Elevated striatal and decreased dorsolateral prefrontal cortical activity in response to emotional stimuli in euthymic bipolar disorder: no associations with psychotropic medication load

Distinct patterns of dysfunctional appetitive and aversive motivation in bipolar disorder versus schizophrenia: An event-related potential study

Schizophrenia and bipolar disorder are associated with different clinical profiles of disturbances in motivation, yet few studies have compared the neurophysiological correlates of such disturbances. Outpatients with schizophrenia (n = 34), or bipolar disorder I (n = 33), and healthy controls (n = 31) completed a task in which the late positive potential (LPP), an index of motivated attention, was assessed along motivational gradients determined by apparent distance from potential rewards or punishments. Sequences of cues signaling possible monetary gains or losses appeared to loom progressively closer to the viewer; a reaction time (RT) task after the final cue determined the outcome. Controls showed the expected pattern with LPPs for appetitive and aversive cues that were initially elevated, smaller during intermediate positions, and escalated just prior to the RT task. The clinical groups showed different patterns in the final positions just prior to the RT task: the bipolar group's LPPs to both types of cues peaked relatively early during looming sequences and subsequently decreased, whereas the schizophrenia group showed relatively small LPP escalations, particularly for aversive cues. These distinct patterns suggest that the temporal unfolding of attentional resource allocation for motivationally significant events may qualitatively differ between these disorders. (PsycINFO Database Record

Deficient inhibitory control as an outcome of childhood trauma

Childhood trauma has been linked to the development and severity of psychiatric disorders as well as deficits in cognitive functioning. This study aimed to investigate the performance of bipolar disorder (BD) patients and healthy controls (HC), with or without a history of childhood trauma, on a parametric Go/No-Go (PGNG) task measuring important aspects of executive functions, namely attention and inhibitory control. Two hundred and thirty-three individuals with BD and 90 HC completed diagnostic interview, childhood trauma questionnaire (CTQ), symptom severity scales, and a PGNG task. Four comparison groups were created using a 1.0 standard deviation cut-off of the mean of the HC total CTQ score: BD-trauma, BD-normative, HC-trauma and HC-normative. We assessed interactions between diagnosis and trauma on Go/No-Go levels of interest by using a two-way multivariate analysis of covariance. Results showed a significant main effect of trauma on inhibitory control accuracy, as the trauma group exhibited significantly poorer accuracy on inhibition trials compared to the normative group. There was also a main effect of diagnosis on response time. These findings suggest that early trauma might adversely impact the development of cognitive systems and brain circuits that support inhibitory aspects of executive functioning in individuals with a history of trauma.

Impact of the glucocorticoid receptor BclI polymorphism on reward expectancy and prediction error related ventral striatal reactivity in depressed and healthy individuals

There is evidence that reward-related neural reactivity is altered in depressive disorders. Glucocorticoids influence dopaminergic transmission, which is widely implicated in reward processing. However, no studies have examined the effect of glucocorticoid receptor gene polymorphisms on reward-related neural reactivity in depressed or healthy individuals. Fifty-nine depressed individuals with major depressive disorder (n=33) or bipolar disorder (n=26), and 32 healthy individuals were genotyped for the glucocorticoid receptor BclI G/C polymorphism, and underwent functional magnetic resonance imaging during a monetary reward task. We examined the effect of the glucocorticoid receptor BclI G/C polymorphism on reward expectancy (RE; expected outcome value) and prediction error (PE; discrepancy between expected and actual outcome) related ventral striatal reactivity. There was a significant interaction between reward condition and BclI genotype (p=0.007). C-allele carriers showed higher PE than RE-related right ventral striatal reactivity (p<0.001), whereas no such difference was observed in G/G homozygotes. Accordingly, C-allele carriers showed a greater difference between PE and RE-related right ventral striatal reactivity than G/G homozygotes (p<0.005), and also showed lower RE-related right ventral striatal reactivity than G/G homozygotes (p=0.011). These findings suggest a slowed transfer from PE to RE-related ventral striatal responses during reinforcement learning in C-allele carriers, regardless of diagnosis, possibly due to altered dopamine release associated with increased sensitivity to glucocorticoids.

Differentiating unipolar and bipolar depression by alterations in large-scale brain networks

BACKGROUND

Misdiagnosing bipolar depression can lead to very deleterious consequences of mistreatment. Although depressive symptoms may be similarly expressed in unipolar and bipolar disorder, changes in specific brain networks could be very distinct, being therefore informative markers for the differential diagnosis. We aimed to characterize specific alterations in candidate large-scale networks (frontoparietal, cingulo-opercular, and default mode) in symptomatic unipolar and bipolar patients using resting state fMRI, a cognitively low demanding paradigm ideal to investigate patients.

METHODS

Networks were selected after independent component analysis, compared across 40 patients acutely depressed (20 unipolar, 20 bipolar), and 20 controls well-matched for age, gender, and education levels, and alterations were correlated to clinical parameters.

RESULTS

Despite comparable symptoms, patient groups were robustly differentiated by large-scale network alterations. Differences were driven in bipolar patients by increased functional connectivity in the frontoparietal network, a central executive and externally-oriented network. Conversely, unipolar patients presented increased functional connectivity in the default mode network, an introspective and self-referential network, as much as reduced connectivity of the cingulo-opercular network to default mode regions, a network involved in detecting the need to switch between internally and externally oriented demands. These findings were mostly unaffected by current medication, comorbidity, and structural changes. Moreover, network alterations in unipolar patients were significantly correlated to the number of depressive episodes.

CONCLUSION

Unipolar and bipolar groups displaying similar symptomatology could be clearly distinguished by characteristic changes in large-scale networks, encouraging further investigation of network fingerprints for clinical use. Hum Brain Mapp 37:808-818, 2016. © 2015 Wiley Periodicals, Inc.

Fear extinction memory performance in a sample of stable, euthymic patients with bipolar disorder

OBJECTIVES

Affective dysregulation is a core feature of bipolar disorder (BD). Abnormalities in neural circuits underlying affect regulation have been observed in BD, specifically in the structure and function of the amygdala and orbital frontal cortex (OFC). Fear extinction is an automatic affect regulatory process relying on neural circuits that are abnormal in BD. Thus, fear extinction might be useful in probing automatic affect regulation deficits in BD. We tested the hypothesis that BD is associated with reduced ability to extinguish fear responses.

METHODS

We examined fear conditioning, extinction, and extinction memory recall in a sample of stable, euthymic participants with BD (n=19) vs. healthy comparison participants (n=32). A limited number of subjects (BD: n=12; healthy comparison: n=11) underwent structural MRI scanning to examine cortical size associations with extinction recall.

RESULTS

Both healthy comparison and BD participants were successful in acquiring a fear response, but BD participants responded with greater startle to both threat and safety cues. Both groups showed significant extinction. The BD group showed superior extinction recall. Extinction recall was associated with right rostral middle frontal cortex thickness across groups, whereas right OFC surface area was associated with recall only in healthy comparisons.

LIMITATIONS

Limitations include use of a stable, highly screened sample and a relatively small number of participants available for MRI analysis.

CONCLUSIONS

Increased fear reactivity may be related to a "trait" disruption in BD patients similar to that previously described in anxiety disorders. This task may be useful for probing automatic affect regulatory processes in BD, and understanding treatment response.

A voxel-based morphometry study of gray matter correlates of facial emotion recognition in bipolar disorder

Facial emotion recognition (FER) is one of the many cognitive deficits reported in bipolar disorder (BD) patients. The aim of this study was to investigate neuroanatomical correlates of FER impairments in BD type I (BD-I). Participants comprised 21 euthymic BD-I patients without Axis I DSM IV-TR comorbidities and 21 healthy controls who were assessed using magnetic resonance imaging and the Penn Emotion Recognition Test (ER40). Preprocessing of images used DARTEL (diffeomorphic anatomical registration through exponentiated Lie algebra) for optimized voxel-based morphometry in SPM8. Compared with healthy subjects, BD-I patients performed poorly in on the ER40 and had reduced gray matter volume (GMV) in the left orbitofrontal cortex, superior portion of the temporal pole and insula. In the BD-I group, the statistical maps indicated a direct correlation between FER on the ER40 and right middle cingulate gyrus GMV. Our findings are consistent with the previous studies regarding the overlap of multiple brain networks of social cognition and BD neurobiology, particularly components of the anterior-limbic neural network.

Neural correlates of negative emotion processing in bipolar disorder

INTRODUCTION

Bipolar disorder type I (BD-I) is characterized by a severe impairment in emotional processing during both acute and euthymic phases of the illness. The aim of the present study was to investigate negative emotion processing in both euthymic patients and non-affected first-degree relatives, looking for state and trait markers of BD-I.

METHODS

22 healthy relatives of BD-I patients (mean age 31.5±7.3 years; 15 females), 23 euthymic BD-I patients (mean age 35.2±7.9 years; 14 females), and 24 matched controls (mean age 32.5±6.2 years; 16 females) performed an IAPS-based emotional task during 1.5T fMRI. They were required to identify vegetable items (targets) inside neutral or negative pictures.

RESULTS

Euthymic BD-I patients showed a significant reduced accuracy in target detection during both neutral and negative images presentation, whereas first-degree relatives performed similarly to normal comparisons. We found a reduced activation of Left precuneus during negative images condition in the patients only. By contrast, both patients and relatives hyperactivated the Left insula and hypoactivated the Right supramarginal gyrus with respect to controls. Moreover, relatives showed an increased activation of Right lingual gyrus and lower activation of pre-supplementary motor area and Right superior frontal gyrus.

CONCLUSIONS

During a negative emotion task, euthymic BD-I patients and non-affected first-degree relatives shared an abnormal activation of a limbic area (Left insula) coupled with a reduced activation of a parietal region (Right supramarginal gyrus), thus suggesting a trait-like anomalous processing of affective contents. On the other hand, functional abnormalities found only in unaffected relatives and not in patients and controls may correspond to resilience factors.

Altered prefrontal cortical MARCKS and PPP1R9A mRNA expression in schizophrenia and bipolar disorder

BACKGROUND

We previously observed dendritic spine loss in the dorsolateral prefrontal cortex (DLPFC) from schizophrenia and bipolar disorder subjects. In the current study, we sought to determine if the mRNA expression of genes known to regulate the actin cytoskeleton and spines correlated with spine loss.

METHODS

Five candidate genes were identified using previously obtained microarray data from the DLPFC from schizophrenia and control subjects. The relative mRNA expression of the genes linked to dendritic spine growth and function, i.e. IGF1R, MARCKS, PPP1R9A, PTPRF, and ARHGEF2, was assessed using quantitative real-time PCR (qRT-PCR) in the DLPFC from a second cohort including schizophrenia, bipolar disorder, and control subjects. Functional pathway analysis was conducted to determine which actin cytoskeleton-regulatory pathways the genes of interest interact with.

RESULTS

MARCKS mRNA expression was increased in both schizophrenia and bipolar disorder subjects. PPP1R9A mRNA expression was increased in bipolar disorder subjects. For IGF1R, mRNA expression did not differ significantly among groups; however, it did show a significant, negative correlation with dendrite length. MARCKS and PPP1R9A mRNA expression did not correlate with spine loss, but they interact with NMDA receptor signaling pathways that regulate the actin cytoskeleton and spines.

CONCLUSIONS

MARCKS and PPP1R9A might contribute to spine loss in schizophrenia and bipolar disorder through their interactions, possibly indirect ones, with NMDA signaling pathways that regulate spine structure and function.

Fusing Functional MRI and Diffusion Tensor Imaging Measures of Brain Function and Structure to Predict Working Memory and Processing Speed Performance among Inter-episode Bipolar Patients

Evidence for abnormal brain function as measured with diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) and cognitive dysfunction have been observed in inter-episode bipolar disorder (BD) patients. We aimed to create a joint statistical model of white matter integrity and functional response measures in explaining differences in working memory and processing speed among BD patients. Medicated inter-episode BD (n=26; age=45.2±10.1 years) and healthy comparison (HC; n=36; age=46.3±11.5 years) participants completed 51-direction DTI and fMRI while performing a working memory task. Participants also completed a processing speed test. Tract-based spatial statistics identified common white matter tracts where fractional anisotropy was calculated from atlas-defined regions of interest. Brain responses within regions of interest activation clusters were also calculated. Least angle regression was used to fuse fMRI and DTI data to select the best joint neuroimaging predictors of cognitive performance for each group. While there was overlap between groups in which regions were most related to cognitive performance, some relationships differed between groups. For working memory accuracy, BD-specific predictors included bilateral dorsolateral prefrontal cortex from fMRI, splenium of the corpus callosum, left uncinate fasciculus, and bilateral superior longitudinal fasciculi from DTI. For processing speed, the genu and splenium of the corpus callosum and right superior longitudinal fasciculus from DTI were significant predictors of cognitive performance selectively for BD patients. BD patients demonstrated unique brain-cognition relationships compared to HC. These findings are a first step in discovering how interactions of structural and functional brain abnormalities contribute to cognitive impairments in BD.

Assessing cognitive function in bipolar disorder: challenges and recommendations for clinical trial design

OBJECTIVE

Neurocognitive impairment in schizophrenia has been recognized for more than a century. In contrast, only recently have significant neurocognitive deficits been recognized in bipolar disorder. Converging data suggest the importance of cognitive problems in relation to quality of life in bipolar disorder, highlighting the need for treatment and prevention efforts targeting cognition in bipolar patients. Future treatment trials targeting cognitive deficits will be met with methodological challenges due to the inherent complexity and heterogeneity of the disorder, including significant diagnostic comorbidities, the episodic nature of the illness, frequent use of polypharmacy, cognitive heterogeneity, and a lack of consensus regarding measurement of cognition and outcome in bipolar patients. Guidelines for use in designing future trials are needed.

PARTICIPANTS

The members of the consensus panel (each of the bylined authors) were selected based upon their expertise in bipolar disorder. Dr Burdick is a neuropsychologist who has studied cognition in this illness for 15 years; Drs Ketter, Calabrese, and Goldberg each bring considerable expertise in the treatment of bipolar disorder, both within and outside of controlled clinical trials. This consensus statement was derived from work together at scientific meetings (eg, symposium presentation at the 2014 Annual Meeting of the American Society of Clinical Psychopharmacology, among others) and ongoing discussions by conference call. With the exception of the public presentations on this topic, these meetings were closed to outside participants.

EVIDENCE

A literature review was undertaken by the authors to identify illness-specific challenges relevant to the design and conduct of treatment trials targeting neurocognition in bipolar disorder. Expert opinion from each of the authors guided the consensus recommendations.

CONSENSUS PROCESS

Consensus recommendations, reached by unanimous opinion of the authors, are provided here as a preliminary guide for future trial design. Recommendations comprise exclusion of certain syndromal-level comorbid diagnoses and current affective instability, restrictions on numbers and types of medications, and use of prescreening assessment to ensure enrollment of subjects with adequate objective evidence of baseline cognitive impairment.

CONCLUSIONS

Clinical trials to address cognitive deficits in bipolar disorder face distinctive design challenges. As such trials move from proof-of-concept to confirmation of clinical efficacy, it will be important to incorporate distinctive design modifications to adequately address these challenges and increase the likelihood of demonstrating cognitive remediation effects. The field is now primed to address these challenges, and a comprehensive effort to formalize best practice guidelines will be a critically important next step.

Cognitive functioning after deep brain stimulation in subcallosal cingulate gyrus for treatment-resistant depression: an exploratory study

Deep brain stimulation (DBS) is being investigated as a therapeutic alternative for patients with treatment-resistant depression (TRD), but its cognitive safety has been scarcely explored. The aim of this exploratory study is to evaluate cognitive function of patients before and after deep brain stimulation of the subgenual cingulate gyrus (SCG). Eight treatment-resistant depressed patients were implanted in subgenual cingulate gyrus. A neuropsychological battery was used to evaluate patients before surgery and 1-year after. A matched group of eight first-episode patients was also assessed. A MANOVA was performed for each cognitive domain and those tests showing main time effects were then correlated with depressive symptoms and with medication load. There were significant group and time effects for memory and a group effect for language. No significant interactions between groups or cognitive domains were observed. Medication load was negatively correlated with memory at time 1, and clinical change negatively correlated with memory improvement. These findings support the cognitive safety of DBS of subgenual cingulate gyrus, as cognitive function did not worsen after chronic stimulation and memory performance even improved. The results, though, should be interpreted cautiously given the small sample size and the fact that some treatment-resistant patients received electroconvulsive therapy (ECT) before implantation.

Increased cerebral blood flow associated with better response inhibition in bipolar disorder

Impairment on inhibitory tasks has been well documented in bipolar disorder (BD). Differences in cerebral blood flow (CBF) between BD patients and healthy comparison (HC) participants have also been reported. Few studies have examined the relationship between cognitive performance and regional CBF in this patient population. We hypothesized that group differences on an inhibitory task (the Delis-Kaplan Executive Function Scale's Color-Word Inhibition task) would be associated with differential CBF in bilateral anterior cingulate cortex (ACC), inferior parietal lobule (IPL) and dorsolateral prefrontal cortex (DLPFC) regions. Whole brain resting CBF was measured using Multiphase Pseudocontinuous Arterial Spin Labeling MR imaging for 28 euthymic BD and 36 HC participants. Total gray matter (GM) CBF was measured, and regional CBF values were extracted for each region of interest (ROI) using Freesurfer-based individual parcellations. Group, CBF, and group-by-CBF interaction were examined as predictors of inhibition performance. Groups did not differ in age, gender or education. BD patients performed significantly worse on Color-Word inhibition. There were no significant group differences in CBF in either total GM or in any ROI. There was a group by CBF interaction in the bilateral ACC, right IPL and right DLPFC such that better inhibitory performance was generally associated with higher resting state CBF in BD subjects, but not HC participants. Although CBF was not abnormal in this euthymic BD sample, results confirm previous reports of inter-episode inhibitory deficits and indicate that the perfusion-cognition relationship is different in BD compared to HC individuals.

The development and course of bipolar spectrum disorders: an integrated reward and circadian rhythm dysregulation model

In this article, we present and review the evidence for two major biopsychosocial theories of the onset and course of bipolar spectrum disorders (BSDs) that integrate behavioral, environmental, and neurobiological mechanisms: the reward hypersensitivity and the social/circadian rhythm disruption models. We describe the clinical features, spectrum, age of onset, and course of BSDs. We then discuss research designs relevant to demonstrating whether a hypothesized mechanism represents a correlate, vulnerability, or predictor of the course of BSDs, as well as important methodological issues. We next present the reward hypersensitivity model of BSD, followed by the social/circadian rhythm disruption model of BSD. For each model, we review evidence regarding whether the proposed underlying mechanism is associated with BSDs, provides vulnerability to the onset of BSDs, and predicts the course of BSDs. We then present a new integrated reward/circadian rhythm (RCR) dysregulation model of BSD and discuss how the RCR model explains the symptoms, onset, and course of BSDs. We end with recommendations for future research directions.

Subjective and physiological emotional response in euthymic bipolar patients: a pilot study

The euthymic phase of bipolar disorders may be associated with residual emotional and/or subsyndromal symptoms. The aim of this study was to compare subjective and physiologic emotional response to negative, neutral and positive emotion eliciting pictures between euthymic bipolar patients (n=26) and healthy controls (n=30). We evaluated emotional response using an emotional induction method with emotional pictures from the International Affective Picture System. We measured subjective emotional response with the Self-Assessment Manikin and physiological emotional response by measuring pupil size. No difference was found between euthymic bipolar patients and controls regarding subjective emotional response. However, upon viewing positive pictures, pupil dilation was significantly lower in euthymic bipolar patients compared to controls. This finding suggests that euthymic bipolar phase may be associated with reduced physiologic emotional response to positive valence, which is consistent with a more general negative emotional bias or can be understood as a residual emotional subsyndromal symptom.

Parametric modulation of neural activity during face emotion processing in unaffected youth at familial risk for bipolar disorder

OBJECTIVES

Both patients with pediatric bipolar disorder (BD) and unaffected youth at familial risk (AR) for the illness show impairments in face emotion labeling. Few studies, however, have examined brain regions engaged in AR youth when processing emotional faces. Moreover, studies have yet to explore neural responsiveness to subtle changes in face emotion in AR youth.

METHODS

Sixty-four unrelated youth, including 20 patients with BD, 15 unaffected AR youth, and 29 healthy comparisons (HC), completed functional magnetic resonance imaging. Neutral faces were morphed with angry or happy faces in 25% intervals. In specific phases of the task, youth alternatively made explicit (hostility) or implicit (nose width) ratings of the faces. The slope of blood oxygenated level-dependent activity was calculated across neutral to angry and neutral to happy face stimuli.

RESULTS

Behaviorally, both subjects with BD (p ≤ 0.001) and AR youth (p ≤ 0.05) rated faces as less hostile relative to HC. Consistent with this, in response to increasing anger on the face, patients with BD and AR youth showed decreased modulation in the amygdala and inferior frontal gyrus (IFG; BA 46) compared to HC (all p ≤ 0.05). Amygdala dysfunction was present across both implicit and explicit rating conditions, but IFG modulation deficits were specific to the explicit condition. With increasing happiness, AR youth showed aberrant modulation in the IFG, which was also sensitive to task demands (all p ≤ 0.05).

CONCLUSIONS

Decreased amygdala and IFG modulation in patients with BD and AR youth may be pathophysiological risk markers for BD, and may underlie the social cognition and face emotion labeling deficits observed in BD and AR youth.

Increased temporo-insular engagement in unmedicated bipolar II disorder: an exploratory resting state study using independent component analysis

OBJECTIVES

Despite numerous structural and functional magnetic resonance imaging studies, the neurobiology of bipolar disorder (BD) is still incompletely understood. Resting-state functional magnetic resonance imaging (rsFMRI) allows for the study of intrinsic functional connections between brain areas, which may reflect the pathophysiology of BD. Most previous rsFMRI studies conducted in BD have included a majority of medicated patients, making simple interpretation with respect to pathophysiology difficult.

METHODS

Participants were 15 antipsychotic agent- and mood-stabilizer-naïve young adults with bipolar II disorder (BD-II), and 20 healthy controls group-matched for gender, age, and cognitive ability. Independent component analysis (ICA) was used to identify eight commonly studied resting-state networks (RSNs). Between-group comparisons were conducted using dual regression and corrected for family-wise error (FWE) across space and the number of components (pFWE < 0.05).

RESULTS

In comparison to controls, participants with BD-II had increased coherence across several brain regions, including the bilateral insula and putamen, across a temporo-insular network. No between-group differences in engagement of the default mode network were found.

CONCLUSIONS

This was the first ICA-based rsFMRI study conducted among unmedicated individuals with BD. Given the young age (mean = 23 years) and antipsychotic agent- and mood-stabilizer-naïve status of our participants with BD-II, temporo-insular functional connectivity is a candidate vulnerability marker for BD. Further work is needed to relate resting-state differences to detailed understanding of pathophysiology.

Prolonged hemodynamic response during incidental facial emotion processing in inter-episode bipolar I disorder

This fMRI study examined whether hemodynamic responses to affectively-salient stimuli were abnormally prolonged in remitted bipolar disorder, possibly representing a novel illness biomarker. A group of 18 DSM-IV bipolar I-diagnosed adults in remission and a demographically-matched control group performed an event-related fMRI gender-discrimination task in which face stimuli had task-irrelevant neutral, happy or angry expressions designed to elicit incidental emotional processing. Participants' brain activation was modeled using a "fully informed" SPM5 basis set. Mixed-model ANOVA tested for diagnostic group differences in BOLD response amplitude and shape within brain regions-of-interest selected from ALE meta-analysis of previous comparable fMRI studies. Bipolar-diagnosed patients had a generally longer duration and/or later-peaking hemodynamic response in amygdala and numerous prefrontal cortex brain regions. Data are consistent with existing models of bipolar limbic hyperactivity, but the prolonged frontolimbic response more precisely details abnormalities recognized in previous studies. Prolonged hemodynamic responses were unrelated to stimulus type, task performance, or degree of residual mood symptoms, suggesting an important novel trait vulnerability brain dysfunction in bipolar disorder. Bipolar patients also failed to engage pregenual cingulate and left orbitofrontal cortex-regions important to models of automatic emotion regulation-while engaging a delayed dorsolateral prefrontal cortex response not seen in controls. These results raise questions about whether there are meaningful relationships between bipolar dysfunction of specific ventromedial prefrontal cortex regions believed to automatically regulate emotional reactions and the prolonged responses in more lateral aspects of prefrontal cortex.

Emotion regulation strategies can predict task-switching abilities in euthymic bipolar patients

This study examined task-switching abilities and emotion regulation strategies in euthymic bipolar patients (EBP). Forty EBP and 40 healthy individuals performed face categorization tasks where they switched between emotion and non-emotion (i.e., gender) features among faces and completed emotion regulation questionnaire (Gross and John, 2003). Subject groups showed substantial differences in task-switching abilities and emotion regulation strategies: (1) there was a dissociation between emotion and gender classification in EBP. The switch cost was larger [i.e., higher reaction times (RTs) on switch as compared to no-switch trials] for gender categorization as compared to the emotion categorization task. In contrast, such asymmetries were absent among healthy participants. The differential pattern of task switching reflected functional disturbances in frontotemporal neural system and an attentional bias to emotion features of the faces in EBP. This suggests that when a euthymic bipolar patient is preoccupied with emotion recognition, an instruction to perform gender categorization results in greater cost on RTs. (2) In contrast to healthy individuals, EBP reported more frequent use of emotion suppression and lesser use of cognitive reappraisal as emotion regulation strategy. (3) Emotion regulation was found to be a significant predictor of task-switching abilities. It is argued that task switching deficits rely on maladaptive emotion regulation strategies in EBP specifically when tasks of emotional significance are involved.

Openness predicts cognitive functioning in bipolar disorder

OBJECTIVES

Openness to experience (O) is a well-established personality factor and is associated with cognitive performance. Little is known about the personality-cognitive relationship in bipolar disorder, an illness with significant variability in mood. Cognitive evaluation is essential in psychopathology assessment as it may reflect underlying disease processes and psychosocial functional capacity. Screening using a proxy personality variable may identify those in need of comprehensive cognitive testing. We hypothesized that O and measures of cognition would associate in both the Bipolar Disorder (BD) and healthy control (HC) samples, whereas neuroticism and extraversion would correlate with cognition only in the BD sample.

METHODS

Data from a longitudinal study of BD were used to study the association between personality factors and cognitive measures of attention, executive functioning, memory and fine motor skills. Regression analyses were used to determine the variables that account for the association between personality and cognition.

RESULTS

Aspects of O explained significant cognitive variance (~5%) in both groups; this persisted when demographic variables (including BD versus HC status) were considered. Neuroticism and extraversion did not consistently correlate with cognitive performance in either group.

LIMITATIONS

There were more females in the HC group who were slightly younger compared to the BD group. We lack direct measures of positive affect, and there is a reliance on a single measure of personality.

CONCLUSIONS

BD Individuals scoring low on self-reported Openness are potential candidates for more comprehensive cognitive assessments (which represent a limited resource).

Elevated reward-related neural activation as a unique biological marker of bipolar disorder: assessment and treatment implications

Growing evidence indicates that risk for bipolar disorder is characterized by elevated activation in a fronto-striatal reward neural circuit involving the ventral striatum and orbitofrontal cortex, among other regions. It is proposed that individuals with abnormally elevated reward-related neural activation are at risk for experiencing an excessive increase in approach-related motivation during life events involving rewards or goal striving and attainment. In the extreme, this increase in motivation is reflected in hypomanic/manic symptoms. By contrast, unipolar depression (without a history of hypomania/mania) is characterized by decreased reward responsivity and decreased reward-related neural activation. Collectively, this suggests that risk for bipolar disorder and unipolar depression are characterized by distinct and opposite profiles of reward processing and reward-related neural activation. The objective of the present paper is threefold. First, we review the literature on reward processing and reward-related neural activation in bipolar disorder, and in particular risk for hypomania/mania. Second, we propose that reward-related neural activation reflects a biological marker of differential risk for bipolar disorder versus unipolar depression that may help facilitate psychiatric assessment and differential diagnosis. We also discuss, however, the challenges to using neuroscience techniques and biological markers in a clinical setting for assessment and diagnostic purposes. Lastly, we address the pharmacological and psychosocial treatment implications of research on reward-related neural activation in bipolar disorder.

Elevated reward-related neural activation as a unique biological marker of bipolar disorder: assessment and treatment implications

Growing evidence indicates that risk for bipolar disorder is characterized by elevated activation in a fronto-striatal reward neural circuit involving the ventral striatum and orbitofrontal cortex, among other regions. It is proposed that individuals with abnormally elevated reward-related neural activation are at risk for experiencing an excessive increase in approach-related motivation during life events involving rewards or goal striving and attainment. In the extreme, this increase in motivation is reflected in hypomanic/manic symptoms. By contrast, unipolar depression (without a history of hypomania/mania) is characterized by decreased reward responsivity and decreased reward-related neural activation. Collectively, this suggests that risk for bipolar disorder and unipolar depression are characterized by distinct and opposite profiles of reward processing and reward-related neural activation. The objective of the present paper is threefold. First, we review the literature on reward processing and reward-related neural activation in bipolar disorder, and in particular risk for hypomania/mania. Second, we propose that reward-related neural activation reflects a biological marker of differential risk for bipolar disorder versus unipolar depression that may help facilitate psychiatric assessment and differential diagnosis. We also discuss, however, the challenges to using neuroscience techniques and biological markers in a clinical setting for assessment and diagnostic purposes. Lastly, we address the pharmacological and psychosocial treatment implications of research on reward-related neural activation in bipolar disorder.

The double burden of age and disease on cognition and quality of life in bipolar disorder

OBJECTIVE

Bipolar disorder (BPD) and normal aging are known to impact cognitive skills and health-related quality of life (HRQOL). This study investigated how aging and disease interact in predicting cognitive and psychosocial outcomes.

METHODS

Eight cognitive and ten subjective HRQOL domain ratings were measured. Subjects included 80 young (18-29 years) and late middle-aged (50-65 years) BPD patients in the euthymic phase and 70 age-equivalent healthy comparison participants.

RESULTS

An age X disease interaction was detected in three domains of cognitive functioning that reflect emotion processing, processing speed, and executive functioning skills, with BPD patients in the older group performing most poorly. There was a double burden of aging and disease on reported ability to perform physical tasks. However, regardless of age, disease status was associated with lower ratings of HRQOL in the psychosocial/affective sphere and the majority of cognitive domains. Post hoc analyses revealed that number of years ill was positively associated with select HRQOL ratings in older, but not younger BPD adults.

CONCLUSIONS

These findings may stimulate future longitudinal study of cognition and quality of life in BPD patients across the life span, focusing on additive and interactive effects of aging and disease burden, which could culminate in developing more effective treatment and rehabilitation strategies for this traditionally challenging to treat population.

fMRI evidence for abnormal resting-state functional connectivity in euthymic bipolar patients

BACKGROUND

Neural substrates of bipolar disorder (BD) have frequently been characterized by dysregulation of fronto-limbic networks that may persist during euthymic periods. Only a few studies have investigated euthymic bipolar patients (BP) functional connectivity at rest. The current study aims to assess resting-state functional connectivity in euthymic BP in order to identify trait abnormalities responsible for enduring mood dysregulation in these patients.

METHODS

Medial prefrontal cortex (mPFC) functional connectivity was investigated in 20 euthymic BP and 20 healthy subjects (HS). The functional connectivity maps were compared across groups using a between-group random effect analysis. Additional region of interest (ROI) analysis focused on mPFC-amygdala functional connectivity as well as correlations between the clinical features in euthymic BP was also conducted.

RESULTS

A significant difference between euthymic BP and HS was observed in terms of connectivity between the mPFC and the right dorsolateral prefrontal cortex (dlPFC). A significant negative correlation between the activity of these regions was found in HS but not in euthymic BP. In addition, euthymic BP showed greater connectivity between mPFC and right amygdala compared to HS, which was also correlated with the duration of the disease.

LIMITATIONS

The BP group was heterogeneous with respect to the bipolarity subtype and the medication. The robustness of results could be improved with an increased sample size.

CONCLUSIONS

Compared to HS, the euthymic BP showed abnormal decoupling (decreased functional connectivity) activity between mPFC-dlPFC and hyperconnectivity (increased functional connectivity) and between mPFC and amygdala. These abnormalities could underlie the pathophysiology of BD, and may deteriorate further in accordance with disease duration.

Mindfulness based cognitive therapy may improve emotional processing in bipolar disorder: pilot ERP and HRV study

Emotional processing in bipolar disorder (BD) is impaired. We aimed to measure the effects of mindfulness based cognitive-behavioral therapy (MBCT) in BD on emotional processing, as measured by event related potentials (ERP) and by heart rate variability (HRV). ERP and HRV were recorded during the completion of a visual matching task, which included object matching, affect matching, and affect labeling. Individuals with BD (n = 12) were compared with controls (n = 9) to obtain baseline data prior to the individuals with BD undergoing an 8-week MBCT intervention. ERP and HRV recording was repeated after the MBCT intervention in BD. Participants with BD had exaggerated ERP N170 amplitude and increased HRV HF peak compared to controls, particularly during the affect matching condition. After an 8-week MBCT intervention, participants with BD showed attenuation of ERP N170 amplitude and reduced HRV HF peak. Our findings support findings from the literature emphasizing that emotional processing in BD is altered, and suggesting that MBCT may improve emotional processing in BD.

Correlates of real world executive dysfunction in bipolar I disorder

BACKGROUND

Bipolar disorder is characterized by impairments in cognitive functioning, both during acute mood episodes and periods of euthymia, which interfere with functioning. Cognitive functioning is typically assessed using laboratory-based tests, which may not capture how cognitive dysfunction is experienced in real-life settings. Little is known about the specific illness characteristics of bipolar disorder that contribute to cognitive dysfunction in everyday life.

METHODS

Participants met DSM-IV criteria for bipolar I disorder (n = 68) in a depressed or euthymic state. Everyday executive functioning was evaluated using the Behavior Rating Inventory of Executive Functioning (BRIEF) and the Frontal Systems Behavior Rating Scale (FrSBe). Participants completed clinician rated measures of mood state (Hamilton Depression Rating Scale, Young Mania Rating Scale), prior illness course and co-morbidities (Mini International Neuropsychiatric Interview), as well as self-report measures of psychotropic medication use and medical co-morbidity.

RESULTS

Individuals in this study reported significant impairment in every domain of executive functioning. These deficits were associated with a multitude of illness factors, some directly impacted by mood symptoms and others shaped by illness chronicity, psychiatric comorbidity, medical co-morbidity, and medication use.

DISCUSSION

Executive functioning problems observed in everyday functioning in bipolar disorder are not entirely mood-state dependent. Cognitive rehabilitation for executive dysfunction should be considered an important adjunctive treatment for many individuals with bipolar disorder.

Fronto-limbic-striatal dysfunction in pediatric and adult patients with bipolar disorder: impact of face emotion and attentional demands

BACKGROUND

Research in bipolar disorder (BD) implicates fronto-limbic-striatal dysfunction during face emotion processing but it is unknown how such dysfunction varies by task demands, face emotion and patient age.

METHOD

During functional magnetic resonance imaging (fMRI), 181 participants, including 62 BD (36 children and 26 adults) and 119 healthy comparison (HC) subjects (57 children and 62 adults), engaged in constrained and unconstrained processing of emotional (angry, fearful, happy) and non-emotional (neutral) faces. During constrained processing, subjects answered questions focusing their attention on the face; this was processed either implicitly (nose width rating) or explicitly (hostility; subjective fear ratings). Unconstrained processing consisted of passive viewing.

RESULTS

Pediatric BD rated neutral faces as more hostile than did other groups. In BD patients, family-wise error (FWE)-corrected region of interest (ROI) analyses revealed dysfunction in the amygdala, inferior frontal gyrus (IFG), anterior cingulate cortex (ACC) and putamen. Patients with BD showed amygdala hyperactivation during explicit processing (hostility ratings) of fearful faces and passive viewing of angry and neutral faces but IFG hypoactivation during implicit processing of neutral and happy faces. In the ACC and striatum, the direction of dysfunction varied by task demand: BD demonstrated hyperactivation during unconstrained processing of angry or neutral faces but hypoactivation during constrained processing (implicit or explicit) of angry, neutral or happy faces.

CONCLUSIONS

Findings suggest amygdala hyperactivation in BD while processing negatively valenced and neutral faces, regardless of attentional condition, and BD IFG hypoactivation during implicit processing. In the cognitive control circuit involving the ACC and putamen, BD neural dysfunction was sensitive to task demands.

Abnormalities of brain response during encoding into verbal working memory among euthymic patients with bipolar disorder

OBJECTIVES

Individuals with bipolar disorder (BD) have trait-like deficits in attention and working memory (WM). A fundamental dissociation for most verbal WM theories involves the separation of sensory-perceptual encoding, reliant upon attention, from the maintenance of this information in WM proper. The present study examined if patients with BD demonstrate differential neural changes in encoding and maintenance WM processes that underlie cognitive impairment.

METHODS

Event-related functional magnetic resonance imaging during a delayed match-to-sample WM paradigm was employed in 23 inter-episode medicated patients with BD and 23 demographically similar healthy comparison participants. We examined brain regions during encoding and maintenance task intervals to identify regions that demonstrated differential effects between groups. Medication effects and functional connectivity between prefrontal cortex and basal ganglia/thalamus were examined during the encoding interval due to the importance of these regions and the connection among them for encoding into WM.

RESULTS

Patients with BD exhibited deficits in task accuracy and attenuated brain response during the encoding interval in areas of the prefrontal cortex, caudate, thalamus, and posterior visual regions. In contrast, patients with BD exhibited hyperactivation in posterior sensory regions during the maintenance interval. Among the BD group, those with greater medication load exhibited the greatest brain response within the prefrontal cortex.

CONCLUSIONS

Reduction in activation during the encoding interval suggests that attentional deficits underlie WM deficits in patients with BD. These deficits appear to be trait-like in so far as they were observed during periods of euthymia in patients with BD. Medication effects remain to be further explored as there was evidence of prefrontal changes dependent on medication load.

Differential Anterior Cingulate Activity during Response Inhibition in Depressed Adolescents with Bipolar and Unipolar Major Depressive Disorder

OBJECTIVE

Cognitive control deficits are commonly seen in Depression of Bipolar Disorder (BDd) and Unipolar Major Depressive Disorder (UDd). Because failure to differentiate BDd from UDd has significant clinical consequences we aimed to identify differential patterns of neural activity in BDd versus UDd underlying response inhibition and motor control in adolescents.

METHODS

Functional MRI was used to compare 12 BDd adolescents (mean age= 15.5±1.2) with age- and sex-matched ten UDd and ten healthy control (HC) adolescents during the performance of well-validated Go/NoGo task. NoGo response inhibition versus Go motor control blocks was used in whole-brain analysis and results were corrected for multiple comparisons.

RESULTS

There were no significant behavioral or neuroimaging findings between adolescents with BDd and UDd. However, both groups relative to HC showed significantly higher left superior temporal and left caudate activity during the NoGo condition. Moreover, left anterior cingulate (ACC) activity relative to HC was significantly higher only in BDd - not UDd - adolescents during the NoGo condition, and left caudate activity was higher only in UDd - not BDd - adolescents during the Go condition. In addition, several neural regions including dorsolateral prefrontal (DLPFC) were positively correlated with increased reaction time in UDd - not BDd - adolescents.

CONCLUSIONS

Despite some similarities, neural correlates of depression are different in BDd and UDd relative to HC, and greater recruitment of ACC resources during response inhibition can help distinguish BDd.

Neural correlates of delusion in bipolar depression

Approximately one-half of all patients affected by bipolar disorder present psychotic features at least in one occasion. This factor worsens the personal and social burden of the disease. Several studies find an altered brain activity in mesolimbic and prefrontal regions in relation to aberrant attribution of salience to stimuli in delusional patients. The aim of the present study is to investigate gray matter (GM) structural correlates of the past history of delusions in a sample of bipolar patients. The sample includes 34 delusional and 39 non-delusional bipolar patients. Brain-imaging volumetric sequences were acquired on a 3.0 T scanner. Voxel based morphometry (VBM) was performed comparing delusional and non-delusional patients. VBM analysis found significant (p=0.001) differences in prefrontal areas and in the insula where delusional patients show lower GM volume compared to non-delusional patients. The main finding of the present study is a reduction of gray matter volume in the dorsolateral prefrontal cortex and in the insula of delusional patients. This result supports the hypothesis of abnormalities in salience and executive-control networks of delusional patients, which could be associated with an aberrant assignment of salience to the elements of one's own experience that is linked to delusion and psychotic symptoms.

Differences in attention and impulsivity between borderline personality disorder and bipolar disorder

This study aims at investigating attention and impulsivity differences between borderline personality disorder and bipolar disorder, as both diseases may share neuropsychological deficits. Differential cognitive outcomes on the Continuous Performance Test-II were observed between disorders, and also when compared to healthy controls.

Social cognition throughout the three phases of bipolar disorder: a state-of-the-art overview

Although it is now well documented that bipolar disorder (BD) often presents with cognitive deficits and suboptimal social adjustment, the social cognitive profile of the illness throughout its three phases remains unclear. An extensive search was conducted through the online databases EBSCO, PsychInfo, PubMed, ScienceDirect, and Wiley-Blackwell, covering the period between 1990 and 2012. Fifty-one studies comparing the social cognitive performance of bipolar patients with that of healthy controls were identified. Deficits in emotion recognition and theory of mind were found in manic, depressed, and euthymic bipolar subjects. Furthermore, altered face emotion recognition and brain-related abnormalities were noted both in euthymic patients and subjects at risk for BD. The influence of clinical and neurocognitive variables on the social cognitive performance of bipolar patients remains to be ascertained. Future directions for research are discussed.

Neural activity to intense positive versus negative stimuli can help differentiate bipolar disorder from unipolar major depressive disorder in depressed adolescents: a pilot fMRI study

Failure to distinguish bipolar depression (BDd) from the unipolar depression of major depressive disorder (UDd) in adolescents has significant clinical consequences. We aimed to identify differential patterns of functional neural activity in BDd versus UDd and employed two (fearful and happy) facial expression/ gender labeling functional magnetic resonance imaging (fMRI) experiments to study emotion processing in 10 BDd (8 females, mean age=15.1 ± 1.1) compared to age- and gender-matched 10 UDd and 10 healthy control (HC) adolescents who were age- and gender-matched to the BDd group. BDd adolescents, relative to UDd, showed significantly lower activity to both intense happy (e.g., insula and temporal cortex) and intense fearful faces (e.g., frontal precentral cortex). Although the neural regions recruited in each group were not the same, both BDd and UDd adolescents, relative to HC, showed significantly lower neural activity to intense happy and mild happy faces, but elevated neural activity to mild fearful faces. Our results indicated that patterns of neural activity to intense positive and negative emotional stimuli can help differentiate BDd from UDd in adolescents.

Modulation of fronto-limbic activity by the psychoeducation in euthymic bipolar patients. A functional MRI study

Bipolar disorders (BD) are mainly characterized by emotional and cognitive processing impairment. The cerebral substrate explaining BD impairment and the action mechanisms of therapies are not completely understood, especially for psychosocial interventions. This fMRI study aims at assessing cerebral correlates of euthymic bipolar patients (EBP) before and after psychoeducation therapy. Sixteen EBP and 16 matched healthy subjects (HS) performed a word-face emotional Stroop task in two separate fMRI sessions at 3-month interval. Between fMRI sessions, EBP underwent psychoeducation. Before psychoeducation, the comparison of EBP vs. HS in fMRI data revealed (a) significant decreased activity of cognitive control regions such as bilateral inferior and left superior frontal gyri, right insula, right fusiform gyrus and bilateral occipital gyri and (b) significant increased activity of emotion-related processing regions such as bilateral hippocampus, parahippocampal gyri and the left middle temporal gyrus. After psychoeducation, EBP showed significant clinical improvement, increased activity of inferior frontal gyri and a tendency toward decreased activity of right hippocampus and parahippocampal gyrus. These results suggest that the imbalance between cognitive control and emotion processing systems characterizing BD acute episodes may persist during euthymic periods. Moreover, this imbalance may be improved by psychoeducation, which enhances the cognitive control and modulates emotional fluctuations in EBP.

Emotion perception and executive functioning predict work status in euthymic bipolar disorder

Functional recovery, including return to work, in Bipolar Disorder (BD) lags behind clinical recovery and may be incomplete when acute mood symptoms have subsided. We examined impact of cognition on work status and underemployment in a sample of 156 Euthymic-BD and 143 controls (HC) who were divided into working/not working groups. Clinical, health, social support, and personality data were collected, and eight cognitive factors were derived from a battery of neuropsychological tests. The HC groups outperformed the BD groups on seven of eight cognitive factors. The working-BD group outperformed the not working-BD group on 4 cognitive factors composed of tasks of emotion processing and executive functioning including processing speed and set shifting. Emotion processing and executive tasks were predictive of BD unemployment, after accounting for number of mood episodes. Four cognitive factors accounted for a significant amount of the variance in work status among the BD participants. Results indicate that patients with BD who are unemployed/unable to work exhibit greater difficulties processing emotional information and on executive tasks that comprise a set shifting or interference resolution component as compared to those who are employed, independent of other factors. These cognitive and affective factors are suggested as targets for treatment and/or accommodations.

Neural correlates of treatment response in depressed bipolar adolescents during emotion processing

Depressive mood in adolescents with bipolar disorder (BDd) is associated with significant morbidity and mortality, but we have limited information about neural correlates of depression and treatment response in BDd. Ten adolescents with BDd (8 females, mean age = 15.6 ± 0.9) completed two (fearful and happy) face gender labeling fMRI experiments at baseline and after 6-weeks of open treatment. Whole-brain analysis was used at baseline to compare their neural activity with those of 10 age and sex-matched healthy controls (HC). For comparisons of the neural activity at baseline and after treatment of youth with BDd, region of interest analysis for dorsal/ventral prefrontal, anterior cingulate, and amygdala activity, and significant regions identified by wholebrain analysis between BDd and HC were analyzed. There was significant improvement in depression scores (mean percentage change on the Child Depression Rating Scale-Revised 57 % ± 28). Neural activity after treatment was decreased in left occipital cortex in the intense fearful experiment, but increased in left insula, left cerebellum, and right ventrolateral prefrontal cortex in the intense happy experiment. Greater improvement in depression was associated with baseline higher activity in ventral ACC to mild happy faces. Study sample size was relatively small for subgroup analysis and consisted of mainly female adolescents that were predominantly on psychotropic medications during scanning. Our results of reduced negative emotion processing versus increased positive emotion processing after treatment of depression (improvement of cognitive bias to negative and away from positive) are consistent with the improvement of depression according to Beck's cognitive theory.

Dissociable patterns of abnormal frontal cortical activation during anticipation of an uncertain reward or loss in bipolar versus major depression

OBJECTIVES

Recent research has found abnormalities in reward-related neural activation in bipolar disorder (BD), during both manic and euthymic phases. However, reward-related neural activation in currently depressed individuals with BD and that in currently depressed individuals with major depressive disorder (MDD) have yet to be directly compared. Here, we studied these groups, examining the neural activation elicited during a guessing task in fronto-striatal regions identified by previous studies.

METHODS

We evaluated neural activation during a reward task using fMRI in two groups of depressed individuals, one with bipolar I disorder (BD-I) (n = 23) and one with MDD (n = 40), with similar levels of illness severity, and a group of healthy individuals (n = 37).

RESULTS

Reward expectancy-related activation in the anterior cingulate cortex was observed in the healthy individuals, but was significantly reduced in depressed patients (BD-I and MDD together). Anticipation-related activation was increased in the left ventrolateral prefrontal cortex in the BD-I depressed group compared with the other two groups. There were no significant differences in prediction error-related activation in the ventral striatum across the three groups.

CONCLUSIONS

The findings extend previous research which has identified dysfunction within the ventrolateral prefrontal cortex in BD, and show that abnormally elevated activity in this region during anticipation of either reward or loss may distinguish depressed individuals with BD-I from those with MDD. Altered activation of the anterior cingulate cortex during reward expectancy characterizes both types of depression. These findings have important implications for identifying both common and distinct properties of the neural circuitry underlying BD-I and MDD.

Differential patterns of activity and functional connectivity in emotion processing neural circuitry to angry and happy faces in adolescents with and without suicide attempt

BACKGROUND

Neural substrates of emotion dysregulation in adolescent suicide attempters remain unexamined.

METHOD

We used functional magnetic resonance imaging to measure neural activity to neutral, mild or intense (i.e., 0%, 50% or 100% intensity) emotion face morphs in two separate emotion-processing runs (angry and happy) in three adolescent groups: (1) history of suicide attempt and depression (ATT, n=14) ; (2) history of depression alone (NAT, n=15) ; and (3) healthy controls (HC, n=15). Post-hoc analyses were conducted on interactions from 3 group x 3 condition (intensities) whole-brain analyses (p<0.05, corrected) for each emotion run.

RESULTS

To 50% intensity angry faces, ATT showed significantly greater activity than NAT in anterior cingulate gyral–dorsolateral prefrontal cortical attentional control circuitry, primary sensory and temporal cortices; and significantly greater activity than HC in the primary sensory cortex, while NAT had significantly lower activity than HC in the anterior cingulate gyrus and ventromedial prefrontal cortex. To neutral faces during the angry emotion processing run, ATT had significantly lower activity than NAT in the fusiform gyrus. ATT also showed significantly lower activity than HC to 100% intensity happy faces in the primary sensory cortex, and to neutral faces in the happy run in the anterior cingulate and left medial frontal gyri (all p<0.006,corrected). Psychophysiological interaction analyses revealed significantly reduced anterior cingulate gyral–insula functional connectivity to 50% intensity angry faces in ATT v. NAT or HC.

CONCLUSIONS

Elevated activity in attention control circuitry, and reduced anterior cingulate gyral–insula functional connectivity, to 50% intensity angry faces in ATT than other groups suggest that ATT may show inefficient recruitment of attentional control neural circuitry when regulating attention to mild intensity angry faces, which may represent a potential biological marker for suicide risk.

Modeling bipolar disorder suicidality

OBJECTIVES

To review the psychosocial, neuropsychological, and neurobiological evidence regarding suicide and bipolar disorder (BD), to enable the development of an integrated model that facilitates understanding, and to provide a useful framework for future research.

METHODS

A two-stage literature review was conducted. First, an electronic literature search was performed using key words (e.g., bipolar disorder, suicide risk, and neuroimaging) and standard databases (e.g., MEDLINE). Second, theoretical suicide models were reviewed, and their evidence base and relevance to BD were evaluated in order to determine a guiding theoretical framework for contextualizing suicide in BD.

RESULTS

Although accumulating clinical, cognitive, and neurobiological correlates of suicide have been identified in BD, extant research has been largely atheoretical. The Cry of Pain (CoP) and an adapted version of the model, the Schematic Appraisals Model of Suicide (SAMS), provide a useful schema for examining vulnerability to suicide in BD, by taking into account biopsychosocial determinants of suicidality. In combination, these also provide a model within which the neural correlates of suicide can be integrated.

CONCLUSIONS

The proposed Bipolar Suicidality Model (BSM) highlights the psychosocial precursors to suicidality in BD, while recognizing the key role of cognitive deficits and underlying functional neurobiological abnormalities. It usefully integrates our knowledge, and provides a novel perspective that is intended to meaningfully inform future research initiatives, and can lead to a better understanding of suicidality in bipolar disorder. Ultimately, it is hoped that it will facilitate the development of targeted interventions that diminish the risk of suicide in bipolar disorder.

Emotion in Aging and Bipolar Disorder: Similarities, Differences, and Lessons for Further Research

In this article, we consider similarities and differences in emotion research on older adults and individuals with bipolar disorder (BD). Recent research and theory within both areas has focused on the importance of positive emotion, but the case of older adults is generally considered a case of "adaptive" positivity whereas BD is usually considered maladaptive positivity. We explore the paradox of the same phenomenon being labeled as adaptive in one group and yet maladaptive in another, with attention to commonalities and distinctions between these two groups. We identify only limited areas of overlap, and suggest a refinement of models of positive emotionality in the two populations.

Prefrontal activation in response to emotional words in patients with bipolar disorder and major depressive disorder

Abnormal emotional processing is involved in the pathophysiology of bipolar disorder (BD) and major depressive disorder (MDD). However, whether the neural mechanism underlying this deficit is a trait characteristic of BD and MDD is unclear. The aim of this study was to elucidate the similarities and differences in processing of emotional stimuli between patients with BD and MDD in remission, using functional near-infrared spectroscopy (fNIRS). Thirty-two patients (16 with BD and 16 with MDD) and 20 healthy control subjects matched for age, sex, handedness, and years of education were included. An emotional Stroop task, including happy, sad, and threat words, was used. The relative oxygenated and deoxygenated hemoglobin concentration ([oxy-Hb] and [deoxy-Hb]) changes in the frontal region were measured using 52-channels of NIRS. During the threat task, compared to healthy control subjects, patients with BD showed significantly increased [oxy-Hb] in the left inferior frontal region whereas patients with MDD showed significantly increased [oxy-Hb] in the left middle frontal region. During the happy task, compared to healthy control subjects, patients with BD showed significantly decreased [oxy-Hb] in the middle frontal region in both hemispheres. Moreover, patients with BD exhibited decreased [oxy-Hb] and increased [deoxy-Hb] in the superior frontal and middle frontal regions compared to MDD in response to the happy stimulus. No significant differences in [oxy-Hb] or [deoxy-Hb] were seen between the groups during the sad task. These results suggest that abnormal neural responses to emotional stimuli in patients with mood disorders in remission may be a trait characteristic, that negative emotional stimuli are associated with similar prefrontal responses, and that positive emotional stimuli are associated with different prefrontal responses in patients with BD and MDD. These findings indicate that different neural circuits play a role in emotional processing in BD and MDD; this may aid the elucidation of the pathophysiology of these two disorders.

Emotional face identification in youths with primary bipolar disorder or primary attention-deficit/hyperactivity disorder

OBJECTIVE

Bipolar disorder (BD) and attention-deficit/hyperactivity disorder (ADHD) are often comorbid or confounded; therefore, we evaluated emotional face identification to better understand brain/behavior interactions in children and adolescents with either primary BD, primary ADHD, or typically developing controls (TDC).

METHOD

Participants included individuals 7 to 17 years of age (overall sample mean age 12.40 ± 3.01 years), with "narrow-phenotype" pediatric BD (n = 30) or ADHD (n = 38), or typically developing controls (TDC) with no psychiatric disorders themselves or in their first-degree relatives (n = 41). In the BD group, comorbid diagnoses were allowed; however, youth in the ADHD group were excluded for comorbid mood or anxiety disorders. Patient groups were not excluded for psychotropic medication use. Emotional face identification was assessed using the computerized Diagnostic Analysis of Non-Verbal Accuracy (DANVA).

RESULTS

Participants with BD made significantly more identification errors on child happy faces than either TDCs (p = .03) or participants with ADHD (p = .01). Furthermore, youth with BD (0.33 ± 0.55) were more likely than youth with ADHD (0.11 ± 0.31) to make errors on low-intensity child happy faces (p = .05) but not high-intensity happy faces (p = NS). Participants with BD and ADHD made significantly more total errors in child face labeling than did TDCs, although participants with BD and ADHD did not differ from one another.

CONCLUSION

Our data suggest that youths with BD have specific alterations in emotional face identification of happy faces, an important finding that supports theories that response to positively valenced emotional stimuli may be especially salient in BD. Clinical trial registration information-Brain Imaging and Computer Games in Children With Either Bipolar Disorder, ADHD, Anxiety or Healthy Controls (BBPP); http://clinicaltrials.gov/; NCT01570426.

Where, when, how high, and how long? The hemodynamics of emotional response in psychotropic-naïve patients with adolescent bipolar disorder

BACKGROUND

In response to emotional faces, patients with adolescent bipolar disorder (ABD) exhibit increased neural activity in subcortical emotional processing regions (e.g., amygdala, ventral striatum) and variable prefrontal activity. We extend previous research by identifying cortical and subcortical regions showing altered hemodynamic response shapes in ABD relative to healthy controls (HC).

METHODS

ABD (N=65) and matched HC (N=79) completed a slow event-related affective hemodynamic probe task that required indicating the gender of fearful and neutral faces. An informed basis set in SPM8 evaluated shape variations of the hemodynamic responses to these faces.

RESULTS

Patients with ABD showed higher activity for fearful relative to neutral faces in the amygdala and prefrontal cortex and a delayed hemodynamic response to fearful faces in dorsolateral and ventrolateral prefrontal cortices (PFC), as well as bilateral amygdala and caudate. Furthermore, the ABD group, relative to HC, showed a prolonged response to fearful faces in right dorsolateral PFC. Clinical measures of mania and depression severity correlated with increased processing delays in the amygdala and striatum.

LIMITATIONS

By design, the task contained fewer, more widely-spaced stimuli, possibly reducing its power to detect group differences. The use of fearful faces makes comparisons with prior literature in ABD somewhat more difficult.

CONCLUSIONS

The ABD group engaged in enhanced neural processing of the fearful faces which was associated with increasingly severe manic/mixed mood states. These exploratory findings could help elucidate a "biosignature" of emotion-attention interactions in ABD and present a potential target for reversal with medication treatment.

Ventral striatum activity in response to reward: differences between bipolar I and II disorders

OBJECTIVE

Little is known about the neurobiology of bipolar II disorder. While bipolar I disorder is associated with abnormally elevated activity in response to reward in the ventral striatum, a key component of reward circuitry, no studies have compared reward circuitry function in bipolar I and bipolar II disorders. Furthermore, associations among reward circuitry activity, reward sensitivity, and striatal volume remain underexplored in bipolar and healthy individuals. The authors examined reward activity in the ventral striatum in participants with bipolar I and II disorders and healthy individuals, the relationships between ventral striatal activity and reward sensitivity across all participants, and between-group differences in striatal gray matter volume and relationships with ventral striatal activity across all participants.

METHOD

Twenty healthy comparison subjects and 32 euthymic bipolar I (N=17) and bipolar II (N=15) patients underwent a neuroimaging reward paradigm during functional MRI scanning, structural scanning, and completed psychometric and clinical assessments.

RESULTS

Region-of-interest analyses revealed significant ventral striatal activity in all participants during reward anticipation that was significantly greater in bipolar II patients compared with the other groups. Ventral striatal activity during reward anticipation correlated positively with reward sensitivity and fun seeking across all participants. Bipolar II patients had significantly greater left putamen volume than bipolar I patients, and left putamen volume correlated positively with left ventral striatal activity to reward anticipation in all participants.

CONCLUSIONS

Abnormally elevated ventral striatal activity during reward anticipation may be a potential biomarker of bipolar II disorder. These findings highlight the importance of adopting a dimensional approach in the study of neural mechanisms supporting key pathophysiological processes that may cut across psychiatric disorders.

A unique emotional processing profile of euthymic bipolar disorder? A critical review

OBJECTIVES

To undertake a critical review of the literature on emotional processing (EP) in bipolar patients in remission. This literature review focuses on a number of dimensions of EP including facial emotion recognition, emotional memory, affective theory of mind (ToM), affective attention and affective auditory information processing.

METHODS

A systematic search was conducted through PsychINFO and Medline databases to obtain relevant literature. Studies that include behavioural measures of EP were included.

RESULTS

The findings from this review demonstrate that bipolar disorder (BD) patients continue to exhibit some EP deficits during euthymic phases. A number of factors believed to contribute to such findings have been highlighted.

CONCLUSIONS

This review has shed light on some of the conflicting findings reported in the literature and thus offers a more comprehensive profile of euthymic bipolar patients' EP abilities. This information could enrich clinicians' therapeutic efforts to minimise relapse by attending to euthymic bipolar patients' specific emotional processing difficulties.

Evidence of diagnostic specificity in the neural correlates of facial affect processing in bipolar disorder and schizophrenia: a meta-analysis of functional imaging studies

BACKGROUND

Schizophrenia (SZ) and bipolar disorder (BD) may overlap in etiology and phenomenology but differ with regard to emotional processing. We used facial affect as a probe for emotional processing to determine whether there are diagnosis-related differences between SZ and BD in the function of the underlying neural circuitry.

METHOD

Functional magnetic resonance imaging (fMRI) studies published up to 30 April 2012 investigating facial affect processing in patients with SZ or BD were identified through computerized and manual literature searches. Activation foci from 29 studies encompassing 483 healthy individuals, 268 patients with SZ and 267 patients with BD were subjected to voxel-based quantitative meta-analysis using activation likelihood estimation (ALE).

RESULTS

Compared to healthy individuals, when emotional facial stimuli were contrasted to neutral stimuli, patients with BD showed overactivation within the parahippocampus/amygdala and thalamus and reduced engagement within the ventrolateral prefrontal cortex (PFC) whereas patients with SZ showed underactivation throughout the entire facial affect processing network and increased activation in visual processing regions within the cuneus. Patients with BD showed greater thalamic engagement compared to patients with SZ; in the reverse comparison, patients with SZ showed greater engagement in posterior associative visual cortices.

CONCLUSIONS

During facial affect processing, patients with BD show overactivation in subcortical regions and underactivation in prefrontal regions of the facial affect processing network, consistent with the notion of reduced emotional regulation. By contrast, overactivation within visual processing regions coupled with reduced engagement of facial affect processing regions points to abnormal visual integration as the core underlying deficit in SZ.