Patterns of Default Mode Network Deactivation in Obsessive Compulsive Disorder.

The objective of the present study was to research the patterns of Default Mode Network (DMN) deactivation in Obsessive Compulsive Disorder (OCD) in the transition between a resting and a non-rest emotional condition. Twenty-seven participants, 15 diagnosed with OCD and 12 healthy controls (HC), underwent a functional neuroimaging paradigm in which DMN brain activation in a resting condition was contrasted with activity during a non-rest condition consisting in the presentation of emotionally pleasant and unpleasant images. Results showed that HC, when compared with OCD, had a significant deactivation in two anterior nodes of the DMN (medial frontal and superior frontal) in the non-rest pleasant stimuli condition. Additional analysis for the whole brain, contrasting the resting condition with all the non-rest conditions grouped together, showed that, compared with OCD, HC had a significantly deactivation of a widespread brain network (superior frontal, insula, middle and superior temporal, putamen, lingual, cuneus, and cerebellum). Concluding, the present study found that OCD patients had difficulties with the deactivation of DMN even when the non-rest condition includes the presentation of emotional provoking stimuli, particularly evident for images with pleasant content.

Alterations of gray and white matter morphology in obsessive compulsive disorder / Las alteraciones de morfología de la sustancia blanca y gris en el trastorno obsesivo compulsivo

BACKGROUND: While the ethio-pathogenesis of Obsessive-Compulsive disorder (OCD) remains unknown, there is increased evidence of widespread structural alterations in both white and gray matter in OCD patients that include, but are not restricted, to abnormalities in corticostriatal-thalamo-cortical (CSTC) regions. The objective of this study was to test the existence of structural alterations in both white and gray matter in a sample of OCD patients when compared with a group of non-clinical matched controls (NCC), using voxel-based morphometry (VBM). METHOD: Fifteen patients with OCD and 15 NCC underwent MRI structural scanning. RESULTS: Frontal (increased gray matter in the middle frontal gyrus) and subcortical regions (increased white matter in the pallidum) were found to be affected in patients. Additionally, temporalparietal regions were also found to be affected and highly correlated with OCD symptom severity (decrease of gray matter in the superior parietal lobe and white matter in the angular and superior temporal gyri). CONCLUSIONS: These alterations may be associated with prominent OCD symptoms, such as diffi culties with inhibitory control (pallidum, angular gyrus), executive functioning (middle frontal gyris), compulsive checking (superior temporal gyrus) and visual-spatial defi cits (superior parietal lobe)

ANTECEDENTES: mientras que la etiopatogenia del trastorno obsesivo-compulsivo (TOC) sigue siendo desconocida, hay una mayor evidencia en las personas que sufren este trastorno de alteraciones estructurales que incluyen, pero no se limitan, a anormalidades en regiones cortico-estriado-tálamo-corticales (CSTC). El objetivo de este estudio fue comprobar la existencia de alteraciones estructurales tanto en la materia blanca como en la materia gris en una muestra de pacientes con TOC en comparación con un grupo de controles no clínicos (NCC), utilizándose para ello análisis morfométricos basados en «voxel» (VBM). MÉTODO: quince pacientes con TOC y quince NCC fueron estudiados mediante resonancia magnética estructural. RESULTADOS: se encontraron alteraciones en los pacientes en regiones frontales (aumento de la materia gris en la circunvolución frontal media) y subcorticales (aumento de la materia blanca en el pallidum). Además, también se encontraron afectadas regiones témporo-parietales con una alta correlación con la gravedad de los síntomas del TOC (disminución de la materia gris en el lóbulo parietal superior y de la materia blanca en las circunvoluciones temporales angular y superior). CONCLUSIONES: las alteraciones encontradas pueden estar asociados con síntomas predominantes en el TOC, como dificultades en el control inhibitorio (pallidum, giro angular), función ejecutiva (circunvolución frontal media), verificaciones compulsivas (circunvolución temporal superior) y déficit visual-espacial (lóbulo parietal superior)

Alterations of gray and white matter morphology in obsessive compulsive disorder.

BACKGROUND: While the ethio-pathogenesis of Obsessive-Compulsive disorder (OCD) remains unknown, there is increased evidence of widespread structural alterations in both white and gray matter in OCD patients that include, but are not restricted, to abnormalities in cortico-striatal-thalamo-cortical (CSTC) regions. The objective of this study was to test the existence of structural alterations in both white and gray matter in a sample of OCD patients when compared with a group of non-clinical matched controls (NCC), using voxel-based morphometry (VBM). METHOD: Fifteen patients with OCD and 15 NCC underwent MRI structural scanning. RESULTS: Frontal (increased gray matter in the middle frontal gyrus) and subcortical regions (increased white matter in the pallidum) were found to be affected in patients. Additionally, temporal-parietal regions were also found to be affected and highly correlated with OCD symptom severity (decrease of gray matter in the superior parietal lobe and white matter in the angular and superior temporal gyri). CONCLUSIONS: These alterations may be associated with prominent OCD symptoms, such as difficulties with inhibitory control (pallidum, angular gyrus), executive functioning (middle frontal gyris), compulsive checking (superior temporal gyrus) and visual-spatial deficits (superior parietal lobe).

Inferior frontal gyrus white matter abnormalities in obsessive-compulsive disorder.

The aim of the present study is to explore obsessive-compulsive disorder (OCD)-related abnormalities in white matter connectivity in OCD for a core region associated with inhibitory control [i.e. inferior frontal gyrus (IFG)]. Fifteen patients with OCD (11 men) and 15 healthy controls (nine men) underwent diffusion tensor imaging scanning to study four diffusivity indexes of white matter integrity [fractional anisotropy, mean diffusivity (MD), axial diffusivity and radial diffusivity (RD)]. The results showed that persons with OCD manifested significantly lower fractional anisotropy levels in the bilateral IFG as well as its parcellations in the pars opercularis, pars triangularis, and pars orbitalis. Significantly higher levels of MD, RD were evident for the OCD group in the IFG as a whole as well as in the bilateral subregions of the pars triangularis and pars opercularis (for MD and RD), the right side of the pars orbitalis (for RD), and the left side of the pars triangularis and right side pars opercularis (for axial diffusivity). Overall, the results suggest significant alterations in structural connectivity, probably associated with myelination and axonal abnormalities in the IFG of OCD patients.

Imbalance in habitual versus goal directed neural systems during symptom provocation in obsessive-compulsive disorder.

Intrusive thoughts and compulsive urges to perform stereotyped behaviours are typical symptoms of obsessive-compulsive disorder. Emerging evidence suggests a cognitive bias towards habit formation at the expense of goal-directed performance in obsessive-compulsive disorder. In this study, we test this hypothesis using a novel individualized ecologically valid symptom provocation design: a live provocation functional magnetic resonance imaging paradigm with synchronous video-recording of behavioural avoidance responses. By pairing symptom provocation with online avoidance responses on a trial-by-trial basis, we sought to investigate the neural mechanisms leading to the compulsive avoidance response. In keeping with the model of habit formation in obsessive-compulsive disorder, we hypothesized that this disorder would be associated with lower activity in regions implicated in goal-directed behaviours and higher activity in regions implicated in habitual behaviours. Fifteen patients with obsessive-compulsive disorder and 15 healthy control volunteers participated in this functional magnetic resonance imaging study. Online stimuli were individually tailored to achieve effective symptom provocation at neutral, intermediate and strong intensity levels. During the symptom provocation block, the participant could choose to reject or terminate the provoking stimuli resulting in cessation of the symptom provocation. We thus separately analysed the neural correlates of symptom provocation, the urge to avoid, rejection and relief. Strongly symptom-provoking conditions evoked a dichotomous pattern of deactivation/activation in patients, which was not observed either in control conditions or in healthy subjects: a deactivation of caudate-prefrontal circuits accompanied by hyperactivation of subthalamic nucleus/putaminal regions. This finding suggests a dissociation between regions engaged in goal-directed and habitual behaviours. The putaminal hyperactivity during patients' symptom provocation preceded subsequent deactivation during avoidance and relief events, indicating a pivotal role of putamen in regulation of behaviour and habit formation in obsessive-compulsive disorder. Effective connectivity analysis identified the ventromedial prefrontal cortex/orbitofrontal cortex as the main structure in this circuitry involved in the modulation of compulsivity in obsessive-compulsive disorder. These findings suggest an imbalance in circuitry underlying habitual and goal-directed action control, which may represent a fundamental mechanism underlying compulsivity in obsessive-compulsive disorder. Our results complement current models of symptom generation in obsessive-compulsive disorder and may enable the development of future therapeutic approaches that aim to alleviate this imbalance.

Brain activation of the defensive and appetitive survival systems in obsessive compulsive disorder.

Several studies have shown that basic emotions are responsible for a significant enhancement of early visual processes and increased activation in visual processing brain regions. It may be possible that the cognitive uncertainty and repeated behavioral checking evident in Obsessive Compulsive Disorder (OCD) is due to the existence of abnormalities in basic survival circuits, particularly those associated with the visual processing of the physical characteristics of emotional-laden stimuli. The objective of the present study was to test if patients with OCD show evidence of altered basic survival circuits, particularly those associated with the visual processing of the physical characteristics of emotional stimuli. Fifteen patients with OCD and 12 healthy controls underwent functional magnetic resonance imaging acquisition while being exposed to emotional pictures, with different levels of arousal, intended to trigger the defensive and appetitive basic survival circuits. Overall, the present results seem to indicate dissociation in the activity of the defense and appetitive survival systems in OCD. Results suggest that the clinical group reacts to basic threat with a strong activation of the defensive system mobilizing widespread brain networks (i.e., frontal, temporal, occipital-parietal, and subcortical nucleus) and blocking the activation of the appetitive system when facing positive emotional triggers from the initial stages of visual processing (i.e., superior occipital gyrus).

Obsessive Compulsive Disorder as a functional interhemispheric imbalance at the thalamic level.

Obsessive Compulsive Disorder (OCD) involves failures in two main inhibitory processes, namely cognitive (obsessions) and behavioral (compulsions). Recent research has supported two cortical-subcortical pathways on OCD pathogenesis: (a) the frontostriatal loop (dorsolateral-caudate-striatum-thalamus) responsible for impairments of behavioral inhibition; (b) the orbitofrontal loop (orbitofrontal, medial prefrontal and cingulate) responsible for impairments with cognitive inhibitory processes. These failures in both cognitive and motor inhibitory systems may mediate several neuropsychological deficits in these patients, namely memory, attention, planning and decision making. But are those deficits related to specific hemispheric effects, namely functional imbalance between hemispheres? In this article we hypothesize that: (1) OCD patients have an inter-hemispheric functional imbalance, probably due to inadequate filtering at the thalamic level; (2) the restoration of inter-hemispheric balance, will be correlative to symptomatic improvement.

Perfectionism in obsessive-compulsive and eating disorders / Perfeccionismo no transtorno obsessivo-compulsivo e nos transtornos alimentares

OBJECTIVE: The main aims of this article are twofold. First, to assess perfectionism dimensions in obsessive-compulsive disorder and eating disorders in comparison with psychiatric control (depression/anxiety) and non-clinical control groups. Second, to examine if perfectionism is specifically related to these different clinical conditions. METHOD: Thirty-nine outpatients with obsessive-compulsive disorder, 24 outpatients with eating disorders, 65 outpatients with a diagnosis of depression and/or anxiety, and 70 non-clinical participants completed the Portuguese version of the Multidimensional Perfectionism Scale. RESULTS: Compared to non-clinical subjects, individuals of all clinical samples had significantly higher scores on Multidimensional Perfectionism Scale total score, Self-Oriented and Socially-Prescribed Perfectionism. There were no significantly differences in Self-Oriented Perfectionism and Multidimensional Perfectionism Scale total score in all the three clinical samples. Subjects from the eating disorders sample had significantly higher scores of Socially-Prescribed Perfectionism in comparison to obsessive-compulsive disorder and psychiatric control samples. CONCLUSION: Perfectionism showed to be related with this broad range of psychopathologies. However, the differences between eating disorders versus obsessive-compulsive disorder and psychiatric control on Socially-Prescribed Perfectionism warrant further investigation in order to clarify the specificity of this perfectionism dimension in eating disorders.

OBJETIVO: Este estudo tem dois objetivos principais. Primeiro, avaliar as dimensões do perfeccionismo no transtorno obsessivo-compulsivo e nos transtornos alimentares em comparação com duas amostras controle: psiquiátrica (depressão/ansiedade) e não clínica. Segundo, avaliar se o perfeccionismo é um traço de personalidade especificamente relacionado com estas diferentes condições clínicas. MÉTODO: 39 pacientes com transtorno obsessivo-compulsivo, 24 com transtornos alimentares, 65 com um diagnóstico de depressão e/ou ansiedade (todos estes pacientes encontravam-se em regime de ambulatório) e 70 controles não clínicos completaram a versão portuguesa da Multidimensional Perfectionism Scale. RESULTADOS: Comparativamente à amostra não clínica, todas as amostras clínicas apresentaram níveis significativamente mais elevados na Multidimensional Perfectionism Scale total, no Perfeccionismo Auto-Orientado e no Perfeccionismo-Socialmente-Prescrito. Não houve diferenças estatisticamente significativas no Perfeccionismo-Auto-Orientado e na Multidimensional Perfectionism Scale total nas três amostras clínicas. No entanto, a amostra com transtornos alimentares apresentou níveis significativamente mais elevados de Perfeccionismo-Socialmente-Prescrito, comparativamente à transtornos alimentares e à amostra psiquiátrica (depressão/ansiedade). CONCLUSÃO: O perfeccionismo revelou estar associado a uma grande variedade de condições psicopatológicas. Contudo, as diferenças encontradas entre a amostra de transtornos alimentares, de transtorno obsessivo-compulsivo e a psiquiátrica no Perfeccionismo-Socialmente-Prescrito necessitam de investigação subsequente no sentido de clarificar a especificidade desta dimensão com os transtornos alimentares.

Perfectionism in obsessive-compulsive and eating disorders.

OBJECTIVE: The main aims of this article are twofold. First, to assess perfectionism dimensions in obsessive-compulsive disorder and eating disorders in comparison with psychiatric control (depression/anxiety) and non-clinical control groups. Second, to examine if perfectionism is specifically related to these different clinical conditions. METHOD: Thirty-nine outpatients with obsessive-compulsive disorder, 24 outpatients with eating disorders, 65 outpatients with a diagnosis of depression and/or anxiety, and 70 non-clinical participants completed the Portuguese version of the Multidimensional Perfectionism Scale. RESULTS: Compared to non-clinical subjects, individuals of all clinical samples had significantly higher scores on Multidimensional Perfectionism Scale total score, Self-Oriented and Socially-Prescribed Perfectionism. There were no significantly differences in Self-Oriented Perfectionism and Multidimensional Perfectionism Scale total score in all the three clinical samples. Subjects from the eating disorders sample had significantly higher scores of Socially-Prescribed Perfectionism in comparison to obsessive-compulsive disorder and psychiatric control samples. CONCLUSION: Perfectionism showed to be related with this broad range of psychopathologies. However, the differences between eating disorders versus obsessive-compulsive disorder and psychiatric control on Socially-Prescribed Perfectionism warrant further investigation in order to clarify the specificity of this perfectionism dimension in eating disorders.