Identification of the main components of spontaneous speech in primary progressive aphasia and their neural underpinnings using multimodal MRI and FDG-PET imaging

Connected Speech Alterations and Progression in Patients With Primary Progressive Aphasia Variants

BACKGROUND AND OBJECTIVES

Diagnosing the different variants of primary progressive aphasia (PPA) is challenging, but more accurate characterization can improve patient management and treatment outcomes. This study aimed to identify the following: (1) which speech features, alone or combined with language assessment and gray matter volumes (GMVs), best distinguish PPA variants and (2) how connected speech evolves in PPA.

METHODS

This prospective study was conducted at IRCCS San Raffaele Hospital in Milan, Italy, between 2010 and 2021. We included patients with PPA who underwent neuropsychological assessments, including standard evaluation of language and the "Picnic Scene" speech test, and, when available, brain structural MRI. Clinical and language assessments were also performed at follow-up in a subgroup. Sequential feature selection models identified speech parameters that best differentiated groups, incorporating age, sex, education, standard language tests, and GMVs. In each PPA group, linear mixed-effect models analyzed speech changes over time.

RESULTS

We included 95 patients with PPA (mean age 69 ± 9 years, 55 women [58%]; 40 with nonfluent variant PPA [nfvPPA], 35 with semantic variant PPA [svPPA], 20 with logopenic variant PPA [lvPPA]), of whom 82 underwent brain MRI and 34 had a follow-up visit after 10.2 months. Each model distinguished svPPA from the other PPA groups with high accuracy (R2 range 0.93-1.00; p < 0.001). No differences in accuracy were observed among models for this distinction. In differentiating nfvPPA and lvPPA groups, the models incorporating speech parameters (R2 = 0.92; p < 0.001), GMVs (R2 = 0.95; p < 0.001), and their combination (speech + GMVs; R2 = 0.97; p < 0.001) outperformed those using only standard language scores (R2 = 0.75; p = 0.01). Over time, patients with nfvPPA showed more phonological errors, the svPPA group exhibited more semantic and morphosyntactic errors along with difficulties in naming and syntax production, and patients with lvPPA exhibited reduced number of words per second and fewer words per sentence.

DISCUSSION

All models were equally effective in distinguishing the svPPA group from the other 2 PPA subtypes. However, compared with using standard measures alone, incorporating speech measures from the "Picnic Scene" speech test, GMVs, or their combination into the models significantly improved accuracy in differentiating nfvPPA and lvPPA groups. The PPA variants showed distinct speech trajectories. These variables can aid in understanding disease progression, predicting patient outcomes, and planning speech therapy interventions in clinical practice.

Partial volume effect correction impairs the diagnostic utility of [18F]-THK-5351 PET in nonfluent-agrammatic variant primary progressive aphasia

OBJECTIVES

Partial volume effects in positron emission tomography occur frequently in neurodegenerative diseases due to increasing cortical atrophy during the disease course, and fronto-temporal dementia is often characterized by severe atrophy. The aim of this study was to challenge partial volume effect correction (PVEC) in patients with nonfluent-agrammatic variant primary progressive aphasia (nfv-PPA) imaged with [18F]-THK-5351 PET a marker of reactive neuroinflammatory astrogliosis as well as tau-binding.

METHODS

Patients with nfv-PPA (n = 20) were imaged with [18F]-THK-5351 PET accompanied by structural magnetic resonance tomography imaging (MRI). Region specific cortical grey matter volumes and standard uptake value ratios (SUVr) of the Hammers atlas were compared with eight healthy control (HC) (n = 8) data before and after performing region-based voxel-wise PVEC. We evaluated regional coefficients of variance (CoV) and the number of regions with significant [18F]-THK-5351 PET signal differences between nfv-PPA and controls before and after PVEC. Additionally, a blinded visual read was performed by three nuclear medicine physicians (consensus) before and after PVEC.

RESULTS

Prior to PVEC, [18F]-THK-5351 tracer uptake was significantly higher in the bilateral frontal cortex of patients with nfv-PPA when compared to HC (left > right), despite significant grey matter atrophy in the same brain regions in patients with nfv-PPA. SUVr differences between nfv-PPA and HC were further increased by PVEC in frontal brain regions, but group level variance increased in parallel and reduced the number of significant differences between SUVr of nfv-PPA and HC (uncorrected: 10 significant regions, CoV[nfv-PPA]: 20.8 % ± 4.7 %, CoV[HC]: 7.9 % ± 2.4 %/PVEC: 3 significant regions, CoV[nfv-PPA]: 28.4 % ± 8.9 %, CoV[HC]: 9.8 % ± 2.5 %). Sensitivity/specificity of the visual read for detection of nfv-PPA was 0.85/1.00 without PVEC and 0.85/0.75 with PVEC.

CONCLUSIONS

[18F]-THK-5351 PET facilitates detection of pathological alterations in patients with nfvPPA with severe atrophy. PVEC increases quantitative SUVr differences between patients with nfv-PPA and HC but introduces a parallel increase of variance at the group level. Visual assessment of [18F]-THK-5351 images in patients with nfv-PPA is impaired by PVEC due to loss of specificity and does not support the use of PVEC even in patients with severe atrophy.

White matter tract correlations with spoken language in cerebrovascular disease

Assessment of spoken language is a promising marker for cognitive impairment in individuals with cerebrovascular disease. However, the underlying neurological basis for spoken language beyond single words and sentences remains poorly defined in this cohort, particularly with respect to white matter. This study aimed to examine and compare white matter hyperintensity volumes and diffusion tensor metrics in normal-appearing white matter (NAWM) as potential correlates of spoken language performance. Baseline imaging and spoken language data were obtained from the cerebrovascular disease cohort of the Ontario Neurodegenerative Disease Research Initiative (n = 127; age: 55-85 years). Most participants had subclinical or very mild strokes, with very little to no aphasia symptoms. Spoken language samples were analysed to compute 10 different measures related to syntax, productivity, lexical diversity, fluency, and information content. Structural and diffusion MRI data were analysed to segment white matter hyperintensities and tracts. Normalized white matter hyperintensity volume, as well as average fractional anisotropy and mean diffusivity in the normal-appearing portion of eight white matter tracts, were correlated with the 10 spoken language measures using canonical correlation analyses. White matter and spoken language variate scores for individual participants then were correlated separately in male (n = 86) and female (n = 41) participants to probe potential sex differences. Spoken language performance was significantly associated with the fractional anisotropy (rc = 0.51, P  = 0.041) and mean diffusivity (rc = 0.56, P  = 0.011) of NAWM, particularly in the left superior longitudinal fasciculus, but not with white matter hyperintensity volumes (rc = 0.41, P  = 0.80) in the same tracts. Measures related to syntax, fluency, and information content loaded most strongly in the spoken language variate. No significant sex differences were found in NAWM microstructure, and female and male participants exhibited similarly strong associations between spoken language and NAWM microstructure (fractional anisotropy: z = 1.44, P = 0.15; mean diffusivity: z = 1.03, P = 0.30). These results suggest that diffusion MRI in NAWM may be superior to white matter hyperintensity volumetrics when evaluating the role of white matter tract integrity on cognitive outcomes in people with relatively mild cerebrovascular pathology. These results also demonstrate that multi-domain spoken language analysis is sensitive to underlying white matter microstructure in participants with cerebrovascular disease without significant aphasia, supporting its value as a tool for assessing cognitive status.

Effects of single-session repetitive transcranial magnetic stimulation to identify the optimal brain target in primary progressive aphasia

BACKGROUND

Non-invasive brain stimulation has shown positive results in maximizing the effects of language therapy in primary progressive aphasia (PPA). Due to the different patterns of brain damage in each aphasia variant, we hypothesized that patients with non-fluent and semantic variants would show a differential response to transcranial magnetic stimulation (TMS).

OBJECTIVE

We aimed to compare the clinical responses after a single session of repetitive TMS in the left inferior frontal gyrus (IFG) and the left dorsolateral prefrontal cortex (DLPC).

METHODOLOGY

Twenty patients with PPA (14 with non-fluent and 6 with semantic variants) were assessed before and after repetitive TMS over the IFG, DLPC, and vertex with several language tasks, connected speech, and a subjective impression of change scale.

RESULTS

IFG stimulation was associated with an improvement in words per minute and the subjective assessment in the non-fluent variant, but no effects were found in the semantic variant. DLPC stimulation was associated with an improvement in words per minute, repetition, and naming latency in the non-fluent variant, and in naming and subjective impression of change in the semantic variant.

CONCLUSIONS

Our study showed a differential effect of one session of brain stimulation over the IFG and DLPC in patients with non-fluent and semantic PPA variants. These findings suggest that the selection of the target of stimulation may be relevant for the success of brain stimulation and favor the use of DLPC over the IFG.

The use of low-density EEG for the classification of PPA and MCI

Objective

Dissociating Primary Progressive Aphasia (PPA) from Mild Cognitive Impairment (MCI) is an important, yet challenging task. Given the need for low-cost and time-efficient classification, we used low-density electroencephalography (EEG) recordings to automatically classify PPA, MCI and healthy control (HC) individuals. To the best of our knowledge, this is the first attempt to classify individuals from these three populations at the same time.

Methods

We collected three-minute EEG recordings with an 8-channel system from eight MCI, fourteen PPA and eight HC individuals. Utilizing the Relative Wavelet Entropy method, we derived (i) functional connectivity, (ii) graph theory metrics and extracted (iii) various energy rhythms. Features from all three sources were used for classification. The k-Nearest Neighbor and Support Vector Machines classifiers were used.

Results

A 100% individual classification accuracy was achieved in the HC-MCI, HC-PPA, and MCI-PPA comparisons, and a 77.78% accuracy in the HC-MCI-PPA comparison.

Conclusion

We showed for the first time that successful automatic classification between HC, MCI and PPA is possible with short, low-density EEG recordings. Despite methodological limitations of the current study, these results have important implications for clinical practice since they show that fast, low-cost and accurate disease diagnosis of these disorders is possible. Future studies need to establish the generalizability of the current findings with larger sample sizes and the efficient use of this methodology in a clinical setting.

Beyond neuropsychological tests: AI speech analysis in PKU

Phenylketonuria (PKU) is a rare inherited metabolic disorder characterized by toxic phenylalanine (Phe) concentrations in blood and brain. State-of-the-art analyses of speech detected a dimension of verbal discourse providing insights that extend beyond those captured by existing paradigms to measure performance associated with biochemical markers in PKU. The Cookie Theft Picture Task provided a standardized stimulus for eliciting spontaneous speech from 42 adults with PKU and 41 adults without PKU. Subtests measuring language and memory from the Wechsler Adult Intelligence Scale-Fourth Edition showed no differences between the groups and no correlations with biomarkers in PKU. In contrast, AI analyses of responses to the Cookie Theft Task revealed significant differences between the PKU and non-PKU groups on 23 linguistic features. Using multidimensional scaling (MDS), these features were aggregated into a single quantifiable Dimension 1 that significantly correlated with biomarkers. When extreme examples of Dimension 1 were presented to chatGPT, the differences noted reflected attention to detail, clarity in word choice, expression cohesion, contextual awareness and emotion recognition. We subsequently defined Dimension 1 as Proficiency in Verbal Discourse. This novel measure elucidated discourse styles possibly associated with suboptimal achievement and learning disabilities, often reported in PKU. In summary, AI captured a characteristic associated with metabolic status undetectable through traditional neuropsychological measures. Future studies will expand upon this novel paradigm, leveraging speech AI to quantify meaningful aspects of everyday functioning and possibly provide information for management decisions. Once validated, this measure holds promise for extension to other rare diseases and incorporation into clinical trials.

A systematic review of the quantitative markers of speech and language of the frontotemporal degeneration spectrum and their potential for cross-linguistic implementation

Frontotemporal dementia (FTD) is a neurodegenerative disease spectrum with an urgent need for reliable biomarkers for early diagnosis and monitoring. Speech and language changes occur in the early stages of FTD and offer a potential non-invasive, early, and accessible diagnostic tool. The use of speech and language markers in this disease spectrum is limited by the fact that most studies investigate English-speaking patients. This systematic review examines the literature on psychoacoustic and linguistic features of speech that occur across the FTD spectrum across as many different languages as possible. 76 papers were identified that investigate psychoacoustic and linguistic markers in discursive speech. 75 % of these papers studied English-speaking patients. The most generalizable features found across different languages, are speech rate, articulation rate, pause frequency, total pause duration, noun-verb ratio, and total number of nouns. While there are clear interlinguistic differences across patient groups, the results show promise for implementation of cross-linguistic markers of speech and language across the FTD spectrum particularly for psychoacoustic features.

Dysfluency in primary progressive aphasia: Temporal speech parameters

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.

Connected Speech Fluency in Poststroke and Progressive Aphasia: A Scoping Review of Quantitative Approaches and Features

PURPOSE

Speech fluency has important diagnostic implications for individuals with poststroke aphasia (PSA) as well as primary progressive aphasia (PPA), and quantitative assessment of connected speech has emerged as a widely used approach across both etiologies. The purpose of this review was to provide a clearer picture on the range, nature, and utility of individual quantitative speech/language measures and methods used to assess connected speech fluency in PSA and PPA, and to compare approaches across etiologies.

METHOD

We conducted a scoping review of literature published between 2012 and 2022 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews guidelines. Forty-five studies were included in the review. Literature was charted and summarized by etiology and characteristics of included patient populations and method(s) used for derivation and analysis of speech/language features. For a subset of included articles, we also charted the individual quantitative speech/language features reported and the level of significance of reported results.

RESULTS

Results showed that similar methodological approaches have been used to quantify connected speech fluency in both PSA and PPA. Two hundred nine individual speech-language features were analyzed in total, with low levels of convergence across etiology on specific features but greater agreement on the most salient features. The most useful features for differentiating fluent from nonfluent aphasia in both PSA and PPA were features related to overall speech quantity, speech rate, or grammatical competence.

CONCLUSIONS

Data from this review demonstrate the feasibility and utility of quantitative approaches to index connected speech fluency in PSA and PPA. We identified emergent trends toward automated analysis methods and data-driven approaches, which offer promising avenues for clinical translation of quantitative approaches. There is a further need for improved consensus on which subset of individual features might be most clinically useful for assessment and monitoring of fluency.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.25537237.

Role of pause duration in primary progressive aphasia

Aims

To detect differences in speech fluency in separate primary progressive aphasia syndromes (PPA) using automated analysis techniques. The resulting linguistic features are evaluated for their use in a predictive model to identify common patterns in speakers with PPA. As fluency is observable in audio recordings, its quantification may provide a low-cost instrument that augments spontaneous speech analyses in clinical practice.

Methods and Procedures

Speech was recorded in 14 controls, 7 nonfluent variant (nfvPPA) and 8 semantic variant (svPPA) speakers. The recordings were annotated for speech and non-speech with Kaldi, a common toolkit for speech processing software. Variables relating to fluency (pause rate, number of pauses, length of pauses) were analyzed.

Outcomes and Results

The best fitting distribution of pause duration was a combination of two Gaussian distributions, corresponding with pause categories short vs. long.Group level differences were found in the rate of pauses and proportion of silence: nfvPPA speakers use more short pauses relative to long pauses than control speakers, and the duration of short and long pauses is longer; svPPA speakers use more longer pauses relative to short pauses. Their short pauses are significantly shorter than those from control speakers.Participants in both PPA groups pause more frequently. SvPPA speakers are typically perceived as fluent. However, our analysis shows their fluency patterns to be distinct from control speakers, if the long-short distinction is observed.

Conclusions

Automatic measurements of pause duration show meaningful distinctions across the groups and might provide future aid in clinical assessment.

Multimodal cross-examination of progressive apraxia of speech by diffusion tensor imaging-based tractography and Tau-PET scans

Progressive apraxia of speech (PAOS) is a 4R tauopathy characterized by difficulties with motor speech planning. Neurodegeneration in PAOS targets the premotor cortex, particularly the supplementary motor area (SMA), with degeneration of white matter (WM) tracts connecting premotor and motor cortices and Broca's area observed on diffusion tensor imaging (DTI). We aimed to assess flortaucipir uptake across speech-language-related WM tracts identified using DTI tractography in PAOS. Twenty-two patients with PAOS and 26 matched healthy controls were recruited by the Neurodegenerative Research Group (NRG) and underwent MRI and flortaucipir-PET. The patient population included patients with primary progressive apraxia of speech (PPAOS) and non-fluent variant/agrammatic primary progressive aphasia (agPPA). Flortaucipir PET scans and DTI were coregistered using rigid registration with a mutual information cost function in subject space. Alignments between DTI and flortaucipir PET were inspected in all cases. Whole-brain tractography was calculated using deterministic algorithms by a tractography reconstruction tool (DSI-studio) and specific tracts were identified using an automatic fiber tracking atlas-based method. Fractional anisotropy (FA) and flortaucipir standardized uptake value ratios (SUVRs) were averaged across the frontal aslant tract, arcuate fasciculi, inferior frontal-occipital fasciculus, inferior and middle longitudinal fasciculi, as well as the SMA commissural fibers. Reduced FA (p < .0001) and elevated flortaucipir SUVR (p = .0012) were observed in PAOS cases compared to controls across all combined WM tracts. For flortaucipir SUVR, the greatest differentiation of PAOS from controls was achieved with the SMA commissural fibers (area under the receiver operator characteristic curve [AUROC] = 0.83), followed by the left arcuate fasciculus (AUROC = 0.75) and left frontal aslant tract (AUROC = 0.71). Our findings demonstrate that flortaucipir uptake is increased across WM tracts related to speech/language difficulties in PAOS.

Discriminating nonfluent/agrammatic and logopenic PPA variants with automatically extracted morphosyntactic measures from connected speech

Morphosyntactic assessments are important for characterizing individuals with nonfluent/agrammatic variant primary progressive aphasia (nfvPPA). Yet, standard tests are subject to examiner bias and often fail to differentiate between nfvPPA and logopenic variant PPA (lvPPA). Moreover, relevant neural signatures remain underexplored. Here, we leverage natural language processing tools to automatically capture morphosyntactic disturbances and their neuroanatomical correlates in 35 individuals with nfvPPA relative to 10 healthy controls (HC) and 26 individuals with lvPPA. Participants described a picture, and ensuing transcripts were analyzed via part-of-speech tagging to extract sentence-related features (e.g., subordinating and coordinating conjunctions), verbal-related features (e.g., tense markers), and nominal-related features (e.g., subjective and possessive pronouns). Gradient boosting machines were used to classify between groups using all features. We identified the most discriminant morphosyntactic marker via a feature importance algorithm and examined its neural correlates via voxel-based morphometry. Individuals with nfvPPA produced fewer morphosyntactic elements than the other two groups. Such features robustly discriminated them from both individuals with lvPPA and HCs with an AUC of .95 and .82, respectively. The most discriminatory feature corresponded to subordinating conjunctions was correlated with cortical atrophy within the left posterior inferior frontal gyrus across groups (pFWE < .05). Automated morphosyntactic analysis can efficiently differentiate nfvPPA from lvPPA. Also, the most sensitive morphosyntactic markers correlate with a core atrophy region of nfvPPA. Our approach, thus, can contribute to a key challenge in PPA diagnosis.

Functional and structural abnormalities of the speech disorders: a multimodal activation likelihood estimation meta-analysis

Speech disorders are associated with different degrees of functional and structural abnormalities. However, the abnormalities associated with specific disorders, and the common abnormalities shown by all disorders, remain unclear. Herein, a meta-analysis was conducted to integrate the results of 70 studies that compared 1843 speech disorder patients (dysarthria, dysphonia, stuttering, and aphasia) to 1950 healthy controls in terms of brain activity, functional connectivity, gray matter, and white matter fractional anisotropy. The analysis revealed that compared to controls, the dysarthria group showed higher activity in the left superior temporal gyrus and lower activity in the left postcentral gyrus. The dysphonia group had higher activity in the right precentral and postcentral gyrus. The stuttering group had higher activity in the right inferior frontal gyrus and lower activity in the left inferior frontal gyrus. The aphasia group showed lower activity in the bilateral anterior cingulate gyrus and left superior frontal gyrus. Across the four disorders, there were concurrent lower activity, gray matter, and fractional anisotropy in motor and auditory cortices, and stronger connectivity between the default mode network and frontoparietal network. These findings enhance our understanding of the neural basis of speech disorders, potentially aiding clinical diagnosis and intervention.

Phase I trial of the MuSic to CONnect (MuSiCON) protocol: feasibility and effect of choir participation for individuals with cognitive impairment

BACKGROUND

Individuals living in residential aged care facilities with cognitive decline are at risk of social isolation and decreased wellbeing. These risks may be exacerbated by decline in communication skills. There is growing awareness that group singing may improve sense of wellbeing for individuals with dementia. However, to date few studies have examined broader rehabilitative effects on skills such as communication of individuals with dementia.

AIMS

To determine the feasibility and acceptability of the MuSic to Connect (MuSiCON) choir and language/communication assessment protocol in people with cognitive impairment living in non-high-care wards of a residential facility.

METHODS

Six individuals with mild-moderate cognitive impairment participated (age range 55-91 years, five female, one male). A mixed method approach was used. Quantitative outcomes included attendance rates, quality of life and communication measures. The qualitative measure was a brief survey of experience completed by participants and carers post-intervention.

RESULTS

Overall, MuSiCON was perceived as positive and beneficial, with high attendance, perception of improved daily functioning and high therapeutic benefit without harmful effects. While there was no reliable change in communication skills over the course of the six-week intervention, most participants successfully engaged in the conversational task, suggesting it is a suitable and ecologically valid method for data collection.

CONCLUSIONS

The MuSiCON protocol demonstrated feasibility and was well received by participants and staff at the residential facility. A co-design approach is recommended to improve upon feasibility, acceptability and validity of the assessment protocol prior to Phase II testing.

Turning the Spotlight to Cholinergic Pharmacotherapy of the Human Language System

Even though language is essential in human communication, research on pharmacological therapies for language deficits in highly prevalent neurodegenerative and vascular brain diseases has received little attention. Emerging scientific evidence suggests that disruption of the cholinergic system may play an essential role in language deficits associated with Alzheimer's disease and vascular cognitive impairment, including post-stroke aphasia. Therefore, current models of cognitive processing are beginning to appraise the implications of the brain modulator acetylcholine in human language functions. Future work should be directed further to analyze the interplay between the cholinergic system and language, focusing on identifying brain regions receiving cholinergic innervation susceptible to modulation with pharmacotherapy to improve affected language domains. The evaluation of language deficits in pharmacological cholinergic trials for Alzheimer's disease and vascular cognitive impairment has thus far been limited to coarse-grained methods. More precise, fine-grained language testing is needed to refine patient selection for pharmacotherapy to detect subtle deficits in the initial phases of cognitive decline. Additionally, noninvasive biomarkers can help identify cholinergic depletion. However, despite the investigation of cholinergic treatment for language deficits in Alzheimer's disease and vascular cognitive impairment, data on its effectiveness are insufficient and controversial. In the case of post-stroke aphasia, cholinergic agents are showing promise, particularly when combined with speech-language therapy to promote trained-dependent neural plasticity. Future research should explore the potential benefits of cholinergic pharmacotherapy in language deficits and investigate optimal strategies for combining these agents with other therapeutic approaches.

Neuropsychological endpoints for clinical trials in methylmalonic acidemia and propionic acidemia: A pilot study

Introduction

This pilot study assessed instruments measuring relatively discrete neuropsychological domains to inform the selection of clinical outcome assessments that may be considered for interventional trials in methylmalonic acidemia (MMA) and propionic acidemia (PA).

Methods

Tests and questionnaires were selected for their possible relevance to MMA and PA and potential sensitivity to modest changes in functioning and behavior.

Results

Twenty-one patients (<18 years, n = 10;>18 years, n = 11) and/or their caregivers responded to video interviews and paper tests. Language deficits and significant motor deficits in some participants impacted scoring, especially in the verbal and processing speed sections of the Wechsler Intelligence Scale for Children, Fifth Edition (WISC-V) and the Wechsler Adult Intelligence Scale, Fourth Edition (WAIS-IV). However, all participants ≥12 years of age were able to complete the Cookie Theft Picture Task. Thus, verbal discourse remains a potentially useful endpoint for participants in this age group. The Vineland Adaptive Behavior Scales (VABS-3) Adaptive Behavior Composite and Communication Scores confirmed delayed or immature functioning in day-to-day activities in these participants. Significant motor deficits prevented completion of some tests. Computerized processing speed tasks, which require pressing a button or tapping a computer screen, may be easier than writing or checking off boxes on paper in this cohort. Sleep characteristics among MMA participants were within normative ranges of the Child and Adolescent Sleep Checklist (CASC), indicating that this measurement would not provide valuable data in a clinical trial. Despite their challenges, responses to the Metabolic Quality of Life Questionnaire indicated these patients and their caregivers perceive an overall high quality of life.

Conclusion

Overall, test and questionnaire results were notably different between participants with MMA and participants with PA. The study demonstrates that pilot studies can detect instruments that may not be appropriate for individuals with language or motor deficits and that may not provide a broad range of scores reflecting disease severity. It also provides a rationale for focusing on discrete neuropsychological domains since some aspects of functioning were less affected than others and some were more closely related to disease severity. When global measures are used, overall scores may mask specific deficits. A pilot study like this one cannot ensure that scores will change over time in response to a specific treatment in a clinical trial. However, it can avert the selection of instruments that do not show associations with severity or biomedical parameters likely to be the target of a clinical trial. A pilot study can also identify when differences in diagnoses and baseline functioning need to be addressed prior to developing the analytical plan for the trial.

Neural basis of visuospatial tests in behavioral variant frontotemporal dementia

Background

Recent models of visuospatial functioning suggest the existence of three main circuits emerging from the dorsal (“where”) route: parieto-prefrontal pathway, parieto-premotor, and parieto-medial temporal. Neural underpinnings of visuospatial task performance and the sparing of visuospatial functioning in bvFTD are unclear. We hypothesized different neural and cognitive mechanisms in visuospatial tasks performance in bvFTD and AD.

Methods

Two hundred and sixteen participants were enrolled for this study: 72 patients with bvFTD dementia and 144 patients with AD. Visual Object and Space Perception Battery Position Discrimination and Number Location (VOSP-PD and VOSP-NL) and Rey-Osterrieth Complex Figure (ROCF) were administered to examine visuospatial functioning, together with a comprehensive neuropsychological battery. FDG-PET was acquired to evaluate brain metabolism. Voxel-based brain mapping analyses were conducted to evaluate the brain regions associated with visuospatial function in bvFTD and AD.

Results

Patients with AD performed worst in visuospatial tasks in mild dementia, but not at prodromal stage. Attention and executive functioning tests showed higher correlations in bvFTD than AD with ROCF, but not VOSP subtests. Visuospatial performance in patients with bvFTD was associated with bilateral frontal regions, including the superior and medial frontal gyri, supplementary motor area, insula and middle cingulate gyrus.

Conclusion

These findings support the role of prefrontal and premotor regions in visuospatial processing through the connection with the posterior parietal cortex and other posterior cortical regions. Visuospatial deficits should be interpreted with caution in patients with bvFTD, and should not be regarded as hallmarks of posterior cortical dysfunction.

White matter tract strength correlates with therapy outcome in persistent developmental stuttering

Persistent stuttering is a prevalent neurodevelopmental speech disorder, which presents with involuntary speech blocks, sound and syllable repetitions, and sound prolongations. Affected individuals often struggle with negative feelings, elevated anxiety, and low self-esteem. Neuroimaging studies frequently link persistent stuttering with cortical alterations and dysfunctional cortico-basal ganglia-thalamocortical loops; dMRI data also point toward connectivity changes of the superior longitudinal fasciculus (SLF) and the frontal aslant tract (FAT). Both tracts are involved in speech and language functions, and the FAT also supports inhibitory control and conflict monitoring. Whether the two tracts are involved in therapy-associated improvements and how they relate to therapeutic outcomes is currently unknown. Here, we analyzed dMRI data of 22 patients who participated in a fluency-shaping program, 18 patients not participating in therapy, and 27 fluent control participants, measured 1 year apart. We used diffusion tractography to segment the SLF and FAT bilaterally and to quantify their microstructural properties before and after a fluency-shaping program. Participants learned to speak with soft articulation, pitch, and voicing during a 2-week on-site boot camp and computer-assisted biofeedback-based daily training for 1 year. Therapy had no impact on the microstructural properties of the two tracts. Yet, after therapy, stuttering severity correlated positively with left SLF fractional anisotropy, whereas relief from the social-emotional burden to stutter correlated negatively with right FAT fractional anisotropy. Thus, posttreatment, speech motor performance relates to the left dorsal stream, while the experience of the adverse impact of stuttering relates to the structure recently associated with conflict monitoring and action inhibition.