Regional brain changes in bipolar I depression: a functional magnetic resonance imaging study

Continuous theta burst stimulation for bipolar depression: A multicenter, double-blind randomized controlled study exploring treatment efficacy and predictive potential of kynurenine metabolites

BACKGROUND

While theta burst stimulation (TBS) shows promise in Major Depressive Disorder (MDD), its effectiveness in bipolar depression (BD-D) remains uncertain. Optimizing treatment parameters is crucial in the pursuit of rapid symptom relief. Moreover, aligning with personalized treatment strategies and increased interest in immunopsychiatry, biomarker-based stratification of patients most likely to benefit from TBS might improve remission rates. We investigated treatment effectiveness of continuous TBS (cTBS) compared to sham in BD-D, and assessed the capacity of plasma kynurenine pathway metabolites to predict treatment outcome.

METHODS

Thirty-seven patients with BD-D underwent accelerated active or sham cTBS treatment in a multicenter, double-blind, randomized controlled trial. Depressive symptoms were measured with the 17-item Hamilton Depression Rating Scale (HDRS-17) before treatment (T0), 3-4 days posttreatment (T1) and 10-11 days posttreatment (T2). Plasma tryptophan, kynurenine, kynurenic acid and quinolinic acid concentrations were quantified with ELISA. Linear mixed models were used for statistical analyses.

RESULTS

Although the total sample showed depressive symptom improvement, active cTBS did not demonstrate greater symptom alleviation compared to sham. However, higher baseline quinolinic acid significantly predicted symptom improvement in the active treatment group, not in sham-stimulated patients.

LIMITATIONS

The modest sample size limited the power to detect significant differences with regard to treatment effect. Also, the follow-up period was 10-11 days, whereas similar studies usually follow up for at least one month.

CONCLUSION

More research is required to optimize cTBS for BD-D and explore the involvement of quinolinic acid in treatment outcome.

Right ventrolateral and left dorsolateral 10 Hz transcranial magnetic stimulation as an add-on treatment for bipolar I and II depression: a double-blind, randomised, three-arm, sham-controlled study

OBJECTIVES

Despite the clinical importance of bipolar depression (BDE), effective treatment options are still limited. Transcranial magnetic stimulation (rTMS) has proven of moderate efficacy in major depression, but the evidence remains inconclusive for BDE.

METHODS

A 4-week, double-blind, randomised, parallel-group, sham-controlled study (trial ID ISRCTN77188420) explored the benefits of 10 Hz MRI-guided right ventrolateral (RVL) rTMS and left dorsolateral (LDL) rTMS as add-on treatments for BDE. Outcome measures included changes in the Montgomery-Åsberg Depression Rating Scale (MADRS) score, self-assessment, response and remission rates, and side effects.

RESULTS

Sixty patients were randomly assigned to study groups, and forty-six completed the double-blind phase. The mean change from baseline to Week 4 in MADRS was greater in both active groups compared to the sham, yet differences did not achieve significance (RVL vs sham: -4.50, 95%CI -10.63 to 1.64, p = 0.3; LDL vs sham: -4.07, 95%CI -10.24 to 2.10, p = 0.4). None of the other outcome measures yielded significant results.

CONCLUSIONS

While not demonstrating the superiority of either 10 Hz rTMS over sham, with the limited sample size, we can not rule out a moderate yet clinically meaningful effect. Further well-powered studies are essential to elucidate the role of rTMS in managing BDE.

Effects of electroconvulsive therapy on cortical thickness in depression: a systematic review

OBJECTIVE

Electroconvulsive therapy (ECT) is one of the most studied and validated available treatments for severe or treatment-resistant depression. However, little is known about the neural mechanisms underlying ECT. This systematic review aims to critically review all structural magnetic resonance imaging studies investigating longitudinal cortical thickness (CT) changes after ECT in patients with unipolar or bipolar depression.

METHODS

We performed a search on PubMed, Medline, and Embase to identify all available studies published before April 20, 2023. A total of 10 studies were included.

RESULTS

The investigations showed widespread increases in CT after ECT in depressed patients, involving mainly the temporal, insular, and frontal regions. In five studies, CT increases in a non-overlapping set of brain areas correlated with the clinical efficacy of ECT. The small sample size, heterogeneity in terms of populations, comorbidities, and ECT protocols, and the lack of a control group in some investigations limit the generalisability of the results.

CONCLUSIONS

Our findings support the idea that ECT can increase CT in patients with unipolar and bipolar depression. It remains unclear whether these changes are related to the clinical response. Future larger studies with longer follow-up are warranted to thoroughly address the potential role of CT as a biomarker of clinical response after ECT.

How do bipolar disease states affect positive and negative emotion processing? Insights from a meta-analysis on the neural fingerprints of emotional processing

BACKGROUND

Functional magnetic resonance imaging studies on emotion processing in patients with bipolar disorder (BD) show hyperactivity of limbic-striatal brain areas and hypoactivity in inferior frontal areas compared to healthy participants. However, heterogeneous results in patients with different disease states and different valences of emotional stimuli have been identified.

METHODS

To integrate previous results and elucidate the impact of disease state and stimulus valence, we conducted a systematic literature search for journal articles in the Web of Science Core Collection including MEDLINE databases and employed a coordinate-based-meta-analysis of functional-MRI studies comparing emotion processing in BD-patients with healthy participants using seed-based d mapping (SDM) to test for between-subjects-effects. We included 31 studies published before 11/2022 with a total of N = 766 BD-patients and N = 836 controls.

RESULTS

Patients with BD showed hyperactivated regions involved in salience processing of emotional stimuli (e.g., the bilateral insula) and hypoactivation of regions associated with emotion regulation (e.g., inferior frontal gyrus) during emotion processing, compared to healthy participants. A more detailed descriptive analysis revealed a hypoactive (anterior) insula in manic BD-patients specifically for negative in comparison to positive emotion processing.

DISCUSSION

This meta-analysis corroborates the overall tenor of existing literature that patients with BD show an increased emotional reactivity (hyperactivity of salience-processing regions) together with a lower (cognitive) control (hypoactivity of brain areas associated with emotion regulation) over emotional states. Our analysis suggests reduced interoceptive processing of negative stimuli in mania, pointing out the need for longitudinal within-subject analyses of emotion processing.

Predicting depressed and elevated mood symptomatology in bipolar disorder using brain functional connectomes

BACKGROUND

The study is aimed to identify brain functional connectomes predictive of depressed and elevated mood symptomatology in individuals with bipolar disorder (BD) using the machine learning approach Connectome-based Predictive Modeling (CPM).

METHODS

Functional magnetic resonance imaging data were obtained from 81 adults with BD while they performed an emotion processing task. CPM with 5000 permutations of leave-one-out cross-validation was applied to identify functional connectomes predictive of depressed and elevated mood symptom scores on the Hamilton Depression and Young Mania rating scales. The predictive ability of the identified connectomes was tested in an independent sample of 43 adults with BD.

RESULTS

CPM predicted the severity of depressed [concordance between actual and predicted values (r = 0.23, pperm (permutation test) = 0.031) and elevated (r = 0.27, pperm = 0.01) mood. Functional connectivity of left dorsolateral prefrontal cortex and supplementary motor area nodes, with inter- and intra-hemispheric connections to other anterior and posterior cortical, limbic, motor, and cerebellar regions, predicted depressed mood severity. Connectivity of left fusiform and right visual association area nodes with inter- and intra-hemispheric connections to the motor, insular, limbic, and posterior cortices predicted elevated mood severity. These networks were predictive of mood symptomatology in the independent sample (r ⩾ 0.45, p = 0.002).

CONCLUSIONS

This study identified distributed functional connectomes predictive of depressed and elevated mood severity in BD. Connectomes subserving emotional, cognitive, and psychomotor control predicted depressed mood severity, while those subserving emotional and social perceptual functions predicted elevated mood severity. Identification of these connectome networks may help inform the development of targeted treatments for mood symptoms.

Limbic and cortical regions as functional biomarkers associated with emotion regulation in bipolar disorder: A meta-analysis of neuroimaging studies

BACKGROUND

Bipolar disorder (BD) is a psychiatric disorder characterized by episodes of depression and mania, associated with impaired emotion processing. Several functional MRI (fMRI) studies have been used to investigate the structural and functional alteration in BD. Here, we aim to investigate the current fMRI findings of brain activation during emotion-regulation tasks between BD patients and healthy controls (HC).

METHODS

A systematic search through PubMed database for fMRI studies on bipolar patients and HC yielded 685 studies. We performed an activation likelihood estimation (ALE) on 21 studies for emotion regulation in BD patients and HC. Furthermore, we performed subgroup analyses for task performances in response time and accuracy between bipolar patients and HC.

RESULTS

The total sample included 21 fMRI studies, comprising 543 BD patients, compared to 565 HC. ALE maps for emotion-related tasks showed hyperactivation in BD patients in the caudate, amygdala, precentral gyrus, middle frontal gyri, and sub-gyrus. Whereas hypoactivation was seen in the inferior frontal gyrus and anterior cingulate gyrus.

LIMITATIONS

We could not apply a correction for p-value thresholds, as it needs large number of foci. Second, functional abnormalities were investigated for adult BD patients only, as BD patients have functional differences correlated with age.

CONCLUSIONS

Our results showed that limbic and cortical regions can represent a potential biomarker for the diagnosis and management of BD, by showing clustered brain regions of abnormal patterns of increased activation between BD patients and HC.

Gender-related association among childhood maltreatment, brain structure and clinical features in bipolar disorder

Bipolar disorder (BD) and exposure to childhood maltreatment (CM), which is present at high rates in BD, are both associated with hippocampus and prefrontal cortex structural alterations thought to contribute to clinical features. Gender-related differences are implicated in BD for CM exposure, brain structure and clinical features. However, relationships among these factors in BD are understudied. This study aimed to investigate associations among gender, CM, hippocampus and prefrontal gray matter structure and clinical features in BD. Childhood trauma questionnaire, structured clinical assessments and 3 Tesla structural magnetic resonance imaging were obtained for 236 adults (18-63 years, 32.0 ± 12.6): 119 with BD (58.8% women) and 117 healthy controls (HCs, 50.4% women). Women with BD reported higher CM severity than men with BD and HCs (B=-14.34, 95% confidence intervals (CI)[-22.71,-5.97], p<.001). CM and gender showed a significant interaction for left hippocampus (B=-7.41, 95% CI[-14.10,-0.71], p<.05); CM severity was negatively associated with left hippocampus only in women with BD. In women with BD, CM was associated with post-traumatic stress disorder comorbidity (B = 25.68, 95% CI[15.11,36.25], p<.001). In men with BD, CM severity was associated with lower left frontal pole (B=-0.71, 95% CI[-1.14,-0.28], p<.05) and right superior frontal (B=-17.78, 95% CI[-30.66,-4.90], p<.05) surface area; the latter related to earlier age of first mood symptoms (B = 33.97, 95% CI[7.61, 60.33], p<.05). Findings support gender-related effects of CM on frontotemporal structure and clinical features of BD. The findings bring novel perspectives for gendered pathophysiological models of effects of CM in BD.

Shared and disease-sensitive dysfunction across bipolar and unipolar disorder during depressive episodes: a transdiagnostic study

Patients with depressive episodes (PDE), such as unipolar disorder (UD) and bipolar disorder (BD), are often defined as distinct diagnostic categories, but increasing converging evidence indicated shared etiologies and pathophysiological characteristics across different clinical diagnoses. We explored whether these transdiagnostic deficits are caused by the common neural substrates across diseases or disease-sensitive mechanisms, or a combination of both. In this study, we utilized a Bayesian model to decompose the resting-state brain activity into multiple hyper- and hypo-activity patterns (refer to as "factors"), so as to explore the shared and disease-sensitive alteration patterns in PDE. The model was constructed over a total of 259 patients (131 UD and 128 BD) with 100 healthy controls as the reference. The other 32 initial depressive episode BD (IDE-BD) patients who had symptoms of mania or hypomania during follow-up were taken as an independent set to estimate the factor composition using the established model for further analysis. We revealed three transdiagnostic alteration factors in PDE. Based on the distribution of factors and the tendency of factor composition at the group level, these factors were defined as BD sensitive factor, UD sensitive factor and shared basic alteration factor. We further found that the factor composition and the ROIs-based alteration degree (mainly involving in orbitofrontal gyrus and part of parietal lobe) were associated with the bipolar index in IDE-BD patients. Our findings contributed to understanding the core transdiagnostic shared and disease-sensitive alterations in PDE and to predicting the risk of emotional state transition in IDE-BD patients.

Valproate Adjuvant Cognitive Behavioral Therapy in Panic Disorder Patients With Comorbid Bipolar Disorder: Case Series and Review of the Literature

Anxiety disorders are the most common comorbid psychiatric disorders in patients with bipolar disorder. Managing anxiety symptoms in comorbid conditions is challenging and has received little research interest. The findings from preclinical research on fear conditioning, an animal model of anxiety disorder, have suggested that memory reconsolidation updating (exposure-based therapy) combined with valproate might facilitate the amelioration of fear memories. Here, three cases of successful amelioration of agoraphobia and panic symptoms through valproate adjuvant therapy for cognitive behavioral therapy in patients who failed to respond to two to three consecutive standard pharmacotherapy trials over several years are described. To the best of the author's knowledge, this is the first attempt to combine CBT with valproate in patients with panic disorder, agoraphobia, and comorbid bipolar disorder. Additionally, the background preclinical research on this combination therapy based on the reconsolidation-updating mechanism, the inhibition of histone deacetylase 2, and critical period reopening, off-label use of valproate in panic disorder, plasticity-augmented psychotherapy, and how to combine valproate with CBT is discussed.

Characteristics of prefrontal activity during emotional and cognitive processing in patients with bipolar disorder: A multi-channel functional near-infrared spectroscopy study

Bipolar disorder (BD) is a recurrent chronic mental disorder with a broad profile of functional deficits including disturbed emotional processing and cognitive impairments. The goal of the current study was to further explore the underlying neural mechanism of dysfunction in patients with BD from a comprehensive perspective of both cognition and emotion. Forty-six clinical patients with BD and forty-five healthy controls performed emotion induction task and verbal fluency task (VFT), with frontal activity measured by functional near-infrared spectroscopy (fNIRS). Our results show distinct hemodynamic activity in the prefrontal region during emotional and cognitive processing between patients with BD and healthy controls. Patients with BD exhibit valence-dependent prefrontal cortex (PFC) hemodynamic response to emotional stimuli, with bilateral frontal hypoactivity indicating decreased positive reactivity and left frontal hyperactivity indicating increased negative reactivity. On the other hand, patients with BD showed impaired performance with bilateral frontal hypoactivity during VFT. Taken together, frontal dysfunction of cognition and emotionality in patients with BD probed by fNIRS would be a potential biomarker in clinical assessment.

What to Believe? Impact of Knowledge and Message Length on Neural Activity in Message Credibility Evaluation

Understanding how humans evaluate credibility is an important scientific question in the era of fake news. Message credibility is among crucial aspects of credibility evaluations. One of the most direct ways to understand message credibility is to use measurements of brain activity of humans performing credibility evaluations. Nevertheless, message credibility has never been investigated using such a method before. This article reports the results of an experiment during which we have measured brain activity during message credibility evaluation, using EEG. The experiment allowed for identification of brain areas that were active when participant made positive or negative message credibility evaluations. Based on experimental data, we modeled and predicted human message credibility evaluations using EEG brain activity measurements with F1 score exceeding 0.7.

Aberrant brain network topology in the frontoparietal-limbic circuit in bipolar disorder: a graph-theory study

Characterizing the properties of brain networks across mood states seen in bipolar disorder (BP) can provide a deeper insight into the mechanisms involved in this type of affective disorder. In this study, graph theoretical methods were used to examine global, modular and nodal brain network topology in the resting state using functional magnetic resonance imaging data acquired from 95 participants, including those with bipolar depression (BPD; n = 30) and bipolar mania (BPM; n = 39) and healthy control (HC) subjects (n = 26). The threshold value of the individual subjects' connectivity matrix varied from 0.15 to 0.30 with steps of 0.01. We found that: (1) at the global level, BP patients showed a significantly increased global efficiency and synchronization and a decreased path length; (2) at the nodal level, BP patients showed impaired nodal parameters, predominantly within the frontoparietal and limbic sub-network; (3) at the module level, BP patients were characterized by denser FCs (edges) between Module III (the front-parietal system) and Module V (limbic/paralimbic systems); (4) at the nodal level, the BPD and BPM groups showed state-specific differences in the orbital part of the left superior-frontal gyrus, right putamen, right parahippocampal gyrus and left fusiform gyrus. These results revealed abnormalities in topological organization in the whole brain, especially in the frontoparietal-limbic circuit in both BPD and BPM. These deficits may reflect the pathophysiological processes occurring in BP. In addition, state-specific regional nodal alterations in BP could potentially provide biomarkers of conversion across different mood states.

Neural function during emotion regulation and future depressive symptoms in youth at risk for affective disorders

Affective disorders (AD, including bipolar disorder, BD, and major depressive disorder) are severe recurrent illnesses. Identifying neural markers of processes underlying AD development in at-risk youth can provide objective, "early-warning" signs that may predate onset or worsening of symptoms. Using data (n = 34) from the Bipolar Offspring Study, we examined relationships between neural response in regions supporting executive function, and those supporting self-monitoring, during an emotional n-back task (focusing on the 2-back face distractor versus the 0-back no-face control conditions) and future depressive and hypo/manic symptoms across two groups of youth at familial risk for AD: Offspring of parents with BD (n = 15, age = 14.15) and offspring of parents with non-BD psychopathology (n = 19, age = 13.62). Participants were scanned and assessed twice, approximately 4 years apart. Across groups, less deactivation in the mid-cingulate cortex during emotional regulation (Rate Ratio = 3.07(95% CI:1.09-8.66), χ²(1) = 4.48, p = 0.03) at Time-1, and increases in functional connectivity from Time-1 to 2 (Rate Ratio = 1.45(95% CI:1.15-1.84), χ²(1) = 8.69, p = 0.003) between regions that showed deactivation during emotional regulation and the right caudate, predicted higher depression severity at Time-2. Both effects were robust to sensitivity analyses controlling for clinical characteristics. Decreases in deactivation between Times 1 and 2 in the right putamen tail were associated with increases in hypo/mania at Time-2, but this effect was not robust to sensitivity analyses. Our findings reflect neural mechanisms of risk for worsening affective symptoms, particularly depression, in youth across a range of familial risk for affective disorders. They may serve as potential objective, early-warning signs of AD in youth.

The activity and connectivity of the facial emotion processing neural circuitry in bipolar disorder: a systematic review

BACKGROUND

Facial emotion processing abnormalities may be a trait feature of bipolar disorder (BD). These social cognitive impairments may be due to alterations in the neural processing of facial affective information in visual ("core"), and limbic and prefrontal ("extended") networks, however, the precise neurobiological mechanism(s) underlying these symptoms are unclear.

METHODS

We conducted a systematic review to appraise the literature on the activity and connectivity of the facial emotion processing neural circuitry in BD. Two reviewers undertook a search of the electronic databases PubMed, Scopus and PsycINFO, to identify relevant literature published since inception up until September 2019. Study eligibility criteria included; BD participants, neuroimaging, and facial emotion processing tasks.

RESULTS

Out of an initial yield of 6121 articles, 66 were eligible for inclusion in this review. We identified differences in neural activity and connectivity within and between occipitotemporal, limbic, and prefrontal regions, in response to facial affective stimuli, in BD compared to healthy controls.

LIMITATIONS

The methodologies used across studies varied considerably.

CONCLUSIONS

The findings from this review suggest abnormalities in both the activity and connectivity of facial emotion processing neural circuitry in BD. It is recommended that future research aims to further define the connectivity and spatiotemporal course of neural events within and between occipitotemporal, limbic, and prefrontal regions.

Abnormal Large-Scale Network Activation Present in Bipolar Mania and Bipolar Depression Under Resting State

Introduction: Previous studies have primarily focused on the neuropathological mechanisms of the emotional circuit present in bipolar mania and bipolar depression. Recent studies applying resting-state functional magnetic resonance imaging (fMRI) have raise the possibility of examining brain-wide networks abnormality between the two oppositional emotion states, thus this study aimed to characterize the different functional architecture represented in mania and depression by employing group-independent component analysis (gICA). Materials and Methods: Forty-one bipolar depressive patients, 20 bipolar manic patients, and 40 healthy controls (HCs) were recruited and received resting-state fMRI scans. Group-independent component analysis was applied to the brain network functional connectivity analysis. Then, we calculated the correlation between the value of between-group differences and clinical variables. Results: Group-independent component analysis identified 15 components in all subjects, and ANOVA showed that functional connectivity (FC) differed significantly in the default mode network, central executive network, and frontoparietal network across the three groups. Further post-hoc t-tests showed a gradient descent of activity-depression > HC > mania-in all three networks, with the differences between depression and HCs, as well as between depression and mania, surviving after family wise error (FWE) correction. Moreover, central executive network and frontoparietal network activities were positively correlated with Hamilton depression rating scale (HAMD) scores and negatively correlated with Young manic rating scale (YMRS) scores. Conclusions: Three brain networks heighten activity in depression, but not mania; and the discrepancy regions mainly located in prefrontal, which may imply that the differences in cognition and emotion between the two states is associated with top-down regulation in task-independent networks.

Magnetic seizure therapy is efficacious and well tolerated for treatment-resistant bipolar depression: an open-label clinical trial

BACKGROUND

Treatment-resistant bipolar depression can be treated effectively using electroconvulsive therapy, but its use is limited because of stigma and cognitive adverse effects. Magnetic seizure therapy is a new convulsive therapy with promising early evidence of antidepressant effects and minimal cognitive adverse effects. However, there are no clinical trials of the efficacy and safety of magnetic seizure therapy for treatment-resistant bipolar depression.

METHODS

Participants with treatment-resistant bipolar depression were treated with magnetic seizure therapy for up to 24 sessions or until remission. Magnetic seizure therapy was applied over the prefrontal cortex at high (100 Hz; n = 8), medium (50 or 60 Hz; n = 9) or low (25 Hz; n = 3) frequency, or over the vertex at high frequency (n = 6). The primary outcome measure was the 24-item Hamilton Rating Scale for Depression. Participants completed a comprehensive battery of neurocognitive tests.

RESULTS

Twenty-six participants completed a minimally adequate trial of magnetic seizure therapy (i.e., ≥ 8 sessions), and 20 completed full treatment per protocol. Participants showed a significant reduction in scores on the Hamilton Rating Scale for Depression. Adequate trial completers had a remission rate of 23.1% and a response rate of 38.5%. Per-protocol completers had a remission rate of 30% and a response rate of 50%. Almost all cognitive measures remained stable, except for significantly worsened recall consistency on the autobiographical memory inventory.

LIMITATIONS

The open-label study design and modest sample size did not allow for comparisons between stimulation parameters.

CONCLUSION

In treatment-resistant bipolar depression, magnetic seizure therapy produced significant improvements in depression symptoms with minimal effects on cognitive performance. These promising results warrant further investigation with larger randomized clinical trials comparing magnetic seizure therapy to electroconvulsive therapy.

CLINICAL TRIAL REGISTRATION

NCT01596608; clinicaltrials.gov

Frontolimbic, Frontoparietal, and Default Mode Involvement in Functional Dysconnectivity in Psychotic Bipolar Disorder

BACKGROUND

Functional abnormalities, mostly involving functionally specialized subsystems, have been associated with disorders of emotion regulation such as bipolar disorder (BD). Understanding how independent functional subsystems integrate globally and how they relate with anatomical cortical and subcortical networks is key to understanding how the human brain's architecture constrains functional interactions and underpins abnormalities of mood and emotion, particularly in BD.

METHODS

Resting-state functional magnetic resonance time series were averaged to obtain individual functional connectivity matrices (using AFNI software); individual structural connectivity matrices were derived using deterministic non-tensor-based tractography (using ExploreDTI, version 4.8.6), weighted by streamline count and fractional anisotropy. Structural and functional nodes were defined using a subject-specific cortico-subcortical mapping (using Desikan-Killiany Atlas, FreeSurfer, version 5.3). Whole-brain connectivity alongside a permutation-based statistical approach and structure-function coupling were employed to investigate topological variance in individuals with predominantly euthymic BD relative to psychiatrically healthy control subjects.

RESULTS

Patients with BD (n = 41) exhibited decreased (synchronous) connectivity in a subnetwork encompassing frontolimbic and posterior-occipital functional connections (T > 3, p = .048), alongside increased (antisynchronous) connectivity within a frontotemporal subnetwork (T > 3, p = .014); all relative to control subjects (n = 56). Preserved whole-brain functional connectivity and comparable structure-function coupling among whole-brain and edge-class connections were observed in patients with BD relative to control subjects.

CONCLUSIONS

This study presents a functional map of BD dysconnectivity that differentially involves communication within nodes belonging to functionally specialized subsystems-default mode, frontoparietal, and frontolimbic systems; these changes do not extend to be detected globally and may be necessary to maintain a remitted clinical state of BD. Preserved structure-function coupling in BD despite evidence of regional anatomical and functional deficits suggests a dynamic interplay between structural and functional subnetworks.

Disrupted brain structural connectivity in Pediatric Bipolar Disorder with psychosis

Bipolar disorder (BD) has been linked to disrupted structural and functional connectivity between prefrontal networks and limbic brain regions. Studies of patients with pediatric bipolar disorder (PBD) can help elucidate the developmental origins of altered structural connectivity underlying BD and provide novel insights into the aetiology of BD. Here we compare the network properties of whole-brain structural connectomes of euthymic PBD patients with psychosis, a variant of PBD, and matched healthy controls. Our results show widespread changes in the structural connectivity of PBD patients with psychosis in both cortical and subcortical networks, notably affecting the orbitofrontal cortex, frontal gyrus, amygdala, hippocampus and basal ganglia. Graph theoretical analysis revealed that PBD connectomes have fewer hubs, weaker rich club organization, different modular fingerprint and inter-modular communication, compared to healthy participants. The relationship between network features and neurocognitive and psychotic scores was also assessed, revealing trends of association between patients’ IQ and affective psychotic symptoms with the local efficiency of the orbitofrontal cortex. Our findings reveal that PBD with psychosis is associated with significant widespread changes in structural network topology, thus strengthening the hypothesis of a reduced capacity for integrative processing of information across brain regions. Localised network changes involve core regions for emotional processing and regulation, as well as memory and executive function, some of which show trends of association with neurocognitive faculties and symptoms. Together, our findings provide the first comprehensive characterisation of the alterations in local and global structural brain connectivity and network topology, which may contribute to the deficits in cognition and emotion processing and regulation found in PBD.

Connectomics of bipolar disorder: a critical review, and evidence for dynamic instabilities within interoceptive networks

The notion that specific cognitive and emotional processes arise from functionally distinct brain regions has lately shifted toward a connectivity-based approach that emphasizes the role of network-mediated integration across regions. The clinical neurosciences have likewise shifted from a predominantly lesion-based approach to a connectomic paradigm-framing disorders as diverse as stroke, schizophrenia (SCZ), and dementia as "dysconnection syndromes". Here we position bipolar disorder (BD) within this paradigm. We first summarise the disruptions in structural, functional and effective connectivity that have been documented in BD. Not surprisingly, these disturbances show a preferential impact on circuits that support emotional processes, cognitive control and executive functions. Those at high risk (HR) for BD also show patterns of connectivity that differ from both matched control populations and those with BD, and which may thus speak to neurobiological markers of both risk and resilience. We highlight research fields that aim to link brain network disturbances to the phenotype of BD, including the study of large-scale brain dynamics, the principles of network stability and control, and the study of interoception (the perception of physiological states). Together, these findings suggest that the affective dysregulation of BD arises from dynamic instabilities in interoceptive circuits which subsequently impact on fear circuitry and cognitive control systems. We describe the resulting disturbance as a "psychosis of interoception".

Neurofunctional Correlates of Response to Quetiapine in Adolescents with Bipolar Depression

OBJECTIVES

Prior studies have shown that youth with bipolar disorder demonstrate neurofunctional changes in key prefrontal and subcortical brain regions implicated in emotional regulation following treatment with pharmacological agents. We recently reported a large response rate (>60%) to quetiapine (QUET) for treating depressive symptoms in adolescents with bipolar depression. This study investigates the neurofunctional effects of QUET using functional magnetic resonance imaging (fMRI).

METHODS

Thirty-three unmedicated subjects, 10-17 years of age, with a current depressive episode (Children's Depression Rating Scale-Revised [CDRS-R] > 40) associated with bipolar I or II disorder were recruited in a two-site randomized, placebo (PBO)-controlled trial of QUET monotherapy for treatment of bipolar depression in adolescents. Twenty-three of these participants (nine male) underwent an MRI scan at baseline, then were randomized to QUET or PBO, followed for 8 weeks, and at the end of their study participation underwent another MRI scan. During the fMRI scan, subjects viewed negative and neutral pictures and rated the valence of each picture.

RESULTS

Sixteen subjects had usable data at both time points: 10 subjects randomized to QUET, and 6 randomized to PBO. For QUET subjects, lower baseline activation in the left dorsolateral prefrontal cortex (p < 0.005) and higher baseline activation in the left ventrolateral prefrontal cortex (p = 0.0024) predicted greater improvement in CDRS-R scores from baseline to follow-up. When QUET and PBO groups were combined (n = 16), region-of-interest activation did not significantly predict change in CDRS-R.

CONCLUSIONS

Baseline activation patterns in dorsal and ventral portions of the prefrontal cortex that are critical for the regulation of emotion-predicted response, but only within the QUET group. Thus, specific medications may be more effective in the context of specific prefrontal activation patterns in youth with bipolar depression. Larger studies of these youth would help to clarify the effects of QUET on brain activation.

Impaired sensory processing measured by functional MRI in Bipolar disorder manic and depressed mood states

Bipolar disorder is characterized by recurring episodes of depression and mania. Defining differences in brain function during these states is an important goal of bipolar disorder research. However, few imaging studies have directly compared brain activity between bipolar mood states. Herein, we compare functional magnetic resonance imaging (fMRI) responses during a flashing checkerboard stimulus between bipolar participants across mood states (euthymia, depression, and mania) in order to identify functional differences between these states. 40 participants with bipolar I disorder and 33 healthy controls underwent fMRI during the presentation of the stimulus. A total of 23 euthymic-state, 16 manic-state, 15 depressed-state, and 32 healthy control imaging sessions were analyzed in order to compare functional activation during the stimulus between mood states and with healthy controls. A reduced response was identified in the visual cortex in both the depressed and manic groups compared to euthymic and healthy participants. Functional differences between bipolar mood states were also observed in the cerebellum, thalamus, striatum, and hippocampus. Functional differences between mood states occurred in several brain regions involved in visual and other sensory processing. These differences suggest that altered visual processing may be a feature of mood states in bipolar disorder. The key limitations of this study are modest mood-state group size and the limited temporal resolution of fMRI which prevents the segregation of primary visual activity from regulatory feedback mechanisms.

Shared and distinct regional homogeneity changes in bipolar and unipolar depression

BACKGROUND

Bipolar depression (BD) is easily misdiagnosed as unipolar depression (UD) or major depressive disorder (MDD) because the depressive symptoms can overlap. Regional homogeneity (ReHo), a measure commonly used for analyzing resting-state fMRI data, has been applied to the study of various neuropsychiatric disorders. However, to date, studies directly comparing BD and UD using ReHo have been relatively scarce. Further investigation is needed to study the latent pathophysiological mechanisms of BD and UD.

METHODS

Fifty-five patients with BD and 76 patients with UD, as well as 113 healthy controls (HC), underwent resting-state functional magnetic resonance imaging (fMRI). We compared the voxel-wise ReHo across the whole brain for subjects in each of the three groups.

RESULTS

Significant differences were found in the left frontal cluster (LFC) across the three groups. There were differences between BD and UD in the LFC and left temporal cluster (LTC). In addition, differences between UD and HC existed in the LFC and the occipital cluster (OC). When comparing BD subjects with HC subjects, significant differences were found in all three clusters. No correlations were observed between the 17-item Hamilton Depression Rating Scale (HDRS-17) scores or sub-scores and the ReHo values of BD or UD patients.

CONCLUSION

ReHo values in the LFC differed significantly among BD, UD, and HC subjects. ReHo in the LTC showed significant differences between BD and UD that might serve as neuroimaging markers of BD. Further, BD and UD shared ReHo changes in the cuneus, suggesting that the cuneus might provide a depressive state neuroimaging marker of BD and UD patients.

The Role of Amygdala in Patients With Euthymic Bipolar Disorder During Resting State

The current study aims to explore the functional changes of the amygdala in patients with euthymic Bipolar Disorder (BD) using resting state fMRI (rs-fMRI). Twenty-one euthymic patients with bipolar disorder and 28 healthy controls participated in this study. Two of the euthymic patients with BD and three of the healthy controls were excluded due to excessive head motion. We found that patients with euthymia (38.79 ± 12.03) show higher fALFF (fractional Amplitude of low-frequency fluctuation) value of the amygdala (t = 2.076, P = 0.044), and lower functional connectivity between the amygdala and supplementary motor area (p < 0.01, GRF corrected) than healthy controls (33.40 ± 8.21). However, euthymic patients did not show a differential activity in ReHo (Regional Homogeneity) and gray matter of the amygdala region as compared to healthy controls. Thus, despite the absence of clinical symptoms in euthymic patients with BD, the amygdala functional activity and its connectivity to other brain regions remain altered. Further investigation of negative emotions and social functioning in euthymic patients with BD are needed and can help pave the way for a better understanding of BD psychopathology.

Stress and reward processing in bipolar disorder: a functional magnetic resonance imaging study

OBJECTIVES

A link between negative life stress and the onset of mood episodes in bipolar disorder (BD) has been established, but processes underlying such a link remain unclear. Growing evidence suggests that stress can negatively affect reward processing and related neurobiological substrates, indicating that a dysregulated reward system may provide a partial explanation. The aim of this study was to test the impact of stress on reward-related neural functioning in BD.

METHODS

Thirteen euthymic or mildly depressed individuals with BD and 15 controls performed a Monetary Incentive Delay (MID) task while undergoing functional magnetic resonance imaging during no-stress and stress (negative psychosocial stressor involving poor performance feedback and threat of monetary deductions) conditions.

RESULTS

In hypothesis-driven region-of-interest analyses, a significant group-by-condition interaction emerged in the amygdala during reward anticipation. Relative to controls, while anticipating a potential reward, subjects with BD were characterized by amygdalar hyperactivation in the no-stress condition but hypoactivation during stress. Moreover, relative to controls, subjects with BD had significantly larger amygdala volumes. After controlling for structural differences, the effects of stress on amygdalar function remained, whereas groups no longer differed during the no-stress condition. During reward consumption, a group-by-condition interaction emerged in the putamen due to increased putamen activation in response to rewards in participants with BD during stress, but an opposite pattern in controls.

CONCLUSIONS

Overall, findings highlight possible impairments in using reward-predicting cues to adaptively engage in goal-directed actions in BD, combined with stress-induced hypersensitivity to reward consumption. Potential clinical implications are discussed.

Regional Coherence Changes in Alzheimer's Disease Patients with Depressive Symptoms: A Resting-State Functional MRI Study

Alzheimer's disease (AD) is characterized by progressive cognitive decline along with neuropsychiatric symptoms including depression and psychosis. Depression is a common psychiatric disorder occurring in people across the lifespan. Accumulating evidence indicates that depression may be a prodrome and/or a "risk factor" for AD. However, whether AD and depression share a common pathophysiological pathway is still unclear. The aim of this study was to identify regional alterations in brain function associated with depressive symptoms in mild AD patients. Thirty-two mild AD patients were evaluated using the Neuropsychiatric Inventory and Hamilton Depression Rating Scale, and were divided into two groups: 15 AD patients with depressive symptoms (D-AD) and 17 non-depressed AD (nD-AD) patients. Using the approach of regional homogeneity (ReHo), we characterized resting-state regional brain activity in D-AD and nD-AD patients. Compared with nD-AD patients, D-AD patients showed decreased ReHo in the right precentral gyrus, right superior frontal gyrus, right middle frontal gyrus, and right inferior frontal cortex. Our findings show regional brain activity alterations in D-AD patients. Thus, D-AD pathogenesis may be attributed to abnormal neural activity in multiple brain regions.

Therapeutic Efficacy of Neurostimulation for Depression: Techniques, Current Modalities, and Future Challenges

Depression is the most prevalent debilitating mental illness; it is characterized as a disorder of mood, cognitive function, and neurovegetative function. About one in ten individuals experience depression at some stage of their lives. Antidepressant drugs are used to reduce the symptoms but relapse occurs in ~20% of patients. However, alternate therapies like brain stimulation techniques have shown promising results in this regard. This review covers the brain stimulation techniques electroconvulsive therapy, transcranial direct current stimulation, repetitive transcranial magnetic stimulation, vagus nerve stimulation, and deep brain stimulation, which are used as alternatives to antidepressant drugs, and elucidates their research and clinical outcomes.

Altered functioning of reward circuitry in youth offspring of parents with bipolar disorder

BACKGROUND

Offspring of parents with bipolar disorder (BD) (BO) are at higher risk of BD than offspring of parents with non-BD psychopathology (NBO), although both groups are at higher risk than offspring of psychiatrically healthy parents (HC) for other affective and psychiatric disorders. Abnormal functioning in reward circuitry has been demonstrated previously in individuals with BD. We aimed to determine whether activation and functional connectivity in this circuitry during risky decision-making differentiated BO, NBO and HC.

METHOD

BO (n = 29; mean age = 13.8 years; 14 female), NBO (n = 28; mean age = 13.9 years; 12 female) and HC (n = 23; mean age = 13.7 years; 11 female) were scanned while performing a number-guessing reward task. Of the participants, 11 BO and 12 NBO had current non-BD psychopathology; five BO and four NBO were taking psychotropic medications.

RESULTS

A 3 (group) × 2 (conditions: win-control/loss-control) analysis of variance revealed a main effect of group on right frontal pole activation: BO showed significantly greater activation than HC. There was a significant main effect of group on functional connectivity between the bilateral ventral striatum and the right ventrolateral prefrontal cortex (Z > 3.09, cluster-p < 0.05): BO showed significantly greater negative functional connectivity than other participants. These between-group differences remained after removing youth with psychiatric disorders and psychotropic medications from analyses.

CONCLUSIONS

This is the first study to demonstrate that reward circuitry activation and functional connectivity distinguish BO from NBO and HC. The fact that the pattern of findings remained when comparing healthy BO v. healthy NBO v. HC suggests that these neuroimaging measures may represent trait-level neurobiological markers conferring either risk for, or protection against, BD in youth.

Altered effective connectivity model in the default mode network between bipolar and unipolar depression based on resting-state fMRI

BACKGROUND

Bipolar depression (BD) is characterized by alternating episodes of depression and mania. Patients who spend the majority of their time in episodes of depression rather than mania are often misdiagnosed with unipolar depression (UD) that only exhibits depressive episodes. It would be important to explore the construction of more objective biomarkers which can be used to more accurately differentiate BD and UD.

METHODS

The effective connectivity model of BD and UD in the default mode network (DMN) was constructed based on resting-state fMRI data of 17 BD (32.12±8.57 years old) and 17 UD (32.59±9.77 years old) patients using a linear non-Gaussian acyclic model (LiNGAM). The effective connectivity differences were obtained by conducting a permutation test.

RESULTS

The following connections were stronger in the BD group than in the UD group: medial prefrontal cortex (MPFC) →posterior cingulate cortex (PCC), right inferior parietal cortex (rIPC)→left hippocampus (lHC) and rIPC→right insula (rInsula). In contrast, the following connections were weak or unapparent in the BD group: MPFC→lHC, rHC→MPFC, rHC→rInsula and rInsula→lHC.

LIMITATIONS

First, the medication effect is a confounding factor. Second, as with most fMRI studies, the subjects׳ thoughts during imaging are difficult to control.

CONCLUSIONS

The brain regions in these altered connections, such as the HC, insula, MPFC and IPC, all play important roles in emotional processing, suggesting that these altered connections may be conducive to better distinguish between BD and UD.

Prefrontal hypoactivation during working memory in bipolar II depression

BACKGROUND

Patterns of abnormal neural activation have been observed during working memory tasks in bipolar I depression, yet the neural changes associated with bipolar II depression have yet to be explored.

METHOD

An n-back working memory task was administered during a 3T functional magnetic resonance imaging scan in age- and gender-matched groups of 19 unmedicated, bipolar II depressed subjects and 19 healthy comparison subjects. Whole-brain and region-of-interest analyses were performed to determine regions of differential activation across memory-load conditions (0-, 1- and 2-back).

RESULTS

Accuracy for all subjects decreased with higher memory load, but there was no significant group × memory load interaction. Random-effects analyses of memory load indicated that subjects with bipolar II depression exhibited significantly less activation than healthy subjects in left hemispheric regions of the middle frontal gyrus [Brodmann area (BA) 11], superior frontal gyrus (BA 10), inferior parietal lobule (BA 40), middle temporal gyrus (BA 39) and bilateral occipital regions. There was no evidence of differential activation related to increasing memory load in the dorsolateral prefrontal or anterior cingulate cortex.

CONCLUSIONS

Bipolar II depression is associated with hypoactivation of the left medio-frontal and parietal cortex during working memory performance. Our findings suggest that bipolar II depression is associated with disruption of the fronto-parietal circuit that is engaged in working memory tasks, which is a finding reported across bipolar subtypes and mood states.

Pilot Study: The Role of the Hemispheric Lateralization in Mental Disorders by Use of the Limb (Eye, Hand, Foot) Dominance

INTRODUCTION

Based on the previous studies, we know that the hemispheric lateralization defects, increase the probability of psychological disorders. We also know that dominant limb is controlled by dominant hemisphere and limb preference is used as an indicator for hemisphere dominance. In this study we attempted to explore the hemispheric dominance by the use of three limbs (hand, foot and eye).

METHODS

We performed this survey on two samples, psychiatric patients compared with normal population. For this purpose, knowing that the organ dominance is stabilized in adolescence, and age has no effect on the people above 15, we used 48 high school girls and 65 boys as the final samples of normal population. The patient group included 57 male and 26 female who were chronic psychiatric patients.

RESULTS

The result shows that left-eye dominance is more in patients than the normal group (P=0.000) but the handedness and footedness differences are not significance. In psychotic, bipolar and depressive disorders, eye dominance had significant difference (P=0.018). But this is not true about hand and foot dominance.

DISCUSSION

Our findings proved that generally in psychiatric patients, left-eye dominance is more common, left-eye dominance is also more in psychotic and depressive disorders. It is less common in bipolar disorders.

Frontal lobe hypoactivation in medication-free adults with bipolar II depression during response inhibition

In executive function, specifically in response inhibition, numerous studies support the essential role for the inferior frontal cortex (IFC). Hypoactivation of the IFC during response-inhibition tasks has been found consistently in subjects with bipolar disorder during manic and euthymic states. The aim of this study was to examine whether reduced IFC activation also exists in unmedicated subjects with bipolar disorder during the depressed phase of the disorder. Participants comprised 19 medication-free bipolar II (BP II) depressed patients and 20 healthy control subjects who underwent functional magnetic resonance imaging (fMRI) while performing a Go/NoGo response-inhibition task. Whole-brain analyses were conducted to assess activation differences within and between groups. The BP II depressed group, compared with the control group, showed significantly reduced activation in right frontal regions, including the IFC (Brodmann's area (BA) 47), middle frontal gyrus (BA 10), as well as other frontal and temporal regions. IFC hypoactivation may be a persistent deficit in subjects with bipolar disorder in both acute mood states as well as euthymia, thus representing a trait feature of bipolar disorder.

Sad mood induction has an opposite effect on amygdala response to emotional stimuli in euthymic patients with bipolar disorder and healthy controls

BACKGROUND

Aberrant amygdala reactivity to affective stimuli represents a candidate factor predisposing patients with bipolar disorder (BD) to relapse, but it is unclear to what extent amygdala reactivity is state-dependent. We evaluated the modulatory influence of mood on amygdala reactivity and functional connectivity in patients with remitted BD and healthy controls.

METHODS

Amygdala response to sad versus neutral faces was investigated using fMRI during periods of normal and sad mood induced by autobiographical scripts. We assessed the functional connectivity of the amygdala to characterize the influence of mood state on the network responsible for the amygdala response.

RESULTS

We included 20 patients with remitted BD and 20 controls in our study. The sad and normal mood exerted opposite effects on the amygdala response to emotional faces in patients compared with controls (F1,38 = 5.85, p = 0.020). Sad mood amplified the amygdala response to sad facial stimuli in controls but attenuated the amygdala response in patients. The groups differed in functional connectivity between the amygdala and the inferior prefrontal gyrus (p ≤ 0.05, family-wise error-corrected) of ventrolateral prefrontal cortex (vlPFC) corresponding to Brodmann area 47. The sad mood challenge increased connectivity during the period of processing sad faces in patients but decreased connectivity in controls.

LIMITATIONS

Limitations to our study included long-term medication use in the patient group and the fact that we mapped only depressive (not manic) reactivity.

CONCLUSION

Our results support the role of the amygdala-vlPFC as the system of dysfunctional contextual affective processing in patients with BD. Opposite amygdala reactivity unmasked by the mood challenge paradigm could represent a trait marker of altered mood regulation in patients with BD.

Brain functional changes across the different phases of bipolar disorder

BACKGROUND

Little is known about how functional imaging changes in bipolar disorder relate to different phases of the illness.

AIMS

To compare cognitive task activation in participants with bipolar disorder examined in different phases of illness.

METHOD

Participants with bipolar disorder in mania (n = 38), depression (n = 38) and euthymia (n = 38), as well as healthy controls (n = 38), underwent functional magnetic resonance imaging during performance of the n-back working memory task. Activations and de-activations were compared between the bipolar subgroups and the controls, and among the bipolar subgroups. All participants were also entered into a linear mixed-effects model.

RESULTS

Compared with the controls, the mania and depression subgroups, but not the euthymia subgroup, showed reduced activation in the dorsolateral prefrontal cortex, the parietal cortex and other areas. Compared with the euthymia subgroup, the mania and depression subgroups showed hypoactivation in the parietal cortex. All three bipolar subgroups showed failure of de-activation in the ventromedial frontal cortex. Linear mixed-effects modelling revealed a further cluster of reduced activation in the left dorsolateral prefrontal cortex in the patients; this was significantly more marked in the mania than in the euthymia subgroup.

CONCLUSIONS

Bipolar disorder is characterised by mood state-dependent hypoactivation in the parietal cortex. Reduced dorsolateral prefrontal activation is a further feature of mania and depression, which may improve partially in euthymia. Failure of de-activation in the medial frontal cortex shows trait-like characteristics.

All the world's a (clinical) stage: rethinking bipolar disorder from a longitudinal perspective

Psychiatric disorders have traditionally been classified using a static, categorical approach. However, this approach falls short in facilitating understanding of the development, common comorbid diagnoses, prognosis and treatment of these disorders. We propose a 'staging' model of bipolar disorder that integrates genetic and neural information with mood and activity symptoms to describe how the disease progresses over time. From an early, asymptomatic, but 'at-risk' stage to severe, chronic illness, each stage is described with associated neuroimaging findings as well as strategies for mapping genetic risk factors. Integrating more biologic information relating to cardiovascular and endocrine systems, refining methodology for modeling dimensional approaches to disease and developing outcome measures will all be crucial in examining the validity of this model. Ultimately, this approach should aid in developing targeted interventions for each group that will reduce the significant morbidity and mortality associated with bipolar disorder.

Impaired regulation of emotion: neural correlates of reappraisal and distraction in bipolar disorder and unaffected relatives

Deficient emotion regulation has been proposed as a crucial pathological mechanism in bipolar disorder (BD). We therefore investigated emotion regulation impairments in BD, the related neural underpinnings and their etiological relevance for the disorder. Twenty-two euthymic patients with bipolar-I disorder and 17 unaffected first-degree relatives of BD-I patients, as well as two groups of healthy gender-, age- and education-matched controls (N=22/17, respectively) were included. Participants underwent functional magnetic resonance imaging while applying two different emotion regulation techniques, reappraisal and distraction, when presented with emotional images. BD patients and relatives showed impaired downregulation of amygdala activity during reappraisal, but not during distraction, when compared with controls. This deficit was correlated with the habitual use of reappraisal. The negative connectivity of amygdala and orbitofrontal cortex (OFC) observed during reappraisal in controls was reversed in BD patients and relatives. There were no significant differences between BD patients and relatives. As being observed in BD patients and unaffected relatives, deficits in emotion regulation through reappraisal may represent heritable neurobiological abnormalities underlying BD. The neural mechanisms include impaired control of amygdala reactivity to emotional stimuli and dysfunctional connectivity of the amygdala to regulatory control regions in the OFC. These are, thus, important aspects of the neurobiological basis of increased vulnerability for BD.

Atypical right hemispheric functioning in the euthymic state of bipolar affective disorder

Bipolar disorder (BD) has been associated with right hemisphere dysfunction. These findings usually come from studies that have not distinguished between symptomatic and euthymic states of BD. The present study aims to investigate atypical right (and left) hemispheric functioning in euthymic BD patients. We evaluated 40 participants (18 healthy controls and 22 euthymic BD patients) using an emotional prosody dichotic listening task and a linguistic dichotic listening task which have been shown to produce a strong left ear advantage (LEA) and right ear advantage (REA), indicating a right and left hemisphere superiority, respectively. The results replicate the well-known LEA in emotional prosody for healthy controls. In contrast, no ear advantage was found for emotional prosody in euthymic BD patients. Both groups revealed the well-established REA in the linguistic dichotic listening task. The patient group was heterogeneous with regard to medication, as it consisted of patients with a variety of pharmacological treatments. The results are in line with previous studies in symptomatic BD patients, and suggest that atypical LEA in emotional prosody can be interpreted as a neurobehavioral vulnerability marker of emotional dysregulation and dysfunction in the right hemispheric fronto-temporal network in both symptomatic and euthymic BD patients.

Diagnostic and clinical implications of functional neuroimaging in bipolar disorder

Advances in functional neuroimaging have ushered in studies that have enhanced our understanding of the neuropathophysiology of bipolar disorder, but do not yet have clinical applications. We describe the major circuits (ventrolateral, dorsolateral, ventromedial, and anterior cingulate) thought to be involved in the corticolimbic dysregulation that may underlie mood states in patients with bipolar disorder. The potential clinical application of functional neuroimaging in bipolar disorder is considered in terms of prognostic, predictive, and treatment biomarkers. To date, most research has focused on prognostic biomarkers to differentiate patients with bipolar disorder from those with other affective or psychotic diagnoses, or healthy subjects. The search for treatment biomarkers, which suggest mechanisms of pharmacodynamic or treatment response, and predictive biomarkers has thus far involved only pediatric patients diagnosed with bipolar disorder. The results to date are encouraging and suggest that functional neuroimaging may be of eventual benefit in determining biomarkers of treatment response. Further refinement of biomarker identification, and perhaps even illness characterization are needed to find prognostic and predictive biomarkers of bipolar disorder.

Differential abnormalities of functional connectivity of the amygdala and hippocampus in unipolar and bipolar affective disorders

OBJECTIVE

The amygdala and hippocampus - two structures intimately associated with mood and cognition - have been reported to exhibit altered neural activity or volume in affective disorders. We hypothesized the amygdala and hippocampus would show altered and differential patterns of connectivity in patients with bipolar (BPs) and unipolar (UPs) disorder compared to healthy volunteers.

METHOD

Thirty BPs, 34 UPs, and 66 healthy volunteers were imaged using F-18-fluorodeoxyglucose and positron emission tomography while performing an auditory continuous performance task (CPT). Normalized mean activity of the amygdala and hippocampus was correlated with the rest of the brain.

RESULTS

In BPs, the amygdalae displayed exaggerated positive metabolic correlations with prefrontal and ventral striatal areas, while the hippocampus showed a paucity of normal inter-relations compared to controls. In contrast, in UPs the amygdala was significantly negatively correlated with prefrontal and anterior cingulate cortex, while the hippocampus was significantly more positively correlated to these same prefrontal areas.

CONCLUSIONS

During a simple cognitive task, the functional connectivity of the amygdala and hippocampus, regions usually associated with emotion and memory regulation, was substantially different in affective illness compared to healthy controls whether or not there were baseline abnormalities in these areas. These striking differences in functional connectivity of amygdala and hippocampus should be further explored in ill and well states and using more specific emotion and cognitive evocative tasks.

Developmental meta-analyses of the functional neural correlates of bipolar disorder

IMPORTANCE

Bipolar disorder (BD) is a debilitating mental illness associated with high costs to diagnosed individuals and society. Within the past 2 decades, increasing numbers of children and adolescents have been diagnosed as having BD. While functional magnetic resonance imaging (fMRI) studies have begun to investigate the neural mechanisms underlying BD, few have directly compared differences in youths with BD and adults with BD (hereafter BD-youths and BD-adults, respectively).

OBJECTIVE

To test the hypothesis that BD-youths (<18 years old) would show greater convergence of amygdala hyperactivation and prefrontal cortical hypoactivation vs BD-adults.

DATA SOURCES

PubMed and PsycINFO databases were searched on July 17, 2013, for original, task-related coordinate-based fMRI articles.

STUDY SELECTION

In total, 21 pediatric studies, 73 adult studies, and 2 studies containing distinct pediatric and adult groups within the same study met inclusion criteria for our ALE analyses.

DATA EXTRACTION AND SYNTHESIS

Coordinates of significant between-group differences were extracted from each published study. Recent improvements in GingerALE software were used to perform direct comparisons of pediatric and adult fMRI findings. We conducted activation likelihood estimation (ALE) meta-analyses directly comparing the voxelwise convergence of fMRI findings in BD-youths vs BD-adults, both relative to healthy control (HC) participants.

RESULTS

Analyses of emotional face recognition fMRI studies showed significantly greater convergence of amygdala hyperactivation among BD-youths than BD-adults. More broadly, analyses of fMRI studies using emotional stimuli showed significantly greater convergence of hyperactivation among BD-youths than BD-adults in the inferior frontal gyrus and precuneus. In contrast, analyses of fMRI studies using nonemotional cognitive tasks and analyses aggregating emotional and nonemotional tasks showed significantly greater convergence of hypoactivation among BD-youths than BD-adults in the anterior cingulate cortex.

CONCLUSIONS AND RELEVANCE

Our data suggest that amygdala, prefrontal, and visual system hyperactivation is important in the emotional dysfunction present in BD-youths, as well as that anterior cingulate cortex hypoactivation is relevant to the cognitive deficits in BD-youths. Future studies are required to determine if the developmental fMRI differences between BD-youths and BD-adults identified by our ALE meta-analyses are useful as brain-based diagnostic or treatment markers of BD, including either longitudinal neuroimaging studies of BD-youths as they become adults or cross-sectional imaging studies directly comparing BD-youths with BD-adults.

A critical appraisal of neuroimaging studies of bipolar disorder: toward a new conceptualization of underlying neural circuitry and a road map for future research

OBJECTIVE

In this critical review, the authors appraise neuroimaging findings in bipolar disorder in emotion-processing, emotion-regulation, and reward-processing neural circuitry in order to synthesize the current knowledge of the neural underpinnings of bipolar disorder and provide a neuroimaging research road map for future studies.

METHOD

The authors examined findings from all major studies in bipolar disorder that used functional MRI, volumetric analysis, diffusion imaging, and resting-state techniques, integrating findings to provide a better understanding of larger-scale neural circuitry abnormalities in bipolar disorder.

RESULTS

Bipolar disorder can be conceptualized, in neural circuitry terms, as parallel dysfunction in prefrontal cortical (especially ventrolateral prefrontal cortical)-hippocampal-amygdala emotion-processing and emotion-regulation circuits bilaterally, together with an "overactive" left-sided ventral striatal-ventrolateral and orbitofrontal cortical reward-processing circuitry, resulting in characteristic behavioral abnormalities associated with bipolar disorder: emotional lability, emotional dysregulation, and heightened reward sensitivity. A potential structural basis for these functional abnormalities is gray matter volume decreases in the prefrontal and temporal cortices, the amygdala, and the hippocampus and fractional anisotropy decreases in white matter tracts connecting prefrontal and subcortical regions.

CONCLUSIONS

Neuroimaging studies of bipolar disorder clearly demonstrate abnormalities in neural circuits supporting emotion processing, emotion regulation, and reward processing, although there are several limitations to these studies. Future neuroimaging research in bipolar disorder should include studies adopting dimensional approaches; larger studies examining neurodevelopmental trajectories in youths with bipolar disorder or at risk for bipolar disorder; multimodal neuroimaging studies using integrated systems approaches; and studies using pattern recognition approaches to provide clinically useful individual-level data. Such studies will help identify clinically relevant biomarkers to guide diagnosis and treatment decision making for individuals with bipolar disorder.

Abnormal functional connectivity of the medial cortex in euthymic bipolar II disorder

This project utilized functional MRI (fMRI) and a motor activation paradigm to investigate neural circuitry in euthymic bipolar II disorder. We hypothesized that circuitry involving the cortical midline structures (CMS) would demonstrate abnormal functional connectivity. Nineteen subjects with recurrent bipolar disorder and 18 controls were studied using fMRI and a motor activation paradigm. We used functional connectivity analyses to identify circuits with aberrant connectivity. We found increased functional connectivity among bipolar subjects compared to healthy controls in two CMS circuits. One circuit included the medial aspect of the left superior frontal gyrus and the dorsolateral region of the left superior frontal gyrus. The other included the medial aspect of the right superior frontal gyrus, the dorsolateral region of the left superior frontal gyrus and the right medial frontal gyrus and surrounding region. Our results indicate that CMS circuit dysfunction persists in the euthymic state and thus may represent trait pathology. Future studies should address whether these circuits contribute to relapse of illness. Our results also suggest the possibility that aberrations of superior frontal circuitry may impact default mode network and cognitive processes.

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.

Cortical thickness differences between bipolar depression and major depressive disorder

OBJECTIVES

Bipolar disorder (BD) is a psychiatric disorder with high morbidity and mortality that cannot be distinguished from major depressive disorder (MDD) until the first manic episode. A biomarker able to differentiate BD and MDD could help clinicians avoid risks of treating BD with antidepressants without mood stabilizers.

METHODS

Cortical thickness differences were assessed using magnetic resonance imaging in BD depressed patients (n = 18), MDD depressed patients (n = 56), and healthy volunteers (HVs) (n = 54). A general linear model identified clusters of cortical thickness difference between diagnostic groups.

RESULTS

Compared to the HV group, the BD group had decreased cortical thickness in six regions, after controlling for age and sex, located within the frontal and parietal lobes, and the posterior cingulate cortex. Mean cortical thickness changes in clusters ranged from 7.6 to 9.6% (cluster-wise p-values from 1.0 e-4 to 0.037). When compared to MDD, three clusters of lower cortical thickness in BD were identified that overlapped with clusters that differentiated the BD and HV groups. Mean cortical thickness changes in the clusters ranged from 7.5 to 8.2% (cluster-wise p-values from 1.0 e-4 to 0.023). The difference in cortical thickness was more pronounced when the subgroup of subjects with bipolar I disorder (BD-I) was compared to the MDD group.

CONCLUSIONS

Cortical thickness patterns were distinct between BD and MDD. These results are a step toward developing an imaging test to differentiate the two disorders.

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.

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.

Hyperthymic temperament and rapid reaction time in brightness preference

BACKGROUND

It is well-known that Type A behavior pattern is characterized by hard-driving, competitive behavior and time urgency. Also, people with hyperthymic temperament are known to have high energy levels and are full of plans. It is therefore hypothesized that hyperthymic temperament is associated with rapid processing and fast reaction time in making decisions.

METHODS

Using data from our previous experimental studies (N=58) examining brightness judgment and brightness preference, reaction time (RT) was investigated in relation to hyperthymic temperament scores and fMRI signal changes of the left inferior orbitofrontal cortex during brightness judgment.

RESULTS

RT for brightness judgment was significantly shorter than RT for brightness preference. Significant associations were found between RT for brightness preference and hyperthymic temperament scores, and RT for brightness preference and fMRI signal changes of the left inferior orbitofrontal cortex whilst performing brightness preference task. Multiple regression analysis revealed that RT for brightness preference task was significantly and negatively associated with hyperthymic temperament scores, and significantly and positively associated with fMRI signal changes of the left inferior orbitofrontal cortex.

LIMITATIONS

It is uncertain whether the findings of RT (around 1s) can be extrapolated to routine life (around 24h) and whether RT for brightness preference can be generalized to a variety of daily activities.

CONCLUSIONS

The present findings suggest that hyperthymic temperament is associated with rapid processing. Further studies are required to overcome the above limitations.

Functional neuroanatomy of response inhibition in bipolar disorders--combined voxel based and cognitive performance meta-analysis

OBJECTIVES

Impaired response inhibition underlies symptoms and altered functioning in patients with bipolar disorders (BD). The interpretation of fMRI studies requires an accurate estimation of neurocognitive performance, for which individual studies are typically underpowered. Thus, we performed the first combined meta-analysis of fMRI activations and neurocognitive performance in studies investigating response inhibition in BD.

METHODS

We used signed differential mapping to combine anatomical coordinates of activation and standardized differences between means to evaluate neurocognitive performance in 30 fMRI studies of response inhibition comparing controls (n = 667) and patients with BD (n = 635).

RESULTS

Relative to controls, BD patients underactivated the right inferior frontal gyrus (rIFG) regardless of current mood state and behavioral performance. Unique to euthymia were cortical hyperactivations (left superior temporal, right middle frontal gyri) combined with subcortical hypoactivations (basal ganglia), whereas unique to mania were subcortical hyperactivations (bilateral basal ganglia), combined with cortical hypoactivations (right inferior and medial frontal gyri). The fMRI changes in euthymia were associated with normal cognitive performance, whereas manic patients committed more errors during response inhibition.

CONCLUSIONS

The rIFG hypoactivations were congruent with a BD trait, which may underlie the impaired response inhibition in mania. Euthymic BD subjects may compensate for the rIFG hypoactivations by hyperactivations of adjacent cortical areas, yielding comparable performance in inhibitory functions and suggesting possibilities for neuromodulation treatment of these cognitive impairments. The reversal of the activation pattern between mania and euthymia has implications for monitoring of treatment response and identification of imminent relapse.