Differences in total brain volume between sexes in a cognitively unimpaired elderly population

OBJECTIVES: Although a large number of studies have shown brain volumetric differences between men and women, only a few investigations have analyzed brain tissue volumes in representative samples of the general elderly population. We investigated differences in gray matter (GM) volumes, white matter (WM) volumes, and intracranial volumes (ICVs) between the sexes in individuals older than 66 years using structural magnetic resonance imaging (MRI). METHODS: Using FreeSurfer version 5.3, we obtained the ICVs and GM and WM volumes from the MRI datasets of 84 men and 92 women. To correct for interindividual variations in ICV, GM and WM volumes were adjusted with a method using the residuals of a least-square-derived linear regression between raw volumes and ICVs. We then performed an analysis of covariance comparing men and women, including age and years of schooling as confounding factors. RESULTS: Women had a lower socioeconomic status overall and fewer years of schooling than men. The comparison of unadjusted brain volumes showed larger GM and WM volumes in men. After the ICV correction, the adjusted volumes of GM and WM were larger in women. CONCLUSION: After the ICV correction and taking into account differences in socioeconomic status and years of schooling, our results confirm previous findings of proportionally larger GM in women, as well as larger WM volumes. These results in an elderly population indicate that brain volumetric differences between sexes persist throughout the aging process. Additional studies combining MRI and other biomarkers to identify the hormonal and molecular bases influencing such differences are warranted.

Support vector machine-based classification of neuroimages in Alzheimer's disease: direct comparison of FDG-PET, rCBF-SPECT and MRI data acquired from the same individuals

Objective: To conduct the first support vector machine (SVM)-based study comparing the diagnostic accuracy of T1-weighted magnetic resonance imaging (T1-MRI), F-fluorodeoxyglucose-positron emission tomography (FDG-PET) and regional cerebral blood flow single-photon emission computed tomography (rCBF-SPECT) in Alzheimer's disease (AD). Method: Brain T1-MRI, FDG-PET and rCBF-SPECT scans were acquired from a sample of mild AD patients (n=20) and healthy elderly controls (n=18). SVM-based diagnostic accuracy indices were calculated using whole-brain information and leave-one-out cross-validation. Results: The accuracy obtained using PET and SPECT data were similar. PET accuracy was 68∼71% and area under curve (AUC) 0.77∼0.81; SPECT accuracy was 68∼74% and AUC 0.75∼0.79, and both had better performance than analysis with T1-MRI data (accuracy of 58%, AUC 0.67). The addition of PET or SPECT to MRI produced higher accuracy indices (68∼74%; AUC: 0.74∼0.82) than T1-MRI alone, but these were not clearly superior to the isolated neurofunctional modalities. Conclusion: In line with previous evidence, FDG-PET and rCBF-SPECT more accurately identified patients with AD than T1-MRI, and the addition of either PET or SPECT to T1-MRI data yielded increased accuracy. The comparable SPECT and PET performances, directly demonstrated for the first time in the present study, support the view that rCBF-SPECT still has a role to play in AD diagnosis.

High frequency of silent brain infarcts associated with cognitive deficits in an economically disadvantaged population

OBJECTIVE: Using magnetic resonance imaging, we aimed to assess the presence of silent brain vascular lesions in a sample of apparently healthy elderly individuals who were recruited from an economically disadvantaged urban region (São Paulo, Brazil). We also wished to investigate whether the findings were associated with worse cognitive performance. METHODS: A sample of 250 elderly subjects (66-75 years) without dementia or neuropsychiatric disorders were recruited from predefined census sectors of an economically disadvantaged area of Sao Paulo and received structural magnetic resonance imaging scans and cognitive testing. A high proportion of individuals had very low levels of education (4 years or less, n=185; 21 with no formal education). RESULTS: The prevalence of at least one silent vascular-related cortical or subcortical lesion was 22.8% (95% confidence interval, 17.7-28.5), and the basal ganglia was the most frequently affected site (63.14% of cases). The subgroup with brain infarcts presented significantly lower levels of education than the subgroup with no brain lesions as well as significantly worse current performance in cognitive test domains, including memory and attention (p<0.002). CONCLUSIONS: Silent brain infarcts were present at a substantially high frequency in our elderly sample from an economically disadvantaged urban region and were significantly more prevalent in subjects with lower levels of education. Covert cerebrovascular disease significantly contributes to cognitive deficits, and in the absence of magnetic resonance imaging data, this cognitive impairment may be considered simply related to ageing. Emphatic attention should be paid to potentially deleterious effects of vascular brain lesions in poorly educated elderly individuals from economically disadvantaged environments.

Analysis of the posterior cingulate cortex with [ 18 F]FDG-PET and Naa/mI in mild cognitive impairment and Alzheimer's disease: Correlations and differences between the two methods / Análise do giro do cíngulo posterior com [ 18 f]FDG-PET e relação Naa/mI no comprometimento leve e na doença de Alzheimer: correlações e diferenças entre os métodos

ABSTRACT Reduction of regional brain glucose metabolism (rBGM) measured by [18F]FDG-PET in the posterior cingulate cortex (PCC) has been associated with a higher conversion rate from mild cognitive impairment (MCI) to Alzheimer's disease (AD). Magnetic Resonance Spectroscopy (MRS) is a potential biomarker that has disclosed Naa/mI reductions within the PCC in both MCI and AD. Studies investigating the relationships between the two modalities are scarce. OBJECTIVE To evaluate differences and possible correlations between the findings of rBGM and NAA/mI in the PCC of individuals with AD, MCI and of cognitively normal volunteers. METHODS Patients diagnosed with AD (N=32) or MCI (N=27) and cognitively normal older adults (CG, N=28), were submitted to [18F]FDG-PET and MRS to analyze the PCC. The two methods were compared and possible correlations between the modalities were investigated. RESULTS The AD group exhibited rBGM reduction in the PCC when compared to the CG but not in the MCI group. MRS revealed lower NAA/mI values in the AD group compared to the CG but not in the MCI group. A positive correlation between rBGM and NAA/mI in the PCC was found. NAA/mI reduction in the PCC differentiated AD patients from control subjects with an area under the ROC curve of 0.70, while [18F]FDG-PET yielded a value of 0.93. CONCLUSION rBGM and Naa/mI in the PCC were positively correlated in patients with MCI and AD. [18F]FDG-PET had greater accuracy than MRS for discriminating AD patients from controls.

RESUMO Redução do metabolismo cerebral regional glicolítico (MRG) medido pela PET-18FDG no giro do cíngulo posterior (GCP) está relacionada a maior conversão para doença de Alzheimer (DA) em sujeitos com comprometimento cognitivo leve (CCL). Espectroscopia por ressonância magnética (MRS), um biomarcador promissor, demonstra redução de Naa/mI no GCP na DA. Raros estudos avaliam relações entre Naa/mI e MRG. OBJETIVO Avaliar diferenças e possíveis correlações entre MRG com PET-18FDG e Naa/mI por MRS no GCP de sujeitos com DA, CCL e voluntários normais. MÉTODOS Sujeitos com DA (N=32), CCL amnéstico (N=27) e voluntários idosos normais (GC, N=28), foram submetidos a PET-18FDG e análise de Naa/mI no GCP. A performance de ambos os métodos foi então comparada e verificou-se a existência de correlações entre os achados da PET e da MRS. RESULTADOS Observou-se hipometabolismo glicolítico nos pacientes com DA no GCP em relação ao GC, porém não no CCL. A MRS demonstrou valores menores de Naa/mI no CP do grupo DA em relação ao GC, porém também sem diferenças entre CCL e GC. A área sob a curva ROC demonstrou valor de 0,70 para MRS e 0,93 para o MRG no GCP para diferenciar DA do GC. Houve correlação positiva entre o MRG e o Naa/mI no GCP. CONCLUSÃO Os valores de metabolismo de glicose à PET e de Naa/mI à MRS no giro do cíngulo posterior apresentaram correlação positiva estatisticamente significante na presente amostra. Houve ainda superioridade da PET-18FDG para diferenciar DA do GC.

The fragile x-associated tremor and ataxia syndrome (FXTAS) / A síndrome de tremor e ataxia associada ao X frágil (FXTAS)

FXTAS (Fragile X-associated tremor and ataxia syndrome) is a late- onset neurodegenerative disorder affecting mainly men, over 50 years of age, who are carriers of the FMR1 gene premutation. The full mutation of this gene causes the fragile X syndrome (FXS), the most common cause of inherited mental retardation. Individuals affected by FXTAS generally present intention tremor and gait ataxia that might be associated to specific radiological and/or neuropathological signs. Other features commonly observed are parkinsonism, cognitive decline, peripheral neuropathy and autonomic dysfunction. Nearly a decade after its clinical characterization, FXTAS is poorly recognized in Brazil. Here we present a review of the current knowledge on the clinical, genetic and diagnostic aspects of the disease.

A FXTAS (síndrome de tremor e ataxia associada ao X frágil) é uma doença neurodegenerativa de início tardio que afeta principalmente homens acima dos 50 anos de idade, portadores de pré-mutação do gene FMR1. A mutação completa desse gene é responsável pela síndrome do cromossomo X frágil (SXF), a causa mais comum de deficiência mental herdada. Indivíduos afetados pela FXTAS geralmente apresentam tremor de intenção e ataxia de marcha que podem estar associados a sinais radiológicos ou neuropatológicos específicos. Outras características comumente observadas são parkinsonismo, declínio cognitivo, neuropatia periférica e disfunções autonômicas. Quase uma década após sua caracterização clínica, a FXTAS é mal conhecida por médicos no Brasil. Esta revisão apresenta o conhecimento atual sobre os aspectos clínicos, genéticos e diagnósticos da síndrome.

Cognitive control associated with irritability induction: an autobiographical recall fMRI study / Controle cognitivo associado à indução de irritabilidade: um estudo de RMf usando recordações autobiográficas

OBJECTIVE: Despite the relevance of irritability emotions to the treatment, prognosis and classification of psychiatric disorders, the neurobiological basis of this emotional state has been rarely investigated to date. We assessed the brain circuitry underlying personal script-driven irritability in healthy subjects (n = 11) using functional magnetic resonance imaging. METHOD: Blood oxygen level-dependent signal changes were recorded during auditory presentation of personal scripts of irritability in contrast to scripts of happiness or neutral emotional content. Self-rated emotional measurements and skin conductance recordings were also obtained. Images were acquired using a 1,5T magnetic resonance scanner. Brain activation maps were constructed from individual images, and between-condition differences in the mean power of experimental response were identified by using cluster-wise nonparametric tests. RESULTS: Compared to neutral scripts, increased blood oxygen level-dependent signal during irritability scripts was detected in the left subgenual anterior cingulate cortex, and in the left medial, anterolateral and posterolateral dorsal prefrontal cortex (cluster-wise p-value < 0.05). While the involvement of the subgenual cingulate and dorsal anterolateral prefrontal cortices was unique to the irritability state, increased blood oxygen level-dependent signal in dorsomedial and dorsal posterolateral prefrontal regions were also present during happiness induction. CONCLUSION: Irritability induction is associated with functional changes in a limited set of brain regions previously implicated in the mediation of emotional states. Changes in prefrontal and cingulate areas may be related to effortful cognitive control aspects that gain salience during the emergence of irritability.

OBJETIVO: Apesar da relevância de emoções de irritabilidade para o tratamento, prognóstico e classificação dos transtornos psiquiátricos, as bases neurobiológicas deste tipo de estado emocional foram raramente investigadas até hoje. Este estudo avaliou os circuitos cerebrais subjacentes à irritabilidade induzida por scripts pessoais em voluntários saudáveis (n = 11) usando ressonância magnética funcional. MÉTODO: Mudanças no sinal dependente do nível de oxigenação sanguínea (blood-oxygen level dependent signal) foram registradas durante a apresentação por via auditiva de scripts pessoais de irritabilidade em contraste com scripts de felicidade ou de conteúdo emocional neutro. Escores em escalas de autoavaliação emocional e medidas de condutância da pele também foram obtidos. A aquisição de imagens foi realizada em aparelho de ressonância magnética de 1,5 T. Os mapas de ativação cerebral foram construídos a partir das imagens individuais, e as diferenças entre as condições experimentais foram investigadas utilizando testes não-paramétricos baseados em permutações. RESULTADOS: Em comparação com scripts neutros, a apresentação de scripts de irritabilidade levou a aumentos de sinal dependente do nível de oxigenação sanguínea na porção subgenual do giro do cíngulo anterior esquerdo e nas porções medial, ântero-lateral e póstero-lateral do córtex pré-frontal dorsal (cluster-wise p-valor < 0,05). Enquanto o envolvimento do cíngulo anterior subgenual e do córtex pré-frontal dorsal antero-lateral surgiu apenas em associação com o estado de irritabilidade, aumentos do sinal dependente do nível de oxigenação sanguínea nas porções dorso-medial e dorsal póstero-lateral do córtex pré-frontal também estiveram presentes durante indução de felicidade. CONCLUSÃO: Indução de irritabilidade está associada a mudanças de atividade funcional num conjunto restrito de regiões cerebrais previamente implicadas na mediação de estados emocionais. Mudanças na atividade...

Asymmetric cortical high signal on diffusion weighted-MRI in a case of Creutzfeldt-Jakob disease

Hipersinal no cortex cerebral e/ou nos gânglios da base observado com a técnica de difusão da ressonância magnética (RM-DIF) tem sido descrito como bom marcador diagnóstico da doença de Creutzfeldt-Jakob esporádica (DCJe). Relatamos caso de DCJe com evolução clínica atípica e achados incomuns na RM-DIF. Homem de 53 anos foi examinado com história de dois anos de demência rapidamente progressiva e ataxia cerebelar. Exame do líquido cefalorraqueano, incluindo pesquisa da proteína 14-3-3, foi normal; EEG não revelou atividade periódica; RM-DIF mostrou hiperintensidade nos giros que afetava quase inteiramente o manto cortical do hemisfério cerebral esquerdo e que no hemisfério direito se limitava à parte posterior do giro cíngulo. Análise do DNA revelou ausência de mutação ou de inserção no gene da proteína priônica e a presença de homozigose para metionina no códon 129. Biópsia cerebral confirmou o diagnóstico de DCJ. Hipersinal na RM-DIF pode ser limitado ao córtex cerebral e pode distribuir-se de modo muito assimétrico na DCJe.

Diffusion-weighted MR imaging of cystic lesions of neurocysticercosis: a preliminary study

Neurocysticercosis is an endemic disease in some developing countries. It has pleomorfic clinical and imaging findings, which are variable from patient to patient. In this preliminary note, we studied the magnetic resonance (MR) diffusion-weighted images (DWI) of sixteen patients presenting with cystic lesions of this disease diagnosed by clinical and laboratorial findings. All the lesions had hypointense signal and the similar apparent diffusion coeficient (ADC) values as the cerebrospinal fluid (CSF)

Correlaçäo da medida de espessura intra-abdominal medida pela ultra-sonografia com os fatores de risco cardiovascular / Correlation of intra-abdominal thickness measure for the ultrasound with cardiovascular risk factors

O objetivo do estudo foi determinar se a Gordura intra Abdominal medida pela Ultra-Sonografia (GAUS) em homens e mulheres tem associação com os fatores de risco cardiovascular, comparar essa medida com a circunferência abdominal e diâmetro sagital para precisar qual destes métodos é o melhor preditor de risco cardiovascular (CV), e tentar encontrar um ponto de corte para GAUS que possa definir maior risco de doença CV. Cento e noventa e um homens sadios e 231 mulheres sadias foram submetidas à medidas antropométricas, medidas de pressão arterial sistêmica e dosagens laboratoriais para colesterol, HDL, triglicerídeos e glicemia. A ultra-sonografia intra-abdominal foi realizada para medir espessura visceral. A amostra foi dividida em três grupos de acordo com a presença dos seguintes fatores de risco cardiovascular: 1) grupo de moderado risco - presença de dois ou mais dos fatores: col > 200mg/dL, HDL-colesterol < 45mg/dL, TG > 200mg/dL, Glic > 126mg/dL, PAs > 140mmHg, PAd > 90mmHg; 2) grupo de alto risco com dois ou mais dos fatores: total col > 240mg/dL, HDL-colesterol < 35mg/dL, TG > 200mg/dL +HDL < 35mg/dL, Glic > 126mg/dL, PAs > 140mmHg, PAd > 90mmHg; 3) grupo sem risco: com um ou nenhum dos fatores de risco presentes. Os resultados mostraram que a GAUS tem associação com todos os fatores de risco cardiovascular e tem melhor especificidade e acurácia que a circunferência abdominal e o diâmetro sagital. O valor de 7cm para ambos os sexos foi o ponto de corte para GAUS para predizer risco moderado; 8 e 9cm foram os pontos de cortes obtidos para GAUS para predizer alto risco CV em homens e mulheres, respecti- vamente. A GAUS é um método útil de determinar espessura visceral e parece ser capaz de predizer risco cardiovascular.