Neuroimaging and electroencephalographic (EEG) methods for investigating neural circuits in mental disorders

It is increasingly recognised that dysfunction in neural circuits plays a key role in the neurobiological basis of mental disorders.  The efficacy of pharmacological and behavioural treatments for mental disorders could therefore be improved by targeting dysfunctions in neurocircuits.  However, to achieve this, a better understanding of the specific alterations in neural circuits involved in different mental disorders is required.  Such understanding can be acquired by using advanced neuroscience methods to examine the pathways and function of neurocircuits in both typically developing individuals and in those with mental disorders.  This article provides an overview of currently available neuroscience methods of investigating neural circuits, including advantages and limitations of different techniques, and highlights the importance of using multi-modal imaging in future researchÉ cada vez mais reconhecido que a disfunção nos circuitos neurais desempenha um papel fundamental na base neurobiológica dos transtornos mentais. A eficácia dos tratamentos farmacológicos e comportamentais para os transtornos mentais pode, portanto, ser melhorada por direcionar as disfunções nos neurocircuitos. No entanto, para isso, é necessário um melhor entendimento das alterações específicas nos circuitos neurais envolvidos em diferentes transtornos mentais. Tal entendimento pode ser adquirido usando-se métodos avançados de neurociência para examinar as vias e a função dos neurocircuitos em indivíduos com desenvolvimento típico e naqueles com transtornos mentais. Este artigo fornece uma visão geral dos métodos da neurociência atualmente disponíveis na investigação de circuitos neurais, incluindo vantagens e limitações de diferentes técnicas, e destaca a importância do uso de imagens multimodais em pesquisas futura

Is there any relationship between Neuroscience and Psychiatry

Psychiatry has always been considered a separate field of medicine among other medical specialties. Unlike Cardiology or Oncology, diagnoses of psychiatric disorders are made entirely based on patients’ presenting signs and symptoms. There are no sources of external validity (e.g. laboratory exam, imaging findings) that can be employed reliably to identify individuals with psychiatric disorders. [...

Theoretical models of Obsessive-Compulsive Disorder (OCD): a perspective on future approaches

Obsessive-Compulsive disorder (OCD) is a common psychiatric condition that leads to significant impairment in everyday life. Advancements in neurobiological investigations contributed to a better understanding of pathophysiological mechanisms behind OCD, leading to the understanding that current models employed to conceptualize OCD are not adequate and might be a significant factor in precluding further advancements in how OCD is treated. In this paper, we will use OCD as a model to discuss the limitations of the current diagnostic systems in Psychiatry and to present the novel perspectives based on neurobiological findings that might lead to considerable advancements in treatments for OCD

The validity and reliability of the CAMDEX-DS for assessing dementia in adults with Down syndrome in Brazil.

OBJECTIVE: Alzheimer's disease occurs at a higher prevalence and an earlier age in individuals with Down syndrome (DS) than typically developing individuals. However, diagnosing dementia in individuals with intellectual disability remains a challenge due to pre-existing cognitive deficits. The aim of this study was to investigate the validity and reliability of the Brazilian version of the Cambridge Examination for Mental Disorders of Older People with Down's syndrome and Others with Intellectual Disabilities (CAMDEX-DS) for individuals with DS. METHODS: Two psychiatrists, working independently, evaluated 92 adults with DS ≥ 30 years of age. The concurrent validity of the CAMDEX-DS was analyzed in relation to the gold standard of established international criteria. In a subgroup of 20 subjects, the concurrent validity of the CAMDEX-DS was analyzed in relation to an independent objective assessment of cognitive decline over three years. We analyzed the inter-rater reliability of cognitive assessment. RESULTS: The diagnostic accuracy of the CAMDEX-DS compared to the gold standard was 96.7%. CAMDEX-DS-based diagnosis was considered consistent with cognitive decline. The probability of a participant with dementia having cognitive decline was 83%. Inter-rater reliability for the participant assessment was good, with a kappa of > 0.8 for 93% of the CAMDEX-DS items. CONCLUSION: The CAMDEX-DS can be considered the first valid and reliable instrument for evaluating dementia in adults with DS in Brazil. Its use in such individuals could improve clinical practice and research

The validity and reliability of the CAMDEX-DS for assessing dementia in adults with Down syndrome in Brazil.

OBJECTIVE: Alzheimer's disease occurs at a higher prevalence and an earlier age in individuals with Down syndrome (DS) than typically developing individuals. However, diagnosing dementia in individuals with intellectual disability remains a challenge due to pre-existing cognitive deficits. The aim of this study was to investigate the validity and reliability of the Brazilian version of the Cambridge Examination for Mental Disorders of Older People with Down's syndrome and Others with Intellectual Disabilities (CAMDEX-DS) for individuals with DS. METHODS: Two psychiatrists, working independently, evaluated 92 adults with DS ≥ 30 years of age. The concurrent validity of the CAMDEX-DS was analyzed in relation to the gold standard of established international criteria. In a subgroup of 20 subjects, the concurrent validity of the CAMDEX-DS was analyzed in relation to an independent objective assessment of cognitive decline over three years. We analyzed the inter-rater reliability of cognitive assessment. RESULTS: The diagnostic accuracy of the CAMDEX-DS compared to the gold standard was 96.7%. CAMDEX-DS-based diagnosis was considered consistent with cognitive decline. The probability of a participant with dementia having cognitive decline was 83%. Inter-rater reliability for the participant assessment was good, with a kappa of > 0.8 for 93% of the CAMDEX-DS items. CONCLUSION: The CAMDEX-DS can be considered the first valid and reliable instrument for evaluating dementia in adults with DS in Brazil. Its use in such individuals could improve clinical practice and research

Lateral hypothalamic activity indicates hunger and satiety states in humans

Lateral hypothalamic area (LHA) local field potentials (LFPs) were recorded in a Prader–Willi patient undergoing deep brain stimulation (DBS) for obesity. During hunger, exposure to food-related cues induced an increase in beta/ low-gamma activity. In contrast, recordings during satiety were marked by prominent alpha rhythms. Based on these findings, we have delivered alphafrequency DBS prior to and during food intake. Despite reporting an early sensation of fullness, the patient continued to crave food. This suggests that the pattern of activity in LHA may indicate hunger/satiety states in humans but attest to the complexity of conducting neuromodulation studies in obesity

Brain structural correlates of sensory phenomena in patients with obsessive-compulsive disorder

Background: sensory phenomena (SP) are uncomfortable feelings, including bodily sensations, sense of inner tension, 'just-right' perceptions, feelings of incompleteness, or 'urge-only' phenomena, which have been described to precede, trigger or accompany repetitive behaviours in individuals with obsessive-compulsive disorder (OCD). Sensory phenomena are also observed in individuals with tic disorders, and previous research suggests that sensorimotor cortex abnormalities underpin the presence of SP in such patients. However, to our knowledge, no studies have assessed the neural correlates of SP in patients with OCD. Methods: we assessed the presence of SP using the University of São Paulo Sensory Phenomena Scale in patients with OCD and healthy controls from specialized units in São Paulo, Brazil, and Barcelona. All participants underwent a structural magnetic resonance examination, and brain images were examined using DARTEL voxel-based morphometry. We evaluated grey matter volume differences between patients with and without SP and healthy controls within the sensorimotor and premotor cortices. Results: we included 106 patients with OCD and 87 controls in our study. Patients with SP (67% of the sample) showed grey matter volume increases in the left sensorimotor cortex in comparison to patients without SP and bilateral sensorimotor cortex grey matter volume increases in comparison to controls. No differences were observed between patients without SP and controls. Limitations: most patients were medicated. Participant recruitment and image acquisition were performed in 2 different centres. Conclusion: we have identified a structural correlate of SP in patients with OCD involving grey matter volume increases within the sensorimotor cortex; this finding is in agreement with those of tic disorder studies showing that abnormal activity and volume increases within this region are associated with the urges preceding tic onset

The functional connectome in obsessive-compulsive disorder: resting-state mega-analysis and machine learning classification for the ENIGMA-OCD consortium

Current knowledge about functional connectivity in obsessive-compulsive disorder (OCD) is based on small-scale studies, limiting the generalizability of results. Moreover, the majority of studies have focused only on predefined regions or functional networks rather than connectivity throughout the entire brain. Here, we investigated differences in resting-state functional connectivity between OCD patients and healthy controls (HC) using mega-analysis of data from 1024 OCD patients and 1028 HC from 28 independent samples of the ENIGMA-OCD consortium. We assessed group differences in whole-brain functional connectivity at both the regional and network level, and investigated whether functional connectivity could serve as biomarker to identify patient status at the individual level using machine learning analysis. The mega-analyses revealed widespread abnormalities in functional connectivity in OCD, with global hypo-connectivity (Cohen’s d: -0.27 to -0.13) and few hyper-connections, mainly with the thalamus (Cohen’s d: 0.19 to 0.22). Most hypo-connections were located within the sensorimotor network and no fronto-striatal abnormalities were found. Overall, classification performances were poor, with area-under-the-receiver-operating-characteristic curve (AUC) scores ranging between 0.567 and 0.673, with better classification for medicated (AUC = 0.702) than unmedicated (AUC = 0.608) patients versus healthy controls. These findings provide partial support for existing pathophysiological models of OCD and highlight the important role of the sensorimotor network in OCD. However, resting-state connectivity does not so far provide an accurate biomarker for identifying patients at the individual level

Avaliação do risco cirúrgico nos doentes com cancro colo-rectal: POSSUM ou ACPGBI?

Background: Obsessive-compulsive disorder can be expressed as four potentially overlapping obsessive-compulsive symptom (OCS) dimensions (OCSD) ("symmetry/ordering", "contamination/cleaning", "aggressive/sexual/religious" and "collecting/hoarding"). In clinical samples, some dimensions are more familial and associated with increased psychiatric comorbidity and malfunctioning. However, data concerning OCS and OCSD are scarce in non-clinical samples, particularly among children. The present study aims to estimate: (1) the prevalence and sex/age distribution of OCS/OCSD in a community-based sample of schoolchildren; (2) the association between OCS and additional clinical factors; and (3) the degree of familial aggregation of OCS/OCSD. Methods: OCS and OCSD were evaluated in 9937 Brazilian school-children (6-12 years-old) and their biological relatives using the Family History Screen. Data analyses included gradient estimated equations and post-hoc tests. Results: We included data on 9937 index-children, 3305 siblings (13-18 years-old), and 16,218 parents. Biological mothers were the informants in 87.6% of the interviews. OCS were present in 14.7% of the index-children; 15.6% of their siblings; 34.6% of their mothers and 12.1% of their fathers. The prevalence of OCS and each of the OCSD gradually increased from ages 6 to 12 years. Overall, OCS in children were associated with the presence of other psychiatric symptoms, as well as behavioral/school impairment. OCS and each of the four OCSD aggregated significantly within families. Conclusions: OCS are prevalent and associated with psychiatric symptoms and clinical impairment among school-aged children. OCSD aggregate within families in a dimension-specific fashion. These findings suggest a natural continuum between OCS and OCD with regard to their dimensional character. (C) 2015 Elsevier Ltd. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Structural covariance of neostriatal and limbic regions in patients with obsessive-compulsive disorder

Background: Frontostriatal and frontoamygdalar connectivity alterations in patients with obsessive-compulsive disorder (OCD) have been typically described in functional neuroimaging studies. However, structural covariance, or volumetric correlations across distant brain regions, also provides network-level information. Altered structural covariance has been described in patients with different psychiatric disorders, including OCD, but to our knowledge, alterations within frontostriatal and frontoamygdalar circuits have not been explored. Methods: We performed a mega-analysis pooling structural MRI scans from the Obsessive-compulsive Brain Imaging Consortium and assessed whole-brain voxel-wise structural covariance of 4 striatal regions (dorsal and ventral caudate nucleus, and dorsal-caudal and ventral-rostral putamen) and 2 amygdalar nuclei (basolateral and centromedial-superficial). Images were preprocessed with the standard pipeline of voxel-based morphometry studies using Statistical Parametric Mapping software. Results: Our analyses involved 329 patients with OCD and 316 healthy controls. Patients showed increased structural covariance between the left ventral-rostral putamen and the left inferior frontal gyrus/frontal operculum region. This finding had a significant interaction with age; the association held only in the subgroup of older participants. Patients with OCD also showed increased structural covariance between the right centromedial-superficial amygdala and the ventromedial prefrontal cortex. Limitations: This was a cross-sectional study. Because this is a multisite data set analysis, participant recruitment and image acquisition were performed in different centres. Most patients were taking medication, and treatment protocols differed across centres. Conclusion: Our results provide evidence for structural network-level alterations in patients with OCD involving 2 frontosubcortical circuits of relevance for the disorder and indicate that structural covariance contributes to fully characterizing brain alterations in patients with psychiatric disorders