Neuroimaging Association Scores: reliability and validity of aggregate measures of brain structural features linked to mental disorders in youth.

In genetics, aggregation of many loci with small effect sizes into a single score improved prediction. Nevertheless, studies applying easily replicable weighted scores to neuroimaging data are lacking. Our aim was to assess the reliability and validity of the Neuroimaging Association Score (NAS), which combines information from structural brain features previously linked to mental disorders. Participants were 726 youth (aged 6-14) from two cities in Brazil who underwent MRI and psychopathology assessment at baseline and 387 at 3-year follow-up. Results were replicated in two samples: IMAGEN (n = 1627) and the Healthy Brain Network (n = 843). NAS were derived by summing the product of each standardized brain feature by the effect size of the association of that brain feature with seven psychiatric disorders documented by previous meta-analyses. NAS were calculated for surface area, cortical thickness and subcortical volumes using T1-weighted scans. NAS reliability, temporal stability and psychopathology and cognition prediction were analyzed. NAS for surface area showed high internal consistency and 3-year stability and predicted general psychopathology and cognition with higher replicability than specific symptomatic domains for all samples. They also predicted general psychopathology with higher replicability than single structures alone, accounting for 1-3% of the variance, but without directionality. The NAS for cortical thickness and subcortical volumes showed lower internal consistency and less replicable associations with behavioural phenotypes. These findings indicate the NAS based on surface area might be replicable markers of general psychopathology, but these links are unlikely to be causal or clinically useful yet.

Short-interval intracortical inhibition is decreased in restless legs syndrome across a range of severity.

BACKGROUND: Decreased short-interval intracortical inhibition (SICI) to transcranial magnetic stimulation (TMS) of the primary motor cortex was described in subjects with restless legs syndrome/Willis-Ekbom disease (RLS/WED). It remained to be determined whether the magnitude of SICI decrease would be similar across levels of RLS/WED severity. Moreover, it was unknown whether, in addition to decreases in SICI, changes in cortical thickness or area could be detected in subjects with RLS/WED compared to controls. The objective of this study was to compare SICI, cortical thickness, and cortical area in subjects with idiopathic mild to moderate RLS/WED, severe to very severe RLS/WED, and controls. METHODS: The severity of RLS/WED was assessed by the International Restless Legs Syndrome Severity Scale (IRLSS). SICI and 3T magnetic resonance imaging (MRI) data of subjects with RLS/WED and controls were compared. A receiver operating characteristic curve for SICI was designed for discrimination of participants with RLS/WED from controls. Cortical thickness and area were assessed by automated surface-based analysis. RESULTS: SICI was significantly reduced in patients with mild to moderate and severe to very severe RLS/WED, compared to controls (one-way analysis of variance: F = 9.62, p < 0.001). Receiver operating characteristic curve analysis predicted RLS/WED when SICI was above 35% (area under the curve = 0.79, 95% CI 0.67-0.91, p < 0.001). Analyses of the whole brain and of regions of interest did not reveal differences in gray matter thickness or area between controls and subjects with RLS/WED. CONCLUSION: SICI is an accurate cortical biomarker that can support the diagnosis of RLS/WED even in subjects with mild symptoms, but cortical thickness and area were not useful for discriminating subjects with this condition from controls.

Galvanic vestibular stimulator for fMRI studies

INTRODUCTION: Areas of the brain that are associated with the vestibular system can be activated using galvanic vestibular stimulation. These areas can be studied through a combination of galvanic vestibular stimulation with functional magnetic resonance imaging (fMRI). In order to provide an appropriate sequence of galvanic stimulation synchronous with the MRI pulse sequence, a specific electronic device that was built and assessed is presented. METHODS: The electronic project of the GVS is divided in analog and digital circuits. The analog circuits are mounted in an aluminum case, supplied by sealed batteries, and goes inside the MRI room near to the feet of the subject. The digital circuits are placed in the MRI control room. Those circuits communicate through each other by an optical fiber. Tests to verify the GVS-MRI compatibility were conducted. Silicone (in-house) and Ag/AgCl (commercial) electrodes were evaluated for maximum balance and minimal pain sensations. fMRI experiments were conducted in eight human volunteers. RESULTS: GVS-MRI compatibility experiments demonstrate that the GVS did not interfere with the MRI scanner functionality and vice versa. The circular silicone electrode was considered the most suitable to apply the galvanic vestibular stimulation. The 1 Hz stimulation sinusoid frequency produced the biggest balance and the less pain sensations when compared to 2 Hz. The GVS was capable of eliciting activation in the precentral and postcentral gyri, in the central sulcus, in the supplementary motor area, in the middle and inferior frontal gyri, in the inferior parietal lobule, in the insula, in the superior temporal gyrus, in the middle cingulate cortex, and in the cerebellum. CONCLUSION: This study shows the development and description of a neurovestibular stimulator that can be safely used inside the MRI scanner room without interfering on its operation and vice versa. The developed GVS could successfully activate the major areas involved with multimodal functions of the vestibular system, demonstrating its validity as a stimulator for neurovestibular research. To the best of our knowledge, this is the first work that shows the development and the construction of a galvanic vestibular stimulator that could be safely used inside the MRI room.

[Mortality trend due to ischemic heart diseases in the city of Curitiba--Brazil, from 1980 to 1998]. / Tendência da mortalidade por doenças isquêmicas do coração na cidade de Curitiba--Brasil, de 1980 a 1998.

OBJECTIVE: To assess mortality trends due to ischemic heart diseases, per sex, and acute myocardial infarction, per sex and age range, from 1980 to 1998, in the city of Curitiba. METHODS: Data of death due to ischemic heart disease and acute myocardial infarction from Sistema de Informação sobre Mortalidade do Ministério da Saúde (Information System on Mortality of Ministry of Health), per sex, age range and domicile location in Curitiba were used. Population data were obtained from Fundação Instituto Brasileiro de Geografia e Estatística (Brazilian Institute of Geography and Statistics Foundation). Mortality rates were adjusted per age through direct method, by using the population of Curitiba, in 1980, as reference. The analysis of trend was calculated through simple linear regression, with a significance level of 5%. RESULTS: Mortality rates due to ischemic heart diseases showed a decrease trend among both sexes. In age ranges of acute myocardial infarction, male sex showed a decrease until 79 years of age, among female sex individuals, the decrease was until 59 years of age. They were shown stable after those periods. Among the remaining ischemic diseases, female sex individuals showed a greater decrease than male sex ones. CONCLUSION: The study demonstrates a trend of reduction of mortality due to ischemic heart diseases, in both sexes, in the city of Curitiba, from 1980 to 1998. In acute myocardial infarction, such reduction has been happening in a more pronounced way among men, achieving stability, from 60 years of age, among women. The reasons for differentiated reduction trend between sexes are not clear, remaining as na important matter for new investigations.

Tendência da mortalidade por doencas isquêmicas do coracão na cidade de Curitiba - Brasil, de 1980 a 1998 / Mortality trend due to ischemic heart diseases in the city of Curitiba - Brazil, from 1980 to 1998

OBJETIVO: Analisar a tendência de mortalidade pelas doencas isquêmicas do coracão, por sexo, e do infarto agudo do miocárdio, por sexo e faixa etária, de 1980 a 1998, na cidade de Curitiba. MÉTODOS: Utilizou-se os dados de óbitos por doenca isquêmica do coracão e infarto agudo do miocárdio do Sistema de Informacão sobre Mortalidade do Ministério da Saúde, por sexo, faixa etária e local de residência em Curitiba. Os dados de populacão foram obtidos da Fundacão Instituto Brasileiro de Geografia e Estatística. As taxas de mortalidade foram ajustadas por idade pelo método direto, utilizando como referência a populacão de Curitiba, em 1980. A análise de tendência foi calculada através da regressão linear simples, com um nível de significância de 5 por cento. RESULTADOS: As taxas de mortalidade das doencas isquêmicas do coracão apresentaram uma tendência de declínio em ambos os sexos. Nas faixas etárias do infarto agudo do miocárdio, o sexo masculino apresentou queda até os 79 anos; no sexo feminino, até os 59 anos, mantendo-se estáveis após estes períodos. No restante das doencas isquêmicas, o sexo feminino apresentou uma queda maior que o masculino. CONCLUSAO: O estudo demonstra uma tendência de reducão da mortalidade por doencas isquêmicas do coracão, em ambos os sexos, na cidade de Curitiba, de 1980 a 1998. No infarto agudo do miocárdio, essa reducão vem ocorrendo de forma mais pronunciada nos homens, mantendo-se estável, a partir dos 60 anos, nas mulheres. As razões para a tendência de reducão diferenciada entre os sexos não são claras, permanecendo como importante questão para novas investigacões.