Altered regional homogeneity in pediatric bipolar disorder during manic state: a resting-state fMRI study

Diagnostic value of regional homogeneity and fractional amplitude of low-frequency fluctuations in the classification of schizophrenia and bipolar disorders

Schizophrenia (SCZ) and bipolar disorders (BD) show significant neurobiological and clinical overlap. In this study, we wanted to identify indexes of intrinsic brain activity that could differentiate these disorders. We compared the diagnostic value of the fractional amplitude of low-frequency fluctuations (fALFF) and regional homogeneity (ReHo) estimated from resting-state functional magnetic resonance imaging in a support vector machine classification of 59 healthy controls (HC), 40 individuals with SCZ, and 43 individuals with BD type I. The best performance, measured by balanced accuracy (BAC) for binary classification relative to HC was achieved by a stacking model (87.4% and 90.6% for SCZ and BD, respectively), with ReHo performing better than fALFF, both in SCZ (86.2% vs. 79.4%) and BD (89.9% vs. 76.9%). BD were better differentiated from HC by fronto-temporal ReHo and striato-temporo-thalamic fALFF. SCZ were better classified from HC using fronto-temporal-cerebellar ReHo and insulo-tempo-parietal-cerebellar fALFF. In conclusion, we provided evidence of widespread aberrancies of spontaneous activity and local connectivity in SCZ and BD, demonstrating that ReHo features exhibited superior discriminatory power compared to fALFF and achieved higher classification accuracies. Our results support the complementarity of these measures in the classification of SCZ and BD and suggest the potential for multivariate integration to improve diagnostic precision.

Regional Homogeneity of the Left Posterior Cingulate Gyrus May Be a Potential Imaging Biomarker of Manic Episodes in First-Episode, Drug-Naive Bipolar Disorder

Introduction

Abnormal brain networks with emotional response in bipolar disorder (BD). However, there have been few studies on the local consistency between manic episodes in drug-naive first-episode BD patients and healthy controls (HCs). The purpose of this study is to evaluate the utility of neural activity values analyzed by Regional Homogeneity (ReHo).

Methods

Thirty-seven manic episodes in first-episode, drug-naive BD patients and 37 HCs participated in resting-state functional magnetic resonance rescanning and scale estimation. Reho and receiver operating characteristic (ROC) curve methods were used to analyze the imaging data. Support vector machine (SVM) method was used to analyze ReHo in different brain regions.

Results

Compared to HCs, ReHo increased in the left middle temporal gyrus (MTG.L), posterior cingulate gyrus (PCG), inferior parietal gyrus, and bilateral angular gyrus, and decreased in the left dorsolateral superior frontal gyrus in target group. The ROC results showed that the ReHo value of the left PCG could discriminate the target group from the HCs, and the AUC was 0.8766. In addition, the results of the support vector machine show that the increase in ReHo value in the left PCG can effectively discriminate the patients from the controls, with accuracy, sensitivity, and specificity of 86.02%, 86.49%, and 81.08%, respectively.

Conclusion

The increased activity of the left PCG may contribute new evidence of participation in the pathophysiology of manic episodes in first-episode, drug-naive BD patients. The Reho value of the left posterior cingulate gyrus may be a potential neuroimaging biomarker to discriminate target group from HCs.

Resting-state functional connectivity indicators of risk and resilience for self-harm in adolescent bipolar disorder

BACKGROUND

Suicide is the second leading cause of death in all youth and among adults with bipolar disorder (BD). The risk of suicide in BD is among the highest of all psychiatric conditions. Self-harm, including suicide attempts and non-suicidal self-injury, is a leading risk factor for suicide. Neuroimaging studies suggest reward circuits are implicated in both BD and self-harm; however, studies have yet to examine self-harm related resting-state functional connectivity (rsFC) phenotypes within adolescent BD.

METHODS

Resting-state fMRI data were analyzed for 141 adolescents, ages 13-20 years, including 38 with BD and lifetime self-harm (BD_SH+), 33 with BD and no self-harm (BD_SH-), and 70 healthy controls (HC). The dorsolateral prefrontal cortex (dlPFC), orbitofrontal cortex (OFC) and amygdala were examined as regions of interest in seed-to-voxel analyses. A general linear model was used to explore the bivariate correlations for each seed.

RESULTS

BD_SH- had increased positive rsFC between the left amygdala and left lateral occipital cortex, and between the right dlPFC and right frontal pole, and increased negative rsFC between the left amygdala and left superior frontal gyrus compared to BD_SH+ and HC. BD_SH+ had increased positive rsFC of the right OFC with the precuneus and left paracingulate gyrus compared to BD_SH- and HC.

CONCLUSIONS

This study provides preliminary evidence of altered reward-related rsFC in relation to self-harm in adolescents with BD. Between-group differences conveyed a combination of putative risk and resilience connectivity patterns. Future studies are warranted to evaluate changes in rsFC in response to treatment and related changes in self-harm.

The association of genetic variation in CACNA1C with resting-state functional connectivity in youth bipolar disorder

BACKGROUND

CACNA1C rs1006737 A allele, identified as a genetic risk variant for bipolar disorder (BD), is associated with anomalous functional connectivity in adults with and without BD. Studies have yet to investigate the association of CACNA1C rs1006737 with resting-state functional connectivity (rsFC) in youth BD.

METHODS

Participants included 139 youth with BD-I, -II, or -not otherwise specified, ages 13-20 years, including 27 BD A-carriers, 41 BD non-carriers, 32 healthy controls (HC) A-carriers, and 39 HC non-carriers. Anterior cingulate cortex (ACC), amygdala, and orbitofrontal cortex (OFC) were examined as regions-of-interest in seed-to-voxel analyses. General linear models included main effects of diagnosis and rs1006737, and an interaction term, controlling for age, sex, and race.

RESULTS

We observed a main effect of BD diagnosis on rsFC between the right amygdala and the right occipital pole (p = 0.02), and a main effect of rs1006737 genotypes on rsFC between the right OFC and bilateral occipital cortex (p < 0.001). Two significant BD diagnosis-by-CACNA1C rs1006737 interactions were also identified. The A allele was associated with positive rsFC between the right ACC and right amygdala in BD but negative rsFC in HC (p = 0.01), and negative rsFC between the left OFC and left putamen in BD but positive rsFC in HC (p = 0.01).

CONCLUSION

This study found that the rs1006737 A allele, identified as a genetic risk variant for BD in adults, was differentially associated with rsFC in youth with BD in regions relevant to emotion, executive function, and reward. Future task-based approaches are warranted to better understand brain connectivity in relation to CACNA1C in BD.

Does the Brain Matter? Cortical Alterations in Pediatric Bipolar Disorder: A Critical Review of Structural and Functional Magnetic Resonance Studies

Pediatric bipolar disorder (PBD) is associated with significant psychosocial impairment, high use of mental health services and a high number of relapses and hospitalization. Neuroimaging techniques provide the opportunity to study the neurodevelopmental processes underlying PBD, helping to identify the endophenotypic markers of illness and early biological markers of PBD. The aim of the study is to review available studies assessing structural and functional brain correlates associated with PBD. PubMed, ISI Web of Knowledge and PsychINFO databases have been searched. Studies were included if they enrolled patients aged 0-18 years with a main diagnosis of PBD according to ICD or DSM made by a mental health professional, adopted structural and/or functional magnetic resonance as the main neuroimaging method, were written in English and included a comparison with healthy subjects. Of the 400 identified articles, 46 papers were included. Patients with PBD present functional and anatomic alterations in structures normally affecting regulations and cognition. Structural neuroimaging revealed a significant reduction in gray matter, with cortical thinning in bilateral frontal, parietal and occipital cortices. Functional neuroimaging studies reported a reduced engagement of the frontolimbic and hyperactivation of the frontostriatal circuitry. Available studies on brain connectivity in PBD patients potentially indicate less efficient connections between regions involved in cognitive and emotional functions. A greater functional definition of alteration in brain functioning of PBD patients will be useful to set up a developmentally sensitive targeted pharmacological and nonpharmacological intervention.

The impacts of anhedonia on brain functional alterations in patients with major depressive disorder: A resting-state functional magnetic resonance imaging study of regional homogeneity

BACKGROUND

Anhedonia, as one of the core manifestations of major depressive disorder (MDD), has an effect on prognosis of the disease. However, the neuropathology of MDD is complex and the neural basis of anhedonia remains unclear. The aim of the present study was to investigate the impacts of anhedonia on brain functional alterations in patients with MDD.

METHODS

A total of 62 individuals including MDD patients with anhedonia (n = 22), MDD patients without anhedonia (n = 20), and healthy controls (HCs, n = 20) were recruited. All participants underwent resting-state functional magnetic resonance imaging scanning and intrinsic brain function was explored by using regional homogeneity (ReHo) method. A two-sample t-test was performed to explore ReHo differences between MDD patients and HCs, then analysis of variance (ANOVA) was introduced to obtain brain regions with significant differences among three groups, and finally post hoc tests were calculated for inter-group comparisons. Correlations between ReHo values of each survived area and clinical characteristics in MDD patients were further analyzed.

RESULTS

Compared with HCs, MDD showed increased ReHo in the left superior temporal gyrus (STG) and bilateral inferior frontal gyrus (IFG), as well as decreased ReHo in the left superior frontal gyrus (SFG). Interestingly, this relationship was attenuated and no longer significant after consideration for the effect of anhedonia in MDD patients. MDD patients with anhedonia were more likely to exhibit decreased ReHo in the left SFG and left middle cingulate gyrus (MCG) when comparing to HCs. No significant difference was found between MDD patients without anhedonia and HCs, either the two groups of MDD patients. There was no significant association between ReHo values of each survived area and clinical characteristics in MDD patients.

CONCLUSIONS

The present results suggest that the impacts of anhedonia on brain functional alterations in MDD should be emphasized and disturbed intrinsic brain function in the frontal-limbic regions may be associated with anhedonia in MDD patients.

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.

Cannabis use and resting state functional connectivity in adolescent bipolar disorder

BACKGROUND

Adolescents with bipolar disorder have high rates of cannabis use, and cannabis use is associated with increased symptom severity and treatment resistance in bipolar disorder. Studies have identified anomalous resting-state functional connectivity among reward networks in bipolar disorder and cannabis use independently, but have yet to examine their convergence.

METHODS

Participants included 134 adolescents, aged 13 to 20 years: 40 with bipolar disorder and lifetime cannabis use, 31 with bipolar disorder and no history of cannabis use, and 63 healthy controls without lifetime cannabis use. We used a seed-to-voxel analysis to assess the restingstate functional connectivity of the amygdala, the nucleus accumbens and the orbitofrontal cortex, regions implicated in bipolar disorder and cannabis use. We used a generalized linear model to explore bivariate correlations for each seed, controlling for age and sex.

RESULTS

We found 3 significant clusters. Resting-state functional connectivity between the left nucleus accumbens seed and the left superior parietal lobe was negative in adolescents with bipolar disorder and no history of cannabis use, and positive in healthy controls. Resting-state functional connectivity between the right orbitofrontal cortex seed and the right lateral occipital cortex was positive in adolescents with bipolar disorder and lifetime cannabis use, and negative in healthy controls and adolescents with bipolar disorder and no history of cannabis use. Resting-state functional connectivity between the right orbitofrontal cortex seed and right occipital pole was positive in adolescents with bipolar disorder and lifetime cannabis use, and negative in adolescents with bipolar disorder and no history of cannabis use.

LIMITATIONS

The study did not include a cannabis-using control group.

CONCLUSION

This study provides preliminary evidence of cannabis-related differences in functional reward circuits in adolescents with bipolar disorder. Further studies are necessary to evaluate whether the present findings reflect consequences of or predisposition to cannabis use.

Altered spatiotemporal consistency of corticolimbic circuitry in euthymic pediatric bipolar disorder

Bipolar disorder (BD) is a life-threatening illness which clinically defined by an alternating pattern of depressive and manic episodes with a separated period of euthymia. It remains unknown about the consistency of temporal-spatial spontaneous brain activity in euthymic patients, especially in pediatric BD (PBD) patients.Resting-state fMRI signals of sixteen euthymic PBD patients and 16 healthy controls were processed and FOur-dimensional (spatiotemporal) Consistency of local neural Activities (FOCA) and functional connectivity were calculated in the present study. Voxel-wised correlation between clinical and cognitive indices and FOCA in PBD was calculated.Compared with healthy subjects, euthymic PBD patients showed worse performance in tests of Stroop Color-Word Test, Digit Span Test and Trail Making Test. Euthymic PBD patients demonstrated increased FOCA in left inferior frontal gyrus, left anterior cingulate cortex and left superior frontal gyrus and decreased FOCA in right orbital frontal gyrus, bilateral precuneus, right superior occipital gyrus and bilateral superior parietal gyrus. Decreased functional connectivities were found between right orbital frontal gyrus and left amygdala, between left superior frontal gyrus and left putamen, and between left superior frontal gyrus and left insula. And increased functional connectivity was found between right superior occipital gyrus and right hippocampus. FOCA of parahippocampal gyrus was negatively correlated with the SCWT-B score in PBD patients.Abnormal spatiotemporal consistency of brain regions of corticolimbic circuitry is possible to contribute to an imbalance between emotional processing and cognitive control in euthymic PBD. The measurement of FOCA measure may provide important clues of understanding PBD.

Inflammation is correlated with abnormal functional connectivity in unmedicated bipolar depression: an independent component analysis study of resting-state fMRI

BACKGROUND

Inflammation might play a role in bipolar disorder (BD), but it remains unclear the relationship between inflammation and brain structural and functional abnormalities in patients with BD. In this study, we focused on the alterations of functional connectivity (FC), peripheral pro-inflammatory cytokines and their correlations to investigate the role of inflammation in FC in BD depression.

METHODS

In this study, 42 unmedicated patients with BD II depression and 62 healthy controls (HCs) were enrolled. Resting-state-functional magnetic resonance imaging was performed in all participants and independent component analysis was used. Serum levels of Interleukin-6 (IL-6) and Interleukin-8 (IL-8) were measured in all participants. Correlation between FC values and IL-6 and IL-8 levels in BD was calculated.

RESULTS

Compared with the HCs, BD II patients showed decreased FC in the left orbitofrontal cortex (OFC) implicating the limbic network and the right precentral gyrus implicating the somatomotor network. BD II showed increased IL-6 (p = 0.039), IL-8 (p = 0.002) levels. Moreover, abnormal FC in the right precentral gyrus were inversely correlated with the IL-8 (r = -0.458, p = 0.004) levels in BD II. No significant correlation was found between FC in the left OFC and cytokines levels.

CONCLUSIONS

Our findings that serum IL-8 levels are associated with impaired FC in the right precentral gyrus in BD II patients suggest that inflammation might play a crucial role in brain functional abnormalities in BD.

Identification of bipolar disorder using a combination of multimodality magnetic resonance imaging and machine learning techniques

BACKGROUND

Bipolar disorder (BPD) is a common mood disorder that is often goes misdiagnosed or undiagnosed. Recently, machine learning techniques have been combined with neuroimaging methods to aid in the diagnosis of BPD. However, most studies have focused on the construction of classifiers based on single-modality MRI. Hence, in this study, we aimed to construct a support vector machine (SVM) model using a combination of structural and functional MRI, which could be used to accurately identify patients with BPD.

METHODS

In total, 44 patients with BPD and 36 healthy controls were enrolled in the study. Clinical evaluation and MRI scans were performed for each subject. Next, image pre-processing, VBM and ReHo analyses were performed. The ReHo values of each subject in the clusters showing significant differences were extracted. Further, LASSO approach was recruited to screen features. Based on selected features, the SVM model was established, and discriminant analysis was performed.

RESULTS

After using the two-sample t-test with multiple comparisons, a total of 8 clusters were extracted from the data (VBM = 6; ReHo = 2). Next, we used both VBM and ReHo data to construct the new SVM classifier, which could effectively identify patients with BPD at an accuracy of 87.5% (95%CI: 72.5-95.3%), sensitivity of 86.4% (95%CI: 64.0-96.4%), and specificity of 88.9% (95%CI: 63.9-98.0%) in the test data (p = 0.0022).

CONCLUSIONS

A combination of structural and functional MRI can be of added value in the construction of SVM classifiers to aid in the accurate identification of BPD in the clinic.

Common and distinct neural activities in frontoparietal network in first-episode bipolar disorder and major depressive disorder: Preliminary findings from a follow-up resting state fMRI study

BACKGROUND

It is difficult to distinguish bipolar disorder (BD) from major depressive disorder (MDD), especially with the initial depressive episode. In this study, we compared neural activities of BD and MDD patients during the first-episode (FE) to investigate common and distinct neural activities and further explore predictive indicators in the two diseases.

METHODS

FE-MDD patients were performed resting state functional magnetic resonance imaging and followed up after scanning. After follow-up, FE-MDD patients were regrouped into FE-BD and FE-MDD patients. The study included 24 FE-BD patients, 28 FE-MDD patients, and 30 age- and sex-matched healthy controls (HC) to investigate neural activities with regional homogeneity (ReHo) analysis among the 3 groups.

RESULTS

Compared to HC, FE-BD patients displayed significantly higher ReHo values in the superior frontal gyrus, the medial superior frontal gyrus within right-side cerebral hemisphere than FE-MDD patients and HC. Compared to HC, FE-BD and FE-MDD patients displayed significant decreased ReHo values in the paracentral lobule, the precuneus and the median cingulate and paracingulate gyrus within bilateral cerebral hemisphere, and the postcentral gyrus and the precentral gyrus within the right-side. FE-BD displayed significant lower ReHo values than FE-MDD patients in these regions.

LIMITATIONS

The potential effects of medicine, age, course of disease and handedness on results could not be ignored.

CONCLUSIONS

Abnormal neural activities of frontoparietal network may provide common and distinct markers to affective disorders and scientific basis for further prediction researches of affective disorders.

Investigating spontaneous brain activity in bipolar disorder: A resting-state functional magnetic resonance imaging study

BACKGROUND

Despite several neuroimaging studies in the past few years, the exact pathophysiology responsible for the development of bipolar disorder (BD) is still not completely known. Importantly, to the best of our knowledge, no study from India has examined resting state (RS) connectivity abnormalities in BD using regional homogeneity (ReHo). Hence, we examined spontaneous brain activity in patients with BD using RS functional magnetic resonance imaging (RS-fMRI).

AIM

The aim of the study is to examine the spontaneous brain activity in patients with BD-I using ReHo approach and RS-fMRI compared to age- and gender-matched healthy control (HC).

MATERIALS AND METHODS

A total of 20 patients with BD and 20 age-, gender-, and education-matched HCs participated in the study. The fMRI data were obtained using 1.5T scanner. RS-fMRI abnormalities were analyzed using ReHo method.

RESULTS

Compared to healthy adults, significantly increased ReHo in the BD group was found in the right precuneus, right insula, right supramarginal gyrus, left superior frontal gyrus, right inferior frontal gyrus, right precentral gyrus, and right paracentral lobule. No region had significantly lower ReHo values in BD patients compared to controls.

CONCLUSION

These results suggested that abnormal local synchronization of spontaneous brain activity is present in the frontoparietoinsular region which may be related to the pathophysiology of BD.

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.

Abnormal resting-state regional homogeneity in unmedicated bipolar II disorder

BACKGROUND

Previous studies demonstrated that patients with bipolar disorder (BD) exhibited abnormal neural activity in multiple brain regions. However, no study has been conducted to identify regional intrinsic neural activity changes in BD II. In the present study, we used the regional homogeneity (ReHo) approach to explore the regional abnormal neural activity in bipolar II disorder METHODS: One hundred unmedicated patients with BD II depression and 100 healthy controls (HC) underwent the resting-state functional magnetic resonance imaging. The ReHo values of each voxel was calculated in the whole brain. The two-sample t-test and threshold-free cluster enhancement (TFCE) correction were applied for the ReHo analysis.

RESULTS

Compared with the HC group, the BD II group showed significantly decreased ReHo in the left orbitofrontal cortex, and increased ReHo in the right precentral gyrus, right supplementary motor area and bilateral middle occipital gyrus (P < .05, TFCE corrected).

LIMITATIONS

This study lacks the evidence of brain structural changes, and used the cross-sectional design which did not explore local alterations of remitted and manic patients.

CONCLUSION

Our findings revealed abnormal local intrinsic neural activity during resting state which may contribute to the pathophysiology of bipolar II disorder. Particularly the disrupted balance between the prefrontal cortex and primary sensorimotor regions provides evidence for the unique pathological mechanism underlying BD.

Aberrant Resting-State Functional Connectivity in the Default Mode Network in Pediatric Bipolar Disorder Patients with and without Psychotic Symptoms

Mood disorders/psychosis have been associated with dysfunctions in the default mode network (DMN). However, the relative contributions of DMN regions to state and trait disturbances in pediatric bipolar disorder (PBD) remain unclear. The aim of this study was to investigate the possible mechanisms of PBD through brain imaging and explore the influence of psychotic symptoms on functional alterations in PBD patients. Twenty-nine psychotic and 26 non-psychotic PBD patients, as well as 19 age- and sex-matched healthy controls underwent a resting-state functional MRI scan and the data were analyzed by independent component analysis. The DMN component from the fMRI data was extracted for each participant. Spearman's rank correlation analysis was performed between aberrant connectivity and clinical measurements. The results demonstrated that psychotic PBD was characterized by aberrant DMN connectivity in the anterior cingulate cortex/medial prefrontal cortex, bilateral caudate nucleus, bilateral angular gyri, and left middle temporal gyrus, while non-psychotic PBD was not, suggesting further impairment with the development of psychosis. In summary, we demonstrated unique impairment in DMN functional connectivity in the psychotic PBD group. These specific neuroanatomical abnormalities may shed light on the underlying pathophysiology and presentation of PBD.

Decreased anterior cingulate activation in a motor task in youths with bipolar disorder

BACKGROUND

Bipolar disorder (BP) is characterized by abnormal shifts in mood between episodes of mania and severe depression, both of which have been linked with psychomotor disturbances. This study compares brain activation patterns in motor networks between euthymic youths with BP and healthy controls (HC) during the completion of a simple motor task.

METHODS

Thirty-five youths with BP and 35 HC (aged 10-19) completed a self-paced sequential bilateral finger-tapping task, consisting of a 4-minute scan block with alternating 20-second periods of either the tapping task (six blocks) or rest (six blocks), while undergoing functional magnetic resonance imaging. Clinical and behavioral symptoms were assessed using the Child Behavior Checklist (CBCL). A between-group whole-brain analysis compared activation pattern differences while controlling for effects of age and sex. Clusters meeting whole-brain false discovery rate (FDR) correction (qFDR < .05) were considered statistically significant. Post hoc analyses evaluating comorbid attention-deficit/hyperactivity disorder (ADHD) in the BP group were also conducted.

RESULTS

Significantly decreased activation was found in the anterior cingulate cortex (ACC) in youths with BP compared to HC. Furthermore, ACC activation was negatively correlated with CBCL mood dysregulation profile scores in the BP group. No significant differences in functional activation patterns were found between youths with BP and comorbid ADHD and those with only BP.

CONCLUSIONS

These findings suggest a potential common mechanism of impaired ACC modulation between emotion dysregulation and motor processing in youths with BP.

Neurobiological Evidence for the Primacy of Mania Hypothesis

BACKGROUND

Athanasios Koukopoulos proposed the primacy of mania hypothesis (PoM) in a 2006 book chapter and later, in two peer-reviewed papers with Nassir Ghaemi and other collaborators. This hypothesis supports that in bipolar disorder, mania leads to depression, while depression does not lead to mania.

OBJECTIVE

To identify evidence in literature that supports or falsifies this hypothesis.

METHOD

We searched the medical literature (PubMed, Embase, PsycINFO, and the Cochrane Library) for peer-reviewed papers on the primacy of mania, the default mode function of the brain in normal people and in bipolar disorder patients, and on illusion superiority until 6 June, 2016. Papers resulting from searches were considered for appropriateness to our objective. We adopted the PRISMA method for our review. The search for consistency with PoM was filtered through the neurobiological results of superiority illusion studies.

RESULTS

Out of a grand total of 139 records, 59 were included in our analysis. Of these, 36 were of uncertain value as to the primacy of mania hypothesis, 22 favoured it, and 1 was contrary, but the latter pooled patients in their manic and depressive phases, so to invalidate possible conclusions about its consistency with regard to PoM. All considered studies were not focused on PoM or superiority illusion, hence most of their results were, as expected, unrelated to the circuitry involved in superiority illusion. A considerable amount of evidence is consistent with the hypothesis, although indirectly so.

LIMITATIONS

Only few studies compared manic with depressive phases, with the majority including patients in euthymia.

CONCLUSION

It is possible that humans have a natural tendency for elation/optimism and positive self-consideration, that are more akin to mania; the depressive state could be a consequence of frustrated or unsustainable mania. This would be consistent with PoM.

The International Society for Bipolar Disorders Task Force report on pediatric bipolar disorder: Knowledge to date and directions for future research

OBJECTIVES

Over the past two decades, there has been tremendous growth in research regarding bipolar disorder (BD) among children and adolescents (ie, pediatric BD [PBD]). The primary purpose of this article is to distill the extant literature, dispel myths or exaggerated assertions in the field, and disseminate clinically relevant findings.

METHODS

An international group of experts completed a selective review of the literature, emphasizing areas of consensus, identifying limitations and gaps in the literature, and highlighting future directions to mitigate these gaps.

RESULTS

Substantial, and increasingly international, research has accumulated regarding the phenomenology, differential diagnosis, course, treatment, and neurobiology of PBD. Prior division around the role of irritability and of screening tools in diagnosis has largely abated. Gold-standard pharmacologic trials inform treatment of manic/mixed episodes, whereas fewer data address bipolar depression and maintenance/continuation treatment. Adjunctive psychosocial treatment provides a forum for psychoeducation and targets primarily depressive symptoms. Numerous neurocognitive and neuroimaging studies, and increasing peripheral biomarker studies, largely converge with prior findings from adults with BD.

CONCLUSIONS

As data have accumulated and controversy has dissipated, the field has moved past existential questions about PBD toward defining and pursuing pressing clinical and scientific priorities that remain. The overall body of evidence supports the position that perceptions about marked international (US vs elsewhere) and developmental (pediatric vs adult) differences have been overstated, although additional research on these topics is warranted. Traction toward improved outcomes will be supported by continued emphasis on pathophysiology and novel therapeutics.

A Brain on a Roller Coaster: Can the Dopamine Reward System Act as a Protagonist to Subdue the Ups and Downs of Bipolar Disorder?

One of the most interesting but tenebrous parts of the bipolar disorder (BD) story is the switch between (hypo)mania and depression, which can give bipolar patients a thrilling, but somewhat perilous, ‘ride’. Numerous studies have pointed out that there are some recognizable differences (either state-dependent or state-independent) in several brain regions of people with BD, including components of the brain’s reward system. Understanding the underpinning mechanisms of high and low mood statuses in BD has potential, not only for the development of highly specific and selective pharmaceutical agents, but also for better treatment approaches and psychological interventions to manage BD and, thus, give patients a safer ride. Herein, we review evidence that supports involvement of the reward system in the pathophysiology of mood swings, with the main focus on the mesocorticolimbic dopaminergic neural circuitry. Principally using findings from neuroimaging studies, we aim to signpost readers as to how mood alterations may affect different areas of the reward system and how antipsychotic drugs can influence the activity of these brain areas. Finally, we critically evaluate the hypothesis that the mesocorticolimbic dopamine reward system may act as a functional rheostat for different mood states.

A functional connectivity comparison between attention deficit hyperactivity disorder and bipolar disorder in medication-naïve adolescents with mood fluctuation and attention problems

In order to compare patterns of connectivity between affective and attention networks in adolescents with bipolar disorder (BD) and attention deficit hyperactivity disorder (ADHD), we investigated differences in resting state functional connectivity (RSFC) between these populations. Study participants were medication-naïve adolescents (aged 13-18 years) with BD (N=22) or ADHD (N=25) and age- and sex-matched healthy adolescents (healthy controls [HC]) (N=22). Forty-seven adolescents with mood fluctuation and attention problems showed increased functional correlation (FC) between two pairs of regions within the affective network (AFN), compared to 22 HC: the left orbitofrontal cortex (OFC) to the left thalamus and the left OFC to the right thalamus. In post-hoc testing, adolescents with BD showed increased FC between two pairs of regions compared to ADHD: the right amygdala to the left temporoparietal junction (TPJ) and the right amygdala to the right TPJ. Adolescents with BD showed increased FC within the attention network (ATN) as well as increased FC between the ATN and the AFN, while those with ADHD showed decreased FC within the ATN. The current suggests that these features could be used as biomarkers for differentiating BD from ADHD in adolescents.

Functional Dysconnection of the Inferior Frontal Gyrus in Young People With Bipolar Disorder or at Genetic High Risk

BACKGROUND

Bipolar disorder (BD) is characterized by a dysregulation of affect and impaired integration of emotion with cognition. These traits are also expressed in probands at high genetic risk of BD. The inferior frontal gyrus (IFG) is a key cortical hub in the circuits of emotion and cognitive control, and it has been frequently associated with BD. Here, we studied resting-state functional connectivity of the left IFG in participants with BD and in those at increased genetic risk.

METHODS

Using resting-state functional magnetic resonance imaging we compared 49 young BD participants, 71 individuals with at least one first-degree relative with BD (at-risk), and 80 control subjects. We performed between-group analyses of the functional connectivity of the left IFG and used graph theory to study its local functional network topology. We also used machine learning to study classification based solely on the functional connectivity of the IFG.

RESULTS

In BD, the left IFG was functionally dysconnected from a network of regions, including bilateral insulae, ventrolateral prefrontal gyri, superior temporal gyri, and the putamen (p < .001). A small network incorporating neighboring insular regions and the anterior cingulate cortex showed weaker functional connectivity in at-risk than control participants (p < .006). These constellations of regions overlapped with frontolimbic regions that a machine learning classifier selected as predicting group membership with an accuracy significantly greater than chance.

CONCLUSIONS

Functional dysconnectivity of the IFG from regions involved in emotional regulation may represent a trait abnormality for BD and could potentially aid clinical diagnosis.

A genome wide association study suggests the association of muskelin with early onset bipolar disorder: Implications for a GABAergic epileptogenic neurogenesis model

BACKGROUND

Although multiple genes have been implicated in bipolar disorder (BD), they explain only a small proportion of its heritability. Identifying additional BD risk variants may be impaired by phenotypic heterogeneity, which is usually not taken into account in genome-wide association studies (GWAS). BD with early age at onset is a more homogeneous familial form of the disorder associated with greater symptom severity.

METHODS

We conducted a GWAS of early-onset BD (onset of mania/hypomania ≤19 years old) in a discovery sample of 419 cases and 1034 controls and a replication sample of 181 cases and 777 controls. These two samples were meta-analyzed, followed by replication of one signal in a third independent sample of 141 cases and 746 controls.

RESULTS

No single nucleotide polymorphism (SNP) associations were genome-wide significant in the discovery sample. Of the top 15 SNPs in the discovery analysis, rs114034759 in the muskelin (MKLN1) gene was nominally significant in the replication analysis, and was among the top associations in the meta-analysis (p=2.63E-06, OR=1.9). In the third sample, this SNP was again associated with early-onset BD (p=0.036, OR=1.6). Gene expression analysis showed that the rs114034759 risk allele is associated with decreased hippocampal MKLN1 expression.

LIMITATIONS

The sample sizes of the early-onset BD subgroups were relatively small.

CONCLUSIONS

Our results suggest MKLN1 is associated with early-onset BD. MKLN1 regulates cellular trafficking of GABA-A receptors, which is involved in synaptic transmission and plasticity, and is implicated in the mechanism of action of a group of antiepileptic mood stabilizers. These results therefore indicate that GABAergic neurotransmission may be implicated in early-onset BD. We propose that an increase in GABA-A receptors in the hippocampus in BD patients due to lower MKLN1 expression might increase the excitability during the GABA-excited early phase of young neurons, leading to an increased risk of developing a manic/hypomanic episode. Further studies are needed to test this model.

Abnormal Functional Connectivity Between Default and Salience Networks in Pediatric Bipolar Disorder

BACKGROUND

Pediatric bipolar disorder (PBD) (occurring prior to 18 years of age) is a developmental brain disorder that is among the most severe and disabling psychiatric conditions affecting youth. Despite increasing evidence that brain connectivity is atypical in adults with bipolar disorder, it is not clear how brain connectivity may be altered in youths with PBD.

METHODS

This cross-sectional resting-state functional magnetic resonance imaging study included 80 participants recruited over 4 years: 32 youths with PBD, currently euthymic (13 males; 15.1 years old), and 48 healthy control (HC) subjects (27 males; 14.5 years old). Functional connectivity between eight major intrinsic connectivity networks, along with connectivity measurements between 333 brain regions, was compared between PBD and HC subjects. Additionally, connectivity differences were evaluated between PBD and HC samples in negatively correlated connections, as defined by 839 subjects of the Human Connectome Project dataset.

RESULTS

We found increased inter- but not intranetwork functional connectivity in PBD between the default mode and salience networks (p = .0017). Throughout the brain, atypical connections showed failure to develop anticorrelation with age during adolescence in PBD but not HC samples among connections that exhibit negative correlation in adulthood.

CONCLUSIONS

Youths with PBD demonstrate reduced anticorrelation between default mode and salience networks. Further evaluation of the interaction between these networks is needed in development and with other mood states such as depression and mania to clarify if this atypical connectivity is a PBD trait biomarker.

Aberrant intrinsic functional connectivity within and between corticostriatal and temporal-parietal networks in adults and youth with bipolar disorder

BACKGROUND

Major questions remain regarding the dysfunctional neural circuitry underlying the pathophysiology of bipolar disorder (BD) in both youths and adults. In both age groups, studies implicate abnormal intrinsic functional connectivity among prefrontal, limbic and striatal areas.

METHOD

We collected resting-state functional magnetic resonance imaging (fMRI) data from youths and adults (ages 10-50 years) with BD (n = 39) and healthy volunteers (HV; n = 78). We identified brain regions with aberrant intrinsic functional connectivity in BD by first comparing voxel-wise mean global connectivity and then conducting correlation analyses. We used k-means clustering and multidimensional scaling to organize all detected regions into networks.

RESULTS

Across the brain, we detected areas of dysconnectivity in both youths and adults with BD relative to HV. There were no significant age-group × diagnosis interactions. When organized by interregional connectivity, the areas of dysconnectivity in patients with BD comprised two networks: one of temporal and parietal areas involved in late stages of visual processing, and one of corticostriatal areas involved in attention, cognitive control and response generation.

CONCLUSIONS

These data suggest that two networks show abnormal intrinsic functional connectivity in BD. Regions in these networks have been implicated previously in BD. We observed similar dysconnectivity in youths and adults with BD. These findings provide guidance for refining models of network-based dysfunction in BD.

Altered cortical and subcortical local coherence in PTSD: evidence from resting-state fMRI

BACKGROUND

Post-traumatic stress disorder (PTSD) is often characterized by region-specific brain activation/deactivation and functional abnormalities in corticolimbic circuitry, as elucidated by task-dependent functional neuroimaging. However, little is known about the abnormalities in the local coherence of cortical and subcortical activity occurring during the resting state.

PURPOSE

To evaluate the functional discrepancy of local coherence between cortical and subcortical regions in PTSD patients using resting-state functional magnetic resonance imaging (fMRI).

MATERIAL AND METHODS

Resting-state fMRI (RS-fMRI) was performed on 14 outpatients with PTSD, along with 14 age- and sex-matched normal control subjects. Regional homogeneity (ReHo), a measurement of the coherence of spontaneous RS-fMRI signal oscillations within spatially neighboring voxels, was examined.

RESULTS

Compared with the normal controls, PTSD patients showed increased local coherence in subcortical regions, including amygdala, hippocampus, thalamus, and putamen, and decreased local coherence in cortical regions, including medial prefrontal cortex and dorsolateral prefrontal cortex. Moreover, a correlation analysis of the ReHo measurement versus the severity of the disorder was performed, and highly positive correlation were observed in the right amygdala.

CONCLUSION

The present study identified a functional discrepancy of local coherence between cortical and subcortical regions in PTSD patients compared with normal controls. The findings revealed that resting-state abnormalities might lead to further improvement of the understanding of the neural substrates of cognitive impairment and symptoms in PTSD.

Decreased amygdala-insula resting state connectivity in behaviorally and emotionally dysregulated youth

The Research Domain Criteria (RDoC) adopts a dimensional approach for examining pathophysiological processes underlying categorically defined psychiatric diagnoses. We used this framework to examine relationships among symptom dimensions, diagnostic categories, and resting state connectivity in behaviorally and emotionally dysregulated youth selected from the Longitudinal Assessment of Manic Symptoms study (n=42) and healthy control youth (n=18). Region of interest analyses examined relationships among resting state connectivity, symptom dimensions (behavioral and emotional dysregulation measured with the Parent General Behavior Inventory-10 Item Mania Scale [PGBI-10M]; dimensional severity measures of mania, depression, anxiety), and diagnostic categories (Bipolar Spectrum Disorders, Attention Deficit Hyperactivity Disorder, Anxiety Disorders, and Disruptive Behavior Disorders). After adjusting for demographic variables, two dimensional measures showed significant inverse relationships with resting state connectivity, regardless of diagnosis: 1) PGBI-10M with amygdala-left posterior insula/bilateral putamen; and 2) depressive symptoms with amygdala-right posterior insula connectivity. Diagnostic categories showed no significant relationships with resting state connectivity. Resting state connectivity between amygdala and posterior insula decreased with increasing severity of behavioral and emotional dysregulation and depression; this suggests an intrinsic functional uncoupling of key neural regions supporting emotion processing and regulation. These findings support the RDoC dimensional approach for characterizing pathophysiologic processes that cut across different psychiatric disorders.

Early signs of anomalous neural functional connectivity in healthy offspring of parents with bipolar disorder

OBJECTIVES

Bipolar disorder (BD) has been associated with dysfunctional brain connectivity and with family chaos. It is not known whether aberrant connectivity occurs before illness onset, representing vulnerability for developing BD amidst family chaos. We used resting-state functional magnetic resonance imaging (fMRI) to examine neural network dysfunction in healthy offspring living with parents with BD and healthy comparison youth.

METHODS

Using two complementary methodologies [data-driven independent component analysis (ICA) and hypothesis-driven region-of-interest (ROI)-based intrinsic connectivity], we examined resting-state fMRI data in 8-17-year-old healthy offspring of a parent with BD (n = 24; high risk) and age-matched healthy youth without any personal or family psychopathology (n = 25; low risk).

RESULTS

ICA revealed that, relative to low-risk youth, high-risk youth showed increased connectivity in the ventrolateral prefrontal cortex (VLPFC) subregion of the left executive control network (ECN), which includes frontoparietal regions important for emotion regulation. ROI-based analyses revealed that high-risk versus low-risk youth had decreased connectivities between the left amygdala and pregenual cingulate, between the subgenual cingulate and supplementary motor cortex, and between the left VLPFC and left caudate. High-risk youth showed stronger connections in the VLPFC with age and higher functioning, which may be neuroprotective, and weaker connections between the left VLPFC and caudate with more family chaos, suggesting an environmental influence on frontostriatal connectivity.

CONCLUSIONS

Healthy offspring of parents with BD show atypical patterns of prefrontal and subcortical intrinsic connectivity that may be early markers of resilience to or vulnerability for developing BD. Longitudinal studies are needed to determine whether these patterns predict outcomes.

The neural correlates of tic inhibition in Gilles de la Tourette syndrome

Tics in Gilles de la Tourette syndrome (GTS) resemble fragments of normal motor behaviour but appear in an intrusive, repetitive and context-inappropriate manner. Although tics can be voluntarily inhibited on demand, the neural correlates of this process remain unclear. 14 GTS adults without relevant comorbidities participated in this study. First, tic severity and voluntary tic inhibitory capacity were evaluated outside the scanner. Second, patients were examined with resting state functional magnetic resonance imaging (RS-fMRI) in two states, free ticcing and voluntary tic inhibition. Local synchronization of spontaneous fMRI-signal was analysed with regional homogeneity (ReHo) and differences between both states (free ticcing<tic inhibition) were contrasted. Clinical correlations of the resulting differential ReHo parameters between both states and clinical measures of tic frequency, voluntary tic inhibition and premonitory urges were also performed. ReHo of the left inferior frontal gyrus (IFG) was increased during voluntary tic inhibition compared to free ticcing. ReHo increases were positively correlated with participants׳ ability to inhibit their tics during scanning sessions but also outside the scanner. There was no correlation with ratings of premonitory urges. Voluntary tic inhibition is associated with increased ReHo of the left IFG. Premonitory urges are unrelated to this process.

Alterations of regional homogeneity in pediatric bipolar depression: a resting-state fMRI study

BACKGROUND

Pediatric bipolar disorder (PBD) has attracted increasing attentions due to its high prevalence and great influence on social functions of children and adolescents. However, the pathophysiology underlying PBD remains unclear. In the present study, the resting-state functional magnetic resonance imaging (fMRI) was used to detect abnormalities of baseline brain functions in depressed PBD youth.

METHODS

Seventeen youth with PBD-depression aged 10 - 18 years old and 18 age- and sex-matched normal controls were recruited in this study. The fMRI data under resting state were obtained on a Siemens 3.0 Tesla scanner and were analyzed using the regional homogeneity (ReHo) method. Correlations between the ReHo values of each survived area and the severity of depression symptoms in patients were further analyzed.

RESULTS

As compared with the control group, PBD-depression patients showed decreased ReHo in the medial frontal gyrus, bilateral middle frontal gyrus and middle temporal gyrus, and the right putamen. Significant negative correlations of the mood and feelings questionnaire scores with mean ReHo values in the medial frontal gyrus and the right middle frontal gyrus in PBD-depression patients were observed.

CONCLUSION

Our results suggest that extensive regions with altered baseline brain activities are existed in PBD-depression and these brain regions mainly locate in the fronto-limbic circuit and associated striatal structures. Moreover, the present findings also add to our understanding that there could be unique neuropathophysiological mechanisms underlying PBD-depression.

Developmental Resting State Functional Connectivity for Clinicians

Resting state functional magnetic imaging (fMRI) is a novel means to examine functional brain networks. It allows investigators to identify functional networks defined by distinct, spontaneous signal fluctuations. Resting state functional connectivity (RSFC) studies examining child and adolescent psychiatric disorders are being published with increasing frequency, despite concerns about the impact of motion on findings. Here we review important RSFC findings on typical brain development and recent publications of child and adolescent psychiatric disorders. We close with a summary of the major findings and current strengths and limitations of RSFC studies.

Altered regional homogeneity and efficient response inhibition in restrained eaters

Restrained eaters (REs) characterized by less efficient response inhibition are at risk for future onset of binge eating and bulimic pathology. Previous imaging studies investigating REs have been based on task-related functional magnetic resonance imaging (fMRI) and little is known about resting-state neural activity underlying restrained eating. To illuminate this issue, we investigated resting-state fMRI differences between REs (n=22) and unrestrained eaters (UREs) (n=30) using regional homogeneity (ReHo) analysis, which measures the temporal synchronization of spontaneous fluctuations. Samples were equated on body mass index (BMI) and caloric deprivation levels (i.e., 14±2.1h since last evening meal) before undergoing fMRI. Correlation analyses were performed between the ReHo index of identified regions and response inhibition based on stop-signal reaction time (SSRT) within each sample. Compared with UREs, REs showed more ReHo in brain regions associated with food reward (i.e., orbitofrontal cortex (OFC), dorsal-lateral prefrontal cortex (dlPFC)), attention (i.e., lingual gyrus, cuneus, inferior parietal lobule) and somatosensory functioning (i.e., paracentral lobule, anterior insula). In addition, ReHo values for the left dlPFC and left anterior insula, respectively, were negatively and positively correlated with SSRT among REs but not UREs. In concert with previous studies, these results suggest altered local synchronization may help to explain why dieting to maintain or lose weight often fails or increases risk for binge eating among REs.

Altered baseline brain activity in children with bipolar disorder during mania state: a resting-state study

BACKGROUND

Previous functional magnetic resonance imaging (fMRI) studies have shown abnormal functional connectivity in regions involved in emotion processing and regulation in pediatric bipolar disorder (PBD). Recent studies indicate, however, that task-dependent neural changes only represent a small fraction of the brain's total activity. How the brain allocates the majority of its resources at resting state is still unknown. We used the amplitude of low-frequency fluctuation (ALFF) method of fMRI to explore the spontaneous neuronal activity in resting state in PBD patients.

METHODS

Eighteen PBD patients during the mania phase and 18 sex-, age- and education-matched healthy subjects were enrolled in this study and all patients underwent fMRI scanning. The ALFF method was used to compare the resting-state spontaneous neuronal activity between groups. Correlation analysis was performed between the ALFF values and Young Mania Rating Scale scores.

RESULTS

Compared with healthy controls, PBD patients presented increased ALFF in bilateral caudate and left pallidum as well as decreased ALFF in left precuneus, left superior parietal lobule, and bilateral inferior occipital gyrus. Additionally, ALFF values in left pallidum were positively correlated with Young Mania Rating Scale score in PBD.

CONCLUSION

The abnormal resting-state neuronal activities of the basal ganglia, parietal cortex, and occipital cortex may play an important role in the pathophysiology in PBD patients.

Identify changes of brain regional homogeneity in bipolar disorder and unipolar depression using resting-state FMRI

BACKGROUND

To identify changes in brain activation patterns in bipolar disorder (BD) and unipolar depression (UD) patients.

METHODOLOGY/PRINCIPAL FINDINGS

Resting-state fMRI scans of 16 healthy controls, 17 BD and 16 UD patients were obtained. T-test of normalized regional homogeneity (ReHo) was performed in a voxel-by-voxel manner. A combined threshold of á = 0.05, minimum cluster volume of V = 10503 mm(3) (389 voxels) were used to determine ReHo differences between groups. In UD group, fMRI revealed ReHo increases in the left middle occipital lobe, right inferior parietal lobule, right precuneus and left convolution; and ReHo decreases in the left parahippocampalgyrus, right precentralgyrus, left postcentralgyrus, left precentralgyrus and left cingulated. In BD group, ReHo increases in the right insular cortex, left middle frontal gyrus, left precuneus, left occipital lobe, left parietal, left superior frontal gyrus and left thalamus; and ReHo decreases in the right anterior lobe of cerebellum, pons, right precentralgyrus, left postcentralgyrus, left inferior frontal gyrus, and right cingulate. There were some overlaps in ReHo profiles between UD and BD groups, but a marked difference was seen in the thalamus of BD.

CONCLUSIONS/SIGNIFICANCE

The resting-state fMRI and ReHo mapping are a promising tool to assist the detection of functional deficits and distinguish clinical and pathophysiological signs of BD and UD.

Identify changes of brain regional homogeneity in bipolar disorder and unipolar depression using resting-state FMRI

BACKGROUND

To identify changes in brain activation patterns in bipolar disorder (BD) and unipolar depression (UD) patients.

METHODOLOGY/PRINCIPAL FINDINGS

Resting-state fMRI scans of 16 healthy controls, 17 BD and 16 UD patients were obtained. T-test of normalized regional homogeneity (ReHo) was performed in a voxel-by-voxel manner. A combined threshold of á = 0.05, minimum cluster volume of V = 10503 mm(3) (389 voxels) were used to determine ReHo differences between groups. In UD group, fMRI revealed ReHo increases in the left middle occipital lobe, right inferior parietal lobule, right precuneus and left convolution; and ReHo decreases in the left parahippocampalgyrus, right precentralgyrus, left postcentralgyrus, left precentralgyrus and left cingulated. In BD group, ReHo increases in the right insular cortex, left middle frontal gyrus, left precuneus, left occipital lobe, left parietal, left superior frontal gyrus and left thalamus; and ReHo decreases in the right anterior lobe of cerebellum, pons, right precentralgyrus, left postcentralgyrus, left inferior frontal gyrus, and right cingulate. There were some overlaps in ReHo profiles between UD and BD groups, but a marked difference was seen in the thalamus of BD.

CONCLUSIONS/SIGNIFICANCE

The resting-state fMRI and ReHo mapping are a promising tool to assist the detection of functional deficits and distinguish clinical and pathophysiological signs of BD and UD.

Resting state FMRI research in child psychiatric disorders

Concurring with the shift from linking functions to specific brain areas towards studying network integration, resting state FMRI (R-FMRI) has become an important tool for delineating the functional network architecture of the brain. Fueled by straightforward data collection, R-FMRI analysis methods as well as studies reporting on R-FMRI have flourished, and already impact research on child- and adolescent psychiatric disorders. Here, we review R-FMRI analysis techniques and outline current methodological debates. Furthermore, we provide an overview of the main R-FMRI findings related to child- and adolescent psychiatric disorders. R-FMRI research has contributed significantly to our understanding of brain function in child and adolescent psychiatry: existing hypotheses based on task-based FMRI were confirmed and new insights into the brain's functional architecture of disorders were established. However, results were not always consistent. While resting state networks are robust and reproducible, neuroimaging research in psychiatric disorders is especially complicated by tremendous phenotypic heterogeneity. It is imperative that we overcome this heterogeneity when integrating neuroimaging into the diagnostic and treatment process. As R-FMRI allows investigating the richness of the human functional connectome and can be easily collected and aggregated into large-scale datasets, it is clear that R-FMRI can be a powerful tool in our quest to understand psychiatric pathology.