Differences between Alzheimer's disease and mild cognitive impairment using brain networks from magnetic resonance texture analysis.

Several studies have aimed at identifying biomarkers in the initial phases of Alzheimer's disease (AD). Conversely, texture features, such as those from gray-level co-occurrence matrices (GLCMs), have highlighted important information from several types of medical images. More recently, texture-based brain networks have been shown to provide useful information in characterizing healthy individuals. However, no studies have yet explored the use of this type of network in the context of AD. This work aimed to employ texture brain networks to investigate the distinction between groups of patients with amnestic mild cognitive impairment (aMCI) and mild dementia due to AD, and a group of healthy subjects. Magnetic resonance (MR) images from the three groups acquired at two instances were used. Images were segmented and GLCM texture parameters were calculated for each region. Structural brain networks were generated using regions as nodes and the similarity among texture parameters as links, and graph theory was used to compute five network measures. An ANCOVA was performed for each network measure to assess statistical differences between groups. The thalamus showed significant differences between aMCI and AD patients for four network measures for the right hemisphere and one network measure for the left hemisphere. There were also significant differences between controls and AD patients for the left hippocampus, right superior parietal lobule, and right thalamus-one network measure each. These findings represent changes in the texture of these regions which can be associated with the cortical volume and thickness atrophies reported in the literature for AD. The texture networks showed potential to differentiate between aMCI and AD patients, as well as between controls and AD patients, offering a new tool to help understand these conditions and eventually aid early intervention and personalized treatment, thereby improving patient outcomes and advancing AD research.

Differences in structural and functional default mode network connectivity in amyloid positive mild cognitive impairment: a longitudinal study.

PURPOSE: Default mode network (DMN) has emerged as a potential biomarker of Alzheimer's disease (AD); however, it is not clear whether it can differentiate amnestic mild cognitive impairment with altered amyloid (aMCI-Aß +) who will evolve to AD. We evaluated if structural and functional connectivity (FC), hippocampal volumes (HV), and cerebrospinal fluid biomarkers (CSF-Aß42, p-Tau, and t-Tau) can differentiate aMCI-Aß + converters from non-converters. METHODS: Forty-eight individuals (18 normal controls and 30 aMCI subjects in the AD continuum - with altered Aß42 in the CSF) were followed up for an average of 13 months. We used MultiAtlas, UF2C, and Freesurfer software to evaluate diffusion tensor imaging, FC, and HV, respectively, INNOTEST® kits to measure CSF proteins, and neuropsychological tests. Besides, we performed different MANOVAs with further univariate analyses to differentiate groups. RESULTS: During follow-up, 8/30 aMCI-Aß + converted (26.6%) to AD dementia. There were no differences in multivariate analysis between groups in CSF biomarkers (p = 0.092) or at DMN functional connectivity (p = 0.814). aMCI-Aß + converters had smaller right HV than controls (p = 0.013), and greater right cingulum parahippocampal bundle radial diffusivity than controls (p < 0.001) and non-converters (p = 0.036). CONCLUSION: In this exploratory study, structural, but not functional, DMN connectivity alterations may differentiate aMCI-Aß + subjects who converted to AD dementia.

Slowly progressive behavioral frontotemporal dementia syndrome in a family co-segregating the C9orf72 expansion and a Synaptophysin mutation.

INTRODUCTION: Synaptophysin, already related to X-linked intellectual disability, is expressed mainly in the central nervous system. Studies in humans indicate that the downregulation of synaptophysin could be involved in the development of dementia. Our study presents the first familial case of behavioral variant frontotemporal dementia associated with the co-occurrence of the repeat expansion in C9orf72 and a pathogenic variant in the SYP gene. METHODS: Exome sequencing and repeat-primed PCR for C9orf72 were performed for two siblings with clinical and imaging findings suggestive of slowly progressive behavioral frontotemporal dementia. RESULTS: We found that both siblings have the hexanucleotide expansion in C9orf72 and a null variant in the SYP gene. The most affected sibling presents the putative variant in a hemizygous state. With milder symptoms, his sister has the same pathogenic variant in heterozygosis, compatible with X-linked inheritance. DISCUSSION: Our results strengthened previous suggestive evidence that the phenotypes associated with C9orf72 repeat expansion are variable and probably influenced by additional genetic modifiers. We hypothesized that the pathogenic variant in the SYP gene might have modified the typical phenotype associated with the C9orf72 mutation.

Disease Progression in Frontotemporal Dementia and Alzheimer Disease: The Contribution of Staging Scales.

INTRODUCTION: There is a shortage of validated instruments to estimate disease progression in frontotemporal dementia (FTD). OBJECTIVES: To evaluate the ability of the FTD Rating Scale (FTD-FRS) to detect functional and behavioral changes in patients diagnosed with the behavioral variant of FTD (bvFTD), primary progressive aphasia (PPA), and Alzheimer disease (AD) after 12 months of the initial evaluation, compared to the Clinical Dementia Rating scale-frontotemporal lobar degeneration (CDR-FTLD) and the original Clinical Dementia Rating scale (CDR). METHODS: The sample consisted of 70 individuals, aged 40+ years, with at least 2 years of schooling, 31 with the diagnosis of bvFTD, 12 with PPA (8 with semantic variant and 4 with non-fluent variant), and 27 with AD. The FTD-FRS, the CDR, and the 2 additional CDR-FTLD items were completed by a clinician, based on the information provided by the caregiver with frequent contact with the patient. The Addenbrooke Cognitive Examination-Revised was completed by patients. After 12 months, the same protocol was applied. RESULTS: The FTD-FRS, CDR-FTLD, and CDR detected significant decline after 12 months in the 3 clinical groups (exception: FTD-FRS for PPA). The CDR was less sensitive to severe disease stages. CONCLUSIONS: The FTD-FRS and the CDR-FTLD are especially useful tools for dementia staging in AD and in the FTD spectrum.

Dementia in Latin America: Paving the way toward a regional action plan.

Across Latin American and Caribbean countries (LACs), the fight against dementia faces pressing challenges, such as heterogeneity, diversity, political instability, and socioeconomic disparities. These can be addressed more effectively in a collaborative setting that fosters open exchange of knowledge. In this work, the Latin American and Caribbean Consortium on Dementia (LAC-CD) proposes an agenda for integration to deliver a Knowledge to Action Framework (KtAF). First, we summarize evidence-based strategies (epidemiology, genetics, biomarkers, clinical trials, nonpharmacological interventions, networking, and translational research) and align them to current global strategies to translate regional knowledge into transformative actions. Then we characterize key sources of complexity (genetic isolates, admixture in populations, environmental factors, and barriers to effective interventions), map them to the above challenges, and provide the basic mosaics of knowledge toward a KtAF. Finally, we describe strategies supporting the knowledge creation stage that underpins the translational impact of KtAF.

ADAM10 Plasma and CSF Levels Are Increased in Mild Alzheimer's Disease.

ADAM10 is the main α-secretase that participates in the non-amyloidogenic cleavage of amyloid precursor protein (APP) in neurons, inhibiting the production of ß-amyloid peptide (Aß) in Alzheimer's disease (AD). Strong recent evidence indicates the importance of the localization of ADAM10 for its activity as a protease. In this study, we investigated ADAM10 activity in plasma and CSF samples of patients with amnestic mild cognitive impairment (aMCI) and mild AD compared with cognitively healthy controls. Our results indicated that plasma levels of soluble ADAM10 were significantly increased in the mild AD group, and that in these samples the protease was inactive, as determined by activity assays. The same results were observed in CSF samples, indicating that the increased plasma ADAM10 levels reflect the levels found in the central nervous system. In SH-SY5Y neuroblastoma cells, ADAM10 achieves its major protease activity in the fraction obtained from plasma membrane lysis, where the mature form of the enzyme is detected, confirming the importance of ADAM10 localization for its activity. Taken together, our results demonstrate the potential of plasma ADAM10 to act as a biomarker for AD, highlighting its advantages as a less invasive, easier, faster, and lower-cost processing procedure, compared to existing biomarkers.

Cerebral Structure and Function in Stroke-free Patients with Atrial Fibrillation.

OBJECTIVES: Atrial fibrillation (AF) is associated with high risk of dementia and brain atrophy in stroke-free patients, but the mechanisms underlying this association remain unclear. We aimed to examine the brain volume and connectivity of paramount cognitive brain networks in stroke-free patients with AF without dementia. MATERIALS AND METHODS: Twenty-six stroke-free patients with AF and 26 age and sex-matched subjects without AF were submitted to a 3-tesla brain structural and functional MRI. An extensive clinical evaluation excluded stroke, dementia, low cardiac output, carotid stenosis and metabolic diseases without optimal therapy. We used CHA2DS2-VASc score to classify the cardiovascular risk factor burden and a broad neuropsychological battery to assess the cognitive performance. Voxel based morphometry analysis of. structural MRI defined whole-brain gray and white matter volumes. Finally, we used eco-plannar MRI images to compare the differences of functional connectivity of 7 large-scale resting-state networks between AF patients and controls. RESULTS: Taking into account the history of hypertension and heart failure, AF was associated to volume decrease of the right basal frontal lobe and right inferior cerebellum. Decreased connectivity of the ventral Default Mode Network (vDMN) was observed in the AF group. No disruption of connectivity was observed in the executive, visuospatial and salience networks. CONCLUSION: Individuals with AF without stroke or dementia have subtle reduction of gray and white matter, restricted to frontal areas and cerebellum. These patients show decreased vDMN connectivity, without other large-scale brain network disruption.

Hippocampal atrophy disrupts the language network but not hemispheric language lateralization.

OBJECTIVE: It is still unclear how temporal lobe epilepsy (TLE) with and without hippocampal atrophy (HA) affects cortical language distribution. We aimed to investigate the role of the hippocampus on language lateralization, activation pattern, and functional connectivity (FC) in patients with TLE. METHODS: We investigated 93 patients with TLE-divided into right HA (RHA), left HA (LHA), and negative magnetic resonance imaging (MRI) (non-HA)-and 101 controls using a semantic-language functional MRI (fMRI) task and the Boston Naming Test (BNT). RESULTS: Groups did not differ in the frequency of atypical language lateralization (LL), which correlated differently with handedness in each brain region and group. Blood-oxygen-level dependend (BOLD) activation patterns and region of interest (ROI)-to-ROI FC differed between LHA and controls, as well as between LHA and non-HA patients. In the task activation pattern analysis, there was a decrease in the activation of patients with LHA relative to controls, exactly in the left hippocampus. However, non-HA patients had increased FC relative to controls in the left superior temporal gyrus region. Seed-to-voxel FC demonstrated greater differences between patients and controls and smaller differences among patient groups. The non-HA group was similar to controls, except for increased BOLD activation and increase FC in the superior temporal gyri. RHA and LHA differed from controls in BNT. BNT correlated with fMRI activation in RHA and non-HA groups. SIGNIFICANCE: LHA affected naming performance, fMRI semantic task activation pattern, and FC more than RHA and non-HA. Contrary to our expectations, LHA did not increase the frequency of atypical LL. Regardless of the side, HA impacts negatively on the language network but not on hemispheric language lateralization.

Default Mode Network Disruption in Stroke-Free Patients with Atrial Fibrillation.

BACKGROUND: Atrial fibrillation (AF) is a widely accepted risk for causing stroke. However, recent studies show AF as a risk factor for dementia, even without causing stroke. The mechanisms by which dementia develops in stroke-free patients with AF are still poorly understood and the association of AF with abnormal function of brain networks activities, such as the default mode network (DMN), has not been previously studied. We aimed to determine whether, in the absence of stroke and dementia, patients with AF have abnormal resting-state brain networks compared to controls without AF. METHODS: Twenty-one stroke-free patients with AF and 21 age- and sex-matched controls without AF underwent brain functional magnetic resonance imaging acquired at a 3.0 Tesla scanner. During the exam, the subjects were instructed to lie still with eyes closed. At first-level analysis, connectivity of the DMN was obtained for all subjects. Second-level analysis compared the DMN connectivity between AF patients and controls with a general linear model (two-sample t test, p < 0.05, False Discovery Rate corrected, minimum of 50 contiguous voxels). RESULTS: Patients with AF compared with controls showed decreased connectivity in regions of the DMN including the frontal lobe (left medial frontal gyrus, left superior frontal gyrus and anterior cingulate), left angular gyrus, and bilateral precuneus. CONCLUSIONS: Stroke-free patients with AF have evidence of abnormal DMN connectivity. This study adds evidence to the occurrence of cerebral dysfunction in patients with AF.

Validity and Reliability of the Frontotemporal Dementia Rating Scale (FTD-FRS) for the Progression and Staging of Dementia in Brazilian Patients.

INTRODUCTION: Few studies on instruments for staging frontotemporal dementia (FTD) have been conducted. OBJECTIVE: The objective of this study was to analyze the factor structure, internal consistency, reliability, and convergent validity of the Brazilian version of the Frontotemporal Dementia Rating Scale (FTD-FRS). METHODS: A total of 97 individuals aged 40 years and above with >2 years' education took part in the study, 31 patients diagnosed with behavioral variant FTD (bvFTD), 8 patients with primary progressive aphasia, 28 with Alzheimer disease, 8 with mild cognitive impairment, and a control group of 22 healthy subjects. The FTD-FRS was completed by family members or caregivers, and Neurologists completed the 8-item Clinical Dementia Rating for Frontotemporal Lobar Degeneration (CDR-FTLD) scale (6 original domains plus Language and Behavior). The Alzheimer disease and FTD patients had equivalent disease severity level. RESULTS: The internal consistency of the FTD-FRS, estimated by Cronbach α, was 0.975 whereas test-retest reliability was 0.977. Scree plot and exploratory factor (Varimax rotation) analyses revealed the existence of 4 factors, with eigenvalues >1, which together explained 77.13% of the total variance with values of 1.28 to 17.52. The domains of the Brazilian version of the FTD-FRS scale correlated with the domains of the CDR-FTLD. CONCLUSIONS: The present study is the first to document the factorial structure of the FTD-FRS and its convergent validity with the CDR-FTLD. These tools are key to determine dementia severity in FTD. The Brazilian FTD-FRS demonstrated adequate psychometric properties for use in Brazil. This instrument may contribute to disease staging in FTD and may help to document intervention-related changes.

The Accuracy of INECO Frontal Screening in the Diagnosis of Executive Dysfunction in Frontotemporal Dementia and Alzheimer Disease.

INTRODUCTION: Executive dysfunction is a common symptom in neurodegenerative disorders and is in need of easy-to-apply screening tools that might identify it. The aims of the present study were to examine some of the psychometric characteristics of the Brazilian version of the INECO frontal screening (IFS), and to investigate its accuracy to diagnose executive dysfunction in dementia and its accuracy to differentiate Alzheimer disease (AD) from the behavioral variant of frontotemporal dementia (bvFTD). METHODS: Patients diagnosed with bvFTD (n=18) and AD (n=20), and 15 healthy controls completed a neuropsychological battery, the Neuropsychiatric Inventory, the Cornell Scale for Depression in Dementia, the Clinical Dementia Rating, and the IFS. RESULTS: The IFS had acceptable internal consistency (α=0.714) and was significantly correlated with general cognitive measures and with neuropsychological tests. The IFS had adequate accuracy to differentiate patients with dementia from healthy controls (AUC=0.768, cutoff=19.75, sensitivity=0.80, specificity=0.63), but low accuracy to differentiate bvFTD from AD (AUC=0.594, cutoff=16.75, sensitivity=0.667, specificity=0.600). CONCLUSION: The present study suggested that the IFS may be used to screen for executive dysfunction in dementia. Nonetheless, it should be used with caution in the differential diagnosis between AD and bvFTD.

Intranetwork and internetwork connectivity in patients with Alzheimer disease and the association with cerebrospinal fluid biomarker levels.

BACKGROUND: In the last decade, many studies have reported abnormal connectivity within the default mode network (DMN) in patients with Alzheimer disease. Few studies, however, have investigated other networks and their association with pathophysiological proteins obtained from cerebrospinal fluid (CSF). METHODS: We performed 3 T imaging in patients with mild Alzheimer disease, patients with amnestic mild cognitive impairment (aMCI) and healthy controls, and we collected CSF samples from the patients with aMCI and mild Alzheimer disease. We analyzed 57 regions from 8 networks. Additionally, we performed correlation tests to investigate possible associations between the networks' functional connectivity and the protein levels obtained from the CSF of patients with aMCI and Alzheimer disease. RESULTS: Our sample included 41 patients with Alzheimer disease, 35 with aMCI and 48 controls. We found that the main connectivity abnormalities in those with Alzheimer disease occurred between the DMN and task-positive networks: these patients presented not only a decreased anticorrelation between some regions, but also an inversion of the correlation signal (positive correlation instead of anticorrelation). Those with aMCI did not present statistically different connectivity from patients with Alzheimer disease or controls. Abnormal levels of CSF proteins were associated with functional disconnectivity between several regions in both the aMCI and mild Alzheimer disease groups, extending well beyond the DMN or temporal areas. LIMITATIONS: The presented data are cross-sectional in nature, and our findings are dependent on the choice of seed regions used. CONCLUSION: We found that the main functional connectivity abnormalities occur between the DMN and task-positive networks and that the pathological levels of CSF biomarkers correlate with functional connectivity disruption in patients with Alzheimer disease.

Neuropsychiatric Symptoms, Caregiver Burden and Distress in Behavioral-Variant Frontotemporal Dementia and Alzheimer's Disease.

BACKGROUND/AIMS: We aimed to compare caregiver burden and distress in behavioral-variant frontotemporal dementia (bvFTD) and Alzheimer's disease (AD) and to investigate which factors contribute to caregivers' burden and distress. METHODS: Fifty patients and their caregivers were invited to participate. Among the patients, 20 had a diagnosis of bvFTD and 30 had AD. Caregivers and patients were statistically equivalent for age, sex, education and dementia severity according to Clinical Dementia Rating. The protocol included the Short Zarit Burden Inventory, the Neuropsychiatric Inventory (NPI), Disability Assessment for Dementia (DAD), the Cornell Scale for Depression in Dementia (CSDD), Addenbrooke's Cognitive Examination-Revised, the Executive Interview with 25 Items, Direct Assessment of Functional Status and the Geriatric Anxiety Inventory (GAI). RESULTS: In the NPI, caregivers of bvFTD patients reported a higher presence and severity of neuropsychiatric symptoms and caregiver distress compared to caregivers of AD patients. There was no significant difference in the perceived burden. In bvFTD, DAD and GAI scores were significantly correlated with burden, whereas in AD, burden was correlated with CSDD and NPI scores. Psychiatric symptoms were associated with distress in both groups. CONCLUSIONS: Caregivers of bvFTD patients experienced higher levels of distress than caregivers of AD patients. Patients' functional limitations were associated with burden of caregivers of bvFTD patients, whereas neuropsychiatric symptoms were associated with caregiver strain in both groups.

Direct and indirect assessments of activities of daily living in behavioral variant frontotemporal dementia and Alzheimer disease.

BACKGROUND: There is limited information about the functional profile of behavioral variant frontotemporal dementia (bvFTD). OBJECTIVE: To compare direct and indirect assessments of activities of daily living (ADLs) in bvFTD and Alzheimer disease (AD) and their relationship with cognitive performance. METHODS: In all, 20 patients with bvFTD, 30 patients with AD, and 34 normal controls (NCs), matched for age, education, and severity of dementia, completed the Direct Assessment of Functional Performance (DAFS-BR) and usual cognitive measures. The Disability Assessment for Dementia (DAD) was completed by caregivers. RESULTS: In DAFS-BR, patients with bvFTD and AD had similar performance but lower than NCs. In DAD, there were no significant differences for effective performance, but patients with bvFTD had lower scores for initiation and planning/organization. Patients with bvFTD were less impaired than AD in cognition. CONCLUSION: Functional changes in bvFTD seem to be better documented by indirect measures.

Neuropsychiatric symptoms in Alzheimer's disease are related to functional connectivity alterations in the salience network.

Neuropsychiatric syndromes are highly prevalent in Alzheimer's disease (AD), but their neurobiology is not completely understood. New methods in functional magnetic resonance imaging, such as intrinsic functional connectivity or "resting-state" analysis, may help to clarify this issue. Using such approaches, alterations in the default-mode and salience networks (SNs) have been described in Alzheimer's, although their relationship with specific symptoms remains unclear. We therefore carried out resting-state functional connectivity analysis with 20 patients with mild to moderate AD, and correlated their scores on neuropsychiatric inventory syndromes (apathy, hyperactivity, affective syndrome, and psychosis) with maps of connectivity in the default mode network and SN. In addition, we compared network connectivity in these patients with that in 17 healthy elderly control subjects. All analyses were controlled for gray matter density and other potential confounds. Alzheimer's patients showed increased functional connectivity within the SN compared with controls (right anterior cingulate cortex and left medial frontal gyrus), along with reduced functional connectivity in the default-mode network (bilateral precuneus). A correlation between increased connectivity in anterior cingulate cortex and right insula areas of the SN and hyperactivity syndrome (agitation, irritability, aberrant motor behavior, euphoria, and disinhibition) was found. These findings demonstrate an association between specific network changes in AD and particular neuropsychiatric symptom types. This underlines the potential clinical significance of resting state alterations in future diagnosis and therapy.

Memory impairment is not necessarily related to seizure frequency in mesial temporal lobe epilepsy with hippocampal sclerosis.

OBJECTIVE: To investigate the effect of seizure frequency on memory, we performed a cross sectional study comparing mesial temporal lobe epilepsy (MTLE) patients with frequent and infrequent seizures. METHODS: We performed magnetic resonance imaging (MRI) hippocampal volume (HV) measurements and neuropsychological assessment in 22 patients with frequent seizures (at least one dyscognitive seizure [DS] per month) that were refractory to antiepileptic drugs and 20 patients with infrequent seizures (three or less DS per year and no event evolving to a bilateral convulsive seizure), all with MRI signs of hippocampal sclerosis (HS) on visual analysis. We also included 29 controls for comparison of volumetric data. RESULTS: There was no difference in memory performance between patients with frequent seizures and infrequent seizures. We observed a significant bilateral reduction of HV in patients with MTLE when compared to controls (p < 0.001). The degree of hippocampal atrophy (HA) between patients with frequent and infrequent seizures was not different. There was a negative correlation between seizure frequency and HV, with r = -0.3 for the HV ipsilateral to the HS and r = -0.55 for the contralateral side, thus, explaining only 9% and 30% of the HV loss. There was a positive correlation between age of onset and degree of HA (r = 0.37). SIGNIFICANCE: Our data suggest that seizure frequency does not explain most of the HV loss or memory impairment in MTLE. Memory impairment appears to be more influenced by hippocampal damage than by seizure frequency. Further studies are necessary to identify the factors that influence memory decline in patients with MTLE.

Carotid stenting versus endarterectomy cognitive outcomes.

BACKGROUND: The objectives are to analyze the impact of carotid revascularization on cognitive performance after a 3-month period in patients, who have undergone carotid artery stenting (CAS) or carotid endarterectomy (CEA), and to compare the cognitive outcomes between these 2 groups of patients. This a nonrandomized and prospective single-center experience. METHODS: This study was performed in the University of Campinas Hospital from January 2010 to January 2012 and included 30 patients with carotid stenosis who received carotid interventions. Nineteen patients received CEA and 11 patients received CAS. Neuropsychologic evaluation included general cognitive, language, visuospatial, attentional, executive function, and memory tests. RESULTS: After the follow-up period, there was improvement in episodic memory, encoding subitem (P = 0.02), and delayed recall (P = 0.02) for the CEA group. The CAS group improved in episodic memory, encoding subitem (P = 0.009), working memory (P = 0.04), and executive functions (P = 0.02). Comparing the techniques, the CAS group showed higher scores only in executive functions (P = 0.02). CONCLUSIONS: Both groups had a similar performance in cognitive tests, comparing preoperative and postoperative results. However, patients who underwent CAS tended to achieve higher scores in executive function and operational memory/attention tests.

Frailty and brain changes in older adults without cognitive impairment: A scoping review.

Little is known about changes in the brain associated with frailty, in particular, which brain areas could be related to frailty in older people without cognitive impairment. This scoping review mapped evidence on functional and/or structural brain changes in frail older adults without cognitive impairment. The methodology proposed by the JBI® was used in this study. The search in PubMed, PubMed PMC, BVS/BIREME, EBSCOHOST, Scopus, Web of Science, Embase, and PROQUEST was conducted up to January 2023. Studies included following the population, concepts, context and the screening and data extraction were performed by two independent reviewers. A total of 9,912 records were identified, 5,676 were duplicates and were excluded. The remaining articles were screened; 31 were read in full and 17 articles were included. The results showed that lesions in white matter hyperintensities, reduced volume of the hippocampus, cerebellum, middle frontal gyrus, low gray matter volume, cortical atrophy, decreased connectivity of the supplementary motor area, presence of amyloid-beta peptide (aß) in the anterior and posterior putamen and precuneus regions were more frequently observed in frail older adults, compared with non-frail individuals. Studies have suggested that such findings may be of neurodegenerative or cerebrovascular origin. The identification of these brain alterations in frail older adults through neuroimaging studies contributes to our understanding of the underlying mechanisms of frailty. Such findings may have implications for the early detection of frailty and implementation of intervention strategies.

Current clinical and research practices on frontotemporal dementia in Brazil: a national survey.

BACKGROUND: Frontotemporal dementia (FTD) is a frequent cause of young-onset dementia and represents a major challenge for the diagnosis and clinical management. It is essential to evaluate the difficulties faced by physicians on the diagnostic workup and on patient care. OBJECTIVE: The aim of this study was to investigate the current practices and the local limits on the diagnosis and management of FTD in Brazil. METHODS: We elaborated an online survey, composed of 29 questions and divided in four parts, comprising questions about existing health facilities, clinical practices related to FTD, and suggestions to increment the national research on FTD. The invitation to participate was sent by email to all neurologists affiliated to the Brazilian Academy of Neurology (n = 3658), and to all physicians who attended the XII Meeting of Researchers on Alzheimer's disease, in 2019 (n = 187). The invitation was also diffused through social media. RESULTS: 256 Brazilian physicians answered the questionnaire. The three most relevant disorders for the differential diagnosis of FTD were Alzheimer's disease (AD) (n = 211), bipolar disorder (n = 117) and dementia with Lewy bodies (n = 92). Most respondents (125/256) reported the difficulty in performing genetic testing as the main limit in the diagnostic of FTD. 93% and 63% of participants considered that the assessment of social cognition and AD CSF biomarkers are useful for the diagnosis of FTD, respectively. CONCLUSIONS: The present study may provide valuable insights for the medical education and clinical training of physicians, and to foster future research on FTD in Brazil.

ANTECEDENTES: A demência frontotemporal (DFT) é causa frequente de demência pré-senil e representa um desafio em termos de diagnóstico e de manejo clínico. É essencial avaliar as dificuldades existentes na propedêutica e nos cuidados médicos. OBJETIVO: Investigar as práticas médicas e as dificuldades para diagnóstico e manejo da DFT no Brasil. MéTODOS: Elaborou-se um questionário online, composto de 29 questões, divididas em quatro partes, com perguntas sobre infraestrutura existente, práticas clínicas relacionadas à DFT e sugestões para desenvolver a pesquisa nacional na área. O convite para participação foi enviado por e-mail a todos neurologistas afiliados à Academia Brasileira de Neurologia (n = 3658), e aos médicos que participaram da XII Reunião de Pesquisadores de Doença de Alzheimer, em 2019 (n = 187). O convite também foi divulgado através de mídias sociais. RESULTADOS: 256 médicos brasileiros responderam o questionário. Os três principais diagnósticos diferenciais de DFT foram doença de Alzheimer (n = 211), transtorno bipolar (n = 117) e demência com corpos de Lewy (n = 92). A maior parte dos respondedores (125/256) apontou a dificuldade em realizar testagem genética como o maior limite no diagnóstico de DFT. 93% e 63% dos respondedores indicaram que a avaliação de cognição social e o uso de biomarcadores liquóricos de doença de Alzheimer são úteis no diagnóstico de DFT, respectivamente. CONCLUSõES: Estes resultados devem ser considerados na educação e treinamento médicos, e no desenvolvimento da pesquisa brasileira em DFT.

Whole-brain DTI parameters associated with tau protein and hippocampal volume in Alzheimer's disease.

The causes of the neurodegenerative processes in Alzheimer's disease (AD) are not completely known. Recent studies have shown that white matter (WM) damage could be more severe and widespread than whole-brain cortical atrophy and that such damage may appear even before the damage to the gray matter (GM). In AD, Amyloid-beta (Aß42 ) and tau proteins could directly affect WM, spreading across brain networks. Since hippocampal atrophy is common in the early phase of disease, it is reasonable to expect that hippocampal volume (HV) might be also related to WM integrity. Our study aimed to evaluate the integrity of the whole-brain WM, through diffusion tensor imaging (DTI) parameters, in mild AD and amnestic mild cognitive impairment (aMCI) due to AD (with Aß42 alteration in cerebrospinal fluid [CSF]) in relation to controls; and possible correlations between those measures and the CSF levels of Aß42 , phosphorylated tau protein (p-Tau) and total tau (t-Tau). We found a widespread WM alteration in the groups, and we also observed correlations between p-Tau and t-Tau with tracts directly linked to mesial temporal lobe (MTL) structures (fornix and hippocampal cingulum). However, linear regressions showed that the HV better explained the variation found in the DTI measures (with weak to moderate effect sizes, explaining from 9% to 31%) than did CSF proteins. In conclusion, we found widespread alterations in WM integrity, particularly in regions commonly affected by the disease in our group of early-stage disease and patients with Alzheimer's disease. Nonetheless, in the statistical models, the HV better predicted the integrity of the MTL tracts than the biomarkers in CSF.