Dominant frontotemporal dementia mutations in 140 cases of primary progressive aphasia and speech apraxia

Apraxia phenotypes and frontotemporal lobar degeneration

BACKGROUND

Apraxia has been identified in all clinical forms of frontotemporal lobar degeneration (FTLD). The characteristics of apraxia symptoms and their underlying cognitive/motor basis are not fully understood. This study investigated apraxia in pathological subtypes of FTLD.

METHODS

The study constituted a retrospective review of 115 pathologically confirmed cases of FTLD from a single cognitive neurology centre. Patients in whom apraxia had been documented as a notable clinical characteristic were identified. Apraxia features, demographic, cognitive, neurological, and imaging findings were recorded.

RESULTS

Eighteen patients were identified: 12 with FTLD-tau pathology (7 corticobasal degeneration (CBD), four Pick type and one progressive supranuclear palsy (PSP)) and six with FTLD-TDP pathology, all type A and four linked to progranulin gene mutations. Apraxia as a dominant presenting feature was typically associated with tau pathologies, whereas it emerged in the context of aphasia in TDP pathology. Apraxia typically predominated in one body part (face or limb) in tau but not TDP pathology. Relatively preserved activities in daily life were associated with TDP. Apraxia of speech was associated with tau pathology. Pick-type pathology was linked to symmetrical atrophy and late development of limb rigidity.

CONCLUSION

Apraxia in FTLD subtypes has variable characteristics. Apraxia associated with CBD pathology conformed to criteria for probable corticobasal syndrome (CBS), whereas apraxia with Pick-type pathology did not. Apraxia in patients with TDP-A pathology was interpreted as one manifestation of their generalised communication disorder. Apraxia in FTLD may have distinct cognitive and motor substrates that require prospective investigation.

Primary progressive aphasia: six questions in search of an answer

Here, we review recent progress in the diagnosis and management of primary progressive aphasia-the language-led dementias. We pose six key unanswered questions that challenge current assumptions and highlight the unresolved difficulties that surround these diseases. How many syndromes of primary progressive aphasia are there-and is syndromic diagnosis even useful? Are these truly 'language-led' dementias? How can we diagnose (and track) primary progressive aphasia better? Can brain pathology be predicted in these diseases? What is their core pathophysiology? In addition, how can primary progressive aphasia best be treated? We propose that pathophysiological mechanisms linking proteinopathies to phenotypes may help resolve the clinical complexity of primary progressive aphasia, and may suggest novel diagnostic tools and markers and guide the deployment of effective therapies.

Speech and phonological impairment across Alzheimer's disease severity

INTRODUCTION

Phonetic-phonological impairments have been described in dementia due to Alzheimer's disease (AD). However, whether the likely phonological-linguistic changes progress with the evolution of the disease or whether phonetic-motor manifestations occur in all three stages of AD (mild, moderate, and severe) has not yet been clarified. Thus, the aim of this study was to verify whether phonological-linguistic and phonetic-motor speech manifestations occur in the mild, moderate, and severe stages of AD.

METHODS

Thirty participants in each stage of probable AD (mild, moderate, and severe) and 30 healthy older adults underwent cognitive, instrumental activities of daily living and phonetic-phonological assessments. Phonetic-phonological manifestations were classified into three types: likely phonetic-motor, likely phonological-linguistic, and manifestations that may occur in disorders of both phonetic and phonological origin.

RESULTS

The manifestations analyzed in this study occurred rarely. The manifestations that may occur in disorders of both phonetic and phonological origin were the most common in all stages of the disease. The likely phonetic-motor manifestations emerged during the mild stage of the disease (distortions, prolonged intersegment duration, and vowel prolongations), while the likely phonological-linguistic manifestations were present mainly in the moderate (substitutions and attempts at the word level) and severe stages (substitutions, attempts at the word level, self-corrections, and anticipations). The occurrence of phonetic-phonological manifestations increased with disease progression.

CONCLUSIONS

The type of phonological and phonetic manifestations in the individuals with AD differed according to the dementia stage and were statistically more frequent as dementia worsened.

An Update on Apraxia of Speech

PURPOSE OF REVIEW

Apraxia of speech (AOS) is a motor speech disorder that has long been recognized to occur secondary to acute neurologic insults and, more recently, to neurodegenerative diseases as a harbinger for progressive supranuclear palsy and corticobasal syndrome. This article reviews recent findings regarding the clinic phenotypes of AOS, neuroimaging correlates, and the underlying disease processes.

RECENT FINDINGS

Two clinical subtypes of AOS map onto two underlying 4-repeat tauopathies. New imaging techniques have recently been applied to the study of progressive AOS. There is no data on the impact of behavioral intervention, although studies of nonfluent/agrammatic primary progressive aphasia that include patients with AOS suggest some benefit in speech intelligibility and maintenance. While recent findings suggest subtypes of AOS exist that are linked to molecular pathology and have important implications for disease progression, further research is needed to assess outcome of behavioral and other types of intervention.

Primary progressive aphasias associated with C9orf72 expansions: Another side of the story

C9orf72 repeat expansions are rarely associated with primary progressive aphasias (PPA). In-depth characterization of the linguistic deficits, and the underlying patterns of grey-matter atrophy in PPA associated with the C9orf72 expansions (PPA-C9orf72) are currently lacking. In this study, we comprehensively analyzed a unique series of 16 patients affected by PPA-C9orf72. Eleven patients were issued from two independent French and Finnish cohorts, and five were identified by means of literature review. Voxel-based morphometry (VBM) studies were performed on three of them. This study depicts the spectrum of C9orf72-related aphasic phenotypes, and illustrates their linguistic presentation. The non-fluent/agrammatic variant was the most frequent phenotype in our series (9/16 patients, 56%), with apraxia of speech being the main defining feature. Left frontal lobe atrophy was present in these subjects, peaking in inferior frontal gyrus. Three patients (19%) showed the semantic variant, with progression of atrophy in temporo-polar regions, later involving orbitofrontal cortex. Anterior temporal lobe dysfunction was also particularly relevant in two patients (12.5%) with mixed forms of PPA. Lastly, two patients (12.5%) had unclassifiable PPA with predominating word-finding difficulties. No PPA-C9orf72 patients in our series fulfilled the criteria of the logopenic variant. Importantly, this study underlines the role of C9orf72 mutation in the disruption of the most anterior parts of the language network, including prefrontal and temporo-polar areas. It provides guidelines for C9orf72 testing in PPA patients, with important clinical impact as gene-specific therapies are upcoming.

Whole-Exome Sequencing and C9orf72 Analysis in Primary Progressive Aphasia

Primary progressive aphasia (PPA) is mainly considered a sporadic disease and few studies have systematically analyzed its genetic basis. We here report the analyses of C9orf72 genotyping and whole-exome sequencing data in a consecutive and well-characterized cohort of 50 patients with PPA. We identified three pathogenic GRN variants, one of them unreported, and two cases with C9orf72 expansions. In addition, one likely pathogenic variant was found in the SQSTM1 gene. Overall, we found 12%of patients carrying pathogenic or likely pathogenic variants. These results support the genetic role in the pathophysiology of a proportion of patients with PPA.

Primary Progressive Aphasia Associated With GRN Mutations: New Insights Into the Nonamyloid Logopenic Variant

OBJECTIVE

To determine relative frequencies and linguistic profiles of primary progressive aphasia (PPA) variants associated with GRN (progranulin) mutations and to study their neuroanatomic correlates.

METHODS

Patients with PPA carrying GRN mutations (PPA-GRN) were selected among a national prospective research cohort of 1,696 patients with frontotemporal dementia, including 235 patients with PPA. All patients with amyloid-positive CSF biomarkers were excluded. In this cross-sectional study, speech/language and cognitive profiles were characterized with standardized evaluations, and gray matter (GM) atrophy patterns using voxel-based morphometry. Comparisons were performed with controls and patients with sporadic PPA.

RESULTS

Among the 235 patients with PPA, 45 (19%) carried GRN mutations, and we studied 32 of these. We showed that logopenic PPA (lvPPA) was the most frequent linguistic variant (n = 13, 41%), followed by nonfluent/agrammatic (nfvPPA; n = 9, 28%) and mixed forms (n = 8, 25%). Semantic variant was rather rare (n = 2, 6%). Patients with lvPPA, qualified as nonamyloid lvPPA, presented canonical logopenic deficit. Seven of 13 had a pure form; 6 showed subtle additional linguistic deficits not fitting criteria for mixed PPA and hence were labeled as logopenic-spectrum variant. GM atrophy involved primarily left posterior temporal gyrus, mirroring neuroanatomic changes of amyloid-positive-lvPPA. Patients with nfvPPA presented agrammatism (89%) rather than apraxia of speech (11%).

CONCLUSIONS

This study shows that the most frequent PPA variant associated with GRN mutations is nonamyloid lvPPA, preceding nfvPPA and mixed forms, and illustrates that the language network may be affected at different levels. GRN testing is indicated for patients with PPA, whether familial or sporadic. This finding is important for upcoming GRN gene-specific therapies.

Neurobehavioral Characteristics of FDG-PET Defined Right-Dominant Semantic Dementia: A Longitudinal Study

INTRODUCTION

Semantic dementia (SD) is characterized by fluent speech, anomia, and loss of word and object knowledge with varying degrees of right and left anterior-medial temporal lobe hypometabolism on [18F] fluorodeoxyglucose (FDG)-PET. We assessed neurobehavioral features in SD patients across 3 FDG-PET-defined metabolic patterns and investigated progression over time.

METHODS

Thirty-four patients with SD who completed FDG-PET were classified into a left- and right-dominant group based on the degree of hypometabolism in each temporal lobe. The left-dominant group was further subdivided depending on whether hypometabolism in the right temporal lobe was more or less than 2 standard deviations from controls (left+ group). Neurobehavioral characteristics determined using the Neuropsychiatric Inventory Questionnaire (NPI-Q) were compared across groups. Progression of NPI-Q scores and FDG-PET hypometabolism was assessed in 14 patients with longitudinal follow-up.

RESULTS

The right-dominant group performed worse on the NPI-Q and had a greater frequency of abnormal behaviors and more severe disinhibition compared to the left-dominant group. Performance on the NPI-Q and severity of disinhibition correlated with right medial and lateral, but not left, temporal lobe hypometabolism. Severity of abnormal behaviors worsened over time in most left-dominant and left+ patients but appeared to improve in the 2 right-dominant patients with longitudinal follow-up. All groups showed progressive worsening of metabolism in both temporal lobes over time, with hypometabolism spreading from anteromedial to posterior temporal regions. However, the degree of temporal lobe asymmetry remained relatively constant over time.

CONCLUSION

In SD, neurobehavioral features, especially disinhibition, are associated with right medial and lateral temporal lobe hypometabolism and commonly develop over time even in patients that present with left-dominant patterns of hypometabolism.

Clinical Update on C9orf72: Frontotemporal Dementia, Amyotrophic Lateral Sclerosis, and Beyond

The identification of C9orf72 gene has led to important scientific progresses and has considerably changed our clinical practice. However, a decade after C9orf72 discovery, some important clinical questions remain unsolved. The reliable cutoff for the pathogenic repeat number and the implication of intermediate alleles in frontotemporal dementia, amyotrophic lateral sclerosis, or in other diseases are still uncertain. The occurrence of an anticipation phenomenon - at the clinical and molecular levels - in C9orf72 kindreds is still debated as well, and the factors driving age at onset and phenotype variability are largely unknown. All these questions have a significant impact not only in clinical practice for diagnosis and genetic counseling but also in a research context for the initiation of therapeutic trials. In this chapter, we will address all those issues and summarize the recent updates about clinical aspects of C9orf72 disease, focusing on both the common and the less typical phenotypes.

C9orf72 Repeat Expansion Does Not Affect the Phenotype in Primary Progressive Aphasia

Primary progressive aphasia (PPA) forms the spectrum of language variants of frontotemporal lobar degeneration (FTLD), including three subtypes each consisting of distinctive speech and language features. Repeat expansion in C9orf72 gene is the most common genetic cause of FTLD. However, thus far only little is known about the effects of the C9orf72 repeat expansion on the phenotype of PPA. This retrospective study aimed at determining the differences between the PPA phenotypes of the C9orf72 expansion carriers and non-carriers. Our results demonstrated no significant differences between these groups, indicating that the C9orf72 repeat expansion does not substantially affect the phenotype of PPA.

Primary Progressive Apraxia of Speech: From Recognition to Diagnosis and Care

BACKGROUND

Apraxia of speech (AOS) can be caused by neurodegenerative disease and sometimes is its presenting sign (i.e., primary progressive apraxia of speech, PPAOS). During the last several decades our understanding of PPAOS has evolved from clinical recognition to a fuller understanding of its core and associated clinical features, its distinction from but relationship with primary progressive aphasia, its temporal course and eventual progression to include other neurological deficits, and its neuroimaging correlates and underlying pathology.

AIMS

This paper provides a comprehensive summary of the literature that has built the current knowledge base about PPAOS and progressive AOS as it co-occurs with progressive aphasia. It reviews the history of its emergence as a recognized syndrome; its relationship with the agrammatic/nonfluent variant of primary progressive aphasia; its salient perceptual features and subtypes; the acoustic and structural/physiological imaging measures that index its presence, severity, and distinction from aphasia; and principles and available data regarding its management and care.

MAIN CONTRIBUTION

A broad summary of what is known about AOS as a manifestation of neurodegenerative disease.

CONCLUSIONS

Primary progressive apraxia of speech is a recognizable syndrome that can be distinguished from other neurodegenerative conditions that affect speech and language.

Genotype-phenotype links in frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) represents a group of neurodegenerative brain diseases with highly heterogeneous clinical, neuropathological and genetic characteristics. This high degree of heterogeneity results from the presence of several different underlying molecular disease processes; consequently, it is unlikely that all patients with FTLD will benefit from a single therapy. Therapeutic strategies for FTLD are currently being explored, and tools are urgently needed that enable the selection of patients who are the most likely to benefit from a particular therapy. Definition of the phenotypic characteristics in patients with different FTLD subtypes that share the same underlying disease processes would assist in the stratification of patients into homogeneous groups. The most common subtype of FTLD is characterized by TAR DNA-binding protein 43 (TDP43) pathology (FTLD-TDP). In this group, pathogenic mutations have been identified in four genes: C9orf72, GRN, TBK1 and VCP. Here, we provide a comprehensive overview of the phenotypic characteristics of patients with FTLD-TDP, highlighting shared features and differences among groups of patients who have a pathogenic mutation in one of these four genes.

Genetic screen in a large series of patients with primary progressive aphasia

INTRODUCTION

Primary progressive aphasia (PPA) is a neurological syndrome, associated with both frontotemporal dementia and Alzheimer's disease, in which progressive language impairment emerges as the most salient clinical feature during the initial stages of disease.

METHODS

We screened the main genes associated with Alzheimer's disease and frontotemporal dementia for pathogenic and risk variants in a cohort of 403 PPA cases.

RESULTS

In this case series study, 14 (3.5%) cases carried (likely) pathogenic variants: four C9orf72 expansions, nine GRN, and one TARDBP mutation. Rare risk variants, TREM2 R47H and MAPT A152T, were associated with a three- to seven-fold increase in risk for PPA.

DISCUSSION

Our results show that while pathogenic variants within the most common dementia genes were rarely associated with PPA, these were found almost exclusively in GRN and C9orf72, suggesting that PPA is more TDP43- than tau-related in our series. This is consistent with the finding that PPA frequency in dominantly inherited dementias is the highest in kindreds with GRN variants.

Primary Progressive Aphasias and Apraxia of Speech

PURPOSE OF REVIEW

This article reviews two of the primary progressive aphasias (PPAs), disorders characterized by the early and predominant impairment of language, and primary progressive apraxia of speech, a degenerative motor speech disorder that is closely related to PPA. An outline of the history and controversy surrounding how these disorders are classified is provided before the article focuses on each disorder's clinical and imaging features.

RECENT FINDINGS

Over the past decade, the classification of degenerative speech and language disorders has been refined. Clinical, imaging, and pathologic evidence suggests that primary progressive apraxia of speech is a distinct degenerative disorder. Furthermore, multiple lines of evidence have highlighted issues with nonfluent/agrammatic variant PPA, which complicates the diagnosis, prognosis, and study of this disorder. Semantic variant PPA, while not without controversy, remains one of the most well-defined disorders, with good clinicopathologic correlation.

SUMMARY

Accurate classification and diagnosis of these degenerative speech and language disorders is crucial in clinical practice and ongoing research efforts. For nonfluent/agrammatic variant PPA, the authors suggest emphasizing agrammatism as the core inclusion criterion and taking care not to include patients with isolated or predominant apraxia of speech. Isolated apraxia of speech can be the manifestation of a degenerative disease and, based on the different prognosis, should be recognized as distinct from PPA. Finally, it is important to recognize that some patients with semantic dementia, despite sharing the same pathologic associations, may not meet criteria for PPA.

Frontotemporal Dementia Caused by the P301L Mutation in the MAPT Gene: Clinicopathological Features of 13 Cases from the Same Geographical Origin in Barcelona, Spain

BACKGROUND/AIMS

We identified and studied 13 patients carrying the P301L mutation in the MAPT gene from the same area (Baix Llobregat County) in Barcelona, Spain.

METHODS

The demographic and clinical features were reviewed retrospectively. Detailed neuropathological characterization was obtained in 9 subjects. To investigate the origin of the P301L mutation in these families, 20 single nucleotide polymorphisms (SNPs) in the MAPT gene were analyzed.

RESULTS

The mean age at disease onset was 51 years and the mean disease duration was 7 years. The most common initial symptoms were behavioral changes (54%), followed by language disturbances (31%) and memory loss (15%). 46% developed parkinsonism. Neuropathology showed an extensive neuronal and glial 4-repeat (4R) tauopathy with "mini-Pick"-like bodies in the dentate gyrus as the characteristic underlying pathology in all cases. In 1 subject, additional 4R globular glial inclusions were observed. All the mutation carriers showed the same haplotype for the SNPs analyzed, suggesting a common ancestor.

CONCLUSION

These findings suggest a relative homogeneous clinicopathological phenotype in P301L MAPT mutation carriers in our series. This phenotype might help in the differential diagnosis from other tauopathies and be a morphological hint for genetic testing. The haplotype analysis results suggest a founder effect of the P301L mutation in this area.

Functional characterization of a novel progranulin mutation in a patient with progressive nonfluent aphasia

Loss-of-function mutations in progranulin (PGRN) gene cause frontotemporal lobar degeneration. Here, we report a case of a 63-year-old woman with a 2-year history of speech impairment, diagnosed with a nonfluent variant of primary progressive aphasia, a subtype of frontotemporal lobar degeneration. In this patient, a novel heterozygous frameshift mutation, c.77delG, in exon 2 of PGRN gene, introducing premature stop codon, p.(C26SfsX28), has been identified. Cultured fibroblasts derived from the patient and her asymptomatic first-degree relative with c.77delG mutation had decreased levels of PGRN messenger RNA (mRNA) and protein. However, PGRN mRNA levels did not recover upon incubation with inhibitors of nonsense-mediated mRNA decay (cycloheximide or puromycin), suggesting involvement of other mRNA degradation pathways. In addition, we observed upregulated wingless-type mouse mammary tumor virus integration site (WNT) signaling pathway gene, WNT3A, in fibroblasts of the patient and her asymptomatic first-degree relative with c.77delG mutation. As reported previously, this is an early hallmark of PGRN deficiency.

A new MAPT deletion in a case of speech apraxia leading to corticobasal syndrome

Speech apraxia is a disorder of speech motor planning/programming leading to slow rate, articulatory distortion, and distorted sound substitutions. We describe the clinical profile evolution of a patient presenting with slowly progressive isolated speech apraxia that eventually led to the diagnosis of corticobasal syndrome (CBS), supporting the evidence that this rare speech disorder can be the first presentation of CBS. Moreover, we found a novel variant in MAPT gene, which is hypothesized to be disease-causing mutation. These results underscore the importance of genetic analysis - particularly in selected atypical cases - for in vivo understanding of possible pathophysiological disease process.

Diagnostic Distortions: A Case Report of Progressive Apraxia of Speech

Apraxia of speech (AOS) can be the presenting symptom of neurodegenerative disease. The position of primary progressive AOS in the nosology of the dementias is still controversial. Despite seeing many specialists, patients are often misdiagnosed, in part due to a lack of quantitative measures of speech dysfunction. We present a single case report of a patient presenting with AOS, including acoustic analysis, language assessment, and brain imaging. A 52-year-old woman presenting with AOS had remained undiagnosed for 6 years despite seeing 8 specialists. Results of her MRI scans, genetic testing, and computerized speech analysis are provided. AOS is an underdiagnosed clinical syndrome causing great distress to patients and families. Using acoustic analysis of speech may lead to improved diagnostic accuracy. AOS is a complex entity with an expanding phenotype, and quantitative clinical measures will be critical for detection and to assess progression.

Frontotemporal Dementia

Frontotemporal dementia (FTD) is a heterogeneous disorder with distinct clinical phenotypes associated with multiple neuropathologic entities. Presently, the term FTD encompasses clinical disorders that include changes in behavior, language, executive control, and often motor symptoms. The core FTD spectrum disorders include behavioral variant FTD, nonfluent/agrammatic variant primary progressive aphasia, and semantic variant PPA. Related FTD disorders include frontotemporal dementia with motor neuron disease, progressive supranuclear palsy syndrome, and corticobasal syndrome. In this article, the authors discuss the clinical presentation, diagnostic criteria, neuropathology, genetics, and treatments of these disorders.

Tracking the development of agrammatic aphasia: A tensor-based morphometry study

Agrammatic aphasia can be observed in neurodegenerative disorders and has been traditionally linked with damage to Broca's area, although there have been disagreements concerning whether damage to Broca's area is necessary or sufficient for the development of agrammatism. We aimed to investigate the neuroanatomical correlates of the emergence of agrammatic aphasia utilizing a unique cohort of patients with primary progressive apraxia of speech (PPAOS) that did not have agrammatism at baseline but developed agrammatic aphasia over time. Twenty PPAOS patients were recruited and underwent detailed speech/language assessments and 3T MRI at two visits, approximately two years apart. None of the patients showed evidence of agrammatism in writing or speech at baseline. Eight patients developed aphasia at follow-up (progressors) and 12 did not (non-progressors). Tensor-based morphometry utilizing symmetric normalization (SyN) was used to assess patterns of grey matter atrophy and voxel-based morphometry was used to assess patterns of grey matter loss at baseline. The progressors were younger at onset and more likely to show distorted sound substitutions or additions compared to non-progressors. Both groups showed change over time in premotor and motor cortices, posterior frontal lobe, basal ganglia, thalamus and midbrain, but the progressors showed greater rates of atrophy in left pars triangularis, thalamus and putamen compared to non-progressors. The progressors also showed greater grey matter loss in pars triangularis and putamen at baseline. This cohort provided a unique opportunity to assess the anatomical changes that accompany the development of agrammatic aphasia. The results suggest that damage to a network of regions including Broca's area, thalamus and basal ganglia are responsible for the development of agrammatic aphasia in PPAOS. Clinical and neuroimaging abnormalities were also present before the onset of agrammatism that could help improve prognosis in these subjects.

A Novel MAPT Mutation Causing Corticobasal Syndrome Led by Progressive Apraxia of Speech

The authors describe a case of corticobasal syndrome led by progressive apraxia of speech, associated with a novel mutation in exon 10 of the MAPT gene. Genetic bases for progressive apraxia of speech and corticobasal syndrome are only rarely described, and have not been described in conjunction.

Clinical and MRI models predicting amyloid deposition in progressive aphasia and apraxia of speech

Beta-amyloid (Aβ) deposition can be observed in primary progressive aphasia (PPA) and progressive apraxia of speech (PAOS). While it is typically associated with logopenic PPA, there are exceptions that make predicting Aβ status challenging based on clinical diagnosis alone. We aimed to determine whether MRI regional volumes or clinical data could help predict Aβ deposition. One hundred and thirty-nine PPA (n = 97; 15 agrammatic, 53 logopenic, 13 semantic and 16 unclassified) and PAOS (n = 42) subjects were prospectively recruited into a cross-sectional study and underwent speech/language assessments, 3.0 T MRI and C11-Pittsburgh Compound B PET. The presence of Aβ was determined using a 1.5 SUVR cut-point. Atlas-based parcellation was used to calculate gray matter volumes of 42 regions-of-interest across the brain. Penalized binary logistic regression was utilized to determine what combination of MRI regions, and what combination of speech and language tests, best predicts Aβ (+) status. The optimal MRI model and optimal clinical model both performed comparably in their ability to accurately classify subjects according to Aβ status. MRI accurately classified 81% of subjects using 14 regions. Small left superior temporal and inferior parietal volumes and large left Broca's area volumes were particularly predictive of Aβ (+) status. Clinical scores accurately classified 83% of subjects using 12 tests. Phonological errors and repetition deficits, and absence of agrammatism and motor speech deficits were particularly predictive of Aβ (+) status. In comparison, clinical diagnosis was able to accurately classify 89% of subjects. However, the MRI model performed well in predicting Aβ deposition in unclassified PPA. Clinical diagnosis provides optimum prediction of Aβ status at the group level, although regional MRI measurements and speech and language testing also performed well and could have advantages in predicting Aβ status in unclassified PPA subjects.

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We examine whether MRI or clinical data can predict Aβ deposition in PPA and PAOS.

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MRI and clinical data accurately classified 81% and 83% of subjects, respectively.

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Small superior temporal gyri and phonological errors best predicted Aβ deposition.

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In comparison, clinical diagnosis accurately classified 89% of subjects.

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MRI and clinical data could predict discordant svPPA, lvPPA and unclassified cases.

Understanding Neuropsychiatric Diseases, Analyzing the Peptide Sharing between Infectious Agents and the Language-Associated NMDA 2A Protein

Language disorders and infections may occur together and often concur, to a different extent and via different modalities, in characterizing brain pathologies, such as schizophrenia, autism, epilepsies, bipolar disorders, frontotemporal neurodegeneration, and encephalitis, inter alia. The biological mechanism(s) that might channel language dysfunctions and infections into etiological pathways connected to neuropathologic sequelae are unclear. Searching for molecular link(s) between language disorders and infections, the present study explores the language-associated NMDA 2A subunit for peptide sharing with pathogens that have been described in concomitance with neuropsychiatric diseases. It was found that a vast peptide commonality links the human glutamate ionotropic receptor NMDA 2A subunit to infectious agents. Such a link expands to and interfaces with neuropsychiatric disorders in light of the specific allocation of NMDA 2A gene expression in brain areas related to language functions. The data hint at a possible pathologic scenario based on anti-pathogen immune responses cross-reacting with NMDA 2A in the brain.

GBA-associated parkinsonism and dementia: beyond α-synucleinopathies?

BACKGROUND AND PURPOSE

To date the role of GBA mutations beyond α-synucleinopathies in the parkinsonism-dementia spectrum is still unclear. The aim of the study was to screen for GBA mutations in progressive supranuclear palsy (PSP), corticobasal syndrome (CBS), primary progressive aphasia (PPA) and the behavioural variant of frontotemporal dementia (bvFTD).

METHODS

In all, 303 patients with a clinical diagnosis of PSP (n = 157), CBS (n = 39), PPA (n = 35) and bvFTD (n = 72) and 587 neurologically healthy controls were screened for the most common GBA mutations.

RESULTS

GBA mutations were detected in one healthy control and four patients with a clinical diagnosis of PSP (n = 1), probable CBS (n = 2) and PPA (n = 1, with concomitant C9orf72 expansion). Overall the prevalence of GBA mutations was low in non-α-synucleinopathies but significantly higher in the CBS subgroup compared to controls.

CONCLUSION

Although numbers are small, our findings indicate that the clinical phenotype of GBA-associated neurodegenerative disease is more heterogeneous than previously assumed, including phenotypes not usually associated with underlying α-synucleinopathies. This may be of relevance, once causal therapeutic strategies for GBA-associated neurodegenerative disease are developed.

Semantic and nonfluent aphasic variants, secondarily associated with amyotrophic lateral sclerosis, are predominant frontotemporal lobar degeneration phenotypes in TBK1 carriers

INTRODUCTION

TBK1 mutations represent a rare novel genetic cause of amyotrophic lateral sclerosis (ALS) without or with dementia. The full spectrum of TBK1 phenotypes has not been completely defined so far.

METHODS

We describe the clinical and neuroimaging characteristics of loss-of-function mutation carriers initially presenting with frontotemporal lobar degeneration (FTLD) phenotypes.

RESULTS

Two carriers initially presented semantic variant of FTLD (svFTLD); two other developed nonfluent variant of FTLD (nfvFTLD) and corticobasal syndrome (CBS), associated with severe anterior temporal and opercular atrophy. All secondarily developed ALS.

DISCUSSION

This study enlarges the phenotypic spectrum of TBK1 mutations, including svFTLD and nfvFTLD/CBS, not reported so far. Aphasic presentations seem to be more evocative of TBK1 genotype than behavioral variant of FTLD, and TBK1 should be analyzed in patients with isolated FTLD at onset, particularly in rare aphasic cases secondarily associated with ALS.