad subtypes, based on the presence of abnormal inclusions inside nerve cells. Filamentous cytoplasmic inclusions made of hyperphosphorylated tau protein characterize a proportion of cases with FTLD, including Pick's disease (Spillantini et al ., 1998). In recent years, it has become apparent that a substantial number of disease cases is characterized by the presence of tau-negative, ubiquitin-positive inclusions (FTLD-U) (Hodges et al ., 2004). The third subtype, FTLD lacking distinctive histopathology, where abnormal inclusions are not observed, now appears to be much less common than believed previously (Mackenzie et al ., 2006 a ). FTLD has a substantial genetic component, in that up to 40% of cases are inherited in a dominant manner (Rosso et al ., 2003). Several disease loci and genes have been identified on chromosomes 3, 9 and 17. Mutations in the Tau gene on …

Structural anatomy of empathy in neurodegenerative disease

Empathy is a complex social behaviour mediated by a network of brain structures. Recently, several functional imaging studies have investigated the neural basis of empathy, but few corroborative human lesion studies exist. Severe empathy loss is a common feature of frontotemporal lobar degeneration (FTLD), and is also seen in other neurodegenerative diseases. In this study, the neuroanatomic basis of empathy was investigated in 123 patients with FTLD, Alzheimer's disease, corticobasal degeneration and progressive supranuclear palsy using the Interpersonal Reactivity Index (IRI). IRI Empathic Concern and Perspective taking scores were correlated with structural MRI brain volume using voxel-based morphometry. Voxels in the right temporal pole, the right fusiform gyrus, the right caudate and right subcallosal gyrus correlated significantly with total empathy score (P < 0.05 after whole-brain correction for multiple comparisons). Empathy score correlated positively with the volume of right temporal structures in semantic dementia, and with subcallosal gyrus volume in frontotemporal dementia. These findings are consistent with previous research suggesting that a primarily right frontotemporal network of brain regions is involved in emotion processing, and highlights the roles of the right temporal pole and inferior frontal/striatal regions in regulating complex social interactions. This is the first large-scale lesion study to investigate the neural basis of empathy using correlational analytic methods. The results suggest that the right anterior temporal and medial frontal regions are essential for real-life empathic behaviour.

P3-103: Demographic features of frontotemporal lobar degeneration

P3-103: Demographic features of frontotemporal lobar degeneration

In vivo detection of microglial activation in frontotemporal dementia

Using positron emission tomography and [(11)C](R)-PK11195, a marker of "peripheral benzodiazepine sites" that is upregulated on activated microglia during progressive tissue pathology, we show increased binding of [(11)C](R)-PK11195 in frontotemporal lobar degeneration in the typically affected frontotemporal brain regions. This implies the presence of an active glial response reflecting progressive neuronal degeneration. It also suggests that increased [(11)C](R)-PK11195 binding, previously demonstrated for Alzheimer's disease, may occur independently from increased amyloid plaque formation, given that it is not a characteristic feature of frontotemporal lobar degeneration.