scholarly journals Graded, multidimensional intra- and intergroup variations in primary progressive aphasia and post-stroke aphasia

Brain ◽  
2020 ◽  
Vol 143 (10) ◽  
pp. 3121-3135 ◽  
Author(s):  
Ruth U Ingram ◽  
Ajay D Halai ◽  
Gorana Pobric ◽  
Seyed Sajjadi ◽  
Karalyn Patterson ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Diagnostic Category ◽  
Principal Component ◽  
Primary Progressive Aphasia ◽  
Component Analysis ◽  
Underlying Structure ◽  
Progressive Aphasia ◽  
Primary Progressive ◽  
Post Stroke ◽  
Group Homogeneity

Abstract Language impairments caused by stroke (post-stroke aphasia, PSA) and neurodegeneration (primary progressive aphasia, PPA) have overlapping symptomatology, nomenclature and are classically divided into categorical subtypes. Surprisingly, PPA and PSA have rarely been directly compared in detail. Rather, previous studies have compared certain subtypes (e.g. semantic variants) or have focused on a specific cognitive/linguistic task (e.g. reading). This study assessed a large range of linguistic and cognitive tasks across the full spectra of PSA and PPA. We applied varimax-rotated principal component analysis to explore the underlying structure of the variance in the assessment scores. Similar phonological, semantic and fluency-related components were found for PSA and PPA. A combined principal component analysis across the two aetiologies revealed graded intra- and intergroup variations on all four extracted components. Classification analysis was used to test, formally, whether there were any categorical boundaries for any subtypes of PPA or PSA. Semantic dementia formed a true diagnostic category (i.e. within group homogeneity and distinct between-group differences), whereas there was considerable overlap and graded variations within and between other subtypes of PPA and PSA. These results suggest that (i) a multidimensional rather than categorical classification system may be a better conceptualization of aphasia from both causes; and (ii) despite the very different types of pathology, these broad classes of aphasia have considerable features in common.

scholarly journals Graded, multi-dimensional intragroup and intergroup variations in primary progressive aphasia and post-stroke aphasia

2019 ◽  
Author(s):  
Ruth U. Ingram ◽  
Ajay D. Halai ◽  
Gorana Pobric ◽  
Seyed Sajjadi ◽  
Karalyn Patterson ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Diagnostic Category ◽  
Principal Component ◽  
Primary Progressive Aphasia ◽  
Component Analysis ◽  
Underlying Structure ◽  
Progressive Aphasia ◽  
Primary Progressive ◽  
Post Stroke ◽  
Group Homogeneity

AbstractLanguage impairments caused by stroke (post-stroke aphasia) and neurodegeneration (primary progressive aphasia) have overlapping symptomatology, nomenclature and are classically divided into categorical subtypes. Surprisingly, primary progressive aphasia (PPA) and post-stroke aphasia (PSA) have rarely been directly compared in detail. Rather previous studies have compared certain subtypes (e.g., semantic variants) or have focussed on a specific cognitive/linguistic task (e.g., reading). This study assessed a large range of linguistic and cognitive tasks across the full spectra of PSA and PPA. We applied varimax-rotated principal component analysis to explore the underlying structure of the variance in the assessment scores. Similar phonological, semantic and fluency-related components were found for PSA and PPA. A combined principal component analysis across the two aetiologies revealed graded intragroup and intergroup variations on all four extracted components. Classification analysis was employed to test, formally, whether there were any categorical boundaries for any subtypes of PPA or PSA. Semantic dementia proved to form a true diagnostic category (i.e., within group homogeneity and distinct between group differences), whereas there was considerable overlap and graded variations within and between other subtypes of PPA and PSA. These results suggest that (a) a multi-dimensional rather than categorical classification system may be a better conceptualisation of aphasia from both causes, and (b) despite the very different types of pathology, these broad classes of aphasia have considerable features in common.

scholarly journals A new methodology based on functional principal component analysis to study postural stability post-stroke

2018 ◽  
Vol 56 ◽  
pp. 18-26 ◽  
Author(s):  
M. Luz Sánchez-Sánchez ◽  
Juan-Manuel Belda-Lois ◽  
Silvia Mena-del Horno ◽  
Enrique Viosca-Herrero ◽  
Celedonia Igual-Camacho ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Postural Stability ◽  
Principal Component ◽  
Component Analysis ◽  
Functional Principal Component Analysis ◽  
Post Stroke ◽  
Functional Principal Component

scholarly journals Effects of tDCS on Sound Duration in Patients with Apraxia of Speech in Primary Progressive Aphasia

2021 ◽  
Vol 11 (3) ◽  
pp. 335
Author(s):  
Charalambos Themistocleous ◽  
Kimberly Webster ◽  
Kyrana Tsapkini
Keyword(s):  
Speech Therapy ◽  
Inferior Frontal Gyrus ◽  
Primary Progressive Aphasia ◽  
Motor Disorder ◽  
Apraxia Of Speech ◽  
Post Intervention ◽  
Progressive Aphasia ◽  
Primary Progressive ◽  
Post Stroke ◽  
Sound Duration

Transcranial direct current stimulation (tDCS) over the left inferior frontal gyrus (IFG) was found to improve oral and written naming in post-stroke and primary progressive aphasia (PPA), speech fluency in stuttering, a developmental speech-motor disorder, and apraxia of speech (AOS) symptoms in post-stroke aphasia. This paper addressed the question of whether tDCS over the left IFG coupled with speech therapy may improve sound duration in patients with apraxia of speech (AOS) symptoms in non-fluent PPA (nfvPPA/AOS) more than sham. Eight patients with non-fluent PPA/AOS received either active or sham tDCS, along with speech therapy for 15 sessions. Speech therapy involved repeating words of increasing syllable-length. Evaluations took place before, immediately after, and two months post-intervention. Words were segmented into vowels and consonants and the duration of each vowel and consonant was measured. Segmental duration was significantly shorter after tDCS compared to sham and tDCS gains generalized to untrained words. The effects of tDCS sustained over two months post-treatment in trained and untrained sounds. Taken together, these results demonstrate that tDCS over the left IFG may facilitate speech production by reducing segmental duration. The results provide preliminary evidence that tDCS may maximize efficacy of speech therapy in patients with nfvPPA/AOS.

scholarly journals Evaluating the granularity and statistical structure of lesions and behaviour in post-stroke aphasia

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Ying Zhao ◽  
Ajay D Halai ◽  
Matthew A Lambon Ralph
Keyword(s):  
Principal Component Analysis ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Principal Component ◽  
Component Analysis ◽  
Vascular Supply ◽  
Angular Gyrus ◽  
Statistical Structure ◽  
Speech Fluency ◽  
Post Stroke

Abstract The pursuit of relating the location of neural damage to the pattern of acquired language and general cognitive deficits post-stroke stems back to the 19th century behavioural neurology. While spatial specificity has improved dramatically over time, from the large areas of damage specified by post-mortem investigation to the millimetre precision of modern MRI, there is an underlying issue that is rarely addressed, which relates to the fact that damage to a given area of the brain is not random but constrained by the brain’s vasculature. Accordingly, the aim of this study was to uncover the statistical structure underlying the lesion profile in chronic aphasia post-stroke. By applying varimax-rotated principal component analysis to the lesions of 70 patients with chronic post-stroke aphasia, we identified 17 interpretable clusters, largely reflecting the vascular supply of middle cerebral artery sub-branches and other sources of individual variation in vascular supply as shown in classical angiography studies. This vascular parcellation produced smaller displacement error in simulated lesion–symptom analysis compared with individual voxels and Brodmann regions. A second principal component analysis of the patients’ detailed neuropsychological data revealed a four-factor solution reflecting phonological, semantic, executive-demand and speech fluency abilities. As a preliminary exploration, stepwise regression was used to relate behavioural factor scores to the lesion principal components. Phonological ability was related to two components, which covered the posterior temporal region including the posterior segment of the arcuate fasciculus, and the inferior frontal gyrus. Three components were linked to semantic ability and were located in the white matter underlying the anterior temporal lobe, the supramarginal gyrus and angular gyrus. Executive-demand related to two components covering the dorsal edge of the middle cerebral artery territory, while speech fluency was linked to two components that were located in the middle frontal gyrus, precentral gyrus and subcortical regions (putamen and thalamus). Future studies can explore in formal terms the utility of these principal component analysis-derived lesion components for relating post-stroke lesions and symptoms.

scholarly journals Redefining the multidimensional clinical phenotypes of frontotemporal lobar degeneration syndromes

2019 ◽  
Author(s):  
Alexander G. Murley ◽  
Ian Coyle-Gilchrist ◽  
Matthew Rouse ◽  
P Simon Jones ◽  
Win Li ◽  
...  
Keyword(s):  
Diagnostic Criteria ◽  
Clinical Features ◽  
Frontotemporal Lobar Degeneration ◽  
Clinical Phenotype ◽  
Principal Component ◽  
Primary Progressive Aphasia ◽  
Diagnostic Features ◽  
Cross Sectional ◽  
Progressive Aphasia ◽  
Primary Progressive

AbstractThe syndromes caused by frontotemporal lobar degeneration (FTLD) have highly heterogenous and overlapping clinical features. There has been great progress in the refinement of clinical diagnostic criteria in the last decade, but we propose that a better understanding of aetiology, pathophysiology and symptomatic treatments can arise from a transdiagnostic approach to clinical phenotype and brain morphometry. In a cross-sectional epidemiological study, we examined 310 patients with a syndrome likely to be caused by frontotemporal lobar degeneration, including behavioural variant frontotemporal dementia (bvFTD), the non-fluent (nfvPPA), semantic (svPPA) variants of primary progressive aphasia, progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS). We also included patients with logopenic primary progressive aphasia (lvPPA) and those who met criteria for PPA but not one of the three subtypes. To date, forty-nine patients have a neuropathological diagnosis. A principal component analysis identified symptom dimensions that broadly recapitulated the core features of the main clinical syndromes. However, the subject-specific scores on these dimensions showed considerable overlap across the diagnostic groups. Sixty-two percent of participants had phenotypic features that met the diagnostic criteria for more than one syndrome. Behavioural disturbance was prevalent in all groups. Forty-four percent of patients with CBS had PSP-like features and thirty percent of patients with PSP had CBS-like features. Many patients with PSP and CBS had language impairments consistent with nfvPPA while patients with bvFTD often had semantic impairments. Using multivariate source-based morphometry on a subset of patients (n=133), we identified patterns of co-varying brain atrophy that were represented across the diagnostic groups. Canonical correlation analysis of clinical and imaging components found three key brain-behaviour relationships that revealed a continuous spectrum across the cohort rather than discrete diagnostic entities. In the forty-six patients with longitudinal follow up (mean 3.6 years) syndromic overlap increased with time. Together, these results show that syndromes associated with FTLD do not form discrete mutually exclusive categories from their clinical features or structural brain changes, but instead exist in a multidimensional spectrum. Patients often manifest diagnostic features of multiple disorders and deficits in behaviour, movement and language domains are not confined to specific diagnostic groups. It is important to recognise individual differences in clinical phenotype, both for clinical management and to understand pathogenic mechanisms. We suggest that the adoption of a transdiagnostic approach to the spectrum of FTLD syndromes provides a useful framework with which to understand disease progression, heterogeneity and treatment.

scholarly journals Evaluating the granularity and statistical structure of lesions and behaviour in post-stroke aphasia

2019 ◽  
Author(s):  
Ying Zhao ◽  
Ajay D. Halai ◽  
Matthew A. Lambon Ralph
Keyword(s):  
Principal Component Analysis ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Principal Component ◽  
Component Analysis ◽  
Vascular Supply ◽  
Angular Gyrus ◽  
Statistical Structure ◽  
Speech Fluency ◽  
Post Stroke

AbstractThe pursuit of relating the location of neural damage to the pattern of acquired language and general cognitive deficits post-stroke stems back to 19th century behavioural neurology. Whilst spatial specificity has improved dramatically over time, from the large areas of damage specified by post-mortem investigation to the millimetre precision of modern MRI, there is an underlying issue that is rarely addressed, which relates to the fact that damage to a given area of the brain is not random but constrained by the brain’s vasculature. Accordingly, the aim of this study was to uncover the statistical structure underlying the lesion profile in chronic aphasia post-stroke. By applying varimax-rotated principal component analysis to the lesions of 70 patients with chronic post-stroke aphasia, we identified 17 interpretable clusters, largely reflecting the vascular supply of middle cerebral artery sub-branches and other sources of individual variation in vascular supply as shown in classical angiography studies. This vascular parcellation produced smaller displacement error in simulated lesion-symptom analysis compared with individual voxels and Brodmann regions. A second principal component analysis of the patients’ detailed neuropsychological data revealed a four factor solution reflecting phonological, semantic, executive-demand and speech fluency abilities. As a preliminary exploration, stepwise regression was used to relate behavioural factor scores to the lesion principal components. Phonological ability was related to two components, which covered the posterior temporal region including the posterior segment of the arcuate fasciculus, and the inferior frontal gyrus. Three components were linked to semantic ability and were located in the white matter underlying the anterior temporal lobe, the supramarginal gyrus and angular gyrus. Executive-demand related to two components covering the dorsal edge of the middle cerebral artery territory, while speech fluency was linked to two components that were located in the middle frontal gyrus, precentral gyrus, and subcortical regions (putamen and thalamus). Future studies can explore in formal terms the utility of these PCA-derived lesion components for relating post-stroke lesions and symptoms.

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