The influence of age and sex on the absolute cell numbers of the human brain cerebral cortex.

The human cerebral cortex is one of the most evolved regions of the brain, responsible for most higher-order neural functions. Since nerve cells (together with synapses) are the processing units underlying cortical physiology and morphology, we studied how the human neocortex is composed regarding the number of cells as a function of sex and age. We used the isotropic fractionator for cell quantification of immunocytochemically labeled nuclei from the cerebral cortex donated by 43 cognitively healthy subjects aged 25-87 years old. In addition to previously reported sexual dimorphism in the medial temporal lobe, we found more neurons in the occipital lobe of men, higher neuronal density in women's frontal lobe, but no sex differences in the number and density of cells in the other lobes and the whole neocortex. On average, the neocortex has ~10.2 billion neurons, 34% in the frontal lobe and the remaining 66% uniformly distributed among the other 3 lobes. Along typical aging, there is a loss of non-neuronal cells in the frontal lobe and the preservation of the number of neurons in the cortex. Our study made possible to determine the different degrees of modulation that sex and age evoke on cortical cellularity.

Global and local ancestry modulate APOE association with Alzheimer's neuropathology and cognitive outcomes in an admixed sample.

Dementia is more prevalent in Blacks than in Whites, likely due to a combination of environmental and biological factors. Paradoxically, clinical studies suggest an attenuation of APOE ε4 risk of dementia in African ancestry (AFR), but a dearth of neuropathological data preclude the interpretation of the biological factors underlying these findings, including the association between APOE ε4 risk and Alzheimer's disease (AD) pathology, the most frequent cause of dementia. We investigated the interaction between African ancestry, AD-related neuropathology, APOE genotype, and functional cognition in a postmortem sample of 400 individuals with a range of AD pathology severity and lack of comorbid neuropathology from a cohort of community-dwelling, admixed Brazilians. Increasing proportions of African ancestry (AFR) correlated with a lower burden of neuritic plaques (NP). However, for individuals with a severe burden of NP and neurofibrillary tangles (NFT), AFR proportion was associated with worse Clinical Dementia Rating sum of boxes (CDR-SOB). Among APOE ε4 carriers, the association between AFR proportion and CDR-SOB disappeared. APOE local ancestry inference of a subset of 309 individuals revealed that, in APOE ε4 noncarriers, non-European APOE background correlated with lower NP burden and, also, worse cognitive outcomes than European APOE when adjusting by NP burden. Finally, APOE ε4 was associated with worse AD neuropathological burden only in a European APOE background. APOE genotype and its association with AD neuropathology and clinical pattern are highly influenced by ancestry, with AFR associated with lower NP burden and attenuated APOE ε4 risk compared to European ancestry.

Association between chemosensory impairment with neuropsychiatric morbidity in post-acute COVID-19 syndrome: results from a multidisciplinary cohort study.

Preliminary methodologically limited studies suggested that taste and smell known as chemosensory impairments and neuropsychiatric symptoms are associated in post-COVID-19. The objective of this study is to evaluate whether chemosensory dysfunction and neuropsychiatric impairments in a well-characterized post-COVID-19 sample. This is a cohort study assessing adult patients hospitalized due to moderate or severe forms of COVID-19 between March and August 2020. Baseline information includes several clinical and hospitalization data. Further evaluations were made using several different reliable instruments designed to assess taste and smell functions, parosmia, and neuropsychiatric disorders (using standardized psychiatric and cognitive measures). Out of 1800 eligible individuals, 701 volunteers were assessed on this study. After multivariate analysis, patients reporting parosmia had a worse perception of memory performance (p < 0.001). Moderate/severe hypogeusia was significantly associated with a worse performance on the word list memory task (p = 0.012); Concomitant moderate/severe olfactory and gustatory loss during the acute phase of COVID-19 was also significantly associated with episodic memory impairment (p = 0.006). We found a positive association between reported chemosensory (taste and olfaction) abnormalities and cognition dysfunction in post-COVID-19 patients. These findings may help us identify potential mechanisms linking these two neurobiological functions, and also support the speculation on a possible route through which SARS-CoV-2 may reach the central nervous system.

Risk factors for dementia in Brazil: Differences by region and race.

INTRODUCTION: Twelve risk factors (RFs) account for 40% of dementia cases worldwide. However, most data for population attributable fractions (PAFs) are from high-income countries (HIC). We estimated how much these RFs account for dementia cases in Brazil, stratifying estimates by race and socioeconomic level. METHODS: We calculated the prevalence and communalities of 12 RFs using 9412 Brazilian Longitudinal Study of Aging participants, then stratified according to self-reported race and country macro-regions. RESULTS: The overall weighted PAF was 48.2%. Less education had the largest PAF (7.7%), followed by hypertension (7.6%), and hearing loss (6.8%). PAF was 49.0% and 54.0% in the richest and poorest regions, respectively. PAFs were similar among White and Black individuals (47.8% and 47.2%, respectively) but the importance of the main RF varied by race. DISCUSSION: Brazil's potential for dementia prevention is higher than in HIC. Education, hypertension, and hearing loss should be priority targets.

Neuropathological correlates of neuropsychiatric symptoms in dementia.

INTRODUCTION: Neuropsychiatric symptoms (NPS) are common in Lewy body disease (LBD), but their etiology is poorly understood. METHODS: In a population-based post mortem study neuropathological data was collected for Lewy body (LB) neuropathology, neurofibrillary tangles (NFT), amyloid beta burden, TDP-43, lacunar infarcts, cerebral amyloid angiopathy (CAA), and hyaline atherosclerosis. Post mortem interviews collected systematic information regarding NPS and cognitive status. A total of 1038 cases were included: no pathology (NP; n = 761), Alzheimer's disease (AD; n = 189), LBD (n = 60), and AD+LBD (n = 28). RESULTS: Hallucinations were associated with higher LB Braak stages, while higher NFT Braak staging was associated with depression, agitation, and greater number of symptoms in the Neuropsychiatric Inventory. Cases with dual AD+LBD pathology had the highest risk of hallucinations, agitation, apathy, and total symptoms but a multiplicative interaction between these pathologies was not significant. DISCUSSION: LB and AD pathology contribute differentially to NPS likely with an additive process contributing to the increased burden of NPS.

Dissipating the fog: Cognitive trajectories and risk factors 1 year after COVID-19 hospitalization.

INTRODUCTION: Cognitive impairment is common after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, associations between post-hospital discharge risk factors and cognitive trajectories have not been explored. METHODS: A total of 1105 adults (mean age ± SD 64.9 ± 9.9 years, 44% women, 63% White) with severe coronavirus disease 2019 (COVID-19) were evaluated for cognitive function 1 year after hospital discharge. Scores from cognitive tests were harmonized, and clusters of cognitive impairment were defined using sequential analysis. RESULTS: Three groups of cognitive trajectories were observed during the follow-up: no cognitive impairment, initial short-term cognitive impairment, and long-term cognitive impairment. Predictors of cognitive decline after COVID-19 were older age (ß = -0.013, 95% CI = -0.023;-0.003), female sex (ß = -0.230, 95% CI = -0.413;-0.047), previous dementia diagnosis or substantial memory complaints (ß = -0.606, 95% CI = -0.877;-0.335), frailty before hospitalization (ß = -0.191, 95% CI = -0.264;-0.119), higher platelet count (ß = -0.101, 95% CI = -0.185;-0.018), and delirium (ß = -0.483, 95% CI = -0.724;-0.244). Post-discharge predictors included hospital readmissions and frailty. DISCUSSION: Cognitive impairment was common and the patterns of cognitive trajectories depended on sociodemographic, in-hospital, and post-hospitalization predictors. HIGHLIGHTS: Cognitive impairment after coronavirus disease 2019 (COVID-19) hospital discharge was associated with higher age, less education, delirium during hospitalization, a higher number of hospitalizations post discharge, and frailty before and after hospitalization. Frequent cognitive evaluations for 12-month post-COVID-19 hospitalization showed three possible cognitive trajectories: no cognitive impairment, initial short-term impairment, and long-term impairment. This study highlights the importance of frequent cognitive testing to determine patterns of COVID-19 cognitive impairment, given the high frequency of incident cognitive impairment 1 year after hospitalization.

Biomarkers for dementia in Latin American countries: Gaps and opportunities.

Limited knowledge on dementia biomarkers in Latin American and Caribbean (LAC) countries remains a serious barrier. Here, we reported a survey to explore the ongoing work, needs, interests, potential barriers, and opportunities for future studies related to biomarkers. The results show that neuroimaging is the most used biomarker (73%), followed by genetic studies (40%), peripheral fluids biomarkers (31%), and cerebrospinal fluid biomarkers (29%). Regarding barriers in LAC, lack of funding appears to undermine the implementation of biomarkers in clinical or research settings, followed by insufficient infrastructure and training. The survey revealed that despite the above barriers, the region holds a great potential to advance dementia biomarkers research. Considering the unique contributions that LAC could make to this growing field, we highlight the urgent need to expand biomarker research. These insights allowed us to propose an action plan that addresses the recommendations for a biomarker framework recently proposed by regional experts.

Latin American Initiative for Lifestyle Intervention to Prevent Cognitive Decline (LatAm-FINGERS): Study design and harmonization.

INTRODUCTION: Latin American Initiative for Lifestyle Intervention to Prevent Cognitive Decline (LatAm-FINGERS) is the first non-pharmacological multicenter randomized clinical trial (RCT) to prevent cognitive impairment in Latin America (LA). Our aim is to present the study design and discuss the strategies used for multicultural harmonization. METHODS: This 1-year RCT (working on a 1-year extension) investigates the feasibility of a multi-domain lifestyle intervention in LA and the efficacy of the intervention, primarily on cognitive function. An external harmonization process was carried out to follow the FINGER model, and an internal harmonization was performed to ensure this study was feasible and comparable across the 12 participating LA countries. RESULTS: Currently, 1549 participants have been screened, and 815 randomized. Participants are ethnically diverse (56% are Nestizo) and have high cardiovascular risk (39% have metabolic syndrome). DISCUSSION: LatAm-FINGERS overcame a significant challenge to combine the region's diversity into a multi-domain risk reduction intervention feasible across LA while preserving the original FINGER design.

Apolipoprotein E ε2 allele is associated with lower risk of carotid artery obstruction in a population-based autopsy study.

INTRODUCTION: Apolipoprotein E (APOE) ε4 allele has been associated with higher carotid atherosclerosis risk, while the APOE-ε2 seems to decrease this risk. Data from autopsy studies, where carotid arteries can be evaluated in their full extension, is scarce. Therefore, we investigated the association between APOE alleles and direct morphometric measurements of carotid atherosclerosis in an autopsy study with an admixed sample. METHODS: We measured the intima-media thickness (IMT) and stenosis of the common (CCA) and internal carotid (ICA) arteries. The APOE polymorphisms were determined by real-time polymerase chain reaction. Participants were classified into three groups according to the APOE alleles (ε2, ε3, and ε4). We evaluated the association between APOE groups and carotid atherosclerosis using adjusted regression models and included interaction terms of APOE alleles with age, sex, and race. RESULTS: We evaluated 1,850 carotid artery samples from 185 participants (mean age=75±12 years old, 55% female, and 71% White). The APOE-ε2 group (n=17) had a lower carotid obstruction and a lower number of severe stenoses (≥ 70%). Having at least one ε4 allele (n=51) was not associated with carotid atherosclerosis. APOE alleles were also not associated with carotid IMT. Age, sex, and race did not modify these relationships. CONCLUSION: APOE-ε2 carriers had a lower percentage of carotid obstruction and less severe stenosis. APOE-ε4 was not related to a higher risk of carotid atherosclerosis in this cross-sectional population-based autopsy study.

Effects of dabigatran versus warfarin on 2-year cognitive outcomes in old patients with atrial fibrillation: results from the GIRAF randomized clinical trial.

BACKGROUND: Observational studies support a role for oral anticoagulation to reduce the risk of dementia in atrial fibrillation patients, but conclusive data are lacking. Since dabigatran offers a more stable anticoagulation, we hypothesized it would reduce cognitive decline when compared to warfarin in old patients with atrial fibrillation. METHODS: The GIRAF trial was a 24-month, randomized, parallel-group, controlled, open-label, hypothesis generating trial. The trial was done in six centers including a geriatric care unit, secondary and tertiary care cardiology hospitals in São Paulo, Brazil. We included patients aged ≥ 70 years and CHA2DS2-VASc score > 1. The primary endpoint was the absolute difference in cognitive performance at 2 years. Patients were assigned 1:1 to take dabigatran (110 or 150 mg twice daily) or warfarin, controlled by INR and followed for 24 months. Patients were evaluated at baseline and at 2 years with a comprehensive and thorough cognitive evaluation protocol of tests for different cognitive domains including the Montreal Cognitive Assessment (MoCA), Mini-Mental State Exam (MMSE), a composite neuropsychological test battery (NTB), and computer-generated tests (CGNT). RESULTS: Between 2014 and 2019, 5523 participants were screened and 200 were assigned to dabigatran (N = 99) or warfarin (N = 101) treatment. After adjustment for age, log of years of education, and raw baseline score, the difference between the mean change from baseline in the dabigatran group minus warfarin group was - 0.12 for MMSE (95% confidence interval [CI] - 0.88 to 0.63; P = 0.75), 0.05 (95% CI - 0.07 to 0.18; P = 0.40) for NTB, - 0.15 (95% CI - 0.30 to 0.01; P = 0.06) for CGNT, and - 0.96 (95% CI - 1.80 to 0.13; P = 0.02) for MoCA, with higher values suggesting less cognitive decline in the warfarin group. CONCLUSIONS: For elderly patients with atrial fibrillation, and without cognitive compromise at baseline that did not have stroke and were adequately treated with warfarin (TTR of 70%) or dabigatran for 2 years, there was no statistical difference at 5% significance level in any of the cognitive outcomes after adjusting for multiple comparisons. TRIAL REGISTRATION: Cognitive Impairment Related to Atrial Fibrillation Prevention Trial (GIRAF), NCT01994265 .

Post-acute sequelae of SARS-CoV-2 infection: relationship of central nervous system manifestations with physical disability and systemic inflammation.

BACKGROUND: Despite the multitude of clinical manifestations of post-acute sequelae of SARS-CoV-2 infection (PASC), studies applying statistical methods to directly investigate patterns of symptom co-occurrence and their biological correlates are scarce. METHODS: We assessed 30 symptoms pertaining to different organ systems in 749 adults (age = 55 ± 14 years; 47% female) during in-person visits conducted at 6-11 months after hospitalization due to coronavirus disease 2019 (COVID-19), including six psychiatric and cognitive manifestations. Symptom co-occurrence was initially investigated using exploratory factor analysis (EFA), and latent variable modeling was then conducted using Item Response Theory (IRT). We investigated associations of latent variable severity with objective indices of persistent physical disability, pulmonary and kidney dysfunction, and C-reactive protein and D-dimer blood levels, measured at the same follow-up assessment. RESULTS: The EFA extracted one factor, explaining 64.8% of variance; loadings were positive for all symptoms, and above 0.35 for 16 of them. The latent trait generated using IRT placed fatigue, psychiatric, and cognitive manifestations as the most discriminative symptoms (coefficients > 1.5, p < 0.001). Latent trait severity was associated with decreased body weight and poorer physical performance (coefficients > 0.240; p ⩽ 0.003), and elevated blood levels of C-reactive protein (coefficient = 0.378; 95% CI 0.215-0.541; p < 0.001) and D-dimer (coefficient = 0.412; 95% CI 0.123-0.702; p = 0.005). Results were similar after excluding subjects with pro-inflammatory comorbidities. CONCLUSIONS: Different symptoms that persist for several months after moderate or severe COVID-19 may unite within one latent trait of PASC. This trait is dominated by fatigue and psychiatric symptoms, and is associated with objective signs of physical disability and persistent systemic inflammation.

Increased levels of TAR DNA-binding protein 43 in the hippocampus of subjects with bipolar disorder: a postmortem study.

Bipolar disorder shares symptoms and pathological pathways with other neurodegenerative diseases, including frontotemporal dementia (FTD). Since TAR DNA-binding protein 43 (TDP-43) is a neuropathological marker of frontotemporal dementia and it is involved in synaptic transmission, we explored the role of TDP-43 as a molecular feature of bipolar disorder (BD). Homogenates were acquired from frozen hippocampus of postmortem brains of bipolar disorder subjects. TDP-43 levels were quantified using an ELISA-sandwich method and compared between the postmortem brains of bipolar disorder subjects and age-matched control group. We found higher levels of TDP-43 protein in the hippocampus of BD (n = 15) subjects, when compared to controls (n = 15). We did not find associations of TDP-43 with age at death, postmortem interval, or age of disease onset. Our results suggest that protein TDP-43 may be potentially implicated in behavioral abnormalities seen in BD. Further investigation is needed to validate these findings and to examine the role of this protein during the disease course and mood states.

Two Immersive Virtual Reality Tasks for the Assessment of Spatial Orientation in Older Adults with and Without Cognitive Impairment: Concurrent Validity, Group Comparison, and Accuracy Results.

OBJECTIVE: Spatial disorientation is common in Alzheimer's disease (AD), Mild Cognitive Impairment (MCI), and preclinical individuals with AD biomarkers. However, traditional neuropsychological tests lack ecological validity for the assessment of spatial orientation and to date, there is still no gold standard. The current study aimed to determine the validity and accuracy of two virtual reality tasks for the assessment of spatial orientation. METHODS: We adapted two spatial orientation tasks to immersive virtual environments: a "survey to route" task in which participants had to transfer information from a map to their body position within a maze [Spatial Orientation in Immersive Virtual Environment Test (SOIVET) Maze], and an allocentric-type, route learning task, with well-established topographic landmarks (SOIVET Route). A total of 19 MCI patients and 29 cognitively healthy older adults aged 61-92 participated in this study. Regular neuropsychological assessments were used for correlation analysis and participant performances were compared between groups. Receiver Operating Characteristic (ROC) curve analysis was performed for accuracy. RESULTS: The SOIVET Maze correlated with measures of visuoperception, mental rotation, and planning, and was not related to age, educational level, or technology use profile. The SOIVET Route immediate correlated with measures of mental rotation, memory, and visuoconstruction, and was influenced only by education. Both tasks significantly differentiated MCI and control groups, and demonstrated moderate accuracy for the MCI diagnosis. CONCLUSION: Traditional neuropsychological assessment presents limitations and immersive environments allow for the reproduction of complex cognitive processes. The two immersive virtual reality tasks are valid tools for the assessment of spatial orientation and should be considered for cognitive assessments of older adults.

Cause of Death Determined by Full-body Autopsy in Neuropathologically Diagnosed Dementias: The Biobank for Aging Studies of the University of Sao Paulo (BAS-USP), Brazil.

OBJECTIVE: This study aimed to compare causes of death in the most prevalent neuropathologically diagnosed dementias. METHODS: We analyzed causes of death in a community-based cohort of participants aged 50 or older, submitted to full-body autopsy and a comprehensive neuropathologic examination of the brain. Individuals with Alzheimer disease (AD), vascular dementia (VaD), mixed dementia (AD+VaD), or dementia with Lewy bodies (DLBs) were compared with individuals with no dementia. RESULTS: In a sample of 920 individuals, 456 had no dementia, 147 had AD, 120 had VaD, 53 had DLB, and 37 had AD+VaD. Pneumonia as the cause of death was more frequent in the AD (P=0.023), AD+VaD (P=0.046), and DLB (P=0.043) groups. In addition, VaD (P=0.041) and AD+VaD (P=0.028) groups had a higher frequency of atherosclerosis as detected by full-body autopsy. CONCLUSION: Our findings highlight the importance of preventive measures regarding atherosclerosis and pneumonia in patients with dementia. Moreover, because of cognitive impairment, these patients may not fully account for symptoms to make early detection and diagnosis possible. These results confirm findings from previous studies that were based on clinical data, with added accuracy provided by neuropathologic diagnosis and full-body autopsy reports.

Cognitive decline following acute viral infections: literature review and projections for post-COVID-19.

Recently, much attention has been drawn to the importance of the impact of infectious disease on human cognition. Several theories have been proposed, to explain the cognitive decline following an infection as well as to understand better the pathogenesis of human dementia, especially Alzheimer's disease. This article aims to review the state of the art regarding the knowledge about the impact of acute viral infections on human cognition, laying a foundation to explore the possible cognitive decline followed coronavirus disease 2019 (COVID-19). To reach this goal, we conducted a narrative review systematizing six acute viral infections as well as the current knowledge about COVID-19 and its impact on human cognition. Recent findings suggest probable short- and long-term COVID-19 impacts in cognition, even in asymptomatic individuals, which could be accounted for by direct and indirect pathways to brain dysfunction. Understanding this scenario might help clinicians and health leaders to deal better with a wave of neuropsychiatric issues that may arise following COVID-19 pandemic as well as with other acute viral infections, to alleviate the cognitive sequelae of these infections around the world.

Incidence of dementia in a Brazilian population: The Tremembé Epidemiologic Study.

INTRODUCTION: Few dementia incidence studies have been performed in Latin America. We aimed to provide the incidence of dementia in a Brazilian community-dwelling elderly population. METHODS: This study was conducted in urban and rural areas of Tremembé. The 520 participants without dementia at baseline were invited to participate in the follow-up. RESULTS: After a median follow-up of 5 years, the incidence rate of dementia was 26.1 per 1000 person-years (PY) (95% confidence interval  = 18.7-36.6/1000PY). This rate increased exponentially with age (8.3/1000PY for 60- to 64-year-olds to 110.2/1000PY for ≥80-year-olds) and lower education (10.5/1000PY for > 8 years of education to 59.2/1000PY for illiterates). Higher dementia risk was found among individuals with cognitive impairment no dementia at baseline. DISCUSSION: The dementia incidence rate found was higher than in other countries in people under 65 years. Higher incidence in younger individuals is expected in developing countries probably due to low education and a high burden of cardiovascular diseases.

Education, but not occupation, is associated with cognitive impairment: The role of cognitive reserve in a sample from a low-to-middle-income country.

INTRODUCTION: Education, and less frequently occupation, has been associated with lower dementia risk in studies from high-income countries. We aimed to investigate the association of cognitive impairment with education and occupation in a low-middle-income country sample. METHODS: In this cross-sectional study, cognitive function was assessed by the Clinical Dementia Rating sum of boxes (CDR-SOB). We investigated the association of occupation complexity and education with CDR-SOB using adjusted linear regression models for age, sex, and neuropathological lesions. RESULTS: In 1023 participants, 77% had < 5 years of education, and 56% unskilled occupations. Compared to the group without education, those with formal education had lower CDR-SOB (1-4 years: ß $\beta \;$ = -0.99, 95% confidence interval [CI] = -1.85; -0.14, P = .02; ≥5 years: ß $\beta \;$ = -1.42, 95% CI = -2.47; -0.38, P = .008). Occupation complexity and demands were unrelated to cognition. DISCUSSION: Education, but not occupation, was related to better cognitive abilities independent of the presence of neuropathological insults.

Hippocampal subregional volume changes in elders classified using positron emission tomography-based Alzheimer's biomarkers of ß-amyloid deposition and neurodegeneration.

Changes in hippocampal subfield volumes (HSV) along the Alzheimer's disease (AD) continuum have been scarcely investigated to date in elderly subjects classified based on the presence of ß-amyloid aggregation and signs of neurodegeneration. We classified patients (either sex) with mild dementia compatible with AD (n = 35) or amnestic mild cognitive impairment (n = 39), and cognitively unimpaired subjects (either sex; n = 26) using [11 C]PIB-PET to assess ß-amyloid aggregation (A+) and [18 F]FDG-PET to account for neurodegeneration ((N)+). Magnetic resonance imaging-based automated methods were used for HSV and white matter hyperintensity (WMH) measurements. Significant HSV reductions were found in A+(N)+ subjects in the presubiculum/subiculum complex and molecular layer, related to worse memory performance. In both the A+(N)+ and A+(N)- categories, subicular volumes were inversely correlated with the degree of Aß deposition. The A-(N)+ subgroup showed reduced HSV relative to the A-(N)- subgroup also in the subiculum/presubiculum. Combining all (N)- subjects, HSV were lower in subjects presenting significant cognitive decline irrespective of A+/A- classification (controlling for WMH load); these between-group differences were detected again in the presubiculum, but also involved the CA4 and granular layer. These findings demonstrate that differential HSV reductions are detectable both in (N)+ and (N)- categories along the AD continuum, and are directly related to the severity of cognitive deficits. HSV reductions are larger both in A+(N)+ and A+(N)- subjects in direct proportion to the degree of Aß deposition. The meaningful HSV reductions detected in the A-(N)+ subgroup highlights the strength of biomarker-based classifications outside of the classical AD continuum.

FDG-PET Patterns Predict Amyloid Deposition and Clinical Profile in Corticobasal Syndrome.

BACKGROUND: Corticobasal syndrome (CBS) is an atypical parkinsonian syndrome related to multiple underlying pathologies. OBJECTIVE: To investigate if individual brain [18 F]fluorodeoxyglucose-positron emission tomography (FDG-PET) patterns could distinguish CBS due to Alzheimer's disease (AD) from other pathologies based on [11 C]Pittsburgh Compound-B (PIB)-PET. METHODS: Forty-five patients with probable CBS were prospectively evaluated regarding cognitive and movement disorders profile. They underwent FDG-PET and were distributed into groups: likely related to AD (CBS FDG-AD) or likely non-AD (CBS FDG-nonAD) pathology. Thirty patients underwent PIB-PET on a hybrid PET-magnetic resonance imaging equipment to assess their amyloid status. FDG and PIB-PET images were classified individually based on visual and semi-quantitative analysis, blinded to each other. Quantitative group analyses were also performed. RESULTS: CBS FDG-AD group demonstrated worse cognitive performances, mostly concerning attention, memory, visuospatial domains, and displayed more myoclonus and hallucinations. The non-AD metabolic group presented more often limb dystonia, ocular motor dysfunction, motor perseveration, and dysarthria. All patients classified as CBS FDG-AD tested positive at PIB-PET compared to 3 of 20 in the non-AD group. The individual FDG-PET classification demonstrated 76.92% of sensitivity, 100% of specificity and positive predictive value and 88.5% of balanced accuracy to detect positive PIB-PET scans. Individuals with positive and negative PIB-PET showed hypometabolism in posterior temporoparietal areas and in thalamus and brainstem, respectively, mainly contralateral to most affected side, disclosing possible metabolic signatures of CBS variants. CONCLUSION: FDG-PET was useful to predict AD and non-AD CBS variants depicting their specific degeneration patterns, different clinical features, and brain amyloid deposition. © 2020 International Parkinson and Movement Disorder Society.

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.