Towards a clearer definition of logopenic progressive aphasia

Clinical and cortical trajectories in non-fluent primary progressive aphasia and Alzheimer's disease: A role for emotion processing

OBJECTIVES

To examine the clinical trajectories and neural correlates of cognitive and emotion processing changes in the non-fluent/agrammatic (nfvPPA) and the logopenic (lvPPA) variants of primary progressive aphasia (PPA).

DESIGN

Observational case-control longitudinal cohort study.

SETTING

Research clinic of frontotemporal dementia.

PARTICIPANTS

This study recruited 29 non-semantic PPA patients (15 nfvPPA and 14 lvPPA) and compared them with 15 Alzheimer's disease (AD) patients and 14 healthy controls.

MEASUREMENTS

Participants completed an annual assessment (median = 2 years; range = 1-5 years) of general cognition, emotion processing and structural MRI. Linear mixed effects models investigated clinical and imaging trajectories between groups.

RESULTS

Over time, lvPPA showed the greatest cognitive deterioration. In contrast, nfvPPA showed significant decline in emotion recognition, whereas AD showed preserved emotion recognition, even with disease progression. Importantly, lvPPA also developed emotion processing impairments, with disease progression. Both nfvPPA and lvPPA showed continuing cortical atrophy in hallmark language-processing regions associated with these syndromes, together with progressive involvement of the right hemisphere regions, mirroring left hemisphere atrophy patterns at presentation. Decline in emotion processing was associated with bilateral frontal atrophy in nfvPPA and right temporal atrophy in lvPPA.

CONCLUSIONS

Our results show divergent clinical courses in nfvPPA and lvPPA, with rapid cognitive and neural deterioration in lvPPA and emotion processing decline in both groups and support the concurrent assessment of cognition and emotion processing in the clinic to inform diagnosis and monitoring in the non-semantic variants of PPA.

Secondary language impairment in posterior cortical atrophy: insights from sentence repetition

Introduction

Posterior cortical atrophy (PCA) is a neurodegenerative syndrome characterized by progressive impairment in visuospatial and perceptual function linked to atrophy of the occipito-parietal cortex. Besides the salient visual impairment, several studies have documented subtle changes in language may also be present. Sentence repetition is a highly constrained linguistic task involving multiple linguistic and cognitive processes and have been shown to be impaired in other AD spectrum disorders, with little consensus on its relevance in PCA. This aim of this study was to further delineate the linguistic and cognitive features of impaired language in PCA using a sentence repetition task.

Method

Seven PCA patients and 16 healthy controls verbally repeated 16 sentences from the Boston Diagnostic Aphasia Examination. Responses were transcribed orthographically and coded for accuracy (percentage accuracy; percentage Correct Information Units; Levenshtein Distance) and for temporal characteristics (preparation duration (ms); utterance duration (ms); silent pause duration (ms); speech duration (ms); dysfluency duration (ms)). The potential modulating effects of attentional control and working memory capacity were explored.

Results

PCA patients showed lower overall accuracy with retained semantic content of the sentences, and lower phonological accuracy. Temporal measures revealed longer preparation and utterance duration for PCA patients compared to controls, alongside longer speech duration but comparable dysfluency duration. PCA patients also showed comparable silent pause duration to controls. Attentional control, measured using the Hayling sentence completion task, predicted accuracy of sentence repetition.

Discussion

The findings suggest that sentence repetition is impaired in PCA and is characterized by phonological, response planning and execution difficulties, underpinned in part by attentional control mechanisms. The emerging profile of language impairment in PCA suggests vulnerability of similar cognitive systems to other Alzheimer's syndromes, with subtle differences in clinical presentation.

Comparing two picture naming tasks in primary progressive aphasia: Insights from behavioural and neural results

Picture naming tests are widely used to evaluate language impairments in neurodegenerative diseases, especially in Primary Progressive Aphasia (PPA). The available tests differ for many factors affecting the performance, e.g. format of stimuli and their psycholinguistic properties. We aim to identify the most appropriate naming test to be used on PPA according to the clinical and research demands. We investigated the behavioural characteristics, i.e. proportion of correct responses and error type, and their neural correlates in two Italian naming tests, CaGi naming (CaGi) and naming subtest of the Screening for Aphasia in NeuroDegeneration battery (SAND), administered to 52 PPA patients who underwent an FDG-PET scan. We analysed the effectiveness of the tests in distinguishing PPA versus controls and among PPA variants, considering the psycholinguistic variables affecting performance. We explored the brain metabolic correlates of behavioural performance in the tests. SAND, differently from CaGi, has time limits for the response and its items are less frequent and acquired later. SAND and CaGi differed in terms of number of correct responses and error profile, suggesting a higher difficulty to name SAND items compared to CaGi. Semantic errors predominated in CaGi, while anomic and semantic errors were equally frequent in SAND. Both tests distinguished PPA from controls, but SAND outperformed CaGi in discriminating among PPA variants. FDG-PET imaging revealed a shared metabolic involvement of temporal areas associated with lexico-semantic processing, encompassing anterior fusiform, temporal pole, and extending to posterior fusiform in sv-PPA. Concluding, a picture naming test with response time limit and items which are less frequent and acquired later in life, as SAND, may be effective at highlighting subtle distinctions between PPA variants, improving the diagnosis. Conversely, a naming test without time limit for the response, as CaGi, may be useful for a better characterization of the nature of the naming impairment at the behavioural level, eliciting more naming errors than anomia, possibly helping in the development of rehabilitation protocols.

Understanding the multidimensional cognitive deficits of logopenic variant primary progressive aphasia

The logopenic variant of primary progressive aphasia is characterized by early deficits in language production and phonological short-term memory, attributed to left-lateralized temporoparietal, inferior parietal and posterior temporal neurodegeneration. Despite patients primarily complaining of language difficulties, emerging evidence points to performance deficits in non-linguistic domains. Temporoparietal cortex, and functional brain networks anchored to this region, are implicated as putative neural substrates of non-linguistic cognitive deficits in logopenic variant primary progressive aphasia, suggesting that degeneration of a shared set of brain regions may result in co-occurring linguistic and non-linguistic dysfunction early in the disease course. Here, we provide a Review aimed at broadening the understanding of logopenic variant primary progressive aphasia beyond the lens of an exclusive language disorder. By considering behavioural and neuroimaging research on non-linguistic dysfunction in logopenic variant primary progressive aphasia, we propose that a significant portion of multidimensional cognitive features can be explained by degeneration of temporal/inferior parietal cortices and connected regions. Drawing on insights from normative cognitive neuroscience, we propose that these regions underpin a combination of domain-general and domain-selective cognitive processes, whose disruption results in multifaceted cognitive deficits including aphasia. This account explains the common emergence of linguistic and non-linguistic cognitive difficulties in logopenic variant primary progressive aphasia, and predicts phenotypic diversification associated with progression of pathology in posterior neocortex.

The course of primary progressive aphasia diagnosis: a cross-sectional study

Background

The primary progressive aphasia (PPA) diagnosis trajectory is debated, as several changes in diagnosis occur during PPA course, due to phenotype evolution from isolated language alterations to global cognitive impairment.

The goal of the present study, based on a French cohort, was to describe the demographics and the evolution of subjects with (PPA) in comparison with Alzheimer’s disease (AD) on a period of 7 years.

Methods

We conducted a repeated cross-sectional study. The study population comprised individuals with PPA and AD diagnosis (N=167,191) from 2010 to 2016 in the French National data Bank (BNA). Demographic variables, MMSE scores, diagnosis status at each visit and prescribed treatments were considered.

Results

From 2010 to 2016, 5186 patients were initially diagnosed with PPA, 162,005 with AD. Compared to AD subjects, significant differences were found concerning age (younger at first diagnosis for PPA), gender (more balanced in PPA), education level (higher in PPA) and MMSE score (higher of 1 point in PPA).

Percentage of pending diagnosis, delay between first consultation and first diagnosis and the number of different diagnoses before the diagnosis of interest were significantly higher in PPA group compared to AD group. Pharmacological and non-pharmacological treatments were significatively more recommended following PPA than AD diagnosis.

Conclusion

This study improves the knowledge of PPA epidemiology and has the potential to help adopting appropriate public health service policies. It supports the hypothesis that PPA is diagnosed later than AD. The PPA diagnosis increases the prescription of non-pharmacological treatments, especially speech and language therapy (SLT) that is the main treatment available and most effective when at the initial stage.

Trial registration

ClinicalTrials.gov identifier NCT03687112

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-022-01007-6.

Imaging Clinical Subtypes and Associated Brain Networks in Alzheimer’s Disease

Alzheimer’s disease (AD) does not present uniform symptoms or a uniform rate of progression in all cases. The classification of subtypes can be based on clinical symptoms or patterns of pathological brain alterations. Imaging techniques may allow for the identification of AD subtypes and their differentiation from other neurodegenerative diseases already at an early stage. In this review, the strengths and weaknesses of current clinical imaging methods are described. These include positron emission tomography (PET) to image cerebral glucose metabolism and pathological amyloid or tau deposits. Magnetic resonance imaging (MRI) is more widely available than PET. It provides information on structural or functional changes in brain networks and their relation to AD subtypes. Amyloid PET provides a very early marker of AD but does not distinguish between AD subtypes. Regional patterns of pathology related to AD subtypes are observed with tau and glucose PET, and eventually as atrophy patterns on MRI. Structural and functional network changes occur early in AD but have not yet provided diagnostic specificity.

Heterogeneity of repetition abilities in logopenic variant primary progressive aphasia

The differential diagnosis of primary progressive aphasia (PPA) is challenging due to overlapping clinical manifestations of the different variants of the disease. This is particularly true for the logopenic variant of PPA (lvPPA), in which such overlap was reported with regard to impairments in repetition abilities. In this study, four individuals with lvPPA underwent standard neuropsychological and language assessments. The influence of psycholinguistic variables on their performance of in word, nonword and sentence repetition tasks was also specifically explored. Some level of heterogeneity was found in cognitive functions and in language. The four participants showed impairment in sentence repetition in which their performance was negatively affected by semantic reversibility and syntactic complexity. This study supports the heterogeneity of lvPPA with respect to the cognitive and linguistic status of participants. It also shows that sentence repetition is influenced not only by length, but also by semantic reversibility and syntactic complexity, two psycholinguistic variables known to place additional demands on phonological working memory.

Longitudinal naming and repetition relates to AD pathology and burden in autopsy-confirmed primary progressive aphasia

INTRODUCTION

In primary progressive aphasia (PPA) patients with autopsy-confirmed Alzheimer's disease (AD) or frontotemporal lobar degeneration (FLTD), we tested how the core clinical features of logopenic PPA-naming and repetition-change over time and relate to pathologic burden.

METHODS

In PPA with AD (n = 13) or FTLD (n = 16) pathology, Boston Naming Test and Forward Digit Span measured longitudinal naming and repetition; as reference, Mini-Mental State Examination (MMSE) measured global cognition. Pathologic burden in left peri-Sylvian regions was related to longitudinal cognitive decline.

RESULTS

PPA with AD showed greater decline in naming (P = 0.021) and repetition (P = 0.020), compared to FTLD; there was no difference in MMSE decline (P = 0.99). Across all PPA, declining naming (P = 0.0084) and repetition (P = 0.011) were associated with angular, superior-middle temporal (naming P = 0.014; repetition P = 0.011) and middle frontal (naming P = 0.041; repetition P = 0.030) pathologic burden.

DISCUSSION

Unique longitudinal profiles of naming and repetition performance in PPA with AD are related to left peri-Sylvian pathology.

The Box Task: A novel tool to differentiate the primary progressive aphasias

OBJECTIVE

Differentiating the primary progressive aphasia (PPA) variants in clinical settings remains complex and challenging, especially for the logopenic (lv-PPA) and non-fluent variants (nfv-PPA). Recent studies suggest that visuospatial memory is more compromised in lv-PPA than in nfv-PPA and is relatively spared in the semantic variant (sv-PPA). Accordingly, assessment of visuospatial memory performance may assist in the differential diagnosis of PPA variants. Here, we investigated the utility of a novel computerised visuospatial working memory test-the Box Task-to differentiate the three PPA variants and typical Alzheimer's disease (AD).

METHODS

Eighteen lv-PPA, 14 nfv-PPA, 23 sv-PPA, 33 AD patients, and 32 healthy controls matched for age and education were recruited. All participants completed the computerised Box Task and WMS-III Spatial Span as measures of visuospatial working memory.

RESULTS

The lv-PPA group made significantly more Box Task between-search errors than nfv-PPA, sv-PPA and control groups. The AD group, however, displayed the greatest impairments on this measure relative to the PPA variants. Logistic regression analyses in lv-PPA and nfv-PPA demonstrated that the combination of Box Task between-search error variables (i.e., 4- and 6-box levels) could correctly classify 72% of lv-PPA patients and nearly 79% of nfv-PPA patients. Area under the receiver operator characteristics curve (AUC) analyses revealed the Box Task was more sensitive than Spatial Span at differentiating lv-PPA from nfv-PPA.

CONCLUSIONS

Our findings suggest that a simple, computerised measure of visuospatial working memory-the Box Task-shows potential diagnostic utility in differentiating lv-PPA from the other PPA variants.

Contribution of the Cognitive Approach to Language Assessment to the Differential Diagnosis of Primary Progressive Aphasia

Diagnosis of primary progressive aphasia (PPA) is essentially based on the identification of progressive impairment of language abilities while other cognitive functions are preserved. The three variants of PPA are characterized by core and supportive clinical features related to the presence or absence of language impairment in different linguistic domains. In this article, we review the cognitive neuropsychological approach to the assessment of PPA and its contribution to the differential diagnosis of the three variants. The main advantage of this assessment approach is that it goes beyond the mere description and classification of clinical syndromes and identifies impaired and preserved cognitive and linguistic components and processes. The article is structured according to the main language domains: spoken production, language comprehension, and written language. Each section includes a brief description of the cognitive processes involved in the assessment tasks, followed by a discussion of typical characteristics for each PPA variant and common pitfalls in the interpretation of the results. In addition, the clinical benefit of the cognitive neuropsychological approach for the behavioral management of PPA is briefly sketched out in the conclusion.

Phonological Errors in Posterior Cortical Atrophy

BACKGROUND

Posterior cortical atrophy (PCA) is an atypical variant of Alzheimer's disease (AD) that presents with visuospatial/perceptual deficits. PCA is characterized by atrophy in posterior brain regions, which overlaps with atrophy occurring in logopenic variant of primary progressive aphasia (lvPPA), another atypical AD variant characterized by language difficulties, including phonological errors. Language abnormalities have been observed in PCA, although the prevalence of phonological errors is unknown. We aimed to compare the frequency and severity of phonological errors in PCA and lvPPA and determine the neuroanatomical correlates of phonological errors and language abnormalities in PCA.

METHODS

The presence and number of phonological errors were recorded during the Boston Naming Test and Western Aphasia Battery repetition subtest in 27 PCA patients and 27 age- and disease duration-matched lvPPA patients. Number of phonological errors and scores from language tests were correlated with regional gray matter volumes using Spearman correlations.

RESULTS

Phonological errors were evident in 55% of PCA patients and 70% of lvPPA patients, with lvPPA having higher average number of errors. Phonological errors in PCA correlated with decreased left inferior parietal and lateral temporal volume. Naming and fluency were also associated with decreased left lateral temporal lobe volume.

CONCLUSIONS

Phonological errors are common in PCA, although they are not as prevalent or severe as in lvPPA, and they are related to involvement of left temporoparietal cortex. This highlights the broad spectrum of clinical symptoms associated with AD and overlap between PCA and lvPPA.

Neural correlates of naming errors across different neurodegenerative diseases: An FDG-PET study

OBJECTIVE

To investigate the types of errors produced in a picture naming task by patients with neurodegenerative dementia due to different etiologies and their neural correlates.

METHODS

The same standardized picture naming test was administered to a consecutive sample of patients (n = 148) who had been studied with [¹⁸F] FDG-PET. The errors were analyzed in 3 categories (visual, semantic, and phonologic). The PET data were analyzed using an optimized single-subject procedure, and the statistical parametric mapping multiple regression design was used to explore the correlation between each type of error and brain hypometabolism in the whole group. Metabolic connectivity analyses were run at the group level on 7 left hemisphere cortical areas corresponding to an a priori defined naming network.

RESULTS

Semantic errors were predominant in most patients, independent of clinical diagnosis. In the whole group analysis, visual errors correlated with hypometabolism in the right inferior occipital lobe and in the left middle occipital lobe. Semantic errors correlated with hypometabolism in the left fusiform gyrus, the inferior and middle temporal gyri, and the temporal pole. Phonologic errors were associated with hypometabolism in the left superior and middle temporal gyri. Both positive (occipital-posterior fusiform) and negative (anterior fusiform gyrus and the superior anterior temporal lobe) connectivity changes were associated with semantic errors.

CONCLUSIONS

Naming errors reflect the dysfunction of separate stages of the naming process and are specific markers for different patterns of brain involvement. These correlations are not limited to primary progressive aphasia but extend to other neurodegenerative dementias.

Clinical Assessment of Characteristics of Apraxia of Speech in Primary Progressive Aphasia

Purpose We sought to examine interrater reliability in clinical assessment of apraxia of speech (AOS) in individuals with primary progressive aphasia and to identify speech characteristics predictive of AOS diagnosis. Method Fifty-two individuals with primary progressive aphasia were recorded performing a variety of speech tasks. These recordings were viewed by 2 experienced speech-language pathologists, who independently rated them on the presence and severity of AOS as well as 14 associated speech characteristics. We calculated interrater reliability (percent agreement and Cohen's kappa) for these ratings. For each rater, we used stepwise regression to identify speech characteristics significantly predictive of AOS diagnosis. We used the overlap between raters to create a more parsimonious model, which we evaluated with multiple linear regression. Results Results yielded high agreement on the presence (90%) and severity of AOS (weighted Cohen's κ = .834) but lower agreement for specific speech characteristics (weighted Cohen's κ ranging from .036 to .582). Stepwise regression identified 2 speech characteristics predictive of AOS diagnosis for both raters (articulatory groping and increased errors with increased length/complexity). These alone accounted for ≥ 50% of the variance of AOS severity in the constrained model. Conclusions Our study adds to a growing body of research that highlights the difficulty in objective clinical characterization of AOS and perceptual characterization of speech features. It further supports the need for consensus diagnostic criteria with standardized testing tools and for the identification and validation of objective markers of AOS. Additionally, these findings underscore the need for a training protocol if diagnostic tools are to be effective when shared beyond the research teams that develop and test them and disseminated to practicing speech-language pathologists, in order to ensure consistent application.

Patterns of Neuropsychological Dysfunction and Cortical Volume Changes in Logopenic Aphasia

BACKGROUND

Neuropsychological assessment can add essential information to the characterization of individuals presenting with the logopenic variant of primary progressive aphasia (lvPPA).

OBJECTIVE

This study examined the neuropsychological characteristics of lvPPA patients. We also examined differences in regional and whole brain atrophy based on neuropsychological profiles.

METHODS

We conducted a hierarchical cluster analysis on memory, executive functioning, and visuospatial neuropsychological test data for 56 individuals with lvPPA. We then compared resultant clusters to left middle temporal, inferior parietal, and superior parietal regions-of-interest using multivariate analysis of covariance. We also performed voxel-level analyses.

RESULTS

We identified three clusters characterized as lvPPA with no neurocognitive impairment (n = 5), lvPPA with mild neurocognitive deficits (n = 23), and lvPPA with marked cognitive deficits (n = 28). WAB-AQ was associated with left middle temporal volume. Superior parietal volumes were smaller for the lvPPA group with marked cognitive symptoms compared to the less severe groups. Voxel-level analyses showed greater atrophy in temporal, parietal, lateral occipital, and frontal regions, left worse than right. Age, disease duration, gender, WAB-AQ, and PiB-PET did not account for differences between groups.

CONCLUSIONS

LvPPA patients without cognitive deficits in other domains were relatively uncommon while 50% of our sample exhibited pronounced neurocognitive deficits outside the language domain. Pronounced cognitive deficits in lvPPA are associated with widespread atrophy, left worse than right. Our study underscores the importance of examining neuropsychological function in addition to language in patients with lvPPA.

Networks Disrupted in Linguistic Variants of Frontotemporal Dementia

The non-fluent/agrammatic variant of primary progressive aphasia (nfvPPA) and semantic variant (svPPA) of frontotemporal dementia (FTD) are neurodegenerative diseases. Previous works have shown alterations of fractional anisotropy (FA) and mean diffusivity (MD) from diffusion tensor images (DTIs). This manuscript is aimed at using DTI images to build a global tractography and to identify atrophy patterns of white matter in each variant. Twenty patients with svPPA, 20 patients with nfvPPA, 26 patients with behavioral variant of FTD (bvFTD) and, 33 controls were included. An analysis based on the connectivity of structural networks showed changes in FA and MD in svPPA and nfvPPA with respect to bvFTD. Much damage in the internal networks of the left temporal lobe was found in svPPA patients; in contrast, patients with nfvPPA showed atrophy in networks from the basal ganglia to motor and premotor areas. Those findings support the dual stream model of speech and language.

Profiling sentence repetition deficits in primary progressive aphasia and Alzheimer's disease: Error patterns and association with digit span

The use of sentence repetition tasks to distinguish dementia syndromes, particularly variants of primary progressive aphasia (PPA), is receiving growing attention. Impaired sentence repetition is a core feature of logopenic variant PPA, although the underlying cognitive mechanisms of this impairment and its significance as a diagnostic criterion remain poorly understood. Sentence repetition abilities of 12 people with dementia, using an adapted error classification schema, were analyzed, along with digit span abilities, a measure frequently used to assess working memory capacity, to explore error patterns and correlations. Participants with semantic variant PPA showed the greatest performance on sentence repetition and digit span in comparison to the logopenic variant PPA and Alzheimer's disease participants. Sentence repetition errors were characterized by middle omissions for semantic variant PPA, ending omissions and phonological errors for logopenic variant PPA, and ending omissions and unrelated word substitutions for Alzheimer's disease. Significant correlations were found between sentence repetition and digit span abilities. Findings are discussed in relation to working memory capacity theories, specifically, the dual-component model.

Characterisation of "Positive" Behaviours in Primary Progressive Aphasias

BACKGROUND/AIMS

Although some patients with primary progressive aphasia (PPA) exhibit novel or improved skills after the onset of dementia, these changes have yet to be quantified. Therefore, this study systematically explored and identified the emergence of positive behaviours after dementia onset.

METHODS

This study included 48 carers of patients with PPA: 12 nonfluent/agrammatic PPA (nfvPPA), 22 semantic variant PPA (svPPA), and 14 logopenic variant PPA (lvPPA). The presence and frequency of positive behaviour changes after dementia onset were established using the Hypersensory and Social/Emotional Scale (HSS).

RESULTS

Scores on Sensitivity to Details, Visuospatial Activities, and Music Activities differed significantly among the groups. More specifically, svPPA was associated with increased visuospatial activity, but only in the mild stage of the disease; nfvPPA was associated with increased visuospatial activity and decreased music activity, while lvPPA exhibited the reverse profile.

CONCLUSIONS

The results demonstrate that subsets of PPA patients show novel or increased positive behaviours following dementia onset, and differences among subtypes may be helpful for improving diagnostic accuracy. Additionally, harnessing these skills may improve the quality of life of both patients and carers.

Frontotemporal dementia: latest evidence and clinical implications

BACKGROUND

Frontotemporal dementia (FTD) describes a cluster of neurocognitive syndromes that present with impairment of executive functioning, changes in behavior, and a decrease in language proficiency. FTD is the second most common form of dementia in those younger than 65 years and is expected to increase in prevalence as the population ages. This goal in our review is to describe advances in the understanding of neurobiological pathology, classification, assessment, and treatment of FTD syndromes.

METHODS

PubMed was searched to obtain reviews and studies that pertain to advancements in genetics, neurobiology, neuroimaging, classification, and treatment of FTD syndromes. Articles were chosen with a predilection to more recent preclinical/clinical trials and systematic reviews.

RESULTS

Recent reviews and trials indicate a significant advancement in the understanding of molecular and neurobiological clinical correlates to variants of FTD. Genetic and histopathologic markers have only recently been discovered in the past decade. Current therapeutic modalities are limited, with most studies reporting improvement in symptoms with nonpharmacological interventions. However, a small number of studies have reported improvement of behavioral symptoms with selective serotonin reuptake inhibitor (SSRI) treatment. Stimulants may help with disinhibition, apathy, and risk-taking behavior. Memantine and cholinesterase inhibitors have not demonstrated efficacy in ameliorating FTD symptoms. Antipsychotics have been used to treat agitation and psychosis, but safety concerns and side effect profiles limit utilization in the general FTD population. Nevertheless, recent breakthroughs in the understanding of FTD pathology have led to developments in pharmacological interventions that focus on producing treatments with autoimmune, genetic, and molecular targets.

CONCLUSION

FTD is an underdiagnosed group of neurological syndromes comprising multiple variants with distinct neurobiological profiles and presentations. Recent advances suggest there is an array of potential novel therapeutic targets, although data concerning their effectiveness are still preliminary or preclinical. Further studies are required to develop pharmacological interventions, as there are currently no US Food and Drug administration approved treatments to manage FTD syndromes.

An interdisciplinary approach aiding the diagnosis of primary progressive aphasia: A case report

Frontotemporal dementia (FTD) is one of the most common causes of early-onset dementia with primary progressive aphasia (PPA) being the second-most-frequent form of this degenerative disease. Despite the similarity with progressive dementia (especially in early stages of Alzheimer´s disease), three types of PPA can be differentiated: semantic, agrammatic and logopenic (subtype discussed in this study). To date, no medications have been shown to improve or stabilize cognitive deficits in patients with PPA. We report the case of a 62-year-old woman with difficulty naming objects and planning. An interdisciplinary evaluation, including imaging and lab exams, together with neuropsychological and personality assessments, confirmed that the patient had logopenic PPA on the basis of repetition difficulty, phonemic and semantic paraphasias and absence of agrammatism. The timing of the assessment in this case, along with the resources available and commitment of an integrated interdisciplinary team, allowed a differential diagnosis (from other classical dementias) to be reached.

Neural Correlates of Verbal Episodic Memory and Lexical Retrieval in Logopenic Variant Primary Progressive Aphasia

Objective: Logopenic variant primary progressive aphasia (lvPPA) is commonly associated with Alzheimer's disease (AD) pathology. But lvPPA patients display different cognitive and anatomical profile from the common clinical AD patients, whose verbal episodic memory is primarily affected. Reports of verbal episodic memory difficulty in lvPPA are inconsistent, and we hypothesized that their lexical retrieval impairment contributes to verbal episodic memory performance and is associated with left middle temporal gyrus atrophy.

Methods: We evaluated patients with lvPPA (n = 12) displaying prominent word-finding and repetition difficulties, and a demographically-matched cohort of clinical Alzheimer's disease (AD, n = 26), and healthy seniors (n = 16). We assessed lexical retrieval with confrontation naming and verbal episodic memory with delayed free recall. Whole-brain regressions related naming and delayed free recall to gray matter atrophy. Medial temporal lobe (MTL) subfields were examined using high in-plane resolution imaging.

Results: lvPPA patients had naming and delayed free recall impairments, but intact recognition memory. In lvPPA, delayed free recall was related to naming; both were associated with left middle temporal gyrus atrophy but not MTL atrophy. Despite cerebrospinal fluid evidence consistent with AD pathology, examination of MTL subfields revealed no atrophy in lvPPA. While AD patients displayed impaired delayed free recall, this deficit did not correlate with naming. Regression analyses related delayed free recall deficits in clinical AD patients to MTL subfield atrophy, and naming to left middle temporal gyrus atrophy.

Conclusion: Unlike amnestic AD patients, MTL subfields were not affected in lvPPA patients. Verbal episodic memory deficit observed in lvPPA was unlikely to be due to a hippocampal-mediated mechanism but appeared to be due to poor lexical retrieval. Relative sparing of MTL volume and intact recognition memory are consistent with previous reports of hippocampal-sparing variant cases of AD pathology, where neurofibrillary tangles are disproportionately distributed in cortical areas with relative sparing of the hippocampus. This suggests that AD neuropathology in lvPPA may originate in neuronal networks outside of the MTL, which deviates from the typical Braak staging pattern of spreading pathology in clinical AD.

Genetic Alzheimer Disease and Sporadic Dementia With Lewy Bodies: A Comorbidity Presenting as Primary Progressive Aphasia

We report a 44-year-old woman, with a family history of early-onset dementia, presenting with primary progressive aphasia. This clinically variable syndrome has multiple underlying pathologies, and correlations between clinical manifestations and postmortem neuropathologic findings are controversial. Our patient suffered worsening language impairment with major word-finding difficulties but preserved comprehension. She also developed episodic memory impairment. Her condition progressed to dementia with behavioral changes. Magnetic resonance imaging showed early left perisylvian and bitemporal atrophy. The patient died shortly afterward from colon cancer. Neuropathologic examination revealed advanced early-onset Alzheimer and Lewy body disease, plus a clinically nonrelevant metastasis of her colon cancer in her left parietal lobe. Genetic examination revealed a p.Glu184Asp mutation in the presenilin1 gene. Our findings confirm the importance of a thorough appreciation for the clinical and neuropathologic correlations in patients with atypical neurodegenerative dementias.

The midbrain-to-pons ratio distinguishes progressive supranuclear palsy from non-fluent primary progressive aphasias

BACKGROUND AND PURPOSE

To determine the clinical utility of the midbrain-to-pons (M/P) ratio as a clinical biomarker of progressive supranuclear palsy (PSP) in patients with non-fluent primary progressive aphasia syndromes.

METHODS

Patients with PSP, progressive non-fluent aphasia (PNFA) and logopenic progressive aphasia (LPA) were recruited. Patients were diagnosed clinically, but pathological confirmation was available in a proportion of patients. Midbrain and pons areas were measured using Osirix Lite, a free DICOM viewer. The M/P ratio and Magnetic Resonance Parkinsonism Index were calculated and their diagnostic utility compared.

RESULTS

A total of 72 participants were included (16 PSP, 18 PNFA, 16 LPA and 22 controls). Patients with PSP had motor features typical of the syndrome. Both the M/P ratio and Magnetic Resonance Parkinsonism Index differed significantly in PSP compared with controls. The M/P ratio was disproportionately reduced in PSP compared with PNFA and LPA (PSP, 0.182 ± 0.043; PNFA, 0.255 ± 0.034; LPA, 0.258 ± 0.033; controls, 0.292 ± 0.031; P < 0.001). An M/P ratio of ≤0.215 produced a positive predictive value of 77.8% for the diagnosis of PSP syndrome. Pathological examination revealed Alzheimer's disease in three cases (all LPA), pathological PSP in two cases (one clinical PSP and one PNFA) and corticobasal degeneration in one case (PNFA). The M/P ratio was ≤0.215 in both pathological cases of PSP.

CONCLUSIONS

The M/P ratio was disproportionately reduced in PSP, suggesting its potential as a clinical marker of the PSP syndrome. Larger studies of pathologically confirmed cases are needed to establish the M/P ratio as a biomarker of PSP pathology.

Clinical Aspects of Alzheimer's Disease

Alzheimer's disease is the most common form of dementia accounting for 50-60% of all dementia cases. This chapter briefly reviews the history of Alzheimer's disease and provides an overview of the clinical syndromes associated with Alzheimer pathology and their associated neuroimaging findings. This chapter also reviews the neuropathology and genetics of Alzheimer's disease and concludes by discussing current work undertaken to identify suitable in vivo biomarkers for the disease.

Classification of the primary progressive aphasias: principles and review of progress since 2011

Highly influential recommendations published in 2011 for the classification of the primary progressive aphasias (PPA) distinguished three subtypes: the semantic variant, the nonfluent/agrammatic variant, and the logopenic variant. We review empirical evidence published after 2011 that bears relevance to the validity of the recommended classification scheme. The studies that we review principally rely on monocentric, memory clinic-based consecutive series of PPA patients. We review whether a data-driven analysis of neurolinguistic test scores confirms the subtyping that was based on expert consensus, whether the 2011 subtyping covers the diversity of PPA in a comprehensive manner, and whether the proposed subgroups differ along dimensions that are not explicitly part of the defining criteria, such as diffusion tractography. Data-driven mathematical analyses of neurolinguistic data in PPA broadly confirm the presence of separate clusters corresponding to the subtypes but also leave 15–30 % unclassified. A comprehensive description of PPA requires the addition of the mixed variant as a fourth subtype and needs to leave room for cases fulfilling the criteria for a root diagnosis of PPA but not those of any of the three subtypes. Finally, given the limited predictive value of the clinical phenotype for the underlying neuropathology, biomarkers of the underlying pathology are likely of clinical utility in PPA.

Is descriptive writing useful in the differential diagnosis of logopenic variant of primary progressive aphasia, Alzheimer's disease and mild cognitive impairment?

Current classification of primary progressive aphasia (PPA) encompasses three variants: non-fluent (nfvPPA), semantic (svPPA) and logopenic (lvPPA). Previously lvPPA was regarded as aphasic form of Alzheimer's disease (AD). However, not all patients with lvPPA phenotype present with AD pathology. Despite abundant literature on differentiation of lvPPA from svPPA and nfvPPA, studies comparing lvPPA with AD and mild cognitive impairment (MCI) are scarce. This study aimed at analyzing written descriptive output in lvPPA, AD and MCI. Thirty-five patients participated in the study: 9 with lvPPA, 13 with AD and 13 with MCI. Most aspects of writing performance were comparable in three groups. However, letter insertion errors appeared in 44% patients with lvPPA, while they were absent in AD and MCI. Patients with lvPPA used more verbs than patients with AD. Writing profile may complement other neuropsychological assessment results in the differential diagnosis of lvPPA. Letter insertion errors and frequent verb use may raise a query of lvPPA.