Emotional processing in bipolar disorder: behavioural and neuroimaging findings.
ABSTRACT Existing studies revealed that bipolar patients show an altered identification of emotional stimuli (e.g. facial expressions), however, so far modifications in early emotional processes and the regulation of emotions are less clear. In response to emotional stimuli bipolar patients show a dysfunction in a ventral-limbic brain network including the amygdala, insula, striatum, subgenual cingulate cortex, ventrolateral prefrontal cortex and orbitofrontal cortex. In most studies, a relative hypoactivity of dorsal brain structures, including the dorsolateral prefrontal cortex, the dorsal anterior cingulate and the posterior cingulate cortex, has been reported in bipolar patients. This imbalance between the two networks has been proposed to underlie deficient emotion regulation in bipolar disorder.
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ABSTRACT: Bipolar I disorder is a highly heritable disorder but not all siblings manifest with the illness, even though they may share similar genetic and environmental risk factors. Thus, sibling studies may help to identify brain structural endophenotypes associated with risk and resistance for the disorder. Structural magnetic resonance imaging (MRI) scans were acquired for 28 euthymic patients with bipolar disorder, their healthy siblings, and 30 unrelated healthy controls. Statistical Parametric Mapping 8 (SPM8) was used to identify group differences in regional gray matter volume by voxel-based morphometry (VBM). Using analysis of covariance, gray matter analysis of the groups revealed a group effect indicating that the left orbitofrontal cortex [Brodmann area (BA) 11] was smaller in patients with bipolar disorder than in unrelated healthy controls [F = 14.83, p < 0.05 (family-wise error); 7 mm(3) ]. Paired t-tests indicated that the orbitofrontal cortex of patients with bipolar disorder [t = 5.19, p < 0.05 (family-wise error); 37 mm(3) ] and their healthy siblings [t = 3.89, p < 0.001 (uncorrected); 63 mm(3) ] was smaller than in unrelated healthy controls, and that the left dorsolateral prefrontal cortex was larger in healthy siblings than in patients with bipolar disorder [t = 4.28, p < 0.001 (uncorrected); 323 mm(3) ] and unrelated healthy controls [t = 4.36, p < 0.001 (uncorrected); 245 mm(3) ]. Additional region-of-interest analyses also found volume deficits in the right cerebellum of patients with bipolar disorder [t = 3.92, p < 0.001 (uncorrected); 178 mm(3) ] and their healthy siblings [t = 4.23, p < 0.001 (uncorrected); 489 mm(3) ], and in the left precentral gyrus of patients with bipolar disorder [t = 3.61, p < 0.001 (uncorrected); 115 mm(3) ] compared to unrelated healthy controls. The results of this study suggest that a reduction in the volume of the orbitofrontal cortex, which plays a role in the automatic regulation of emotions and is a part of the medial prefrontal network, is associated with the heritability of bipolar disorder. Conversely, increased dorsolateral prefrontal cortex volume may be a neural marker of a resistance factor as it is part of a network of voluntary emotion regulation and balances the effects of the disrupted automatic emotion regulation system.Bipolar Disorders 03/2014; · 4.62 Impact Factor
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ABSTRACT: Attention-deficit/hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder in children and adolescents. It is characterized by age-inappropriate inattention/impulsiveness and/or hyperactivity symptoms. ADHD shows a high comorbidity with oppositional defiant disorder (ODD), a disorder that features symptoms of emotional lability. Due to this comorbidity, emotional lability was long considered a secondary consequence of ADHD, which could arise under the influence of environmental factors such as inefficient parenting practices, as part of an ODD diagnosis. In this model of heterotypic continuity, emotional lability was considered not to play any causal role regarding ADHD symptomatology. As opposed to this view, it is now well established that a large number of children with ADHD and without any comorbid disorder exhibit symptoms of emotional lability. Furthermore, recent studies have found that negative emotionality accounts for significant unique variance in ADHD symptom severity, along with motor-perceptual and executive function deficits. Barkley proposed that ADHD is characterized by deficits of executive functions, and that a deficiency in the executive control of emotions is a necessary component of ADHD. According to this theory, the extent to which an individual with ADHD displays a deficiency in behavioral inhibition is the extent to which he or she will automatically display an equivalent degree of deficiency in emotional inhibition. However, not all children with ADHD exhibit symptoms of emotional lability, and studies have found that the association between emotional lability and ADHD was not mediated by executive function or motivational deficits. Task-based and resting state neuroimaging studies have disclosed an altered effective connectivity between regions dedicated to emotional regulation in children with ADHD when compared to typically developing children, notably between the amygdala, the prefrontal cortex, the hippocampus and the ventral striatum. Morphological alterations of the amygdala have also been reported in previous structural studies in children with ADHD. Emotional lability can result from different neurobiological mechanisms. In particular, bottom-up and top-down processes can be opposed. Bottom-up related emotional dysregulation involves an increased emotional reactivity, and is thought to be linked to the automatic evaluative activity of the amygdala. Top-down mechanisms are associated with the regulation of such activity, and rely on a prefrontal network including the lateral prefrontal cortex, the anterior cingulate cortex and the orbitofrontal cortex. Since various neuropsychological impairments and alterations in multiple brain networks have been implicated in the etiology of ADHD, contemporary models emphasize its neuropsychological heterogeneity. It is therefore likely that some but not all children with ADHD will exhibit neurobiological alterations in circuits dedicated to emotional regulation, possibly at different levels. Future research will have to identify the different causal pathways and to decide whether emotional lability represents a criterion to subtype ADHD diagnoses. Emotional dysregulation is now known to play a causal role regarding ADHD symptomatology. Along with executive functioning, reaction time variability and potentially delay aversion, emotional dysregulation should therefore be included in future theoretical models of ADHD, as well as in clinical practice when identifying the major impairments in this diagnostic group and when deciding therapeutic strategies.L Encéphale 04/2014; · 0.49 Impact Factor
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ABSTRACT: Bipolar disorder is characterized by a functional imbalance between hyperactive ventral/limbic areas and hypoactive dorsal/cognitive brain regions potentially contributing to affective and cognitive symptoms. Resting-state studies in bipolar disorder have identified abnormal functional connectivity between these brain regions. However, most of these studies used a seed-based approach, thus restricting the number of regions that were analyzed. Using data-driven approaches, researchers identified resting state networks whose spatial maps overlap with frontolimbic areas such as the default mode network, the frontoparietal networks, the salient network, and the meso/paralimbic network. These networks are specifically engaged during affective and cognitive tasks and preliminary evidence suggests that functional connectivity within and between some of these networks is impaired in bipolar disorder. The present study used independent component analysis and functional network connectivity approaches to investigate functional connectivity within and between these resting state networks in bipolar disorder. We compared 30 euthymic bipolar I disorder patients and 35 age- and gender-matched healthy controls. Inter-network connectivity analysis revealed increased functional connectivity between the meso/paralimbic and the right frontoparietal network in bipolar disorder. This abnormal connectivity pattern did not correlate with variables related to the clinical course of the disease. The present finding may reflect abnormal integration of affective and cognitive information in ventral-emotional and dorsal-cognitive networks in euthymic bipolar patients. Furthermore, the results provide novel insights into the role of the meso/paralimbic network in bipolar disorder.PLoS ONE 01/2014; 9(10):e107829. · 3.53 Impact Factor