Brain clocks capture diversity and disparities in aging and dementia across geographically diverse populations.

Brain clocks, which quantify discrepancies between brain age and chronological age, hold promise for understanding brain health and disease. However, the impact of diversity (including geographical, socioeconomic, sociodemographic, sex and neurodegeneration) on the brain-age gap is unknown. We analyzed datasets from 5,306 participants across 15 countries (7 Latin American and Caribbean countries (LAC) and 8 non-LAC countries). Based on higher-order interactions, we developed a brain-age gap deep learning architecture for functional magnetic resonance imaging (2,953) and electroencephalography (2,353). The datasets comprised healthy controls and individuals with mild cognitive impairment, Alzheimer disease and behavioral variant frontotemporal dementia. LAC models evidenced older brain ages (functional magnetic resonance imaging: mean directional error = 5.60, root mean square error (r.m.s.e.) = 11.91; electroencephalography: mean directional error = 5.34, r.m.s.e. = 9.82) associated with frontoposterior networks compared with non-LAC models. Structural socioeconomic inequality, pollution and health disparities were influential predictors of increased brain-age gaps, especially in LAC (R² = 0.37, F² = 0.59, r.m.s.e. = 6.9). An ascending brain-age gap from healthy controls to mild cognitive impairment to Alzheimer disease was found. In LAC, we observed larger brain-age gaps in females in control and Alzheimer disease groups compared with the respective males. The results were not explained by variations in signal quality, demographics or acquisition methods. These findings provide a quantitative framework capturing the diversity of accelerated brain aging.

Brain clocks capture diversity and disparity in aging and dementia.

Brain clocks, which quantify discrepancies between brain age and chronological age, hold promise for understanding brain health and disease. However, the impact of multimodal diversity (geographical, socioeconomic, sociodemographic, sex, neurodegeneration) on the brain age gap (BAG) is unknown. Here, we analyzed datasets from 5,306 participants across 15 countries (7 Latin American countries -LAC, 8 non-LAC). Based on higher-order interactions in brain signals, we developed a BAG deep learning architecture for functional magnetic resonance imaging (fMRI=2,953) and electroencephalography (EEG=2,353). The datasets comprised healthy controls, and individuals with mild cognitive impairment, Alzheimer's disease, and behavioral variant frontotemporal dementia. LAC models evidenced older brain ages (fMRI: MDE=5.60, RMSE=11.91; EEG: MDE=5.34, RMSE=9.82) compared to non-LAC, associated with frontoposterior networks. Structural socioeconomic inequality and other disparity-related factors (pollution, health disparities) were influential predictors of increased brain age gaps, especially in LAC (R2=0.37, F2=0.59, RMSE=6.9). A gradient of increasing BAG from controls to mild cognitive impairment to Alzheimer's disease was found. In LAC, we observed larger BAGs in females in control and Alzheimer's disease groups compared to respective males. Results were not explained by variations in signal quality, demographics, or acquisition methods. Findings provide a quantitative framework capturing the multimodal diversity of accelerated brain aging.

Brain health in diverse settings: How age, demographics and cognition shape brain function.

Diversity in brain health is influenced by individual differences in demographics and cognition. However, most studies on brain health and diseases have typically controlled for these factors rather than explored their potential to predict brain signals. Here, we assessed the role of individual differences in demographics (age, sex, and education; n = 1298) and cognition (n = 725) as predictors of different metrics usually used in case-control studies. These included power spectrum and aperiodic (1/f slope, knee, offset) metrics, as well as complexity (fractal dimension estimation, permutation entropy, Wiener entropy, spectral structure variability) and connectivity (graph-theoretic mutual information, conditional mutual information, organizational information) from the source space resting-state EEG activity in a diverse sample from the global south and north populations. Brain-phenotype models were computed using EEG metrics reflecting local activity (power spectrum and aperiodic components) and brain dynamics and interactions (complexity and graph-theoretic measures). Electrophysiological brain dynamics were modulated by individual differences despite the varied methods of data acquisition and assessments across multiple centers, indicating that results were unlikely to be accounted for by methodological discrepancies. Variations in brain signals were mainly influenced by age and cognition, while education and sex exhibited less importance. Power spectrum activity and graph-theoretic measures were the most sensitive in capturing individual differences. Older age, poorer cognition, and being male were associated with reduced alpha power, whereas older age and less education were associated with reduced network integration and segregation. Findings suggest that basic individual differences impact core metrics of brain function that are used in standard case-control studies. Considering individual variability and diversity in global settings would contribute to a more tailored understanding of brain function.

Brain glucose metabolism and gray matter volume in retired professional soccer players: a cross-sectional [18F]FDG-PET/MRI study.

BACKGROUND: Professional soccer athletes are exposed to repetitive head impacts and are at risk of developing chronic traumatic encephalopathy. OBJECTIVE: To evaluate regional brain glucose metabolism (rBGM) and gray matter (GM) volume in retired soccer players (RSPs). METHODS: Male RSPs and age and sex-matched controls prospectively enrolled between 2017 and 2019 underwent neurological and neuropsychological evaluations, brain MRI and [18F]FDG-PET in a 3.0-Tesla PET/MRI scanner. Visual analysis was performed by a blinded neuroradiologist and a blinded nuclear physician. Regional brain glucose metabolism and GM volume were assessed using SPM8 software. Groups were compared using appropriate statistical tests available at SPM8 and R. RESULTS: Nineteen RSPs (median [IQR]: 62 [50-64.5] years old) and 20 controls (60 [48-73] years old) were included. Retired soccer players performed worse on mini-mental state examination, digit span, clock drawing, phonemic and semantic verbal fluency tests, and had reduced rBGM in the left temporal pole (pFDR = 0.008) and the anterior left middle temporal gyrus (pFDR = 0.043). Semantic verbal fluency correlated with rBGM in the right hippocampus, left temporal pole, and posterior left middle temporal gyrus (p ≤ 0.042). Gray matter volume reduction was observed in similar anatomic regions but was less extensive and did not survive correction for multiple comparisons (pFDR ≥ 0.085). Individual [18F]FDG-PET visual analysis revealed seven RSPs with overt hypometabolism in the medial and lateral temporal lobes, frontal lobes, and temporoparietal regions. Retired soccer players had a higher prevalence of septum pellucidum abnormalities on MRI. CONCLUSION: Retired soccer players had reduced rBGM and GM volume in the temporal lobes and septum pellucidum abnormalities, findings possibly related to repetitive head impacts.

ANTECEDENTES: Jogadores profissionais de futebol estão expostos a impactos cranianos repetitivos e ao risco de desenvolver encefalopatia traumática crônica. OBJETIVO: Avaliar o metabolismo glicolítico cerebral regional (MGCr) e o volume de substância cinzenta (vSC) em jogadores de futebol aposentados (JFAs). MéTODOS: Jogadores de futebol aposentados masculinos e controles pareados por idade e sexo foram incluídos prospectivamente entre 2017 e 2019. Foram realizadas avaliações neurológica e neuropsicológica, ressonância magnética (RM) e [18F]FDG-PET cerebrais (3.0-Tesla PET/RM). As imagens foram analisadas visualmente por um neurorradiologista e um médico nuclear cegos ao grupo de cada participante. O metabolismo glicolítico cerebral regional e o vSC foram avaliados através do programa SPM8. Os grupos foram comparados através de testes estatísticos apropriados disponíveis em SPM8 e R, de acordo com a distribuição e o tipo dos dados. RESULTADOS: Dezenove JFAs (mediana [IIQ]: 62 [50­64.5] anos) e 20 controles (60 [48­73] anos) foram incluídos. Os JFAs tiveram pior desempenho no mini-exame do estado mental e nos testes de dígitos, desenho do relógio, fluência verbal e fluência semântica e apresentaram MGCr significativamente reduzido no polo temporal e no giro temporal médio anterior esquerdos. Fluência semântica (animais) apresentou correlação positiva com MGCr no hipocampo direito, no polo temporal esquerdo e no aspecto posterior do giro temporal médio esquerdo. Menor vSC foi observado nas mesmas regiões, porém este achado não sobreviveu à correção para comparações múltiplas. Análise individual do [18F]FDG-PET cerebral revelou sete JFAs com claro hipometabolismo nas faces medial e lateral dos lobos temporais, nos lobos frontais e nas regiões temporoparietais. Os JFAs apresentaram ainda maior prevalência de anormalidades do septo pelúcido. CONCLUSãO: Os JFAs apresentam MGCr e vSC reduzidos nos lobos temporais, além de anormalidades do septo pelúcido, achados possivelmente relacionados a impactos cranianos repetitivos.

Brain glucose metabolism and gray matter volume in retired professional soccer players: a cross-sectional [18F]FDG-PET/MRI study / Metabolismo glicolítico cerebral e volume de substância cinzenta em jogadores de futebol profissionais aposentados: um estudo transversal de [18F]FDG-PET/RM

Abstract Background Professional soccer athletes are exposed to repetitive head impacts and are at risk of developing chronic traumatic encephalopathy. Objective To evaluate regional brain glucose metabolism (rBGM) and gray matter (GM) volume in retired soccer players (RSPs). Methods Male RSPs and age and sex-matched controls prospectively enrolled between 2017 and 2019 underwent neurological and neuropsychological evaluations, brain MRI and [18F]FDG-PET in a 3.0-Tesla PET/MRI scanner. Visual analysis was performed by a blinded neuroradiologist and a blinded nuclear physician. Regional brain glucose metabolism and GM volume were assessed using SPM8 software. Groups were compared using appropriate statistical tests available at SPM8 and R. Results Nineteen RSPs (median [IQR]: 62 [50-64.5] years old) and 20 controls (60 [48-73] years old) were included. Retired soccer players performed worse on mini-mental state examination, digit span, clock drawing, phonemic and semantic verbal fluency tests, and had reduced rBGM in the left temporal pole (pFDR = 0.008) and the anterior left middle temporal gyrus (pFDR = 0.043). Semantic verbal fluency correlated with rBGM in the right hippocampus, left temporal pole, and posterior left middle temporal gyrus (p ≤ 0.042). Cray matter volume reduction was observed in similar anatomic regions but was less extensive and did not survive correction for multiple comparisons (pFDR ≥ 0.085). Individual [18F]FDG-PET visual analysis revealed seven RSPs with overt hypometabolism in the medial and lateral temporal lobes, frontal lobes, and temporoparietal regions. Retired soccer players had a higher prevalence of septum pellucidum abnormalities on MRI. Conclusion Retired soccer players had reduced rBCM and CM volume in the temporal lobes and septum pellucidum abnormalities, findings possibly related to repetitive head impacts.

Resumo Antecedentes Jogadores profissionais de futebol estão expostos a impactos cranianos repetitivos e ao risco de desenvolver encefalopatia traumática crônica. Objetivo Avaliar o metabolismo glicolítico cerebral regional (MCCr) e o volume de substância cinzenta (vSC) em jogadores de futebol aposentados (JFAs). Métodos Jogadores de futebol aposentados masculinos e controles pareados por idade e sexo foram incluídos prospectivamente entre 2017 e 2019. Foram realizadas avaliações neurológica e neuropsicológica, ressonância magnética (RM) e [18F]FDG-PET cerebrais (3.0-Tesla PET/RM). As imagens foram analisadas visualmente por um neurorradiologista e um médico nuclear cegos ao grupo de cada participante. O metabolismo glicolítico cerebral regional e o vSC foram avaliados através do programa SPM8. Os grupos foram comparados através de testes estatísticos apropriados disponíveis em SPM8 e R, de acordo com a distribuição e o tipo dos dados. Resultados Dezenove JFAs (mediana [IIQ]: 62 [50-64.5] anos) e 20 controles (60 [48-73] anos) foram incluídos. Os JFAs tiveram pior desempenho no mini-exame do estado mental e nos testes de dígitos, desenho do relógio, fluência verbal e fluência semântica e apresentaram MCCr significativamente reduzido no polo temporal e no giro temporal médio anterior esquerdos. Fluência semântica (animais) apresentou correlação positiva com MCCr no hipocampo direito, no polo temporal esquerdo e no aspecto posterior do giro temporal médio esquerdo. Menor vSC foi observado nas mesmas regiões, porém este achado não sobreviveu à correção para comparações múltiplas. Análise individual do [18F]FDG-PET cerebral revelou sete JFAs com claro hipometabolismo nas faces medial e lateral dos lobos temporais, nos lobos frontais e nas regiões temporoparietais. Os JFAs apresentaram ainda maior prevalência de anormalidades do septo pelúcido. Conclusão Os JFAs apresentam MCCr e vSC reduzidos nos lobos temporais, além de anormalidades do septo pelúcido, achados possivelmente relacionados a impactos cranianos repetitivos.

Level of knowledge and misconceptions about brain concussion in Brazilian adults.

BACKGROUND: Brain concussion (BC) is seen as a public health priority due to its high incidence and morbidity rate, among thousands of people around the world. There are needs for fast identification, accurate diagnosis and correct management in order to reduce the short and long-term problems relating to BC. Proper knowledge of BC in the population and among clinicians is a critical factor in achieving this. OBJECTIVES: To evaluate the level of self-reported BC knowledge and gaps/misconceptions, and to identify variables correlated with this level. METHODS: A cross-sectional descriptive survey was performed. A Brain Concussion Knowledge Questionnaire (BCKQ) that had been created to capture data was widely distributed. Total scores, domain partial scores and percentages of correct and incorrect answers were calculated to ascertain the level of knowledge relating to BC. RESULTS: The sample was formed by 1,247 Brazilian adults (age: 41.7±11.8 years). Partial scores of the BCKQ revealed the existence of poor knowledge and misconceptions in all domains of the questionnaire, especially regarding questions about recovery from and management of BC. Moderate correlations between BCKQ scores and professions (p=0.312; P=0.00) or previous brain concussion knowledge (p=0.489; P=0.00) were observed. In a multiple linear regression model, age, profession and sports practice were predictors of BC knowledge. CONCLUSION: This first study to analyze the level of BC knowledge in a sample of Brazilian adults suggests that poor knowledge and misconceptions are present. Thus, meaningful and useful information was provided by this study for developing health education programs about BC for the population in order to improve fast diagnosis and correct BC management.

Cannabinoids in Neurology - Position paper from Scientific Departments from Brazilian Academy of Neurology.

Cannabinoids comprehend endocannabinoids, phytocannabinoids, and synthetic cannabinoids, with actions both in the central and peripherical nervous systems. A considerable amount of publications have been made in recent years, although cannabis has been known for over a thousand years. Scientific Departments from the Brazilian Academy of Neurology described evidence for medical use in their areas. Literature is constantly changing, and possible new evidence can emerge in the next days or months. Prescription of these substances must be discussed with patients and their families, with knowledge about adverse events and their efficacy.

Level of knowledge and misconceptions about brain concussion in Brazilian adults / Nível de conhecimento e de equívocos sobre concussão cerebral em adultos brasileiros

Abstract Background: Brain concussion (BC) is seen as a public health priority due to its high incidence and morbidity rate, among thousands of people around the world. There are needs for fast identification, accurate diagnosis and correct management in order to reduce the short and long-term problems relating to BC. Proper knowledge of BC in the population and among clinicians is a critical factor in achieving this. Objectives: To evaluate the level of self-reported BC knowledge and gaps/misconceptions, and to identify variables correlated with this level. Methods: A cross-sectional descriptive survey was performed. A Brain Concussion Knowledge Questionnaire (BCKQ) that had been created to capture data was widely distributed. Total scores, domain partial scores and percentages of correct and incorrect answers were calculated to ascertain the level of knowledge relating to BC. Results: The sample was formed by 1,247 Brazilian adults (age: 41.7±11.8 years). Partial scores of the BCKQ revealed the existence of poor knowledge and misconceptions in all domains of the questionnaire, especially regarding questions about recovery from and management of BC. Moderate correlations between BCKQ scores and professions (p=0.312; P=0.00) or previous brain concussion knowledge (p=0.489; P=0.00) were observed. In a multiple linear regression model, age, profession and sports practice were predictors of BC knowledge. Conclusion: This first study to analyze the level of BC knowledge in a sample of Brazilian adults suggests that poor knowledge and misconceptions are present. Thus, meaningful and useful information was provided by this study for developing health education programs about BC for the population in order to improve fast diagnosis and correct BC management.

RESUMO Introdução: A concussão cerebral (CC) é considerada prioridade em saúde pública devido à sua alta incidência e taxa de morbidade. Há necessidade de identificação rápida, diagnóstico acurado e manejo correto após essas lesões, com objetivo de reduzir problemas de curto e longo prazo. O conhecimento apropriado da população, atletas e de clínicos é primordial para que isto seja alcançado. Objetivos: Avaliar o nível de conhecimento autorrelatado sobre CC, descrever lacunas/equívocos e identificar variáveis correlacionadas com este nível. Métodos: Foi realizada uma pesquisa descritiva transversal. O Questionário de Conhecimento sobre Concussão Cerebral (QCCC) criado foi amplamente distribuído. Pontuações totais e parciais em domínios e porcentagens de respostas corretas e incorretas foram calculadas para obter o nível de conhecimento sobre CC. Resultados: A amostra foi formada por 1.247 brasileiros adultos (41,7±11,8 anos). Pontuações parciais do QCCC revelaram baixo nível de conhecimento, principalmente em questões sobre recuperação e manejo. Observou-se correlações moderadas entre a pontuação no QCCC e a profissão dos participantes (p=0,312, P=0,00) ou conhecimento prévio sobre CC (p=0,489, P=0,00). A regressão linear múltipla mostrou que a idade, profissão e prática de esportes podem ser preditoras do conhecimento sobre CC. Conclusão: Esse primeiro estudo a analisar o nível de conhecimento sobre CC em uma amostra de adultos brasileiros sugere baixo conhecimento e equívocos sobre esta condição. Assim, informações úteis e significantes foram fornecidas para o desenvolvimento de programas de educação em saúde sobre CC para o público, com objetivo de melhorar a identificação rápida e o manejo correto de concussões.

Cannabinoids in Neurology - Position paper from Scientific Departments from Brazilian Academy of Neurology / Canabinoides em Neurologia - Artigo de posicionamento dos Departamentos Científicos da Academia Brasileira de Neurologia

ABSTRACT Cannabinoids comprehend endocannabinoids, phytocannabinoids, and synthetic cannabinoids, with actions both in the central and peripherical nervous systems. A considerable amount of publications have been made in recent years, although cannabis has been known for over a thousand years. Scientific Departments from the Brazilian Academy of Neurology described evidence for medical use in their areas. Literature is constantly changing, and possible new evidence can emerge in the next days or months. Prescription of these substances must be discussed with patients and their families, with knowledge about adverse events and their efficacy.

RESUMO Os canabinoides compreendem os endocanabinoides, fitocanabinoides e os canabinoides sintéticos e desempenham ações no sistema nervoso central e periférico. Uma quantidade enorme de publicações tem sido lançada nos últimos anos, embora a cannabis seja conhecida por milênios. Os Departamentos Científicos da Academia Brasileira de Neurologia descreveram as evidências do uso médico em suas áreas. A literatura está em constantes mudanças e possíveis novas evidências podem surgir nos próximos dias ou meses. A prescrição dessas substâncias deve ser discutida com os pacientes e suas famílias, com conhecimento sobre eventos adversos e sua eficácia.

Individual versus task differences in slow potential generators.

Average slow potentials (SPs) can be computed from any voluntary task, minimally involving attention to anticipated stimuli. Their topography when recorded by large electrode arrays even during simple tasks is complex, multifocal, and its generators appear to be equally multifocal and highly variable across subjects. Various sources of noise of course contaminate such averages and must contribute to the topographic complexity. Here, we report a study in which the non-averaged SP band (0 to 1 Hz) was analyzed by independent components (ICA), from 256 channel recordings of 18 subjects, during four task conditions (resting, visual attention, CPT, and Stroop). We intended to verify whether the replicable SP generators (between two separate day sessions) modeled as current density reconstruction on structural MRI sets were individual-specific, and if putative task-related differences were systematic across subjects. Typically, 3 ICA components (out of 10) explained SPs in each task and subject, and their combined generators were highly variable across subjects: although some occipito-temporal and medial temporal areas contained generators in most subjects; the overall patterns were obviously variable, with no single area common to all 18 subjects. Linear regression modeling to compare combined generators (from all ICA components) between tasks and sessions showed significantly higher correlations between the four tasks than between sessions for each task. Moreover, it was clear that no common task-specific areas could be seen across subjects. Those results represent one more instance in which individual case analyses favor the hypothesis of individual-specific patterns of cortical activity, regardless of task conditions. We discuss this hypothesis with respect to results from the beta band, from individual-case fMRI studies, and its corroboration by functional neurosurgery and the neuropsychology of focal lesions.

Effectiveness of anodal transcranial direct current stimulation to improve muscle strength and motor functionality after incomplete spinal cord injury: a systematic review and meta-analysis.

STUDY DESIGN: Systematic review and meta-analysis. OBJECTIVES: We aimed to investigate the effects of anodal transcranial direct current stimulation (tDCS) against sham on muscle strength and motor functionality after incomplete spinal cord injury (iSCI). SETTING: University of São Paulo, Brazil. METHODS: A preplanned protocol was registered (PROSPERO, CRD42016050444). Pubmed, Embase, Web of Science, Cochrane Central Library and BVS databases were searched independently by two authors up to March 2018. Cochrane Collaboration's Tool was used for the risk of bias assessments. Generic inverse variance and random-effects model were used to calculate pooled effect sizes (ES), 95% confidence intervals (CIs) and p-values in meta-analyses. RESULTS: Six randomized clinical trials met inclusion criteria (n = 78 iSCI individuals) and were included in the meta-analysis. Results showed a marginal significant pooled effect of active tDCS in improving motor functionality with a small ES (SMD = 0.26, 95% CI = -0.00 to 0.53, p = 0.05, I2 = 0%). On the other hand, the pooled effect of active tDCS on muscle strength did not reach statistical significance, in parallel with a small ES (SMD = 0.35, 95% CI = -0.21 to 0.92, p = 0.22, I2 = 0%) when compared with sham tDCS. No significant adverse events were reported. CONCLUSIONS: Overall, there was a significant effect of tDCS in improving motor functionality following iSCI. However, a small ES and the marginal p-value suggest that these results should be interpreted with caution. Further high-quality clinical trials are needed to support or refute the use of tDCS in daily clinical practice.

Traumatic brain injury pharmacological treatment: recommendations.

This article presents the recommendations on the pharmacological treatment employed in traumatic brain injury (TBI) at the outpatient clinic of the Cognitive Rehabilitation after TBI Service of the Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil. A systematic assessment of the consensus reached in other countries, and of articles on TBI available in the PUBMED and LILACS medical databases, was carried out. We offer recommendations of pharmacological treatments in patients after TBI with different symptoms.

Traumatic brain injury pharmacological treatment: recommendations / Tratamento farmacológico do traumatismo cranioencefálico: recomendações

ABSTRACT This article presents the recommendations on the pharmacological treatment employed in traumatic brain injury (TBI) at the outpatient clinic of the Cognitive Rehabilitation after TBI Service of the Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil. A systematic assessment of the consensus reached in other countries, and of articles on TBI available in the PUBMED and LILACS medical databases, was carried out. We offer recommendations of pharmacological treatments in patients after TBI with different symptoms.

RESUMO Este artigo apresenta as recomendações sobre o tratamento farmacológico empregado para o traumatismo cranioencefálico (TCE) em pacientes ambulatoriais de Reabilitação Cognitiva pós-TCEno Serviço do HCFMUSP Foi realizada uma avaliação sistemática dos consensos publicados em outros países e dos artigos sobre TCE disponíveis nas bases de periódicos médicos como PUBMED e LILACS. Recomendamos tratamentos farmacológicos em pacientes pós-TCE com diferentes sintomas.

Higher similarity in beta topography between tasks than subjects.

We have recently provided evidence for highly idiosyncratic topographic distributions of beta oscillations (as well as slow potentials) across individuals. More recently, by emphasizing the analysis of similarity instead of differences across tasks, we concluded that differences between an attention task and quiet resting may be negligible or at least unsystematic across subjects. Due to the possibility that individual differences could be due to noise in a wide sense or some inherent instability of beta activity, we designed a replication study to explicitly test whether pairs of individuals matched for head size and shape would still present less similar beta topography than each individual between sessions or tasks. We used independent component analysis (ICA) for an exhaustive decomposition of beta activity in a visual attention task and in quiet resting, recorded by 256-channel EEG in 20 subjects, on two separate days. We evaluated whether each ICA component obtained in one task and in one given individual could be explained by a linear regression model based on the topographic patterns of the complementary task (correlation between one component with a linear combination of components from complementary conditions), of the same task in a second session and of a matched individual. Results again showed a high topographic similarity between conditions, as previously seen between reasoning and simple visual attention beta correlates. From an overall number of 16 components representing brain activity obtained for the tasks (out of 60 originally computed where the remaining were considered noise), over 92% could satisfactorily be explained by the complementary task. Although the similarity between sessions was significantly smaller than between tasks on each day, the similarity between sessions was statistically higher than that between subjects in a highly significant way. We discuss the possible biases of group spatial averaging and the emphasis on differences as opposed to similarities, and noise in a wide sense, as the main causes of hardly replicable findings on task-related forms of activity and the inconclusive state of a universal functional mapping of cortical association areas.

Traumatic brain injury: An EEG point of view.

Traumatic brain injury (TBI) is a silent epidemic. Mild traumatic brain injury (mTBI) causes brain injury that results in electrophysiologic abnormalities visible on electroencephalography (EEG) recordings. The purpose of this brief review was to discuss the importance of EEG findings in traumatic brain injury. Relevant articles published during the 1996-2016 period were retrieved from Medline (PubMed). The keywords were in English and included "traumatic brain injury", "EEG" and "quantitative EEG". We found 460 articles, analyzed 52 and selected 13 articles. EEG after TBI shows slowing of the posterior dominant rhythm and increased diffuse theta slowing, which may revert to normal within hours or may clear more slowly over many weeks. There are no clear EEG or quantitative EEG (qEEG) features unique to mild traumatic brain injury. Although the literature indicates the promise of qEEG in reaching a diagnosis and indicating prognosis of mTBI, further study is needed to corroborate and refine these methods.

O trauma cranioencefálico (TCE) é uma epidemia silenciosa. O trauma cranioencefálico leve causa uma lesão cerebral que resulta em anormalidades eletrofisiológicas visíveis nos registros eletroencefalográficos (EEG). O intuito dessa revisão curta foi discutir a importância dos achados eletroencefalográficos no trauma cranioencefálico. Os artigos relevantes publicados durante o período 1996-2016 foram selecionados do Medline (PubMed). As palavras-chave estavam em inglês e incluíam "traumatic brain injury", "EEG" e "quantitative EEG". Foram encontrados 460 artigos, analisados 52 e selecionados 13 artigos. O EEG após o TCE mostra lentificação do ritmo posterior dominante e aumento difuso da atividade lenta teta, o que pode ser revertido dentro de horas ou semanas. Não há características únicas no EEG ou EEG quantitativo (EEGq) de pacientes com TCE leve. Apesar da literatura indicar que no futuro o EEGq será uma ferramenta para diagnosticar e estabelecer um prognóstico para o TCE, mais estudos são necessários para corroborar e refinar esses métodos.

Comparative analysis of the electroencephalogram in patients with Alzheimer's disease, diffuse axonal injury patients and healthy controls using LORETA analysis.

Alzheimer's disease (AD) is a dementia that affects a large contingent of the elderly population characterized by the presence of neurofibrillary tangles and senile plaques. Traumatic brain injury (TBI) is a non-degenerative injury caused by an external mechanical force. One of the main causes of TBI is diffuse axonal injury (DAI), promoted by acceleration-deceleration mechanisms. OBJECTIVE: To understand the electroencephalographic differences in functional mechanisms between AD and DAI groups. METHODS: The study included 20 subjects with AD, 19 with DAI and 17 healthy adults submitted to high resolution EEG with 128 channels. Cortical sources of EEG rhythms were estimated by exact low-resolution electromagnetic tomography (eLORETA) analysis. RESULTS: The eLORETA analysis showed that, in comparison to the control (CTL) group, the AD group had increased theta activity in the parietal and frontal lobes and decreased alpha 2 activity in the parietal, frontal, limbic and occipital lobes. In comparison to the CTL group, the DAI group had increased theta activity in the limbic, occipital sublobar and temporal areas. CONCLUSION: The results suggest that individuals with AD and DAI have impairment of electrical activity in areas important for memory and learning.

A dooença de Alzheimer (DA) é uma demência que acomete uma grande parcela da população idosa e caracteriza-se pela presença de emaranhados neurofibrilares e placas senis. O traumatismo cranioencefálico (TCE) é uma lesão não degenerativa causada por uma força mecânica externa. Uma das principais causas de TCE é a lesão axonal difusa (LAD), causada por mecanismos de aceleração-desaceleração. OBJETIVO: Entender as diferenças dos mecanismos funcionais entre os grupos - DA e LAD do ponto de vista eletroencefalográfico. MÉTODOS: Participaram deste estudo 56 indivíduos adultos. Destes, 20 com DA, 19 com LAD e 17 adultos saudáveis submetidos ao EEG de alta resolução com 128 canais. As fontes corticais dos ritmos do EEG foram estimadas pela análise por tomografia eletromagnética exata de baixa resolução (eLORETA). RESULTADOS: A análise por eLORETA mostrou que, em comparação ao grupo controle (CTL), o grupo DA apresentou aumento da atividade teta nos lobos parietal e frontal e diminuição da atividade alfa 2 nos lobos parietal, frontal, límbico e occipital. Em comparação ao grupo CTL, o grupo LAD apresentou aumento da atividade teta nas áreas límbica, occipital sub-lobar e temporal. CONCLUSÃO: Os resultados sugerem que os indivíduos com DA e com LAD apresentam comprometimento da atividade elétrica em áreas importantes para a memória e aprendizagem.

Alpha band EEG coherence in healthy nonagenarians.

OBJECTIVE: Electroencephalographic (EEG) coherence is a parameter that enables evaluation of cerebral connectivity. It may be related to the functional state of the brain. In the elderly, it may reflect the neuronal loss caused by aging. To describe characteristics of coherence in nonagenarians. METHODS: We evaluated interhemispheric coherence for the alpha band in 42 cognitively normal individuals aged 90 to 101 years. Coherence values in the occipital electrode (O1O2), in the resting state with closed eyes, were calculated by means of spectral analysis using digital EEG EMSA 32 channels, 12 bits and a frequency of 200 Hz. RESULTS: The mean coherence value for the alpha band at O1O2 was 0.65 (SD 0.13). No significant differences were found between men and women. CONCLUSIONS: The findings from this study did not show any decrease in interhemispheric coherence for the alpha band in cognitively normal nonagenarians. This may be useful as a standard value for this age group.

Alpha band EEG coherence in healthy nonagenarians / Coerência da banda alfa do EEG em nonagenários saudáveis

ABSTRACT Electroencephalographic (EEG) coherence is a parameter that enables evaluation of cerebral connectivity. It may be related to the functional state of the brain. In the elderly, it may reflect the neuronal loss caused by aging. Objective To describe characteristics of coherence in nonagenarians. Methods We evaluated interhemispheric coherence for the alpha band in 42 cognitively normal individuals aged 90 to 101 years. Coherence values in the occipital electrode (O1O2), in the resting state with closed eyes, were calculated by means of spectral analysis using digital EEG EMSA 32 channels, 12 bits and a frequency of 200 Hz. Results The mean coherence value for the alpha band at O1O2 was 0.65 (SD 0.13). No significant differences were found between men and women. Conclusions The findings from this study did not show any decrease in interhemispheric coherence for the alpha band in cognitively normal nonagenarians. This may be useful as a standard value for this age group.

RESUMO A coerência é um parâmetro que permite avaliar a conectividade cerebral, podendo se relacionar com o estado funcional do cérebro. Especialmente nos idosos, pode refletir a perda neuronal decorrente do envelhecimento. Objetivo Descrever características da coerência em nonagenários. Métodos Avaliamos a coerência interhemisferica para a banda alfa em 42 indivíduos cognitivamente normais entre 90 e 101 anos. Foram calculados através da análise espectral o valor da coerência nos eletrodos O1O2, em estado de repouso e olhos fechados, com EEG digital 32 canais marca EMSA 12 bits e frequência de amostragem 200 hz. Resultados O valor médio da coerência para a banda alfa entre O1O2 foi de 0,65 (DP 0,13). Não encontramos diferenças significativas entre homens e mulheres. Conclusão Os achados desse estudo não evidenciam diminuição da coerência interhemisferica para a banda alfa nos eletrodos O1O2 em nonagenários saudáveis e cognitivamente normais, podendo indicar um valor padrão para essa faixa etária.