Variant Primary Progressive Aphasia Research Articles

Dysfluency in primary progressive aphasia: Temporal speech parameters

ABSTRACT Analysing spontaneous speech in individuals experiencing fluency difficulties holds potential for diagnosing speech and language disorders, including Primary Progressive Aphasia (PPA). Dysfluency in the spontaneous speech of patients with PPA has mostly been described in terms of abnormal pausing behaviour, but the temporal features related to speech have drawn little attention. This study compares speech-related fluency parameters in the three main variants of PPA and in typical speech. Forty-three adults participated in this research, thirteen with the logopenic variant of PPA (lvPPA), ten with the non-fluent variant (nfvPPA), nine with the semantic variant (svPPA), and eleven who were healthy age-matched adults. Participants’ fluency was assessed through a picture description task from which 42 parameters were computed including syllable duration, speaking pace, the duration of speech chunks (i.e. interpausal units, IPU), and the number of linguistic units per IPU and per second. The results showed that each PPA variant exhibited abnormal speech characteristics reflecting various underlying factors, from motor speech deficits to higher-level issues. Out of the 42 parameters considered, 37 proved useful for characterising dysfluency in the three main PPA variants and 35 in distinguishing among them. Therefore, taking into account not only pausing behaviour but also temporal speech parameters can provide a fuller understanding of dysfluency in PPA. However, no single parameter by itself sufficed to distinguish one PPA group from the other two, further evidence that dysfluency is not dichotomous but rather multidimensional, and that complementary multiparametric analyses are needed.

Perceptual and semantic deficits in face recognition in semantic dementia.

Semantic dementia (SD) patients including semantic variant primary progressive aphasia (svPPA) and semantic behavioral variant frontotemporal dementia (sbvFTD) patients show semantic difficulties identifying faces and known people related to right anterior temporal lobe (ATL) atrophy. However, it remains unclear whether they also have perceptual deficits in face recognition. We selected 74 SD patients (54 with svPPA and predominant left ATL atrophy and 20 with sbvFTD and predominant right ATL atrophy) and 36 cognitively healthy controls (HC) from UCSF Memory and Aging Center. They underwent a perceptual face processing test (Benton facial recognition test-short version; BFRT-S), and semantic face processing tests (UCSF Famous people battery - Recognition, Naming, Semantic associations - pictures and words subtests), as well as structural magnetic resonance imaging (MRI). Neural correlates with the task's performance were conducted with a Voxel-based morphometry approach using CAT12. svPPA and sbvFTD patients were impaired on all semantic face processing tests, with sbvFTD patients performing significantly lower on the famous faces' recognition task in comparison to svPPA, and svPPA performing significantly lower on the naming task in comparison to sbvFTD. These tasks predominantly correlated with gray matter (GM) volumes in the right and left ATL, respectively. Compared to HC, both svPPA and sbvFTD patients showed preserved performance on the perceptual face processing test (BFRT-S), and performance on the BFRT-S negatively correlated with GM volume in the right posterior superior temporal sulcus (pSTS). Our results suggest that early in the disease, with the atrophy mostly restricted to the anterior temporal regions, SD patients do not present with perceptual deficits. However, more severe SD cases with atrophy in right posterior temporal regions might show lower performance on face perception tests, in addition to the semantic face processing deficits. Early sparing of face perceptual deficits in SD patients, regardless of hemispheric lateralization, furthers our understanding of clinical phenomenology and therapeutical approaches of this complex disease.

“I used to be a storyteller”: the perspectives of people with primary progressive aphasia on the communication needs for themselves and their family members

ABSTRACT Background Primary progressive aphasia (PPA) refers to a group of neurological disorders characterised by the progressive deterioration of language functions. The primary avenue of support for the wide-ranging impacts of PPA on the lives of people with PPA and their family members is the delivery of communication care from speech-language pathologists. To align the provision of communication care services and the development of communication interventions with the peoples’ and family members’ needs, it is important to understand those needs from the perspectives of key stakeholders, particularly individuals with PPA. Aims The aims of the current study were to explore (a) the communication needs of people with PPA in the early and middle stages, and (b) the communication needs of their family members, from the perspectives of people with PPA. Methods & Procedures Semi-structured qualitative interviews were conducted with seven people with PPA (all variants of PPA) from one to 96 months post diagnosis. The qualitative data was analysed using qualitative content analysis to identify codes and categories that related to the study’s research aims. Outcomes & Results Qualitative content analysis yielded six categories of communication need pertaining to people with PPA: Diagnosis and disclosure; Wanting information for self and the general public; General communication difficulties; Impact on communication in everyday life; Impact on psychosocial wellbeing; and Future planning. In contrast, only one category of need pertaining to family members was identified: Impact on family and others. Conclusion This study has yielded a breadth of findings on the communication needs of people with PPA and an initial contribution on those of their family members, implicating a range of health and social care professionals and other system level supports, as well as community members and family and friends, in addition to speech-language pathology services. Speech-language pathologists supporting this population might consider needs in areas such as impact on working life, impact on driving, coping with a changing self-perception of their identity (e.g. as a storyteller), and managing fluctuation in communication abilities. Future research can build on these findings to inform clinical practice and to develop interventions which address the needs of this population.

Production of Complex Sentences in the Semantic Variant of Primary Progressive Aphasia: Neuropsychological, Clinical, Neuroanatomical and Demographic Correlates

Production of Complex Sentences in the Semantic Variant of Primary Progressive Aphasia: Neuropsychological, Clinical, Neuroanatomical and Demographic Correlates

Neurofilaments and progranulin are related to atrophy in frontotemporal lobar degeneration - A transdiagnostic study cross-validating atrophy and fluid biomarkers.

Frontotemporal lobar degeneration (FTLD) encompasses behavioral variant frontotemporal dementia (bvFTD), progressive supranuclear palsy, corticobasal syndrome/degeneration, and primary progressive aphasias (PPAs). We cross-validated fluid biomarkers and neuroimaging. Seven fluid biomarkers from cerebrospinal fluid and serum were related to atrophy in 428 participants including these FTLD subtypes, logopenic variant PPA (lvPPA), Alzheimer's disease (AD), and healthy subjects. Atrophy was assessed by structural magnetic resonance imaging and atlas-based volumetry. FTLD subtypes, lvPPA, and AD showed specific profiles for neurofilament light chain, phosphorylated heavy chain, tau, phospho-tau, amyloid beta1-42 from serum/cerebrospinal fluid, and brain atrophy. Neurofilaments related to regional atrophy in bvFTD, whereas progranulin was associated with atrophy in semantic variant PPA. Ubiquitin showed no effects. Results specify biomarker and atrophy patterns in FTLD and AD supporting differential diagnosis. They identify neurofilaments and progranulin in interaction with structural imaging as promising candidates for monitoring disease progression and therapy. Study cross-validated neuroimaging and fluid biomarkers in dementia. Five kinds of frontotemporal lobar degeneration and two variants of Alzheimer's disease. Study identifies disease-specific fluid biomarker and atrophy profiles. Fluid biomarkers and atrophy interact in a disease-specific way. Neurofilaments and progranulin are proposed as biomarkers for diagnosis and therapy.

Clinical and Linguistic Profiles and Challenges in Diagnosis of Primary Progressive Aphasia in Medan, Indonesia: A Hospital-based Study

Background Primary Progressive Aphasia (PPA) is a degenerative condition characterized by progressive loss of language function. Studies on PPA patients in Indonesia are still limited, and none has reported clinical and linguistic profiles of PPA patients who speak Bahasa Indonesia. This study aimed to describe clinical and linguistic profiles and challenges in the diagnosis of PPA patients from referral hospitals in Medan, Indonesia. Methods We retrospectively reviewed the clinical records of patients diagnosed with PPA based on the 2011 diagnostic criteria during the 2022-2023 period and described clinical characteristics data and linguistic profiles using descriptive analysis. Results We included 6 cases that fulfilled the diagnostic criteria for PPA. There were 3 cases categorized as nfvPPA, 1 case as svPPA, and 2 cases as lvPPA. There was female predominance (83.3%) and the mean age at onset was 59±2.96 years. The first symptom reported in the nfvPPA group was effortful, non-fluent speech; in svPPA, it was impaired naming and single word comprehension, while in lvPPA, it was impairment in word retrieval. Challenges in diagnosis included the availability of a standardized language tool aimed specifically for PPA in Bahasa Indonesia and the expertise needed to make such a diagnosis. Conclusion The main clinical features of the PPA reported were similar to previous findings with specific characteristics of Bahasa Indonesia. Determining language profiles of each variant of PPA in Bahasa Indonesia is crucial to establishing a correct diagnosis. Language assessment tool in Bahasa Indonesia is urgently needed to facilitate better assessment and management planning to improve quality of life.

MEM&SO protocol: understanding the determinants of social learning in neurodegenerative diseases

BackgroundPeople with neurodegenerative diseases may have difficulty learning new information, owing to their cognitive impairments. Teaching them techniques for learning in social contexts could alleviate this difficulty. The present study will examine the performances of patients with Alzheimer’s disease and patients with the semantic variant of primary progressive aphasia on a memory test administered in three social contexts. The protocol will make it possible to identify determinants of social interactions, social abilities, cognition, and personality that can explain the potentially beneficial effect of social context on learning in these patients.MethodsThirty dyads (patient with primary memory impairment who meets criteria for Alzheimer’s disease paired with caregiver), 16 dyads (patient meeting criteria for semantic variant of primary progressive aphasia paired with caregiver), and 46 dyads (healthy controls with no cognitive complaints) will be recruited. A nonverbal memory test (social memory task) will be administered to each dyad in three different social contexts (presence-only, observation, collaboration). Patients and healthy controls will also undergo a neuropsychological assessment to measure social (interactions and abilities), cognitive and personality aspects. Patients will be compared with controls on differential social scores calculated between the presence-only and collaboration contexts, and between the presence-only and observation contexts. A multiple comparative case study will be conducted to identify social, cognitive and personality variables that potentially explain the differential scores in the collaboration and observation contexts.DiscussionFor the first time, memory will be assessed in patients with Alzheimer’s disease and patients with the semantic variant of primary progressive aphasia in three different contexts (presence-only, observation, collaboration). The multiple comparative case study will make it possible to identify the determinants of memory performance in the social context, in order to create the most beneficial learning context for individual patients, according to their profile.Trial registrationThis study was approved by the Ile de France XI institutional review board (2022-A00198-35), and registered on ClinicalTrials.gov (no. NCT05800028), on April 27, 2023.

‛It's all communication': Family members' perspectives on the communication needs for themselves and their relatives with primary progressive aphasia.

Communication disabilities, such as primary progressive aphasia (PPA), impact family members as well as the individuals with the condition. To provide adequate communication care to people with PPA (PwPPA) and their family members, it is crucial to understand the communication needs from the family members' perspectives. To date, research on the communication needs of people with primary progressive aphasia and their family members from the perspectives of family members has been limited. The specific research objectives were to explore (a) the communication needs pertaining to PwPPA in the early, middle and late stages; and (b) the communication needs pertaining to family members of PwPPA in the early, middle and late stages, from the perspectives of family members. This study employed a qualitative description approach, underpinned by the pragmatic paradigm. Data collection involved semi-structured qualitative interviews with eight family members (relatives of four individuals with the logopenic variant of PPA, of two individuals with the nonfluent variant of PPA, of one individual with the semantic variant of PPA and of one individual with mixed PPA). Qualitative content analysis was used to identify codes and categories in relation to the research objectives. Qualitative content analysis revealed eight categories of communication needs pertaining to the PwPPA: person-specific needs; diagnosis and disclosure; general communication difficulties; impact on communication in everyday life; impact on cognition; impact on psychosocial well-being; impact on person's dignity and autonomy; and future planning. Six categories were identified pertaining to the family members: information about and awareness of PPA; impact of communication difficulties on family/others; increased responsibilities for the family in everyday life; impact on psychosocial well-being; and future planning. This investigation has expanded our knowledge in the area by providing insights about communication needs which speech-language pathologists and other health professionals should be aware of and take into account when providing communication care to PwPPA and their families. What is already known on the subject Person- and family-centred communication care is optimally guided by the person's and family's needs and values. Research on communication care for people with primary progressive aphasia has underscored the inclusion of family members. Previous research has investigated the impact and experiences of living with primary progressive aphasia from the family member perspective. What this paper adds to existing knowledge To date, research focusing on identifying the communication needs of people with primary progressive aphasia and their family members from the perspective of family members is limited. This study adds the family members' perspectives on the communication needs pertaining to themselves and their relatives with primary progressive aphasia in the early, middle and late stages of primary progressive aphasia. What are the potential or clinical implications of this work? Several clinical implications have been raised. Family members experience communication needs for themselves and should be included as recipients of communication care. Clinicians supporting people with primary progressive aphasia should be cognizant of the impact of communication fatigue on everyday life and therapy tasks. Communication care for this population should include communication partner training, support for psychosocial well-being and support with communication around future planning.

Hemispheric asymmetries in hippocampal volume related to memory in left and right temporal variants of frontotemporal degeneration.

In addition to Alzheimer's disease (AD), the hippocampus is now known to be affected in variants of frontotemporal degeneration (FTD). In semantic variant primary progressive aphasia (svPPA), characterized by language impairments, hippocampal atrophy is greater in the left hemisphere. Nonverbal impairments (e.g., visual object recognition) are prominent in the right temporal variant of FTD (rtvFTD), and hippocampal atrophy may be greater in the right hemisphere. In this study we examined the hypothesis that leftward hippocampal asymmetry (predicted in svPPA) would be associated with selective verbal memory impairments (with relative preservation of visual memory), while rightward asymmetry (predicted in rtvFTD) would be associated with the opposite pattern (greater visual memory impairment). In contrast, we predicted that controls and individuals in the amnestic mild cognitive impairment stage of AD (aMCI), both of whom were expected to show symmetrical hippocampal volumes, would show roughly equivalent scores in verbal and visual memory. Participants completed delayed recall tests with words and geometric shapes, and hippocampal volumes were assessed with MRI. The aMCI sample showed symmetrical hippocampal atrophy, and similar degree of verbal and visual memory impairment. The svPPA sample showed greater left hippocampal atrophy and verbal memory impairment, while rtvFTD showed greater right hippocampal atrophy and visual memory impairment. Greater asymmetry in hippocampal volumes was associated with larger differences between verbal and visual memory in the FTD samples. Unlike AD, asymmetry is a core feature of brain-memory relationships in temporal variants of FTD.

Genetic Screening of Patients with Sporadic Alzheimer's Disease and Frontotemporal Lobar Degeneration in the Chinese Population.

Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD) account for the vast majority of neurodegenerative dementias. AD and FTLD have different clinical phenotypes with a genetic overlap between them and other dementias. This study aimed to identify the genetic spectrum of sporadic AD and FTLD in the Chinese population. A total of 74 sporadic AD and 29 sporadic FTLD participants were recruited. All participants underwent whole-exome sequencing (WES) and testing for a hexanucleotide expansion in C9orf72 was additionally performed for participants with negative WES results. Four known pathogenic or likely pathogenic variants, including PSEN1 (p.G206D), MAPT (p.R5H), LRRK2 (p.W1434*), and CFAP43 (p.C934*), were identified in AD participants, and 1 novel pathogenic variant of ANXA11 (p.D40G) and two known likely pathogenic variants of MAPT (p.D177V) and TARDBP (p.I383V) were identified in FTLD participants. Twenty-four variants of uncertain significance as well as rare variants in risk genes for dementia, such as ABCA7, SORL1, TRPM7, NOS3, MPO, and DCTN1, were also found. Interestingly, several variants in participants with semantic variant primary progressive aphasia were detected. However, no participants with C9orf72 gene variants were found in the FTLD cohort. There was a high frequency of genetic variants in Chinese participants with sporadic AD and FTLD and a complex genetic overlap between these two types of dementia and other neurodegenerative diseases.

Symptom-based staging for logopenic variant primary progressive aphasia.

Logopenic variant primary progressive aphasia (lvPPA) is a major variant presentation of Alzheimer's disease (AD) that signals the importance of communication dysfunction across AD phenotypes. A clinical staging system is lacking for the evolution of AD-associated communication difficulties that could guide diagnosis and care planning. Our aim was to create a symptom-based staging scheme for lvPPA, identifying functional milestones relevant to the broader AD spectrum. An international lvPPA caregiver cohort was surveyed on symptom development under an 'exploratory' survey (34 UK caregivers). Feedback from this survey informed the development of a 'consolidation' survey (27 UK, 10 Australian caregivers) in which caregivers were presented with six provisional clinical stages and feedback was analysed using a mixed-methods approach. Six clinical stages were endorsed. Early symptoms included word-finding difficulty, with loss of message comprehension and speech intelligibility signalling later-stage progression. Additionally, problems with hearing in noise, memory and route-finding were prominent early non-verbal symptoms. 'Milestone' symptoms were identified that anticipate daily-life functional transitions and care needs. This work introduces a new symptom-based staging scheme for lvPPA, and highlights milestone symptoms that could inform future clinical scales for anticipating and managing communication dysfunction across the AD spectrum.

Phonological components analysis (PCA) and transcranial direct current stimulation (tDCS) in semantic variant of primary progressive aphasia (svPPA): A single-case longitudinal study

ABSTRACT Background Semantic variant of primary progressive aphasia (svPPA) is a form of dementia leading to progressive language comprehension and production difficulties. Aims We investigated whether a phonological approach combined with transcranial direct current stimulation (tDCS) would improve naming skills in semantic-based word finding difficulties due to svPPA. Methods & Procedures A 58-year-old female with svPPA was treated with phonological components analysis (PCA) combined with anodal transcranial direct current simulation (atDCS) of the left anterior temporal lobe. She completed four structured therapy blocks, each lasting two weeks and separated by a minimum two-week break including two interim tests. Before and after the intervention, we additionally assessed the participant’s general cognitive and language skills. Outcomes & Results Logistic regression showed that the participant’s ability to name trained and untrained items improved significantly. Furthermore, her overall cognitive and language abilities seemed to stagnate over the eight months, which seems surprising given the underlying progressive svPPA. We therefore concluded that phonological approaches combined with tDCS can enhance naming abilities even though the difficulties are mainly semantically driven.

Assessing informativeness in Spanish-speaking individuals with primary progressive aphasia

ABSTRACT Background Primary progressive aphasia (PPA) is a neurodegenerative disorder associated with atrophy of the frontotemporal region. It is primarily characterized by language impairments that become accentuated over time, often leading to isolation and social exclusion. There are three main subtypes, the semantic (svPPA), non-fluent (nfvPPA), and logopenic (lvPPA) variants, each presenting distinct language deficits, as captured by standard assessment batteries. However, such assessments often fail to adequately identify functional communication (dis)abilities in everyday life, which is crucial for effective diagnosis and treatment. One understudied aspect of communication is informativeness, the conveyance of an appropriate amount of information in an efficient fashion. Aim This study aimed to identify the unique features of each variant of PPA that distinguish it from healthy controls, and the dissimilarity across PPA groups, in terms of the effectiveness and efficiency with which Spanish-speaking individuals with PPA conveyed information. Methods and procedures Thirty-two Spanish-speaking patients with one of the three variants of PPA and 11 healthy individuals were audio-recorded performing a picture description task. The resulting recordings were transcribed, and the contents labelled according to whether they constituted relevant or off-topic content, each type of content being further divided into subcategories. In total, 51 parameters related to the (1) overall amount of speech and number of correct information units, (2) amount of relevant content, (3) completeness of the content, and (4) off-topic information were considered. Nonparametric analyses were conducted to assess the divergence from heathy controls of each PPA group, and the dissimilarity across PPA groups. Outcomes and results Results revealed disruptions in informativeness in all PPA variants compared to controls, with lvPPA characterized by inadequate content and a high concentration of off-topic elements, nfvPPA by inadequate content but efficient delivery, and svPPA by inadequate content delivered inefficiently. Conclusions This study revealed that all three variants of PPA are characterized by reduced informativeness, although each exhibits unique patterns in communicative efficiency and the presence of off-topic information. By assessing the total amount of relevant speech, efficiency in conveying content, and the presence of off-topic elements, this research enhances our understanding of the distinct communication impairments characterizing lvPPA, nfvPPA, and svPPA, and provides valuable insights that can be applied to developing tailored remedial strategies.

The Quebec Semantic Memory Battery: Development, Standardization, and Psychometric Assessment of a Semantic Memory Battery in French.

People with aphasia often experience semantic memory (SM) impairment. To improve diagnostic outcomes, SM tasks should recruit various sensory input channels (oral, written, and pictographic), permitting accessible, complete evaluation. There is a need for SM batteries for French-speaking Quebecers that use multiple input channels. The present study, therefore, describes the development of a novel French-language semantic battery: la Batterie québécoise de la mémoire sémantique (BQMS), the assessment of the BQMS's psychometric properties, and the establishment of normative data for the BQMS. We first developed eight SM tasks. Following a pilot validation study, we determined the BQMS's reliability and validity, to ensure consistent, accurate detection of SM impairment. Among French-speaking Quebecers with cerebrovascular aphasia (n = 10), people with the semantic variant of Primary Progressive Aphasia (n = 4), and healthy controls (n = 14), we examined its convergent validity, concurrent validity, test-retest reliability, and internal consistency. Finally, we established normative data for the BQMS by calculating cut-off scores per task that indicate SM impairment (in 93 cognitively healthy French-speaking Quebecers), stratified by sociodemographic variables associated with performance. The BQMS shows high concurrent, discriminant, and convergent validity, as well as good test-retest reliability and internal consistency. The cut-off score indicating SM impairment ranged from the 2nd to 25th percentiles (stratified by task, age, and sex). The BQMS's psychometric properties indicate that it could be a valuable clinical tool for detecting SM impairment. Our normative data will help clinicians detect such impairments.

Clinical and neuroanatomical characterization of the semantic behavioral variant of frontotemporal dementia in a multicenter Italian cohort

BackgroundSemantic behavioral variant frontotemporal dementia (sbvFTD) is a neurodegenerative condition presenting with specific behavioral and semantic derangements and predominant atrophy of the right anterior temporal lobe (ATL). The objective was to evaluate clinical, neuropsychological, neuroimaging, and genetic features of an Italian sbvFTD cohort, defined according to recently proposed guidelines, compared to semantic variant primary progressive aphasia (svPPA) and behavioral variant FTD (bvFTD) patients.MethodsFifteen sbvFTD, sixty-three bvFTD, and twenty-five svPPA patients and forty controls were enrolled. Patients underwent clinical, cognitive evaluations, and brain MRI. Symptoms of bvFTD patients between onset and first visit were retrospectively recorded and classified as early and late. Grey matter atrophy was investigated using voxel-based morphometry.ResultssbvFTD experienced early criteria-specific symptoms: world, object and person-specific semantic loss (67%), complex compulsions and rigid thought (60%). Sequentially, more behavioral symptoms emerged (apathy/inertia, loss of empathy) along with non-criteria-specific symptoms (anxiety, suspiciousness). sbvFTD showed sparing of attentive/executive functions, especially compared to bvFTD and better language functions compared to svPPA. All sbvFTD patients failed at the famous face recognition test and more than 80% failed in understanding written metaphors and humor. At MRI, sbvFTD had predominant right ATL atrophy, almost specular to svPPA. Three sbvFTD patients presented pathogenic genetic variants.ConclusionWe replicated the application of sbvFTD diagnostic guidelines in an independent Italian cohort, demonstrating that the presence of person-specific semantic knowledge loss and mental rigidity, along with preserved executive functions and a predominant right ATL atrophy with sparing of frontal lobes, should prompt a diagnosis of sbvFTD.

Spontaneous Speech Alterations and Evolution in Primary Progressive Aphasia Variants (P2-9.010)

Spontaneous Speech Alterations and Evolution in Primary Progressive Aphasia Variants (P2-9.010)

Progression to corticobasal syndrome: a longitudinal study of patients with nonfluent primary progressive aphasia and primary progressive apraxia of speech.

Nonfluent variant primary progressive aphasia (nfvPPA) and primary progressive apraxia of speech (PPAOS) can be precursors to corticobasal syndrome (CBS). Details on their progression remain unclear. We aimed to examine the clinical and neuroimaging evolution of nfvPPA and PPAOS into CBS. We conducted a retrospective longitudinal study in 140 nfvPPA or PPAOS patients and applied the consensus criteria for possible and probable CBS for every visit, evaluating limb rigidity, akinesia, limb dystonia, myoclonus, ideomotor apraxia, alien limb phenomenon, and nonverbal oral apraxia (NVOA). Given the association of NVOA with AOS, we also modified the CBS criteria by excluding NVOA and assigned every patient to either a progressors or non-progressors group. We evaluated the frequency of every CBS feature by year from disease onset, and assessed gray and white matter volume loss using SPM12. Asymmetric akinesia, NVOA, and limb apraxia were the most common CBS features that developed; while limb dystonia, myoclonus, and alien limb were rare. Eighty-two patients progressed to possible CBS; only four to probable CBS. nfvPPA and PPAOS had a similar proportion of progressors, although nfvPPA progressed to CBS earlier (p-value = 0.046), driven by an early appearance of limb apraxia (p-value = 0.0041). The non-progressors and progressors both showed premotor/motor cortex involvement at baseline, with spread into prefrontal cortex over time. An important proportion of patients with nfvPPA and PPAOS progress to possible CBS, while they rarely develop features of probable CBS even after long follow-up.

Distinctive whole-brain cell types predict tissue damage patterns in thirteen neurodegenerative conditions

For over a century, brain research narrative has mainly centered on neuron cells. Accordingly, most neurodegenerative studies focus on neuronal dysfunction and their selective vulnerability, while we lack comprehensive analyses of other major cell types’ contribution. By unifying spatial gene expression, structural MRI, and cell deconvolution, here we describe how the human brain distribution of canonical cell types extensively predicts tissue damage in 13 neurodegenerative conditions, including early- and late-onset Alzheimer’s disease, Parkinson’s disease, dementia with Lewy bodies, amyotrophic lateral sclerosis, mutations in presenilin-1, and 3 clinical variants of frontotemporal lobar degeneration (behavioral variant, semantic and non-fluent primary progressive aphasia) along with associated three-repeat and four-repeat tauopathies and TDP43 proteinopathies types A and C. We reconstructed comprehensive whole-brain reference maps of cellular abundance for six major cell types and identified characteristic axes of spatial overlapping with atrophy. Our results support the strong mediating role of non-neuronal cells, primarily microglia and astrocytes, in spatial vulnerability to tissue loss in neurodegeneration, with distinct and shared across-disorder pathomechanisms. These observations provide critical insights into the multicellular pathophysiology underlying spatiotemporal advance in neurodegeneration. Notably, they also emphasize the need to exceed the current neuro-centric view of brain diseases, supporting the imperative for cell-specific therapeutic targets in neurodegeneration.

Gesture profiles distinguish primary progressive aphasia variants: a preliminary study

ABSTRACT Background Primary progressive aphasia (PPA) is a neurodegenerative syndrome characterized by progressive language deficits. The main variants of PPA – semantic (svPPA), logopenic (lvPPA), and nonfluent (nfvPPA) – can be challenging to distinguish. Limb apraxia often co-occurs with PPA, but it is unclear whether PPA variants are associated with different gesture deficits. Prior evidence from stroke indicates that temporal lobe lesions are associated with reduced benefit from meaning in gesture performance. Temporal lesions are also associated with greater deficits in hand postures compared to arm kinematics in gesture imitation. Aims We tested the hypothesis that svPPA, who primarily exhibit temporal lobe atrophy, would differentially show this pattern. In addition, we predicted that as a group, individuals with PPA would more accurately produce meaningful than meaningless gestures and kinematic components than hand postures, as found in neurotypical adults and individuals with stroke. Methods & Procedures Participants with PPA completed meaningful and meaningless gesture imitation tasks. Performance was scored for hand posture and arm kinematic components. Bayesian mixed-effect models examined trial-level gesture imitation accuracy, while controlling for dementia severity and random effects of subjects and items. Fixed effects included an interaction between PPA variant, task condition/meaning, and gesture component. Outcomes & Results We found a critical interaction between PPA variant, meaning, and gesture component. In particular, unlike lvPPA and nfvPPA, svPPA subjects’ hand postures failed to benefit from gesture meaning. This preliminary research extends prior findings on the role of the temporal lobe in action representations associated with manipulable objects, and is among the first to demonstrate distinct gesture imitation patterns between PPA variants. Conclusions Characterizing gesture deficits in PPA may help inform diagnostics, compensatory communication strategies, and models of praxis.

Heterogeneity and overlap in the continuum of linguistic profile of logopenic and semantic variants of primary progressive aphasia: a Profile Analysis based on Multidimensional Scaling study

BackgroundPrimary progressive aphasia (PPA) diagnostic criteria underestimate the complex presentation of semantic (sv) and logopenic (lv) variants, in which symptoms partially overlap, and mixed clinical presentation (mixed-PPA) and heterogenous profile (lvPPA +) are frequent. Conceptualization of similarities and differences of these clinical conditions is still scarce.MethodsLexical, semantic, phonological, and working memory errors from nine language tasks of sixty-seven PPA were analyzed using Profile Analysis based on Multidimensional Scaling, which allowed us to create a distributed representation of patients’ linguistic performance in a shared space. Patients had been studied with [18F] FDG-PET. Correlations were performed between metabolic and behavioral data.ResultsPatients’ profiles were distributed across a continuum. All PPA, but two, presented a lexical retrieval impairment, in terms of reduced production of verbs and nouns. svPPA patients occupied a fairly clumped space along the continuum, showing a preponderant semantic deficit, which correlated to fusiform gyrus hypometabolism, while only few presented working memory deficits. Adjacently, lvPPA + presented a semantic impairment combined with phonological deficits, which correlated with metabolism in the anterior fusiform gyrus and posterior middle temporal gyrus. Starting from the shared phonological deficit side, a large portion of the space was occupied by all lvPPA, showing a combination of phonological, lexical, and working memory deficits, with the latter correlating with posterior temporo-parietal hypometabolism. Mixed PPA did not show unique profile, distributing across the space.DiscussionDifferent clinical PPA entities exist but overlaps are frequent. Identifying shared and unique clinical markers is critical for research and clinical practice. Further research is needed to identify the role of genetic and pathological factors in such distribution, including also higher sample size of less represented groups.