Deficits in frontoparietal activation and anterior insula functional connectivity during regulation of cognitive-affective interference in bipolar disorder

Dynamic functional connectivity in schizophrenia and bipolar disorder: A review of the evidence and associations with psychopathological features

Alterations of functional network connectivity have been implicated in the pathophysiology of schizophrenia (SCZ) and bipolar disorder (BD). Recent studies also suggest that the temporal dynamics of functional connectivity (dFC) can be altered in these disorders. Here, we summarized the existing literature on dFC in SCZ and BD, and their association with psychopathological and cognitive features. We systematically searched PubMed, Web of Science, and Scopus for studies investigating dFC in SCZ and BD and identified 77 studies. Our findings support a general model of dysconnectivity of dFC in SCZ, whereas a heterogeneous picture arose in BD. Although dFC alterations are more severe and widespread in SCZ compared to BD, dysfunctions of a triple network system underlying goal-directed behavior and sensory-motor networks were present in both disorders. Furthermore, in SCZ, positive and negative symptoms were associated with abnormal dFC. Implications for understanding the pathophysiology of disorders, the role of neurotransmitters, and treatments on dFC are discussed. The lack of standards for dFC metrics, replication studies, and the use of small samples represent major limitations for the field.

Intrinsic functional connectivity correlates of cognitive deficits involving sustained attention and executive function in bipolar disorder

BACKGROUND

The neural correlate of cognitive deficits in bipolar disorder (BD) is an issue that warrants further investigation. However, relatively few studies have examined the intrinsic functional connectivity (FC) underlying cognitive deficits involving sustained attention and executive function at both the region and network levels, as well as the different relationships between connectivity patterns and cognitive performance, in BD patients and healthy controls (HCs).

METHODS

Patients with BD (n = 59) and HCs (n = 52) underwent structural and resting-state functional magnetic resonance imaging and completed the Wisconsin Card Sorting Test (WCST), the continuous performance test and a clinical assessment. A seed-based approach was used to evaluate the intrinsic FC alterations in three core neurocognitive networks (the default mode network [DMN], the central executive network [CEN] and the salience network [SN]). Finally, we examined the relationship between FC and cognitive performance by using linear regression analyses.

RESULTS

Decreased FC was observed within the DMN, in the DMN-SN and DMN-CEN and increased FC was observed in the SN-CEN in BD. The alteration direction of regional FC was consistent with that of FC at the brain network level. Decreased FC between the left posterior cingulate cortex and right anterior cingulate cortex was associated with longer WCST completion time in BD patients (but not in HCs).

CONCLUSIONS

These findings emphasize the dominant role of the DMN in the psychopathology of BD and provide evidence that cognitive deficits in BD may be associated with aberrant FC between the anterior and posterior DMN.

Alcohol use is associated with affective and interoceptive network alterations in bipolar disorder

INTRODUCTION

Alcohol use in bipolar disorder (BD) is associated with mood lability and negative illness trajectory, while also impacting functional networks related to emotion, cognition, and introspection. The adverse impact of alcohol use in BD may be explained by its additive effects on these networks, thereby contributing to a poorer clinical outcome.

METHODS

Forty BD-I (DSM-IV-TR) and 46 psychiatrically healthy controls underwent T1 and resting state functional MRI scanning and the Alcohol Use Disorders Identification Test-Consumption (AUDIT-C) to assess alcohol use. Functional images were decomposed using spatial independent component analysis into 14 resting state networks (RSN), which were examined for effect of alcohol use and diagnosis-by-alcohol use accounting for age, sex, and diagnosis.

RESULTS

Despite the groups consuming similar amounts of alcohol (BD: mean score ± SD 3.63 ± 3; HC 4.72 ± 3, U = 713, p = .07), for BD participants, greater alcohol use was associated with increased connectivity of the paracingulate gyrus within a default mode network (DMN) and reduced connectivity within an executive control network (ECN) relative to controls. Independently, greater alcohol use was associated with increased connectivity within an ECN and reduced connectivity within a DMN. A diagnosis of BD was associated with increased connectivity of a DMN and reduced connectivity of an ECN.

CONCLUSION

Affective symptomatology in BD is suggested to arise from the aberrant functionality of networks subserving emotive, cognitive, and introspective processes. Taken together, our results suggest that during euthymic periods, alcohol can contribute to the weakening of emotional regulation and response, potentially explaining the increased lability of mood and vulnerability to relapse within the disorder.

Coping drinking motives, neural functional coupling during emotion processing, and alcohol use in young adults with bipolar disorder

BACKGROUND

Rates of alcohol use disorders in individuals with bipolar disorder are 3 to 5 times greater than in the general population and exceed rates of alcohol use disorders reported in other affective and anxiety disorders. Despite this high rate of comorbidity, our understanding of the psychosocial and neural mechanisms that underlie the initiation of alcohol misuse in young adults with bipolar disorder remains limited. Prior work suggests that individuals with bipolar disorder may misuse alcohol as a coping mechanism, yet the neural correlates of coping drinking motives and associated alcohol use have not been previously investigated in this population.

METHODS

Forty-eight young adults (22 bipolar disorder type I, 26 typically developing; 71% women; average age ± standard deviation = 22 ± 2 years) completed the Drinking Motives and Daily Drinking Questionnaires, and a Continuous Performance Functional magnetic resonance imaging (fMRI) Task with Emotional and Neutral Distracters. We calculated the relative difference in anterior cingulate cortex (ACC) functional coupling with the anterior insula and amygdala in response to emotional distracters compared with neutral stimuli and investigated the relations with coping drinking motives and alcohol use.

RESULTS

Across all participants, coping drinking motives were associated with greater quantity of recent alcohol use. In individuals with bipolar disorder, greater ACC-anterior insula functional coupling was associated with greater coping drinking motives, and greater quantity and frequency of recent alcohol use. The relative difference in ACC-anterior insula functional coupling was not associated with coping drinking motives or alcohol use in the typically developing group. Greater ACC-anterior insula functional coupling in individuals with bipolar disorder was also associated with greater anxiety symptoms and recent perceived psychological stress. Exploratory analyses suggest that the relations between ACC-anterior insula functional coupling and coping drinking motives may be confounded by anticonvulsant use.

CONCLUSION

Results suggest that a difference in ACC-anterior insula functional coupling during emotion processing may underlie alcohol use as a maladaptive coping mechanism in young adults with bipolar disorder.

The neurobiology of misophonia and implications for novel, neuroscience-driven interventions

Decreased tolerance in response to specific every-day sounds (misophonia) is a serious, debilitating disorder that is gaining rapid recognition within the mental health community. Emerging research findings suggest that misophonia may have a unique neural signature. Specifically, when examining responses to misophonic trigger sounds, differences emerge at a physiological and neural level from potentially overlapping psychopathologies. While these findings are preliminary and in need of replication, they support the hypothesis that misophonia is a unique disorder. In this theoretical paper, we begin by reviewing the candidate networks that may be at play in this complex disorder (e.g., regulatory, sensory, and auditory). We then summarize current neuroimaging findings in misophonia and present areas of overlap and divergence from other mental health disorders that are hypothesized to co-occur with misophonia (e.g., obsessive compulsive disorder). Future studies needed to further our understanding of the neuroscience of misophonia will also be discussed. Next, we introduce the potential of neurostimulation as a tool to treat neural dysfunction in misophonia. We describe how neurostimulation research has led to novel interventions in psychiatric disorders, targeting regions that may also be relevant to misophonia. The paper is concluded by presenting several options for how neurostimulation interventions for misophonia could be crafted.

Convergence between behavioral, neural, and self-report measures of cognitive control: The Frontal Systems Behavior Scale in bipolar disorder

The Frontal Systems Behavior Scale (FrSBe) is a self-report measure that assesses difficulties with cognitive and emotional control such as apathetic behavior, lack of inhibitory control, and executive dysfunction. Previous neuroimaging studies highlight the involvement of the anterior cingulate cortex (ACC), orbitofrontal cortex (OFC), and dorsolateral prefrontal cortex (DLPFC) in these processes. In this study, we investigated whether there was convergence across subjective and objective measures of apathy, disinhibition, and executive dysfunction. Specifically, we studied whether ACC, OFC, and DLPFC activation during a modified version of the Multi-Source Interference Task (MSIT), is associated with FrSBe apathy, disinhibition, and executive dysfunction scores, in healthy controls (HC) and individuals with Bipolar Disorder (BD), who commonly exhibit difficulties in these domains. Individuals with BD (n = 31) and HCs (n = 31) with no current or past psychiatric illness completed the FrSBe and the MSIT during fMRI scanning. We investigated task-specific changes in the ACC, DLPFC, and OFC and their correlations with FrSBe apathy, disinhibition, and executive dysfunction subscale scores, respectively. Individuals with BD and the HC group demonstrated greater ACC, DLPFC, and OFC activation during MSIT interference conditions compared with non-interference conditions. Furthermore, there was a significant negative correlation between OFC activation and disinhibition scores, which remained significant after accounting for medication load. Together, these results demonstrate the FrSBe disinhibition subscale, in particular, can be a self-report measure that converges with behavioral and neural markers of disinhibition in BD.

Altered task-modulated functional connectivity during emotional face processing in euthymic bipolar patients: A whole-brain psychophysiological interaction study

BACKGROUND

Patients with bipolar disorder (BD) show deficits of facial emotion processing even in the euthymic phase. However, the large-scale functional brain network mechanism underlying the emotional deficit of BD remains unclear. Specifically, it is of importance to understand how the task-modulated functional connectivity (FC) was alternated over distributed brain networks in BD.

METHODS

In this study, we analyzed functional MRI data of a face-matching task from 29 euthymic BD patients and 29 healthy controls (HC), and performed whole-brain psychophysiological interaction (PPI) analysis to obtain task-modulated FC. Abnormal FC patterns were identified through support vector machine-based classification. The topological organization of task-modulated FC networks was estimated by the graph theoretical analysis and compared between BD and HC.

RESULTS

BD exhibited widely distributed aberrant task-modulated FC patterns not only in core neurocognitive intrinsic brain networks (the fronto-parietal, cingulo-opercular, and default mode networks), but also in the cerebellum and primary processing networks (sensorimotor and visual). Furthermore, the local efficiency of the frontal-parietal network was significantly increased in BD.

LIMITATIONS

The modest sample size. Only face pictures with negative emotion were used. Only unidirectional task-modulated FC was investigated.

CONCLUSIONS

BD patients showed a widely distributed aberrant task-modulated FC pattern. Particularly, the fronto-parietal network, as one of the core neurocognitive intrinsic brain networks, was the primary network that demonstrated changes of both FC strength and local efficiency in BD. These findings on the task-modulated FC between these intrinsic brain networks might be considered an endophenotype of the BD condition persistent in the euthymic state.

Dimensional Affective Processing in BD

Bipolar Disorder (BD) involves altered neural affective processing, but studies comparing BD patients to controls have yielded inconsistent results. This might relate to substantial variability in the nature and severity of mood symptoms among individuals with BD. Hence, we dimensionally examined the relationship between depressive and manic symptom severity and neural responses to positive and negative affective stimuli. 39 Participants with BD completed measures of depression and mania severity prior to completing a cognitive-affective processing task during fMRI. A multiple regression model was run in SPM to identify brain regions correlated with depressive and manic symptoms during positive-neutral and negative-neutral contrasts. A-priori anatomical ROIs were defined bilaterally in frontal, parietal and limbic regions. Results showed that depression severity was associated with increased activation in frontal, parietal, and limbic ROIs, regardless of valence. Mania severity was correlated with both increased and decreased activation, particularly within frontal subdivisions and during the processing of positively valenced images. In conclusion, dimensional modeling of symptom severity captures variance in neural responses to affect, which may have been previously undetected due to heterogeneity when examined at the group level. Future fMRI studies comparing BD patients and controls should account for symptom variability in BD.

Results from a randomized, double-blind, placebo-controlled, crossover, multimodal-MRI pilot study of gabapentin for co-occurring bipolar and cannabis use disorders

Disrupted brain gamma-aminobutyric acid (GABA)/glutamate homeostasis is a promising target for pharmacological intervention in co-occurring bipolar disorder (BD) and cannabis use disorder (CUD). Gabapentin is a safe and well-tolerated medication, FDA-approved to treat other neurological diseases, that restores GABA/glutamate homeostasis, with treatment studies supporting efficacy in treating CUD, as well as anxiety and sleep disorders that are common to both BD and CUD. The present manuscript represents the primary report of a randomized, double-blind, placebo-controlled, crossover (1-week/condition), multimodal-MRI (proton-MR spectroscopy, functional MRI) pilot study of gabapentin (1200 mg/day) in BD + CUD (n = 22). Primary analyses revealed that (1) gabapentin was well tolerated and adherence and retention were high, (2) gabapentin increased dorsal anterior cingulate cortex (dACC) and right basal ganglia (rBG) glutamate levels and (3) gabapentin increased activation to visual cannabis cues in the posterior midcingulate cortex (pMCC, a region involved in response inhibition to rewarding stimuli). Exploratory evaluation of clinical outcomes further found that in participants taking gabapentin versus placebo, (1) elevations of dACC GABA levels were associated with lower manic/mixed and depressive symptoms and (2) elevations of rBG glutamate levels and pMCC activation to cannabis cues were associated with lower cannabis use. Though promising, the findings from this study should be interpreted with caution due to observed randomization order effects on dACC glutamate levels and identification of statistical moderators that differed by randomization order (i.e. cigarette-smoking status on rBG glutamate levels and pMCC cue activation). Nonetheless, they provide the necessary foundation for a more robustly designed (urn-randomized, parallel-group) future study of adjuvant gabapentin for BD + CUD.

Restoration of default mode network and task positive network anti-correlation associated with mindfulness-based cognitive therapy for bipolar disorder

Individuals with bipolar disorder (BP) show abnormalities in the default mode network (DMN), a brain network active at rest and during self-referential cognition. In healthy individuals, the DMN is anti-correlated (strongly negatively correlated) with the task positive network (TPN), a brain network that is active during attention demanding tasks. Mindfulness has been linked to changes in DMN connectivity. We investigated the effects of mindfulness-based cognitive therapy (MBCT) versus supportive psychotherapy (SP) on the relationship between these two networks in individuals with BP. We identified differences in BOLD resting state DMN-TPN connectivity between healthy controls (HC; n = 22) and individuals with DSM-IV BP before treatment (n = 22) using a seed region in the dorsolateral prefrontal cortex (DLPFC), a key TPN node. We then explored changes in DMN-TPN connectivity after 12 weeks of MBCT or SP. Before treatment, BP individuals showed positively correlated activity and the HC group showed negatively correlated activity between the DLPFC and the posterior cingulate cortex (PCC). After treatment, BP individuals who received MBCT showed negatively correlated DLPFC-PCC activity. BP individuals who received SP did not show a significant change. Mindfulness-based cognitive therapy can restore the anti-correlation between the DMN and TPN in individuals with BP.

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.

Altered functional activity in bipolar disorder: A comprehensive review from a large-scale network perspective

BACKGROUND

Growing literature continues to identify brain regions that are functionally altered in bipolar disorder. However, precise functional network correlates of bipolar disorder have yet to be determined due to inconsistent results. The overview of neurological alterations from a large-scale network perspective may provide more comprehensive results and elucidate the neuropathology of bipolar disorder. Here, we critically review recent neuroimaging research on bipolar disorder using a network-based approach.

METHODS

A systematic search was conducted on studies published from 2009 through 2019 in PubMed and Google Scholar. Articles that utilized functional magnetic resonance imaging technique to examine altered functional activity of major regions belonging to a large-scale brain network in bipolar disorder were selected.

RESULTS

A total of 49 studies were reviewed. Within-network hypoconnectivity was reported in bipolar disorder at rest among the default mode, salience, and central executive networks. In contrast, when performing a cognitive task, hyperconnectivity among the central executive network was found. Internetwork functional connectivity in the brain of bipolar disorder was greater between the salience and default mode networks, while reduced between the salience and central executive networks at rest, compared to control.

CONCLUSION

This systematic review suggests disruption in the functional activity of large-scale brain networks at rest as well as during a task stimuli in bipolar disorder. Disrupted intra- and internetwork functional connectivity that are also associated with clinical symptoms suggest altered functional connectivity of and between large-scale networks plays an important role in the pathophysiology of bipolar disorder.

Altered Functional Integration in the Salience and Default Mode Networks in Euthymic Pediatric Bipolar Disorder

Accumulating studies demonstrate emotional and cognitive dysregulation in the euthymic period of pediatric bipolar disorder (PBD). However, the relative contribution of functional integration in human brain to disturbed emotion and cognitive function in the euthymic PBD patients remains unclear. In this study, 16 euthymic PBD patients and 16 healthy controls underwent resting-state functional magnetic resonance imaging. A data-driven functional connectivity analysis was used to investigate functional connectivity changes of the euthymic PBD. Compared with healthy controls, the euthymic PBD exhibited greater global functional connectivity density in the left anterior insula and lower global functional connectivity density in the right temporoparietal junction, the left angular gyrus, and the bilateral occipital lobule. A distant functional connectivity analysis demonstrated altered integration within the salience and default mode networks in euthymic PBD. Correlation analysis found that altered functional connectivity of the salience network was related to the reduced performance in the backward digit span test, and altered functional connectivity of the default mode network was related to the Young Mania Rating Scale in euthymic PBD patients. Our findings indicated that disturbed functional integration in salience and default mode networks might shed light on the physiopathology associated with emotional and cognitive dysregulation in PBD.

Intrinsic functional neurocircuitry associated with treatment response to transdiagnostic CBT in bipolar disorder with anxiety

BACKGROUND

Anxiety in bipolar disorder (BD) exacerbates emotion dysregulation and reduces treatment response. We recently conducted a pilot trial of transdiagnostic CBT to target anxiety and emotion dysregulation in BD adjunctive to pharmacotherapy. Reductions in depression and anxiety symptoms were significantly predicted by baseline levels of neuroticism and perceived affective control, as well as changes over time in emotion regulation skills. The present study investigates mechanism of treatment response by examining the relationship between baseline emotion regulation-related neural circuitry and trial outcomes.

METHODS

Nineteen patients completed baseline resting state fMRI scans prior to treatment randomization. Functional connectivity between the anterior insula (AI) and regions in the salience network (SN), default mode network (DMN), and executive control network (ECN) were examined as predictors of baseline and treatment-related changes in emotion regulation.

RESULTS

Greater improvements in emotion regulation were predicted by weaker right dorsal AI - right ventrolateral prefrontal cortex (VLPFC; SN) and stronger bilateral dorsal AI - bilateral amygdala functional connectivity. Baseline neuroticism was negatively correlated with right dorsal AI- inferior parietal lobule (ECN) functional connectivity, and baseline deficits in perceived affective control were positively associated with ventral AI - bilateral dACC (SN) connectivity.

LIMITATIONS

Small sample limits interpretability of treatment-specific effects.

CONCLUSION

Baseline functional connectivity of emotion-regulation related neural circuitry significantly predicted change in emotion regulation-related dimensions associated with anxiety and depression symptom reduction. Future studies are needed to determine if employing methods such as neuromodulation to rehabilitate relevant neural circuitry may improve ultimate treatment outcomes of transdiagnostic CBT for BD and anxiety.