The right hemisphere's capacity for language: evidence from primary progressive aphasia

The role of the right hemisphere (RH) in core language processes is still a matter of intense debate. Most of the relevant evidence has come from studies of gray matter, with relatively little research on RH white matter (WM) connectivity. Using Diffusion Tensor Imaging-based tractography, the current work examined the role of the two hemispheres in language processing in 33 individuals with Primary Progressive Aphasia (PPA), aiming to better characterize the contribution of the RH to language processing in the context of left hemisphere (LH) damage. The findings confirm the impact of PPA on the integrity of the WM language tracts in the LH. Additionally, an examination of the relationship between tract integrity and language behaviors provides robust evidence of the involvement of the WM language tracts of both hemispheres in language processing in PPA. Importantly, this study provides novel evidence of a unique contribution of the RH to language processing (i.e. a contribution independent from that of the language-dominant LH). Finally, we provide evidence that the RH contribution is specific to language processing rather than being domain general. These findings allow us to better characterize the role of RH in language processing, particularly in the context of LH damage.

Network anatomy in logopenic variant of primary progressive aphasia

The logopenic variant of primary progressive aphasia (lvPPA) is a neurodegenerative syndrome characterized linguistically by gradual loss of repetition and naming skills resulting from left posterior temporal and inferior parietal atrophy. Here, we sought to identify which specific cortical loci are initially targeted by the disease (epicenters) and investigate whether atrophy spreads through predetermined networks. First, we used cross-sectional structural MRI data from individuals with lvPPA to define putative disease epicenters using a surface-based approach paired with an anatomically fine-grained parcellation of the cortical surface (i.e., HCP-MMP1.0 atlas). Second, we combined cross-sectional functional MRI data from healthy controls and longitudinal structural MRI data from individuals with lvPPA to derive the epicenter-seeded resting-state networks most relevant to lvPPA symptomatology and ascertain whether functional connectivity in these networks predicts longitudinal atrophy spread in lvPPA. Our results show that two partially distinct brain networks anchored to the left anterior angular and posterior superior temporal gyri epicenters were preferentially associated with sentence repetition and naming skills in lvPPA. Critically, the strength of connectivity within these two networks in the neurologically-intact brain significantly predicted longitudinal atrophy progression in lvPPA. Taken together, our findings indicate that atrophy progression in lvPPA, starting from inferior parietal and temporoparietal junction regions, predominantly follows at least two partially nonoverlapping pathways, which may influence the heterogeneity in clinical presentation and prognosis.

Anatomical MRI staging of frontotemporal dementia variants

INTRODUCTION

The three clinical variants of frontotemporal dementia (behavioral variant [bvFTD], semantic dementia, and progressive non-fluent aphasia [PNFA]) are likely to develop over decades, from the preclinical stage to death.

METHODS

To describe the long-term chronological anatomical progression of FTD variants, we built lifespan brain charts of normal aging and FTD variants by combining 8022 quality-controlled MRIs from multiple large-scale data-bases, including 107 bvFTD, 44 semantic dementia, and 38 PNFA.

RESULTS

We report in this manuscript the anatomical MRI staging schemes of the three FTD variants by describing the sequential divergence of volumetric trajectories between normal aging and FTD variants. Subcortical atrophy precedes focal cortical atrophy in specific behavioral and/or language networks, with a "radiological" prodromal phase lasting 8-10 years (time elapsed between the first structural alteration and canonical cortical atrophy).

DISCUSSION

Amygdalar and striatal atrophy can be candidate biomarkers for future preclinical/prodromal FTD variants definitions.

HIGHLIGHTS

We describe the chronological MRI staging of the most affected structures in the three frontotemporal dementia (FTD) syndromic variants. In behavioral variant of FTD (bvFTD): bilateral amygdalar, striatal, and insular atrophy precedes fronto-temporal atrophy. In semantic dementia: bilateral amygdalar atrophy precedes left temporal and hippocampal atrophy. In progressive non-fluent aphasia (PNFA): left striatal, insular, and thalamic atrophy precedes opercular atrophy.

A Multimodal Approach for Clinical Diagnosis and Treatment of Primary Progressive Aphasia (MAINSTREAM): A Study Protocol

Primary Progressive Aphasia (PPA) is a syndrome due to different neurodegenerative disorders selectively disrupting language functions. PPA specialist care is underdeveloped. There are very few specialists (neurologists, psychiatrists, neuropsychologists, and speech therapists) and few hospital- or community-based services dedicated to the diagnosis and continuing care of people with PPA. Currently, healthcare systems struggle to provide adequate coverage of care that is too often fragmented, uncoordinated, and unresponsive to the needs of people with PPA and their families. Recently, attention has been gained by non-invasive brain stimulation techniques that allow a personalized treatment approach, such as transcranial Direct Current Stimulation (tDCS). The MAINSTREAM trial looks forward to introducing and evaluating therapeutic innovations such as tDCS coupled with language therapy in rehabilitation settings. A Multimodal Approach for Clinical Diagnosis and Treatment of Primary Progressive Aphasia, MAINSTREAM (ID: 3430931) was registered in the clinicaltrials.gov database (identifier: NCT05730023) on 15 February 2023.

A novel GRN mutation in an Italian patient with non-fluent variant of primary progressive aphasia at onset: a longitudinal case report

Objectives

We report the clinical presentation and evolution of a case with a novel Progranulin gene (GRN) mutation and non-fluent language disturbances at onset.

Materials and methods

A 60 year-old, white patient was followed due to a history of language disturbances. Eighteen months after onset, the patient underwent FDG positron emission tomography (PET), and at month 24 was hospitalized to perform neuropsychological evaluation, brain 3 T MRI, lumbar puncture for cerebrospinal fluid (CSF) analysis, and genotyping. At month 31, the patient repeated the neuropsychological evaluation and brain MRI.

Results

At onset the patient complained prominent language production difficulties, such as effortful speech and anomia. At month 18, FDG-PET showed left fronto-temporal and striatal hypometabolism. At month 24, the neuropsychological evaluation reported prevalent speech and comprehension deficits. Brain MRI reported left fronto-opercular and striatal atrophy, and left frontal periventricular white matter hyperintensities (WMHs). Increased CSF total tau level was observed. Genotyping revealed a new GRN c.1018delC (p.H340TfsX21) mutation. The patient received a diagnosis of non-fluent variant of primary progressive aphasia (nfvPPA). At month 31, language deficits worsened, together with attention and executive functions. The patient presented also with behavioral disturbances, and a progressive atrophy in the left frontal-opercular and temporo-mesial region.

Discussion and conclusion

The new GRN p.H340TfsX21 mutation resulted in a case of nfvPPA characterized by fronto-temporal and striatal alterations, typical frontal asymmetric WMHs, and a fast progression toward a widespread cognitive and behavioral impairment, which reflects a frontotemporal lobar degeneration. Our findings extend the current knowledge of the phenotypic heterogeneity among GRN mutation carriers.

Distinct and shared neuropsychiatric phenotypes in FTLD-tauopathies

Frontotemporal lobar degeneration (FTLD) with tau pathology (FTLD-tau) commonly causes dementia syndromes that include primary progressive aphasia (PPA) and behavioral variant frontotemporal dementia (bvFTD). Cognitive decline in PPA and bvFTD is often accompanied by debilitating neuropsychiatric symptoms. In 44 participants with PPA or bvFTD due to autopsy-confirmed FTLD-tau, we characterized neuropsychiatric symptoms at early and late disease stages and determined whether the presence of certain symptoms predicted a specific underlying FTLD-tauopathy. Participants completed annual research visits at the Northwestern University Alzheimer's Disease Research Center. All participants had an initial Global Clinical Dementia Rating (CDR) Scale score ≤ 2, and neuropsychiatric symptoms were evaluated via the Neuropsychiatric Inventory-Questionnaire (NPI-Q). We assessed the frequency of neuropsychiatric symptoms across all participants at their initial and final visits and performed logistic regression to determine whether symptoms predicted a specific FTLD-tau pathologic diagnosis. Across the FTLD-tau cohort, irritability and apathy were most frequently endorsed at initial and final visits, respectively, whereas psychosis was highly uncommon at both timepoints. Irritability at initial visit predicted greater odds of a 4-repeat compared to a 3-repeat tauopathy (OR = 3.95, 95% CI = 1.10-15.83, p < 0.05). Initial sleep disturbance predicted greater odds of progressive supranuclear palsy (PSP) compared to other FTLD-tau subtypes (OR = 10.68, 95% CI = 2.05-72.40, p < 0.01). Appetite disturbance at final evaluation predicted lower odds of PSP (OR = 0.15, 95% CI = 0.02-0.74, p < 0.05). Our findings suggest that characterization of neuropsychiatric symptoms can aid in the prediction of underlying FTLD-tauopathies. Given considerable pathologic heterogeneity underlying dementias, neuropsychiatric symptoms may be useful for differential diagnosis and treatment planning.

Specificity in Generalization Effects of Transcranial Direct Current Stimulation Over the Left Inferior Frontal Gyrus in Primary Progressive Aphasia

OBJECTIVES

Generalization (or near-transfer) effects of an intervention to tasks not explicitly trained are the most desirable intervention outcomes. However, they are rarely reported and even more rarely explained. One hypothesis for generalization effects is that the tasks improved share the same brain function/computation with the intervention task. We tested this hypothesis in this study of transcranial direct current stimulation (tDCS) over the left inferior frontal gyrus (IFG) that is claimed to be involved in selective semantic retrieval of information from the temporal lobes.

MATERIALS AND METHODS

In this study, we examined whether tDCS over the left IFG in a group of patients with primary progressive aphasia (PPA), paired with a lexical/semantic retrieval intervention (oral and written naming), may specifically improve semantic fluency, a nontrained near-transfer task that relies on selective semantic retrieval, in patients with PPA.

RESULTS

Semantic fluency improved significantly more in the active tDCS than in the sham tDCS condition immediately after and two weeks after treatment. This improvement was marginally significant two months after treatment. We also found that the active tDCS effect was specific to tasks that require this IFG computation (selective semantic retrieval) but not to other tasks that may require different computations of the frontal lobes.

CONCLUSIONS

We provided interventional evidence that the left IFG is critical for selective semantic retrieval, and tDCS over the left IFG may have a near-transfer effect on tasks that depend on the same computation, even if they are not specifically trained.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT02606422.

"They are dealing with people's lives…": Diagnostic and post-diagnostic healthcare experiences in primary progressive aphasia

PURPOSE

The healthcare experience is a multifaceted and varied process, particularly for people living with complex conditions such as primary progressive aphasia (PPA). Different experiences influence pathways through the health system, impacting client outcomes. To our knowledge, no previous studies have directly explored the healthcare experiences of people with PPA and their families. This study aimed to explore the experiences of people living with PPA from the perspective of both the person with PPA and their families during diagnostic and post-diagnostic phases, and to identify factors influencing service access and perceptions of quality of care.

METHOD

The study followed an Interpretive Phenomenological Analysis (IPA) approach. In-depth, semi-structured interviews were completed with three people with PPA and their primary care partner, and two further care partners of people with PPA.

RESULT

Five superordinate themes were identified: characterising the assessment experience, getting a diagnosis, moving beyond the diagnosis, participant interactions with clinicians, and overall service provision. The five superordinate themes comprised 14 subthemes.

CONCLUSION

The study provides preliminary insights into the complexity of the PPA healthcare journey, and the need for increased accessibility of information and supports following diagnosis. The findings inform recommendations for improving quality of care and the development of a PPA service framework or care pathway.

Multifocal Transcranial Direct Current Stimulation in Primary Progressive Aphasia Does Not Provide a Clinical Benefit Over Speech Therapy

BACKGROUND

Primary progressive aphasia (PPA) is a group of neurodegenerative disorders including Alzheimer's disease and frontotemporal dementia characterized by language deterioration. Transcranial direct current stimulation (tDCS) is a non-invasive intervention for brain dysfunction.

OBJECTIVE

To evaluate the tolerability and efficacy of tDCS combined with speech therapy in the three variants of PPA. We evaluate changes in fMRI activity in a subset of patients.

METHODS

Double-blinded, randomized, cross-over, and sham-controlled tDCS study. 15 patients with PPA were included. Each patient underwent two interventions: a) speech therapy + active tDCS and b) speech therapy + sham tDCS stimulation. A multifocal strategy with anodes placed in the left frontal and parietal regions was used to stimulate the entire language network. Efficacy was evaluated by comparing the results of two independent sets of neuropsychological assessments administered at baseline, immediately after the intervention, and at 1 month and 3 months after the intervention. In a subsample, fMRI scanning was performed before and after each intervention.

RESULTS

The interventions were well tolerated. Participants in both arms showed clinical improvement, but no differences were found between active and sham tDCS interventions in any of the evaluations. There were trends toward better outcomes in the active tDCS group for semantic association and reading skills. fMRI identified an activity increase in the right frontal medial cortex and the bilateral paracingulate gyrus after the active tDCS intervention.

CONCLUSION

We did not find differences between active and sham tDCS stimulation in clinical scores of language function in PPA patients.

A Case of Atypical Alzheimer's Disease With Clinical Manifestation That Straddled the Boundary Between Primary Progressive Aphasia and Posterior Cortical Atrophy

INTRODUCTION

In the context of Alzheimer's disease phenotypes, patients may present with symptoms and signs that do not exclusively fit into one of the existing phenotypic categories, which often delays timely diagnosis and initiation of services to optimize patient awareness and coping.

CASE REPORT

A 74-year-old woman presented with the complaint of progressive word-finding difficulty, raising our suspicion for primary progressive aphasia. Clinical evaluations, however, also revealed emerging cortical visual deficits consistent with posterior cortical atrophy. During evaluation 1 year later, Gerstmann syndrome was evident. Her in vivo neuroimaging was positive for beta-amyloid and tau biomarkers of Alzheimer's disease pathology.

CONCLUSION

In addition to contributing to the literature on the heterogeneity of the clinical manifestations of Alzheimer's disease, this report highlights that a breakdown in the visual-lexical interface can account for anomia in posterior cortical atrophy at least in some cases. Other relevant clinical insights pertinent to this case are discussed.

'Like going into a chocolate shop, blindfolded': What do people with primary progressive aphasia want from speech and language therapy?

BACKGROUND

Primary progressive aphasia (PPA) describes a group of language-led dementias. PPAs are complex, diverse and difficult to diagnose, and therefore conventional models of aphasia and dementia treatment do not meet their needs. The research evidence on intervention for PPA is developing, but to date there are only a few case studies exploring the experiences of people with PPA (PwPPA) themselves.

AIMS

To explore the experiences and opinions of PwPPA and their communication partners (CPs) to understand how speech and language therapy (SLT) services can better meet their needs.

METHODS & PROCEDURES

A qualitative research approach was used whereby PwPPA and their friends or family members were recruited to participate in focus groups, via advertisements in the Rare Dementia Support PPA group newsletters. Consenting participants were allocated to attend one of four focus groups hosted on an online video conferencing platform. Participants were asked about their communication difficulties, and how SLT could address these needs. All meetings were transcribed, and data were examined using reflexive thematic analysis.

OUTCOMES & RESULTS

Six PwPPA and 14 CPs representing all three PPA variants and mixed PPA participated in the focus groups. Four main themes were identified during the analysis of the focus group discussions: (1) CPs' burden, (2) adjusting to the diagnosis, (3) communication abilities and difficulties and (4) beyond language. A further 10 subthemes were identified.

CONCLUSIONS & IMPLICATIONS

This study provides a greater understanding of the experiences and needs of PwPPA and their families in relation to SLT. This work underlines the importance of a person-centred approach that considers the broader needs of both the PwPPA and the people around them. This will enable service providers to deliver SLT that meets the needs of PwPPA and their families and will also inform future research in this field.

WHAT THIS PAPER ADDS

What is already known on this subject We know that PwPPA can maintain or even make improvements in word retrieval and speech fluency with SLT exercises. There is also developing evidence of the benefits of interventions such as CP training, communication aid support and other functional interventions. What this paper adds to existing knowledge This study provides an understanding of the experiences and opinions of people living with PPA and their families in relation to SLT. Results demonstrate that PwPPA and their families have to navigate a complex journey, identifying strategies to support communication but also the influence of personality and other cognitive symptoms. SLT was useful, but not always available. What are the potential or actual clinical implications of this work? This study will enable service providers to better plan, justify funding for and delivery of SLT that will meet the needs of PwPPA and their families. Most importantly this work underlines the importance of a person-centred approach, incorporating the broader needs of the person with PPA and those around them.

Less is more in language production: an information-theoretic analysis of agrammatism in primary progressive aphasia

Agrammatism is a disorder of language production characterized by short, simplified sentences, the omission of function words, an increased use of nouns over verbs and a higher use of heavy verbs. Despite observing these phenomena for decades, the accounts of agrammatism have not converged. Here, we propose and test the hypothesis that the lexical profile of agrammatism results from a process that opts for words with a lower frequency of occurrence to increase lexical information. Furthermore, we hypothesize that this process is a compensatory response to patients' core deficit in producing long, complex sentences. In this cross-sectional study, we analysed speech samples of patients with primary progressive aphasia (n = 100) and healthy speakers (n = 65) as they described a picture. The patient cohort included 34 individuals with the non-fluent variant, 41 with the logopenic variant and 25 with the semantic variant of primary progressive aphasia. We first analysed a large corpus of spoken language and found that the word types preferred by patients with agrammatism tend to have lower frequencies of occurrence than less preferred words. We then conducted a computational simulation to examine the impact of word frequency on lexical information as measured by entropy. We found that strings of words that exclude highly frequent words have a more uniform word distribution, thereby increasing lexical entropy. To test whether the lexical profile of agrammatism results from their inability to produce long sentences, we asked healthy speakers to produce short sentences during the picture description task. We found that, under this constrained condition, a similar lexical profile of agrammatism emerged in the short sentences of healthy individuals, including fewer function words, more nouns than verbs and more heavy verbs than light verbs. This lexical profile of short sentences resulted in their lower average word frequency than unconstrained sentences. We extended this finding by showing that, in general, shorter sentences get packaged with lower-frequency words as a basic property of efficient language production, evident in the language of healthy speakers and all primary progressive aphasia variants.

Unravelling neurotransmitters impairment in primary progressive aphasias

Primary progressive aphasias (PPAs) are a group of neurodegenerative diseases mainly characterized by language impairment, and with variably presence of dysexecutive syndrome, behavioural disturbances and parkinsonism. Detailed knowledge of neurotransmitters impairment and its association with clinical features hold the potential to develop new tailored therapeutic approaches. In the present study, we applied JuSpace toolbox, which allowed for cross-modal correlation of magnetic resonance imaging (MRI)-based measures with nuclear imaging derived estimates covering various neurotransmitter systems including dopaminergic, serotonergic, noradrenergic, GABAergic and glutamatergic neurotransmission. We included 103 PPA patients and 80 age-matched healthy controls (HC). We tested if the spatial patterns of grey matter volume (GMV) alterations in PPA patients (relative to HC) are correlated with specific neurotransmitter systems. As compared to HC, voxel-based brain changes in PPA were significantly associated with spatial distribution of serotonin, dopamine, and glutamatergic pathways (p < .05, False Discovery Rate corrected-corrected). Disease severity was negatively correlated with the strength of GMV colocalization of D1 receptors (p = .035) and serotonin transporter (p = .020). Moreover, we observed a significant negative correlation between positive behavioural symptoms, as measured with Frontal Behavioural Inventory, and GMV colocalization of D1 receptors (p = .007) and serotonin transporter (p < .001). This pilot study suggests that JuSpace is a helpful tool to indirectly assess neurotransmitter deficits in neurodegenerative dementias and may provide novel insight into disease mechanisms and associated clinical features.

Error profiles of facial emotion recognition in frontotemporal dementia and Alzheimer's disease

OBJECTIVES

To identify the patterns of errors in facial emotion recognition in frontotemporal dementia (FTD) subtypes compared with Alzheimer's disease (AD) and healthy controls.

DESIGN

Retrospective analysis.

SETTING

Participants were recruited from FRONTIER, the frontotemporal dementia research group at the University of Sydney, Australia.

PARTICIPANTS

A total of 356 participants (behavioral-variant FTD (bvFTD): 62, semantic dementia (SD)-left: 29, SD-right: 14, progressive non-fluent aphasia (PNFA): 21, AD: 76, controls: 90) were included.

MEASUREMENTS

Facial emotion recognition was assessed using the Facial Affect Selection Task, a word-face matching task measuring recognition of the six basic emotions (anger, disgust, fear, happiness, sadness, and surprise), as well as neutral emotion, portrayed by black and white faces.

RESULTS

Overall, all clinical groups performed significantly worse than controls with the exception of the PNFA subgroup (p = .051). The SD-right group scored worse than all other clinical groups (all p values < .027) and the bvFTD subgroup performed worse than the PNFA group (p < .001). The most frequent errors were in response to the facial emotions disgust (26.1%) and fear (22.9%). The primary error response to each target emotion was identified; patterns of errors were similar across all clinical groups.

CONCLUSIONS

Facial emotion recognition is impaired in FTD and AD compared to healthy controls. Within FTD, bvFTD and SD-right are particularly impaired. Dementia groups cannot be distinguished based on error responses alone. Implications for future clinical diagnosis and research are discussed.

The eyes speak when the mouth cannot: Using eye movements to interpret omissions in primary progressive aphasia

Though it may seem simple, object naming is a complex multistage process that can be impaired by lesions at various sites of the language network. Individuals with neurodegenerative disorders of language, known as primary progressive aphasias (PPA), have difficulty with naming objects, and instead frequently say "I don't know" or fail to give a vocal response at all, known as an omission. Whereas other types of naming errors (paraphasias) give clues as to which aspects of the language network have been compromised, the mechanisms underlying omissions remain largely unknown. In this study, we used a novel eye tracking approach to probe the cognitive mechanisms of omissions in the logopenic and semantic variants of PPA (PPA-L and PPA-S). For each participant, we identified pictures of common objects (e.g., animals, tools) that they could name aloud correctly, as well as pictures that elicited an omission. In a separate word-to-picture matching task, those pictures appeared as targets embedded among an array with 15 foils. Participants were given a verbal cue and tasked with pointing to the target, while eye movements were monitored. On trials with correctly-named targets, controls and both PPA groups ceased visual search soon after foveating the target. On omission trials, however, the PPA-S group failed to stop searching, and went on to view many foils "post-target". As further indication of impaired word knowledge, gaze of the PPA-S group was subject to excessive "taxonomic capture", such that they spent less time viewing the target and more time viewing related foils on omission trials. In contrast, viewing behavior of the PPA-L group was similar to controls on both correctly-named and omission trials. These results indicate that the mechanisms of omission in PPA differ by variant. In PPA-S, anterior temporal lobe degeneration causes taxonomic blurring, such that words from the same category can no longer be reliably distinguished. In PPA-L, word knowledge remains relatively intact, and omissions instead appear to be caused by downstream factors (e.g., lexical access, phonological encoding). These findings demonstrate that when words fail, eye movements can be particularly informative.

Baseline Conceptual-Semantic Impairment Predicts Longitudinal Treatment Effects for Anomia in Primary Progressive Aphasia and Alzheimer's Disease

Background

An individual's diagnostic subtype may fail to predict the efficacy of a given type of treatment for anomia. Classification by conceptual-semantic impairment may be more informative.

Aims

This study examined the effects of conceptual-semantic impairment and diagnostic subtype on anomia treatment effects in primary progressive aphasia (PPA) and Alzheimer's disease (AD).

Methods & Procedures

At baseline, the picture and word versions of the Pyramids and Palm Trees and Kissing and Dancing tests were used to measure conceptual-semantic processing. Based on norming that was conducted with unimpaired older adults, participants were classified as being impaired on both the picture and word versions (i.e., modality-general conceptual-semantic impairment), the picture version (Objects or Actions) only (i.e., visual-conceptual impairment), the word version (Nouns or Verbs) only (i.e., lexical-semantic impairment), or neither the picture nor the word version (i.e., no impairment). Following baseline testing, a lexical treatment and a semantic treatment were administered to all participants. The treatment stimuli consisted of nouns and verbs that were consistently named correctly at baseline (Prophylaxis items) and/or nouns and verbs that were consistently named incorrectly at baseline (Remediation items). Naming accuracy was measured at baseline, and it was measured at three, seven, eleven, fourteen, eighteen, and twenty-one months.

Outcomes & Results

Compared to baseline naming performance, lexical and semantic treatments both improved naming accuracy for treated Remediation nouns and verbs. For Prophylaxis items, lexical treatment was effective for both nouns and verbs, and semantic treatment was effective for verbs, but the pattern of results was different for nouns -- the effect of semantic treatment was initially nonsignificant or marginally significant, but it was significant beginning at 11 Months, suggesting that the effects of prophylactic semantic treatment may become more apparent as the disorder progresses. Furthermore, the interaction between baseline Conceptual-Semantic Impairment and the Treatment Condition (Lexical vs. Semantic) was significant for verb Prophylaxis items at 3 and 18 Months, and it was significant for noun Prophylaxis items at 14 and 18 Months.

Conclusions

The pattern of results suggested that individuals who have modality-general conceptual-semantic impairment at baseline are more likely to benefit from lexical treatment, while individuals who have unimpaired conceptual-semantic processing at baseline are more likely to benefit from semantic treatment as the disorder progresses. In contrast to conceptual-semantic impairment, diagnostic subtype did not typically predict the treatment effects.

Prevalence and determinants of language impairment in non-demented amyotrophic lateral sclerosis patients

BACKGROUND AND PURPOSE

This study aimed at estimating the prevalence of language impairment (LI) in a large, clinic-based cohort of non-demented amyotrophic lateral sclerosis (ALS) patients and assessing its underpinnings at motor and non-motor levels.

METHODS

Non-demented ALS patients (N = 348) underwent the Edinburgh Cognitive and Behavioural ALS Screen (ECAS), as well as an assessment of behavioural/psychiatric and motor-functional features. The prevalence of LI was estimated based on the proportion of patients showing a performance below the age- and education-adjusted cut-off on the ECAS-Language. Multiple regression models were run to assess the determinants of language functioning and impairment.

RESULTS

The prevalence of LI was 22.7%. 46.6% of the variance of ECAS-Language scores remained unexplained, with only the ECAS-Executive positively predicting them (p < 0.001; η²  = 0.07). Similarly, only a lower score on the ECAS-Executive predicted a higher probability of a below cut-off ECAS-Language performance (p < 0.001). Spelling and Naming tasks were the major drivers of ECAS-Language performance.

CONCLUSIONS

This study suggests that, in non-demented ALS patients, LI occurs in ≈23% of cases, is significantly driven by executive dysfunction but, at the same time, partially independent of it and is not associated with other motor or non-motor features.

Verbal fluency tests assess global cognitive status but have limited diagnostic differentiation: evidence from a large-scale examination of six neurodegenerative diseases

Verbal fluency is widely used as a clinical test, but its utility in differentiating between neurodegenerative dementias and progressive aphasias, and from healthy controls, remains unclear. We assessed whether various measures of fluency performance could differentiate between Alzheimer's disease, behavioural variant of frontotemporal dementia, non-fluent and semantic variants of primary progressive aphasia, progressive supranuclear palsy, corticobasal syndrome and healthy controls. Category and letter fluency tasks were administered to 33 controls and 139 patients at their baseline clinical visit. We assessed group differences for total number of words produced, psycholinguistic word properties and associations between production order and exemplar psycholinguistic properties. Receiver operating characteristic curves determined which measure could best discriminate patient groups and controls. The total word count distinguished controls from all patient groups, but neither this measure nor the word properties differentiated the patient groups. Receiver operating characteristic curves revealed that, when comparing controls to patients, the strongest discriminators were total word count followed by word frequency. Word frequency was the strongest discriminator for semantic variant of primary progressive aphasia versus other groups. Fluency word counts were associated with global severity as measured by Addenbrooke's Cognitive Examination Revised. Verbal fluency is an efficient test for assessing global brain-cognitive health but has limited utility in differentiating between cognitively and anatomically disparate patient groups. This outcome is consistent with the fact that verbal fluency requires many different aspects of higher cognition and language.

Genetic forms of primary progressive aphasia within the GENetic Frontotemporal dementia Initiative (GENFI) cohort: comparison with sporadic primary progressive aphasia

Primary progressive aphasia is most commonly a sporadic disorder, but in some cases, it can be genetic. This study aimed to understand the clinical, cognitive and imaging phenotype of the genetic forms of primary progressive aphasia in comparison to the canonical nonfluent, semantic and logopenic subtypes seen in sporadic disease. Participants with genetic primary progressive aphasia were recruited from the international multicentre GENetic Frontotemporal dementia Initiative study and compared with healthy controls as well as a cohort of people with sporadic primary progressive aphasia. Symptoms were assessed using the GENetic Frontotemporal dementia Initiative language, behavioural, neuropsychiatric and motor scales. Participants also underwent a cognitive assessment and 3 T volumetric T1-weighted MRI. One C9orf72 (2%), 1 MAPT (6%) and 17 GRN (44%) symptomatic mutation carriers had a diagnosis of primary progressive aphasia. In the GRN cohort, 47% had a diagnosis of nonfluent variant primary progressive aphasia, and 53% had a primary progressive aphasia syndrome that did not fit diagnostic criteria for any of the three subtypes, called primary progressive aphasia-not otherwise specified here. The phenotype of the genetic nonfluent variant primary progressive aphasia group largely overlapped with that of sporadic nonfluent variant primary progressive aphasia, although the presence of an associated atypical parkinsonian syndrome was characteristic of sporadic and not genetic disease. The primary progressive aphasia -not otherwise specified group however was distinct from the sporadic subtypes with impaired grammar/syntax in the presence of relatively intact articulation, alongside other linguistic deficits. The pattern of atrophy seen on MRI in the genetic nonfluent variant primary progressive aphasia group overlapped with that of the sporadic nonfluent variant primary progressive aphasia cohort, although with more posterior cortical involvement, whilst the primary progressive aphasia-not otherwise specified group was strikingly asymmetrical with involvement particularly of the insula and dorsolateral prefrontal cortex but also atrophy of the orbitofrontal cortex and the medial temporal lobes. Whilst there are overlapping symptoms between genetic and sporadic primary progressive aphasia syndromes, there are also distinct features. Future iterations of the primary progressive aphasia consensus criteria should encompass such information with further research needed to understand the earliest features of these disorders, particularly during the prodromal period of genetic disease.

The architecture of abnormal reward behaviour in dementia: multimodal hedonic phenotypes and brain substrate

Abnormal reward processing is a hallmark of neurodegenerative diseases, most strikingly in frontotemporal dementia. However, the phenotypic repertoire and neuroanatomical substrates of abnormal reward behaviour in these diseases remain incompletely characterized and poorly understood. Here we addressed these issues in a large, intensively phenotyped patient cohort representing all major syndromes of sporadic frontotemporal dementia and Alzheimer's disease. We studied 27 patients with behavioural variant frontotemporal dementia, 58 with primary progressive aphasia (22 semantic variant, 24 non-fluent/agrammatic variant and 12 logopenic) and 34 with typical amnestic Alzheimer's disease, in relation to 42 healthy older individuals. Changes in behavioural responsiveness were assessed for canonical primary rewards (appetite, sweet tooth, sexual activity) and non-primary rewards (music, religion, art, colours), using a semi-structured survey completed by patients' primary caregivers. Changes in more general socio-emotional behaviours were also recorded. We applied multiple correspondence analysis and k-means clustering to map relationships between hedonic domains and extract core factors defining aberrant hedonic phenotypes. Neuroanatomical associations were assessed using voxel-based morphometry of brain MRI images across the combined patient cohort. Altered (increased and/or decreased) reward responsiveness was exhibited by most patients in the behavioural and semantic variants of frontotemporal dementia and around two-thirds of patients in other dementia groups, significantly (P < 0.05) more frequently than in healthy controls. While food-directed changes were most prevalent across the patient cohort, behavioural changes directed toward non-primary rewards occurred significantly more frequently (P < 0.05) in the behavioural and semantic variants of frontotemporal dementia than in other patient groups. Hedonic behavioural changes across the patient cohort were underpinned by two principal factors: a 'gating' factor determining the emergence of altered reward behaviour and a 'modulatory' factor determining how that behaviour is directed. These factors were expressed jointly in a set of four core, trans-diagnostic and multimodal hedonic phenotypes: 'reward-seeking', 'reward-restricted', 'eating-predominant' and 'control-like'-variably represented across the cohort and associated with more pervasive socio-emotional behavioural abnormalities. The principal gating factor was associated (P < 0.05 after correction for multiple voxel-wise comparisons over the whole brain) with a common profile of grey matter atrophy in anterior cingulate, bilateral temporal poles, right middle frontal and fusiform gyri: the cortical circuitry that mediates behavioural salience and semantic and affective appraisal of sensory stimuli. Our findings define a multi-domain phenotypic architecture for aberrant reward behaviours in major dementias, with novel implications for the neurobiological understanding and clinical management of these diseases.

Differences of Modality Use between Telepractice and Face-to-Face Administration of the Scenario-Test in Persons with Dementia-Related Speech Disorder

Telepractice is increasingly finding its way into the care of people with dementia. Web-based delivery of speech and language therapy (SLT) is feasible and has the potential to improve communication in people with dementia-related speech disorders. Although experts are discussing the strengths and weaknesses of telepractice, a precise analysis of the differences between analogue and digital communication for this heterogeneous group of patients is still missing. The three current single cases investigated verbal and nonverbal aspects of communication in a face-to-face (F2F) and digital setting through a qualitative research design. Using the scenario-test (ST) in person and via big blue button (BBB; video conferencing system), several decisive factors were detected, influencing the effectiveness of communication in a F2F compared to a digital setting. The most important results of the qualitative content analysis are described for each case individually. Additionally, the influence of person-related factors, such as age, diagnosis, presence of depression, and level of education, is presented. Perceptual, executive, and affective disorders, as well as aids of relatives, are considered separately. The results indicate that executive functions, affects, and perceptual deficits need to be taken into account if telepractice is to be applied. Age, education, and distinct forms of dementia might be decisive for successful telepractice as well.

Gesture profiles distinguish primary progressive aphasia variants

Primary progressive aphasia (PPA) is a neurodegenerative syndrome characterized by progressive language deficits. There are three main variants of PPA - semantic (svPPA), logopenic (lvPPA), and nonfluent (nfvPPA) - that can be challenging to distinguish. Limb praxis may also be affected in PPA, but it is unclear whether different variants of PPA are associated with differences in gesture production. Prior research with neurotypical individuals indicates that the left temporal lobe is a critical locus of manipulable object and hand posture representations. Moreover, when imitating gestures, individuals whose strokes include the left temporal lobe show reduced benefit of gesture meaning and disproportionate impairment in hand posture as compared to arm kinematics. We tested the hypothesis that svPPA - who typically exhibit primarily temporal lobe atrophy - would differentially show these expected patterns of gesture imitation performance. Nineteen participants with PPA completed meaningful and meaningless gesture imitation tasks, and performance was scored for hand posture and arm kinematics accuracy. Generalized logistic mixed-effect regression models controlling for dementia severity showed overall benefits from gesture meaning, and greater impairments in hand posture than arm kinematics. We also found that svPPA participants were the most impaired in gesture imitation overall. Critically, there was also a significant three-way interaction of group, meaning, and gesture component: only svPPA participants showed relative impairments of hand posture for meaningful gestures as well as meaningless gestures. Thus, unlike lvPPA and nfvPPA, the hand postures of svPPA failed to benefit from gesture meaning. This research extends prior findings on the role of the temporal lobe in hand posture representations associated with manipulable objects, and is the first to indicate that there may be distinct gesture imitation patterns as a function of PPA variant. Characterizing componential gesture deficits in PPA may help to inform differential diagnosis, compensatory communication strategies, and cognitive praxis models of PPA.

Asymmetry of radiomics features in the white matter of patients with primary progressive aphasia

Introduction

Primary Progressive Aphasia (PPA) is a neurological disease characterized by linguistic deficits. Semantic (svPPA) and non-fluent/agrammatic (nfvPPA) variants are the two main clinical subtypes. We applied a novel analytical framework, based on radiomic analysis, to investigate White Matter (WM) asymmetry and to examine whether asymmetry is associated with verbal fluency performance.

Methods

Analyses were performed on T1-weighted images including 56 patients with PPA (31 svPPA and 25 nfvPPA) and 53 age- and sex-matched controls. Asymmetry Index (AI) was computed for 86 radiomics features in 34 white matter regions. The relationships between AI, verbal fluency performance (semantic and phonemic) and Boston Naming Test score (BNT) were explored through Spearman correlation analysis.

Results

Relative to controls, WM asymmetry in svPPA patients involved regions adjacent to middle temporal cortex as part of the inferior longitudinal (ILF), fronto-occipital (IFOF) and superior longitudinal fasciculi. Conversely, nfvPPA patients showed an asymmetry of WM in lateral occipital regions (ILF/IFOF). A higher lateralization involving IFOF, cingulum and forceps minor was found in nfvPPA compared to svPPA patients. In nfvPPA patients, semantic fluency was positively correlated to asymmetry in ILF/IFOF tracts. Performances at BNT were associated with AI values of the middle temporal (ILF/SLF) and parahippocampal (ILF/IFOF) gyri in svPPA patients.

Discussion

Radiomics features depicted distinct pathways of asymmetry in svPPA and nfvPPA involving damage of principal fiber tracts associated with speech and language. Assessing asymmetry of radiomics in PPA allows achieving a deeper insight into the neuroanatomical damage and may represent a candidate severity marker for language impairments in PPA patients.

Bilingual Primary Progressive Aphasia: A Scoping Review of Assessment and Treatment Practices

BACKGROUND

Primary progressive aphasia (PPA) is a neurodegenerative syndrome characterized by speech and/or language impairment with relatively spared cognition. Research investigating behavioral speech-language intervention and methods for cognitive-linguistic assessment in PPA has predominantly centered around monolingual speakers. This gap hinders the widespread adoption of evidence-based approaches and exacerbates the inequities faced by culturally and linguistically diverse populations living with PPA.

OBJECTIVE

This scoping review synthesizes the current evidence for assessment and treatment practices in bilingual PPA as well as the operationalization of bilingualism in PPA.

METHODS

Arksey & O'Malley's scoping review methodology was utilized. Information was extracted from each study and entered into a data-charting template designed to capture information regarding operationalization of bilingualism in PPA and assessment and treatment practices.

RESULTS

Of the 16 identified studies, 14 reported the results of assessments conducted in both languages. Three studies reported positive naming treatment outcomes. Thirteen studies included English-speaking participants, revealing linguistic bias. Most studies reported age of acquisition, proficiency, and patterns of language use rather than providing an operational definition for bilingualism.

CONCLUSIONS

Neither formal assessment measures nor clear guidelines for assessment of bilingual PPA currently exist; however, language-specific measures are emerging. Speech-language intervention in bilingual PPA has been relatively unexplored, representing a significant gap in the literature. In order to improve diagnostic and treatment options for bilingual PPA, targeted efforts to increase representation of bilinguals from various sociocultural contexts, as well as those who speak a variety of language pairs, is necessary.

Quality of Life Ratings and Proxy Bias in Primary Progressive Aphasia: Two Sides to the Story?

A valid measure of quality of life is important for clinical goal setting and for evaluating interventions. In the amnestic dementias, proxy-raters (e.g. friends, families, clinicians) typically rate quality of life lower than the self-ratings given by the person with dementia - a proxy bias. This study investigated whether the same proxy bias occurs in Primary Progressive Aphasia (PPA), a language-led dementia.Quality of life was measured in 18 individuals with PPA using self-ratings, and proxy-ratings by their main communication partner, using the Quality of Life in Alzheimer's Disease Scale.There was no strong evidence for proxy bias at a group level, with no consistent pattern across dyads, where proxy- and self-ratings did not show good levels of agreement. We suggest that self-ratings and proxy-ratings of quality of life in PPA are not interchangeable. Higher-powered investigation of the patterns observed here is warranted in future studies.