Publications by authors named "Paulo Loureiro De Sousa"

The differential mechanisms between proteinopathies and neurodegeneration in Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) remain unclear. To address this issue, we conducted a voxel-based morphometry and cerebrospinal fluid biomarker (α-synuclein, Aβ42, t-Tau and p-Tau) level correlation study in patients with DLB, AD and mixed cases (AD + DLB). Cerebrospinal fluid samples obtained by lumbar puncture and whole-brain T1-weighted images were collected in the AlphaLewyMA cohort.

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Although deficits in learning and retrieving new information are well characterized in dementia with Lewy bodies, autobiographical memory has never been explored in this disease. Yet, autobiographical memory impairments are a pervasive feature of dementia, well characterized in other neurodegenerative diseases. Moreover, autobiographical memory corresponds to an extension over time of the self, which we hypothesize is altered in dementia with Lewy bodies and impairment of which could be linked to the insular atrophy occurring from an early stage of the disease.

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Identifying and validating a biomarker with high specificity in early-stage dementia with Lewy bodies (DLB) using a feasible method is crucial to enhance the current suboptimal diagnostic procedure. Previous research revealed abnormalities, including hypoperfusion in the right anterior insular cortex at group level, in prodromal DLB. Exploring hypoperfusion of the right anterior insula, at an individual-level and assessing its relevance as a potential imaging biomarker in early DLB, has, to our knowledge, not been investigated.

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Background: Dementia with Lewy Bodies (DLB) is responsible for cognitive-behavioural disorders but also for gait disorders. The latter are thought to be related to parkinsonism, but the neural bases of these disorders are not well known, especially in the early stages. The aim of this study was to investigate by volumetric Magnetic Resonance Imaging the neuronal basis of gait disorders in DLB patients, compared to Healthy Elderly Controls and Alzheimer's Disease patients.

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Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) are often associated with depressive symptoms from the prodromal stage. The aim of the present study was to investigate the neuroanatomical correlates of depression in prodromal to mild DLB patients compared with AD patients. Eighty-three DLB patients, 37 AD patients, and 18 healthy volunteers were enrolled in this study.

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Article Synopsis
  • Clinical research typically requires careful study designs that account for variables like sex and age, but often overlooks body size factors like height and weight in neuroimaging studies.
  • This study analyzed data from 267 healthy adults to explore how body height and weight relate to various brain and spinal cord MRI metrics, finding significant correlations, especially with brain gray matter volume and cervical spinal cord area.
  • The results suggest that body size is an important biological variable that should be included in clinical neuroimaging study designs to enhance accuracy in understanding brain and spinal cord structures.
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Background: Dementia with Lewy bodies (DLB) is characterized by insular atrophy, which occurs at the early stage of the disease. Damage to the insula has been associated with disorders reflecting impairments of the most fundamental components of the self, such as anosognosia, which is a frequently reported symptom in patients with Lewy bodies (LB). The purpose of this study was to investigate modifications of the self-concept (SC), another component of the self, and to identify neuroanatomical correlates, in prodromal to mild DLB.

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Objectives: We have previously demonstrated difficulties in written production in dementia with Lewy bodies (DLB) patients. We now aim to determine the neural correlates of writing production in DLB, combining clinical data and structural MRI measures.

Method: Sixteen prodromal to mild DLB patients were selected to participate in the study.

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Dementia with Lewy bodies (DLB) is a neurodegenerative disorder with a wide heterogeneity of symptoms, which suggests the existence of different subtypes. We used data-driven analysis of magnetic resonance imaging (MRI) data to investigate DLB subtypes. We included 165 DLB from the Mayo Clinic and 3 centers from the European DLB consortium and performed a hierarchical cluster analysis to identify subtypes based on gray matter (GM) volumes.

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Narrative discourse (ND) comprehension is a complex task that implies not only linguistic abilities but also other cognitive abilities, including efficient executive functioning. An executive dysfunction has been described in dementia with Lewy bodies (DLB) from the early stage. Here, we question the link between executive dysfunction in DLB and narrative comprehension.

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Background: Isolated subjective cognitive impairment (SCI) and mild cognitive impairment (MCI) are the prodromal phases of dementia with Lewy bodies (DLB). MEMENTO is a nationwide study of patients with SCI and MCI with clinic, neuropsychology, biology, and brain imaging data. We aimed to compare SCI and MCI patients with symptoms of prodromal DLB to others in this study at baseline.

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Dementia with Lewy bodies (DLB) patients show few significant macroscopic structural changes, especially at the early stages of the disease, making quantitative MRI especially interesting to explore more subtle changes that are not detectable by conventional volumetric techniques. Microstructural alterations have been reported in DLB at the dementia stage, but no study to date was conducted in prodromal patients. Here, quantitative MRI data were collected from 46 DLB prodromal patients and 20 healthy elderly subjects, who also underwent a detailed clinical examination including the Mayo Clinic Fluctuation Scale.

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Article Synopsis
  • A new standardized quantitative MRI protocol for spinal cord imaging, called the spine generic protocol, has been developed to be used with 3T MRI systems from major manufacturers like GE, Philips, and Siemens.
  • The protocol includes specific imaging techniques for evaluating spinal cord macrostructure and microstructure, such as T1 and T2-weighted imaging to determine cross-sectional areas and diffusion-weighted imaging for white matter assessment.
  • An open-access document detailing the protocol is available online, providing a useful resource for researchers and clinicians aiming to enhance spinal cord imaging in neuroimaging practices.
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Article Synopsis
  • - The paper by Cohen-Adad et al. introduces a standardized MRI protocol for evaluating spinal cord integrity, tested across 19 and 42 centers for single and multi-subject datasets respectively, involving a total of 260 participants.
  • - The datasets are openly available online, allowing researchers to access valuable data for analysis using tools like the Spinal Cord Toolbox, which produces normative values and statistics on variability across sites and manufacturers.
  • - The protocol demonstrated high reproducibility with less than 5% variation across different sites and manufacturers, aiming to enhance the accessibility and reliability of quantitative MRI assessments in spinal research.
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We investigated whether cerebrovascular disease contributes to neurodegeneration and clinical phenotype in dementia with Lewy bodies (DLB). Regional cortical thickness and subcortical gray matter volumes were estimated from structural magnetic resonance imaging (MRI) in 165 DLB patients. Cortical and subcortical infarcts were recorded and white matter hyperintensities (WMHs) were assessed.

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Imaging has become a valuable tool in the assessment of neuromuscular diseases, and, specifically, quantitative MR imaging provides robust biomarkers for the monitoring of disease progression. Quantitative evaluation of fat infiltration and quantification of the T2 values of the muscular tissue's water component (wT2) are two of the most essential indicators currently used. As each voxel of the image can contain both water and fat, a two-component model for the estimation of wT2 must be used.

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Article Synopsis
  • - Down syndrome (DS) is caused by an extra copy of chromosome 21, leading to intellectual disability, and this study investigates various DS mouse models to understand how genes on mouse chromosome 16, which is similar to human chromosome 21, affect cognitive outcomes.
  • - Researchers found key genetic interactions on chromosome 16 that significantly influence brain function and structure, revealing complex relationships that impact cognitive performance in DS models.
  • - The study identified six biological pathways linked to gene expression issues related to synaptic dysfunction, providing new insights into molecular mechanisms that could inform future therapeutic approaches for Down syndrome.
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Fibrosis is a key pathological feature in muscle disorders, but its quantification mainly relies on histological and biochemical assays. Muscle fibrosis most frequently is entangled with other pathological processes, as cell membrane lesions, inflammation, necrosis, regeneration, or fatty infiltration, making in vivo assessment difficult. Here, we (1) describe a novel mouse model with variable levels of induced skeletal muscle fibrosis displaying minimal inflammation and no fat infiltration, and (2) report how fibrosis affects non-invasive metrics derived from nuclear magnetic resonance (NMR) and ultrasound shear-wave elastography (SWE) associated with a passive biomechanical assay.

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According to the Construction-Integration model (Kintsch 1988; Kintsch 1998), two forms of representation are activated during the reading and the comprehension of a text: 1) the text base, which includes semantic propositions and 2) the situation model, corresponding to the integration of the information contained in the text to the memories and knowledge of the reader. Functional neuroimaging studies in healthy subjects have shown that the text base is underpinned by frontal regions and lateral temporal regions whereas the situation model would rather depend on the posterior cingulate cortex, the precuneus and other regions depending on the dimension studied. However, the brain regions highlighted so far were only involved in comprehension and not necessary for this cognitive ability.

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Objectives: To determine the prevalence, localization and associations of cerebral microbleeds (CMB) in dementia with Lewy bodies (DLB) with its core clinical symptoms and cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD). We hypothesize DLB patients with CMB have increased amyloid burden compared to those without CMB, which could also translate into clinical differences.

Methods: Retrospective cross-sectional analysis from the AlphaLewyMA study (https://clinicaltrials.

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Background: Several studies have investigated the value of alpha-synuclein assay in the cerebrospinal fluid (CSF) of Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) patients in the differential diagnosis of these two pathologies. However, very few studies have focused on this assay in AD and DLB patients at the MCI stage.

Methods: All patients were enrolled under a hospital clinical research protocol from the tertiary Memory Clinic (CM2R) of Alsace, France, by an experienced team of clinicians.

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Purpose: To determine optimal constrained tissue parameters and off-resonance sequence parameters for single-point macromolecular proton fraction (SP-MPF) mapping based on a comprehensive quantitative magnetization transfer (qMT) protocol in healthy and demyelinated living mice at 7T.

Methods: Using 3D spoiled gradient echo-based sequences, a comprehensive qMT protocol is performed by sampling the Z-spectrum of mice brains, in vivo. Provided additional T , and B maps allow for the estimation of qMT tissue parameters, among which three will be constrained, namely the longitudinal and transverse relaxation characteristics of the free pool (R T ), the cross-relaxation rate (R) and the bound pool transverse relaxation time (T ).

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Background: Central nervous system damage in multiple sclerosis (MS) is responsible for serious deficiencies. Current therapies are focused on the treatment of inflammation; however, there is an urgent need for innovative therapies promoting neuroregeneration, particularly myelin repair. It is demonstrated that testosterone can act through neural androgen receptors and several clinical observations stimulated an interest in the potential protective effects of testosterone treatment for MS.

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