Attentional engagement increases inferior frontal gyrus activity and mutes limbic activity in pediatric bipolar disorder: Meta-analyses of fMRI studies

Abnormal functional connectivity of the intrinsic networks in adolescent bipolar I versus bipolar II disorder

BACKGROUND

The symptoms of pediatric bipolar disorder (PBD)-I and PBD-II differ, but accurate identification at an early stage is difficult and may prevent effective treatment of this disorder. Therefore, it is urgent to elucidate a biological marker based on objective imaging indicators to help distinguish the two. Therefore, this research aims to compare the functional connectivity between PBD-I patient and PBD-II patient in different brain networks.

METHODS

Our study enrolled 31 PBD-I and 23 PBD-II patients from 12 to 17 years of age. They were analyzed by resting state-functional connectivity through Independent component analysis (ICA).

RESULTS

We found differences between PBD-I and PBD-II in functional connectivity of the default network, frontoparietal network, salience network and limbic system. In addition, the clinical features, cognitive functions are associated with the functional connectivity of the intrinsic networks in PBD-I and PBD-II separately.

CONCLUSION

This research is the first to find differences in functional connectivity between PBD-I and PBD-II, suggesting that abnormality of the functional connectivity within large networks may be biomarkers that help differentiate PBD-I from PBD-II in the future.

Resting-state fMRI is associated with trauma experiences, mood and psychosis in Afro-descendants with bipolar disorder and schizophrenia

BACKGROUND

Bipolar disorder (BD) and schizophrenia (SCZ) may exhibit functional abnormalities in several brain areas, including the medial temporal and prefrontal cortex and hippocampus; however, a less explored topic is how brain connectivity is linked to premorbid trauma experiences and clinical features in non-Caucasian samples of SCZ and BD.

METHODS

Sixty-two individuals with SCZ (n = 20), BD (n = 21), and healthy controls (HC, n = 21) from indigenous and African ethnicity were submitted to clinical screening (Di-PAD), traumata experiences (ETISR-SF), cognitive and functional MRI assessment. The item psychosis/hallucinations in SCZ patients showed a negative correlation with the global efficiency (GE) in the right dorsal attention network. The items mania, irritable mood, and racing thoughts in the Di-PAD scale had a significant negative correlation with the GE in the parietal right default mode network.

CONCLUSIONS

Differences in the activation of specific networks were associated with earlier disease onset, history of physical abuse, and more severe psychotic and mood symptoms in SCZ and BD subjects of indigenous and black ethnicity. Findings provide further evidence on SZ and BD's brain connectivity disturbances, and their clinical significance, in non-Caucasian samples.

Shared and Distinct Neurobiological Bases of Bipolar Disorder and Attention-Deficit/Hyperactivity Disorder in Children and Adolescents: A Comparative Meta-Analysis of Structural Abnormalities

OBJECTIVE

Pediatric bipolar disorder (PBD) and attention-deficit/hyperactivity disorder (ADHD) frequently co-occur and share dysfunctions in affective and cognitive domains. As the neural substrates underlying their overlapping and dissociable symptomatology have not been well delineated, a meta-analysis of whole-brain voxel-based morphometry studies in PBD and ADHD was conducted.

METHOD

A systematic literature search was performed in PubMed, Web of Science, and Embase. The seed-based d mapping toolbox was used to identify altered clusters of PBD or ADHD and obtain their conjunctive and comparative abnormalities. Suprathreshold patterns were subjected to large-scale network analysis to identify affected brain networks.

RESULTS

The search revealed 10 PBD studies (268 patients) and 32 ADHD studies (1,333 patients). Decreased gray matter volumes in the right insula and anterior cingulate cortex relative to typically developing individuals were conjunctive in PBD and ADHD. Reduced volumes in the right inferior frontal gyrus, left orbitofrontal cortex, and hippocampus were more substantial in PBD, while decreased volumes in the left precentral gyrus, left inferior frontal gyrus, and right superior frontal gyrus were more pronounced in ADHD. Neurodevelopmental effects modulated patterns of the left hippocampus in PBD and those of the left inferior frontal gyrus in ADHD.

CONCLUSION

These findings suggest that PBD and ADHD are characterized by both common and distinct patterns of gray matter volume alterations. Their overlapping abnormalities may represent a transdiagnostic problem of attention and emotion regulation shared by PBD and ADHD, whereas the disorder-differentiating substrates may contribute to the relative differences in cognitive and affective features that define the 2 disorders.

PLAIN LANGUAGE SUMMARY

Pediatric bipolar disorder (BD) and attention-deficit/hyperactivity disorder (ADHD) frequently co-occur, with overlapping changes in emotional and cognitive functioning. This meta-analysis summarizes findings from 10 articles on BD and 32 articles on ADHD to identify similarities and differences in brain structure between youth with BD and youth with ADHD. The authors found that both disorders share decreased gray matter volumes in the right insula and anterior cingulate cortex, which play important roles in emotion processing and attention, respectively. Youth with BD had decreased gray matter volume in the right inferior frontal gyrus, left orbitofrontal gyrus, and left hippocampus, while youth with ADHD had decreased volumes in the left precentral gyrus, left inferior frontal gyrus, and right superior frontal gyrus.

STUDY PREREGISTRATION INFORMATION

Structural Brain Abnormalities of Attention-Deficit/Hyperactivity Disorder and Bipolar Disorder in Children/Adolescents: An Overlapping Meta-analysis; https://osf.io; trg4m.

Neuroimaging alterations associated with medication use in early-onset bipolar disorder: An updated review

BACKGROUND

Pediatric bipolar disorder (PBD) is a severe disorder characterized by mood fluctuations starting at a young age. Several neuroimaging studies revealed a specific biological signature of PBD involving alterations in the amygdala and prefrontal regions. Considering the growing concerns regarding the effects of PBD treatments on developing brains, this review aims to provide an overview of the studies investigating the effect of mood stabilizers, antipsychotics, and anticonvulsants on neuroimaging findings in PBD.

METHODS

We searched PubMed, Scopus, and Web of Science to identify all structural magnetic resonance imaging (sMRI), functional magnetic resonance imaging (fMRI), and diffusion tensor imaging (DTI) studies exploring the effects of medications on neuroimaging findings in PBD. A total of 18 studies met our inclusion criteria (fMRI n = 11, sMRI n = 6, DTI n = 1).

RESULTS

Although the findings varied highly across the studies, some investigations consistently indicated that medications primarily affect the prefrontal cortex and the amygdala. Moreover, despite some exceptions, the reported medication effects predominantly lean towards structural and functional normalization.

LIMITATIONS

The reviewed studies differ in methods, medications, and fMRI paradigms. Furthermore, most studies used observational approaches with small sample sizes, minimizing the statistical power.

CONCLUSIONS

Evidence suggests the potential of antipsychotics and mood stabilizers to modulate the neuroimaging findings in PBD patients, mostly normalizing brain structure and function in key mood-regulating regions.

The brain network underlying attentional blink predicts symptoms of attention deficit hyperactivity disorder in children

Attention deficit hyperactivity disorder (ADHD) is a chronic neuropsychiatric disease that can markedly impair educational, social, and occupational function throughout life. Behavioral deficits may provide clues to the underlying neurological impairments. Children with ADHD exhibit a larger attentional blink (AB) deficit in rapid serial visual presentation (RSVP) tasks than typically developing children, so we examined whether brain connectivity in the neural network associated with AB can predict ADHD symptoms and thus serve as potential biomarkers of the underlying neuropathology. We first employed a connectome-based predictive model analysis of adult resting-state functional magnetic resonance imaging data to identify a distributed brain network for AB. The summed functional connectivity (FC) strength within the AB network reliably predicted individual differences in AB magnitude measured by a classical dual-target RSVP task. Furthermore, the summed FC strength within the AB network predicted individual differences in ADHD Rating Scale scores from an independent dataset of pediatric patients. Our findings suggest that the individual AB network could serve as an applicable neuroimaging-based biomarker of AB deficit and ADHD symptoms.

The inferior frontal gyrus and familial risk for bipolar disorder

Bipolar disorder (BD) is a familial disorder with high heritability. Genetic factors have been linked to the pathogenesis of BD. Relatives of probands with BD who are at familial risk can exhibit brain abnormalities prior to illness onset. Given its involvement in prefrontal cognitive control and in frontolimbic circuitry that regulates emotional reactivity, the inferior frontal gyrus (IFG) has been a focus of research in studies of BD-related pathology and BD-risk mechanism. In this review, we discuss multimodal neuroimaging findings of the IFG based on studies comparing at-risk relatives and low-risk controls. Review of these studies in at-risk cases suggests the presence of both risk and resilience markers related to the IFG. At-risk individuals exhibited larger gray matter volume and increased functional activities in IFG compared with low-risk controls, which might result from an adaptive brain compensation to support emotion regulation as an aspect of psychological resilience. Functional connectivity between IFG and downstream limbic or striatal areas was typically decreased in at-risk individuals relative to controls, which could contribute to risk-related problems of cognitive and emotional control. Large-scale and longitudinal investigations on at-risk individuals will further elucidate the role of IFG and other brain regions in relation to familial risk for BD, and together guide identification of at-risk individuals for primary prevention.

Resting-state functional connectivity and spontaneous brain activity in early-onset bipolar disorder: A review of functional Magnetic Resonance Imaging studies

BACKGROUND

Early-onset bipolar disorder (BD) is a complex psychiatric illness characterized by mood swings, irritability and functional impairments. To improve our understanding of the pathophysiology of the disorder, we collected the existing resting-state functional Magnetic Resonance Imaging (rs-fMRI) studies exploring resting-state functional connectivity (rs-FC) and spontaneous activity alterations in children and adolescents with BD.

METHODS

A search on PubMed, Web of Science and Scopus was conducted to identify all the relevant rs-fMRI investigations conducted in early-onset BD. A total of 14 studies employing different methodological approaches to explore rs-FC and spontaneous activity in early-onset BD were included (independent component analysis, n = 1; seed-based analysis, n = 7; amplitude of low frequency fluctuations analysis, n = 2; regional homogeneity analysis, n = 4).

RESULTS

Overall, the studies showed abnormalities within the Default Mode Network (DMN) and between the DMN and the Salience Network (SN). Moreover, widespread alterations in rs-FC and spontaneous brain activity within and between cortico-limbic structures, involving primarily the occipital and frontal lobes, amygdala, hippocampus, insula, thalamus and striatum were also reported.

LIMITATIONS

The small sample sizes, the use of medications, the presence of comorbidities and the heterogeneity in methods hamper the integration of the study findings.

CONCLUSIONS

Early-onset BD seems to be characterized by selective rs-FC and spontaneous activity dysfunctions in DMN and SN as well as in the cortico-limbic and cortico-striatal circuits, which could explain the emotive and cognitive deficits observed in this disabling psychiatric illness.

Pretreatment Alterations and Acute Medication Treatment Effects on Brain Task-Related Functional Connectivity in Youth With Bipolar Disorder: A Neuroimaging Randomized Clinical Trial

OBJECTIVE

Disruptions in cognition are a clinically significant feature of bipolar disorder (BD). The effects of different treatments on these deficits and the brain systems that support them remain to be established.

METHOD

A continuous performance test was administered to 55 healthy controls and 71 acutely ill youths with mixed/manic BD to assess vigilance and working memory during task-based functional magnetic resonance imaging studies. Patients, who were untreated for at least 7 days at baseline, and controls were scanned at pretreatment baseline and at weeks 1 and 6. After baseline testing, patients (n = 71) were randomly assigned to 6-week double-blind treatment with lithium (n = 26; 1.0-1.2 mEq/L) or quetiapine (n = 45; 400-600 mg). Weighted seed-based connectivity (wSBC) was used to assess regional brain interactions during the attention task compared with the control condition.

RESULTS

At baseline, youths with BD showed reduced connectivity between bilateral anterior cingulate cortex and both left ventral lateral prefrontal cortex and left insula and increased connectivity between left ventral lateral prefrontal cortex and left temporal pole, left orbital frontal cortex and right postcentral gyrus, and right amygdala and right occipital pole compared with controls. At 1-week follow-up, quetiapine, but not lithium, treatment led to a significant shift of connectivity patterns toward those of the controls. At week 6, compared with baseline, there was no difference between treatment conditions, at which time both patient groups showed significant normalization of brain connectivity toward that of controls.

CONCLUSION

Functional alterations in several brain regions associated with cognitive processing and the integration of cognitive and affective processing were demonstrated in untreated youths with BD before treatment. Treatment reduced several of these alterations, with significant effects at week 1 only in the quetiapine treatment group. Normalization of functional connectivity might represent a promising biomarker for early target engagement in youth with BD.

CLINICAL TRIAL REGISTRATION INFORMATION

Multimodal Neuroimaging of Treatment Effects in Adolescent Mania; https://clinicaltrials.gov/; NCT00893581.

Research Status in Clinical Practice Regarding Pediatric and Adolescent Bipolar Disorders

Bipolar disorders (BDs) have high morbidity. The first onset of 27.7% of BDs occurs in children under 13 years and of 37.6% occurs in adolescents between 13 and 18 years. However, not all of the pediatric and adolescent patients with BD receive therapy in time. Therefore, studies about pediatric and adolescent patients with disorders have aroused increased attention in the scientific community. Pediatric and adolescent patients with BD present with a high prevalence rate (0.9-3.9%), and the pathogenic factors are mostly due to genetics and the environment; however, the pathological mechanisms remain unclear. Pediatric and adolescent patients with BD manifest differently from adults with BDs and the use of scales can be helpful for diagnosis and treatment evaluation. Pediatric and adolescent patients with BDs have been confirmed to have a high comorbidity rate with many other kinds of disorders. Both medication and psychological therapies have been shown to be safe and efficient methods for the treatment of BD. This review summarizes the research status related to the epidemiology, pathogenic factors, clinical manifestations, comorbidities, diagnostic and treatment scales, medications, and psychological therapies associated with BDs.

Altered spatiotemporal consistency in pediatric bipolar disorder patients with and without psychotic symptoms

OBJECTIVE

Psychotic symptoms are quite common in patients with pediatric bipolar disorder (PBD) and may affect the symptom severity and prognosis of PBD. However, the potential mechanisms are less well elucidated until now. Thus, the purpose of this study was to investigate the brain functional differences between PBD patients with and without psychotic symptoms.

METHOD

A total of 71 individuals including: 27 psychotic PBD (P-PBD), 25 nonpsychotic PBD (NP-PBD), and 19 healthy controls were recruited in the present study. Each subject underwent 3.0 Tesla functional magnetic resonance imaging scan. Four-dimensional (spatiotemporal) Consistency of local neural Activities (FOCA) was employed to detect the local brain activity changes. Analyses of variance (ANOVA) were used to reveal brain regions with significant differences among three groups groups of individuals, and inter-group comparisons were assessed using post hoc tests.

RESULTS

The ANOVA obtained significant among-group FOCA differences in the left triangular inferior frontal gyrus, left supplementary motor area, left precentral gyrus, right postcentral gyrus, right superior occipital gyrus, and right superior frontal gyrus. Compared with the control group, the P-PBD group showed decreased FOCA in the left supplementary motor area and bilateral superior frontal gyrus and showed increased FOCA in the left triangular inferior frontal gyrus. In contrast, the NP-PBD group exhibited decreased FOCA in the right superior occipital gyrus and right postcentral gyrus and showed increased FOCA in the left orbital inferior frontal gyrus. Compared to the NP-PBD group, the P-PBD group showed decreased FOCA in the right superior frontal gyrus.

CONCLUSION

The present findings demonstrated that the two groups of PBD patients exhibited segregated brain functional patterns, providing empirical evidence for the biological basis of different clinical outcomes between PBD patients with and without psychotic symptoms.

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.

A preliminary study on functional activation and connectivity during frustration in youths with bipolar disorder

OBJECTIVES

Frustration is associated with impaired attention, heightened arousal, and greater unhappiness in youths with bipolar disorder (BD) vs healthy volunteers (HV). Little is known about functional activation and connectivity in the brain of BD youths in response to frustration. This exploratory study compared BD youths and HV on attentional abilities, self-reported affect, and functional activation and connectivity during a frustrating attention task.

METHODS

Twenty BD (Mage  = 15.86) and 20 HV (Mage  = 15.55) youths completed an fMRI paradigm that differentiated neural responses during processing of frustrating feedback from neural responses during attention orienting following frustrating feedback. We examined group differences in (a) functional connectivity using amygdala, inferior frontal gyrus (IFG), and striatum as seeds and (b) whole-brain and regions of interest (amygdala, IFG, striatum) activation. We explored task performance (accuracy, reaction time), self-reported frustration and unhappiness, and correlations between these variables and irritability, depressive, and manic symptoms.

RESULTS

Bipolar disorder youths, relative to HV, exhibited positive IFG-ventromedial prefrontal cortex (vmPFC) connectivity yet failed to show negative striatum-insula connectivity during feedback processing. Irritability symptoms were positively associated with striatum-insula connectivity during feedback processing. Moreover, BD vs HV youths showed positive IFG-parahippocampal gyrus (PHG)/periaqueductal gray (PAG) connectivity and negative amygdala-cerebellum connectivity during attention orienting following frustration. BD was not associated with atypical activation patterns.

CONCLUSIONS

Positive IFG-vmPFC connectivity and striatum-insula decoupling in BD during feedback processing may mediate heightened sensitivity to reward-relevant stimuli. Elevated IFG-PAG/PHG connectivity in BD following frustration may suggest greater recruitment of attention network to regulate arousal and maintain goal-directed behavior.

Children with euthymic bipolar disorder during an emotional go/nogo task: Insights into the neural circuits of cognitive-emotional regulation

BACKGROUND

Pediatric bipolar disorder (PBD), manifested by alternating episodes of depression and mania, is more likely to relapse than adult BD and develop into chronic BD. Although it can be asymptomatic during the remission of PBD, subtle changes in the brain neural response can still exist. Abnormal activities in the neural circuits of cognitive-emotional regulation have been found in adult BD patients using fMRI. However, few fMRI studies focus on emotional regulation on cognitive function in euthymic PBD, especially during an emotional go/nogo task. Therefore, this study aims to compare differences in the activities of both emotional and cognitive circuits between euthymic BD children and healthy controls.

METHODS

18 euthymic PBD and 17 healthy subjects from 12 to 17 years of age were enrolled in our study. Simultaneous neural activity was recorded during the overall task and the effect of emotional factors on task performances was assessed.

RESULTS

There were no significant differences in behavioral performances between the PBD group and the control group. During a task with emotional versus neutral distractors, euthymic PBD patients showed increased activities in the DLPFC, inferior parietal lobule, superior/middle frontal gyrus, superior/middle temporal gyrus, insula, posterior cingulate gyrus and posterior cerebellum lobe relative to healthy controls. The insula and DLPFC activities in response to emotional versus neutral distractors were positively associated with the differences in false response errors.

CONCLUSIONS

This study confirms the enhanced neural activities in euthymic PBD during a task with emotional versus control distractors. These brain regions supporting the cognitive and emotional dysregulation of PBD mainly coincide with the salience and executive control networks. As neural responses are more sensitive than behavioral manifestations in euthymic PBD, our findings will inspire more clinical studies to unveil the characteristic neuromechanism of PBD.

Sex difference in glia gene expression in the dorsolateral prefrontal cortex in bipolar disorder: Relation to psychotic features

BACKGROUND

Suicide, psychotic features and gender influence the epidemiology and clinical prognosis of bipolar disorder (BD). Differences in glial function between the genders might contribute to these clinical variables. Here we studied expression of glial genes in human post-mortem prefrontal cortex of BD and control subjects in relation to suicide, psychotic features and sex.

METHODS

Real time PCR was used to detect transcriptional alterations of 16 glia-related genes in two brain areas, the dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC), from 30 patients with BD subdivided by suicide and psychotic features, and from 34 well-matched control cases.

RESULTS

We found no evidence of immune activation in BD. Instead, we found three microglial genes to be downregulated in the DLPFC of non-suicidal individuals with BD, i.e. CD68, triggering receptor expressed on myeloid cells 2 (TREM2) and purinergic receptor 12 (P2RY12). A remarkable sex difference was observed in the DLPFC of patients with BD: 14 glia-related genes were expressed at significantly higher levels in males, including all three glial cell types. A subset analysis showed that the sex differences were closely associated with the presence of psychotic features.

CONCLUSIONS

No evidence of immune activation was found in these two brain regions in BD. The sex-specific differences in glial gene expression in BD, found particularly in patients with psychotic features, may be associated with the potential co-existence of mania and psychotic features and could potentially contribute to the gender-biased characteristics in BD.