Gray and white matter trajectories in patients with bipolar disorder

Decreased dynamic variability of the cerebellum in the euthymic patients with bipolar disorder

BACKGROUND

Bipolar disorder (BD) is a complex mental illness characterized by different mood states, including depression, mania/hypomania, and euthymia. This study aimed to comprehensively evaluate dynamic changes in intrinsic brain activity by using dynamic fractional amplitude of low-frequency fluctuations (dfALFF) and dynamic degree centrality (dDC) in patients with BD euthymia or depression and healthy individuals.

METHODS

The resting-state functional magnetic resonance imaging data were analyzed from 37 euthymic and 28 depressed patients with BD, as well as 85 healthy individuals. Using the sliding-window method, the dfALFF and dDC were calculated for each participant. These values were compared between the 3 groups using one-way analysis of variance (ANOVA). Additional analyses were conducted using different window lengths, step width, and window type to ensure the reliability of the results.

RESULTS

The euthymic group showed significantly lower dfALFF and dDC values of the left and right cerebellum posterior lobe compared with the depressed and control groups (cluster level PFWE < 0.05), while the latter two groups were comparable. Brain regions showing significant group differences in the dfALFF analysis overlapped with those with significant differences in the dDC analysis. These results were consistent across different window lengths, step width, and window type.

CONCLUSIONS

These findings suggested that patients with euthymic BD exhibit less flexibility of temporal functional activities in the cerebellum posterior lobes compared to either depressed patients or healthy individuals. These results could contribute to the development of neuropathological models of BD, ultimately leading to improved diagnosis and treatment of this complex illness.

Functional connectivity between the cerebellar vermis and cerebrum distinguishes early treatment response for major depressive episodes in adolescents

BACKGROUND

The absence of biomarkers for predicting treatment response in adolescent mood disorder calls for further research. The vermis, a component of the cerebellum, is involved in mood disorder pathophysiology and relates to clinical symptoms and treatment outcomes. We investigated vermis functional connectivity (FC) as an early marker for treatment response identification.

METHOD

One hundred thirty-two adolescents with mood disorders including major depressive disorder or bipolar disorder, were recruited, who were experiencing a major depressive episode. All adolescents underwent baseline and 2-week treatment resting-state MRI scans. Hamilton Rating Scale for Depression (HAMD) assessments were completed to assess the severity of symptoms. Patients were divided into treatment-responsive (≥50 % HAMD reduction, n = 75) and treatment-unresponsive subgroups (n = 57). Vermis FCs were compared between subgroups at baseline. And we compared the pre- and post-treatment FC differences within subgroups.

RESULT

Higher vermis-left temporal lobe FC in treatment-responsive group compared to treatment-unresponsive group at baseline. The FC value showed positive prognosis for the efficacy, with the area under the curve (AUC) of 0.760 (95 % confidence interval: 0.678-0.843, p < 0.001), suggesting higher vermis-temporal FC is benefit to improve treatment-response. Furthermore, post-treatment analysis showed significant increases in the vermis-right frontal lobe FC values between in all patients, suggesting that vermis-frontal FCs were independent of treatment-outcome.

LIMITATION

Sample size was relatively small, which may limit the generalizability of our results.

CONCLUSION

Our study revealed that the FC between the vermis and the cortex is not only associated with symptom alleviation but also predictive of treatment outcomes.

Neuroanatomical Correlates of the Late Positive Potential in Youth with Pediatric Bipolar Disorder

BACKGROUND

The late positive potential (LPP) could be a marker of emotion dysregulation in youth with pediatric bipolar disorder (PBD). However, the neuroanatomical correlates of the LPP are still not clarified.

OBJECTIVE

To provide cortical and deep gray matter correlates of the LPP in youth, specifically, youth with PBD.

METHODS

Twenty-four 7 to 17 years-old children with PBD and 28 healthy controls (HC) underwent cortical thickness and deep gray matter volumes measurements through magnetic resonance imaging and LPP measurement elicited by passively viewing emotional faces through electroencephalography. T-tests compared group differences in LPP, cortical thickness, and deep gray matter volumes. Linear regressions tested the relationship between LPP amplitude and cortical thickness/deep gray matter volumes.

RESULTS

PBD had a more pronounced LPP amplitude for happy faces and a thinner cortex in prefrontal areas than HC. While considering both groups, a higher LPP amplitude was associated with a thicker cortex across occipital and frontal lobes, and with a smaller right globus pallidus volume. In addition, a higher LPP amplitude for happy faces was associated with smaller left caudate and left globus pallidus volumes across both groups. Finally, the LPP amplitude correlated negatively with right precentral gyrus thickness across youth with PBD, but positively across HC.

CONCLUSION

Neural correlates of LPP in youth included fronto-occipital areas that have been associated also with emotion processing and control. The opposite relationship between BPD and HC of LPP amplitude and right precentral gyrus thickness might explain the inefficacy of the emotional control system in PBD.

The role of the cerebellum in sequencing and predicting social and non-social events in patients with bipolar disorder

Introduction

Advances in the operational mode of the cerebellum indicate a role in sequencing and predicting non-social and social events, crucial for individuals to optimize high-order functions, such as Theory of Mind (ToM). ToM deficits have been described in patients with remitted bipolar disorders (BD). The literature on BD patients' pathophysiology reports cerebellar alterations; however, sequential abilities have never been investigated and no study has previously focused on prediction abilities, which are needed to properly interpret events and to adapt to changes.

Methods

To address this gap, we compared the performance of BD patients in the euthymic phase with healthy controls using two tests that require predictive processing: a ToM test that require implicit sequential processing and a test that explicitly assesses sequential abilities in non-ToM functions. Additionally, patterns of cerebellar gray matter (GM) alterations were compared between BD patients and controls using voxel-based morphometry.

Results

Impaired ToM and sequential skills were detected in BD patients, specifically when tasks required a greater predictive load. Behavioral performances might be consistent with patterns of GM reduction in cerebellar lobules Crus I-II, which are involved in advanced human functions.

Discussion

These results highlight the importance of deepening the cerebellar role in sequential and prediction abilities in patients with BD.

Functional and structural brain differences in bipolar disorder: a multimodal meta-analysis of neuroimaging studies

BACKGROUND

Numerous studies of resting-state functional imaging and voxel-based morphometry (VBM) have revealed differences in specific brain regions of patients with bipolar disorder (BD), but the results have been inconsistent.

METHODS

A whole-brain voxel-wise meta-analysis was conducted on resting-state functional imaging and VBM studies that compared differences between patients with BD and healthy controls using Seed-based d Mapping with Permutation of Subject Images software.

RESULTS

A systematic literature search identified 51 functional imaging studies (1842 BD and 2190 controls) and 83 VBM studies (2790 BD and 3690 controls). Overall, patients with BD displayed increased resting-state functional activity in the left middle frontal gyrus, right inferior frontal gyrus (IFG) extending to the right insula, right superior frontal gyrus and bilateral striatum, as well as decreased resting-state functional activity in the left middle temporal gyrus extending to the left superior temporal gyrus and post-central gyrus, left cerebellum, and bilateral precuneus. The meta-analysis of VBM showed that patients with BD displayed decreased VBM in the right IFG extending to the right insula, temporal pole and superior temporal gyrus, left superior temporal gyrus extending to the left insula, temporal pole, and IFG, anterior cingulate cortex, left superior frontal gyrus (medial prefrontal cortex), left thalamus, and right fusiform gyrus.

CONCLUSIONS

The multimodal meta-analyses suggested that BD showed similar patterns of aberrant brain activity and structure in the insula extending to the temporal cortex, fronto-striatal-thalamic, and default-mode network regions, which provide useful insights for understanding the underlying pathophysiology of BD.

Theory of mind profile and cerebellar alterations in remitted bipolar disorder 1 and 2: a comparison study

The literature on social cognition abilities in bipolar disorder (BD) is controversial about the occurrence of theory of mind (ToM) alterations. In addition to other cerebral structures, such as the frontal and limbic areas, the processing of socially relevant stimuli has also been attributed to the cerebellum, which has been demonstrated to be involved in the above-mentioned disorder. Nevertheless, the cerebellar contribution to ToM deficits in bipolar patients needs to be elucidated further. To this aim, two tests assessing different components of ToM were used to evaluate the ability to appreciate affective and mental states of others in 17 individuals with a diagnosis of BD type 1 (BD1) and 13 with BD type 2 (BD2), both in the euthymic phase, compared to healthy matched controls. Cerebellar gray matter (GM) volumes were extracted and compared between BD1 and controls and BD2 and controls by using voxel-based morphometry. The results showed that BD1 patients were compromised in the cognitive and advanced components of ToM, while the BD2 ToM profile resulted in a more widespread compromise, also involving affective and automatic components. Both overlapping and differing areas of cerebellar GM reduction were found. The two groups of patients presented a pattern of GM reduction in cerebellar portions that are known to be involved in the affective and social domains, such as the vermis and Crus I and Crus II. Interestingly, in both BD1 and BD2, positive correlations were detected between lower ToM scores and decreased volumes in the cerebellum. Overall, BD2 patients showed a more compromised ToM profile and greater cerebellar impairment than BD1 patients. The different patterns of structural abnormalities may account for the different ToM performances evidenced, thus leading to divergent profiles between BD1 and BD2.

Neuroimaging Studies of Brain Structure in Older Adults with Bipolar Disorder: A Review

Bipolar disorder (BD) is a common mood disorder that can have severe consequences during later life, including suffering and impairment due to mood and cognitive symptoms, elevated risk for dementia and an especially high risk for suicide. Greater understanding of the brain circuitry differences involved in older adults with BD (OABD) in later life and their relationship to aging processes is required to improve outcomes of OABD. The current literature on gray and white matter findings, from high resolution structural and diffusion-weighted magnetic resonance imaging (MRI) studies, has shown that BD in younger age groups is associated with gray matter reductions within cortical and subcortical brain regions that subserve emotion processing and regulation, as well as reduced structural integrity of white matter tracts connecting these brain regions. While fewer neuroimaging studies have focused on OABD, it does appear that many of the structural brain differences found in younger samples are present in OABD. There is also initial suggestion that there are additional brain differences, for at least a subset of OABD, that may result from more pronounced gray and white matter declines with age that may contribute to adverse outcomes. Preclinical and clinical data supporting neuro-plastic and -protective effects of mood-stabilizing medications, suggest that treatments may reverse and/or prevent the progression of brain changes thereby reducing symptoms. Future neuroimaging research implementing longitudinal designs, and large-scale, multi-site initiatives with detailed clinical and treatment data, holds promise for reducing suffering, cognitive dysfunction and suicide in OABD.

Integrity of cerebellar tracts associated with the risk of bipolar disorder

This study examined the structural brain differences across individuals of different BD stages and the risks of developing bipolar disorder (BD) associated with these brain differences. A total of 221 participants who were recruited from the Guangzhou Brain Hospital and the community were categorized into four groups: NC (healthy control) (N = 77), high risk (HR) (N = 42), ultra-high risk (UHR) (N = 38), and bipolar disorder (BD) (N = 64) based on a list of criteria. Their demographics, clinical characteristics, and diffusion magnetic resonance imaging (dMRI) data were collected. ANCOVA results showed that the HR group had significantly reduced mean diffusivity (MD) (p = 0.043) and radial diffusivity (RD) (p = 0.039) of the left portico-ponto-cerebellar tracts when compared with the BD group. Moreover, logistic regression results showed that the specific diffusivity measures of cerebellar tracts (e.g., cortico-ponto-cerebellar tract), particularly the RD and MD revealed differences between groups at different BD stages after controlling for the covariates. The findings suggested that specific diffusivity (RD and MD) of cerebellar tracts (e.g., cortico-ponto-cerebellar tract) revealed differences between groups at different BD stages which is helpful in detecting the trajectory changes in BD syndromes in the early stages of BD, particularly when the BD syndromes start from HR stage.

Cerebellum and Emotion in Social Behavior

Accumulating evidence suggests that the cerebellum plays a crucial role not only in the motor and cognitive domains but also in emotions and social behavior. In the present chapter, after a general introduction on the significance of the emotional components of social behavior, we describe recent efforts to understand the contributions of the cerebellum in social cognition focusing on the emotional and affective aspects. Specifically, starting from the description of the cerebello-cortical networks subtending the social-affective domains, we illustrate the most recent findings on the social cerebellum and the possible functional mechanisms by which the cerebellum modulate social-affective behavior. Finally, we discuss the possible consequences of cerebellar dysfunction in the social-affective domain, focusing on those neurological and psychopathological conditions in which emotional and social behavior difficulties have been described as being associated with cerebellar structural or functional alterations.

Altered cerebellar gray matter and cerebellar-cortex resting-state functional connectivity in patients with bipolar disorder Ⅰ

BACKGROUND

Bipolar disorder (BP) is a common psychiatric disorder characterized by extreme fluctuations in mood. Recent studies have indicated the involvement of cerebellum in the pathogenesis of BP. However, no study has focused on the precise role of cerebellum exclusively in patients with bipolar I disorder (BP-I).

METHODS

Forty-five patients with BP-I and 40 healthy controls were recruited. All subjects underwent clinical evaluation and Magnetic Resonance diffusion Tension Imaging scans. For structural images, we used a spatially unbiased infratentorial template toolbox to isolate the cerebellum and then preformed voxel-based morphometry (VBM) analyses to assess the difference in cerebellar gray matter volume (GMV) between the two groups. For the functional images, we chose the clusters that survived from VBM analysis as seeds and performed functional connectivity (FC) analysis. Between-group differences were assessed using the independent Students t test or the nonparametric Mann-Whitney U Test. For multiple comparisons, the results were further corrected with Gaussian random field (GRF) approach (voxel-level P < 0.001, cluster-level P < 0.05).

RESULTS

Compared with healthy controls, BP-I patients showed significantly decreased GMV in left lobule V and left lobule VI (P < 0.05, GRF corrected). The FC of cerebellum with bilateral superior temporal gyrus, bilateral insula, bilateral rolandic operculum, right putamen, and left precentral gyrus was disrupted in BP-I patients (P < 0.05, GRF corrected).

CONCLUSIONS

BP-I patients showed decreased cerebellar GMV and disrupted cerebellar-cortex resting-state FC. This suggests that cerebellar abnormalities may play an important role in the pathogenesis of BP-I.

Alterations in CRY2 and PER3 gene expression associated with thalamic-limbic community structural abnormalities in patients with bipolar depression or unipolar depression

Objectives The current study aimed to identify shared and distinct brain structure abnormalities and their relationships with the expression of circadian genes in patients with bipolar or unipolar depression. Method A total of 93 subjects participated in this study, including 32 patients with bipolar depression (BDP), 26 patients with unipolar depression (UDP) and 35 age- and sex-matched healthy controls. Brain structural magnetic resonance imaging scans were obtained, and optimized voxel-based morphometry was used to explore group differences in regional gray matter volume (GMV). The mRNA expression levels of circadian genes in peripheral blood were measured using reverse transcription quantitative real-time polymerase chain reaction. Results Our results showed that the GMV in brain regions in the thalamus-limbic pathways had significantly increased in the BDP patients compared to controls, while the increased GMV in UDP patients compared to controls was limited to the thalamus. The mRNA expression levels of circadian-related genes decreased significantly in patients with BDP, but increased in patients with UDP, compared to controls. In addition, the GMV in the right thalamus in the patients with UDP was positively associated with mRNA levels of CRY2, while the GMV in the right hippocampus in the patients with BDP was negatively associated with mRNA levels of PER3. Conclusion Our study suggested that patients with BDP or MDD shared GMV abnormalities in the right thalamus. The PER3 and CRY2 genes might be critical to right hippocampal dysfunction in BDP and right thalamic dysfunction in UDP, respectively. The result provided potentially important molecular targets for the treatment of mood disorders.

Common and specific patterns of functional and structural brain alterations in schizophrenia and bipolar disorder: a multimodal voxel-based meta-analysis

BACKGROUND

Schizophrenia and bipolar disorder have been linked to alterations in the functional activity and grey matter volume of some brain areas, reflected in impaired regional homogeneity and aberrant voxel-based morphometry. However, because of variable findings and methods used across studies, identifying patterns of brain alteration in schizophrenia and bipolar disorder has been difficult.

METHODS

We conducted a meta-analysis of differences in regional homogeneity and voxel-based morphometry between patients and healthy controls for schizophrenia and bipolar disorder separately, using seed-based d mapping.

RESULTS

We included 45 publications on regional homogeneity (26 in schizophrenia and 19 in bipolar disorder) and 190 publications on voxel-based morphometry (120 in schizophrenia and 70 in bipolar disorder). Patients with schizophrenia showed increased regional homogeneity in the frontal cortex and striatum and the supplementary motor area; they showed decreased regional homogeneity in the insula, primary sensory cortex (visual and auditory cortices) and sensorimotor cortex. Patients with bipolar disorder showed increased regional homogeneity in the frontal cortex and striatum; they showed decreased regional homogeneity in the insula. Patients with schizophrenia showed decreased grey matter volume in the superior temporal gyrus, inferior frontal gyrus, cingulate cortex and cerebellum. Patients with bipolar disorder showed decreased grey matter volume in the insula, cingulate cortex, frontal cortex and thalamus. Overlap analysis showed that patients with schizophrenia displayed decreased regional homogeneity and grey matter volume in the left insula and left superior temporal gyrus; patients with bipolar disorder displayed decreased regional homogeneity and grey matter volume in the left insula.

LIMITATIONS

The small sample size for our subgroup analysis (unmedicated versus medicated patients and substantial heterogeneity in the results for some regions could limit the interpretability and generalizability of the results.

CONCLUSION

Patients with schizophrenia and bipolar disorder shared a common pattern of regional functional and structural alterations in the insula and frontal cortex. Patients with schizophrenia showed more widespread functional and structural impairment, most prominently in the primary sensory motor areas.

Large-scale network abnormality in bipolar disorder: A multimodal meta-analysis of resting-state functional and structural magnetic resonance imaging studies

BACKGROUND

Bipolar disorder (BD) has been linked to abnormalities in the communication and gray matter volume (GMV) of large-scale brain networks, as reflected by impaired resting-state functional connectivity (rs-FC) and aberrant voxel-based morphometry (VBM). However, identifying patterns of large-scale network abnormality in BD has been elusive.

METHODS

Whole-brain seed-based rs-FC and VBM studies comparing individuals with BD and healthy controls (HCs) were retrieved from multiple databases. Multilevel kernel density analysis was used to identify brain networks in which BD was linked to hyper-connectivity or hypo-connectivity with each prior network and the overlap between dysconnectivity and GMV changes.

RESULTS

Thirty-six seed-based rs-FC publications (1526 individuals with BD and 1578 HCs) and 70 VBM publications (2715 BD and 3044 HCs) were included in the meta-analysis. Our results showed that BD was characterized by hypo-connectivity within the default network (DN), hyper-connectivity within the affective network (AN), and ventral attention network (VAN) and hypo- and hyper-connectivity within the frontoparietal network (FN). Hyper-connectivity between-network of AN-DN, AN-FN, AN-VAN, AN-thalamus network (TN), VAN-TN, VAN-DN, VAN-FN, and TN-sensorimotor network were found. Hypo-connectivity between-network of FN and DN was observed. Decreased GMV was found in the insula, inferior frontal gyrus, and anterior cingulate cortex.

LIMITATIONS

Differential weights in the number of included studies and sample size of FC and VBM might have a disproportionate influence on the meta-analytic results.

CONCLUSIONS

These results suggest that BD is characterized by both structural and functional abnormalities of large-scale neurocognitive networks, especially in the DN, AN, VAN, FN, and TN.

Aberrant Cerebello-Cerebral Connectivity in Remitted Bipolar Patients 1 and 2: New Insight into Understanding the Cerebellar Role in Mania and Hypomania

Bipolar disorder (BD) is a major mental illness characterized by periods of (hypo) mania and depression with inter-episode remission periods. Functional studies in BD have consistently implicated a set of linked cortical and subcortical limbic regions in the pathophysiology of the disorder, also including the cerebellum. However, the cerebellar role in the neurobiology of BD still needs to be clarified. Seventeen euthymic patients with BD type1 (BD1) (mean age/SD, 38.64/13.48; M/F, 9/8) and 13 euthymic patients with BD type 2 (BD2) (mean age/SD, 41.42/14.38; M/F, 6/7) were compared with 37 sex- and age-matched healthy subjects (HS) (mean age/SD, 45.65/14.15; M/F, 15/22). T1 weighted and resting-state functional connectivity (FC) scans were acquired. The left and right dentate nucleus were used as seed regions for the seed based analysis. FC between each seed and the rest of the brain was compared between patients and HS. Correlations between altered cerebello-cerebral connectivity and clinical scores were then investigated. Different patterns of altered dentate-cerebral connectivity were found in BD1 and BD2. Overall, impaired dentate-cerebral connectivity involved regions of the anterior limbic network specifically related to the (hypo)manic states of BD. Cerebello-cerebral connectivity is altered in BD1 and BD2. Interestingly, the fact that these altered FC patterns persist during euthymia, supports the hypothesis that cerebello-cerebral FC changes reflect the neural correlate of subthreshold symptoms, as trait-based pathophysiology and/or compensatory mechanism to maintain a state of euthymia.

Dissociation Pattern in Default-Mode Network Homogeneity in Drug-Naive Bipolar Disorder

Default mode network (DMN) plays a key role in the pathophysiology of in bipolar disorder (BD). However, the homogeneity of this network in BD is still poorly understood. This study aimed to investigate abnormalities in the NH of the DMN at rest and the correlation between the NH of DMN and clinical variables in patients with BD. Forty drug-naive patients with BD and thirty-seven healthy control subjects participated in the study. Network homogeneity (NH) and independent component analysis (ICA) methods were used for data analysis. Support vector machines (SVM) method was used to analyze NH in different brain regions. Compared with healthy controls, significantly increased NH in the left superior medial prefrontal cortex (MPFC) and decreased NH in the right posterior cingulate cortex (PCC) and bilateral precuneus were found in patients with BD. NH in the right PCC was positively correlated with the verbal fluency test and verbal function total scores. NH in the left superior MPFC was negatively correlated with triglyceride (TG). NH in the right PCC was positively correlated with TG but negatively correlated with high-density lipoprotein cholesterol (HDL-C). NH in the bilateral precuneus was positively correlated with cholesterol and low-density lipoprotein cholesterol (LDL-C). In addition, NH in the left superior MPFC showed high sensitivity (80.00%), specificity (71.43%), and accuracy (75.61%) in the SVM results. These findings contribute new evidence of the participation of the altered NH of the DMN in the pathophysiology of BD.

Comparison of Cerebellar Grey Matter Alterations in Bipolar and Cerebellar Patients: Evidence from Voxel-Based Analysis

The aim of this study was to compare the patterns of cerebellar alterations associated with bipolar disease with those induced by the presence of cerebellar neurodegenerative pathologies to clarify the potential cerebellar contribution to bipolar affective disturbance. Twenty-nine patients affected by bipolar disorder, 32 subjects affected by cerebellar neurodegenerative pathologies, and 37 age-matched healthy subjects underwent a 3T MRI protocol. A voxel-based morphometry analysis was used to show similarities and differences in cerebellar grey matter (GM) loss between the groups. We found a pattern of GM cerebellar alterations in both bipolar and cerebellar groups that involved the anterior and posterior cerebellar regions (p = 0.05). The direct comparison between bipolar and cerebellar patients demonstrated a significant difference in GM loss in cerebellar neurodegenerative patients in the bilateral anterior and posterior motor cerebellar regions, such as lobules I-IV, V, VI, VIIIa, VIIIb, IX, VIIb and vermis VI, while a pattern of overlapping GM loss was evident in right lobule V, right crus I and bilateral crus II. Our findings showed, for the first time, common and different alteration patterns of specific cerebellar lobules in bipolar and neurodegenerative cerebellar patients, which allowed us to hypothesize a cerebellar role in the cognitive and mood dysregulation symptoms that characterize bipolar disorder.

Time to rehospitalization in patients with bipolar mania discharged on long-acting injectable or oral antipsychotics

OBJECTIVE

This study aimed to analyze time to rehospitalization in patients with bipolar mania discharged on long-acting injectable antipsychotics (LAIs) or oral antipsychotics (OAPs). Additionally, temporal trends in LAI prescription were investigated.

METHODS

Patients with bipolar mania discharged from the study hospital on antipsychotics between 2006 and 2018 were included. Survival analysis was used to compare time to rehospitalization within one year of discharge between patients discharged on LAIs and OAPs, and between FGA-LAIs (first- generation antipsychotic) and SGA-LAIs (second-generation antipsychotic). The Cochrane-Armitage trend test was used to test whether a temporal trend existed for LAI prescription rates during the study period.

RESULTS

The LAI group (n = 224) had a significantly lower rehospitalization rate and a significantly longer time to rehospitalization than the OAP group (n = 3836). Rehospitalization rate and time to rehospitalization were not significantly different between patients discharged on FGA-LAIs or SGA-LAIs. The LAI prescription rate grew significantly from 2.20% in 2006 to 11.58% in 2018 (Z = 5.5843, p < 0.0001). The prescription rate of SGA-LAIs also increased significantly (Z = 7.7141, p < 0.0001), but not the prescription rate of FGA-LAIs.

LIMITATIONS

The treatment allocation is not randomized in this retrospective study. Furthermore, various clinical characteristics were unavailable in our analysis, such as symptom severity, functional impairment, and others.

CONCLUSIONS

LAIs were significantly superior to OAPs in reducing rehospitalization risk. However, SGA-LAIs were comparable with FGA-LAIs in reducing rehospitalization risk. Use of LAIs increased significantly in discharged patients with bipolar disorder during the study period, especially SGA-LAIs.

Cerebro-cerebellar white matter connectivity in bipolar disorder and associated polarity subphenotypes

BACKGROUND

The cerebellum has a crucial role in mood regulation. While cerebellar grey matter (GM) alterations have been previously reported in bipolar disorder (BD), cerebro-cerebellar white matter (WM) connectivity alterations and cerebellar GM profiles have not been characterised in the context of predominant polarity (PP) and onset polarity (OP) subphenotypes of BD patients which is the aim of the present study.

METHODS

Forty-two euthymic BD patients stratified for PP and OP and 42 healthy controls (HC) were included in this quantitative neuroimaging study to evaluate cerebellar GM patterns and cerebro-cerebellar WM connections. Diffusion tensor tractography was used to characterise afferent and efferent cerebro-cerebellar tract integrity. False discovery rate corrections were applied in post-hoc comparisons.

RESULTS

BD patients exhibited higher fractional anisotropy (FA) in fronto-ponto-cerebellar tracts bilaterally compared to HC. Subphenotype-specific FA profiles were identified within the BD cohort. Regarding PP subgroups, we found FA changes in a) left contralateral fronto-ponto-cerebellar tract (depressive-PP > HC) and b) contralateral/ipsilateral fronto-ponto-cerebellar tracts bilaterally (manic-PP > HC). Regarding OP subgroups, we observed FA changes in a) left/right contralateral fronto-ponto-cerebellar tracts (depressive-OP > HC) and b) all fronto-ponto-cerebellar, most parieto-ponto-cerebellar and right contralateral occipito-ponto-cerebellar tracts (manic-OP>HC). In general, greater and more widespread cerebro-cerebellar changes were observed in manic-OP patients than in depressive-OP patients compared to HC. Manic-OP showed higher FA compared to depressive-OP patients in several afferent WM tracts. No GM differences were identified between BD and HC and across BD subgroups.

CONCLUSIONS

Our findings highlight fronto-ponto-cerebellar connectivity alterations in euthymic BD. Polarity-related subphenotypes have distinctive cerebro-cerebellar WM signatures with potential clinical and pathobiological implications.

Consensus Paper: Cerebellum and Social Cognition

The traditional view on the cerebellum is that it controls motor behavior. Although recent work has revealed that the cerebellum supports also nonmotor functions such as cognition and affect, only during the last 5 years it has become evident that the cerebellum also plays an important social role. This role is evident in social cognition based on interpreting goal-directed actions through the movements of individuals (social "mirroring") which is very close to its original role in motor learning, as well as in social understanding of other individuals' mental state, such as their intentions, beliefs, past behaviors, future aspirations, and personality traits (social "mentalizing"). Most of this mentalizing role is supported by the posterior cerebellum (e.g., Crus I and II). The most dominant hypothesis is that the cerebellum assists in learning and understanding social action sequences, and so facilitates social cognition by supporting optimal predictions about imminent or future social interaction and cooperation. This consensus paper brings together experts from different fields to discuss recent efforts in understanding the role of the cerebellum in social cognition, and the understanding of social behaviors and mental states by others, its effect on clinical impairments such as cerebellar ataxia and autism spectrum disorder, and how the cerebellum can become a potential target for noninvasive brain stimulation as a therapeutic intervention. We report on the most recent empirical findings and techniques for understanding and manipulating cerebellar circuits in humans. Cerebellar circuitry appears now as a key structure to elucidate social interactions.

Comparison of first-episode and multiple-episode bipolar disorder: A surface-based morphometry study

It is still unclear whether the structural abnormalities in Bipolar disorder (BD) are static or progressive. We aimed to compare differences in cortical thickness, surface area, and volume between patients with BD and healthy volunteers (HV) and to examine whether there are differences between patients who have had a single manic episode and those with multiple episodes. We recruited 30 patients with Type I BD and 30 age and sex matched HV. All participants underwent structural magnetic resonance imaging. Cortical volume, thickness, and surface area were measured using the QDEC tool from the Freesurfer software with age and intracranial volume as covariates. Study groups were comparable across age, sex distribution, and intracranial volume. Patients had significantly lower surface area in bilateral cuneus, right postcentral gyrus, and rostral middle frontal gyri; and lower cortical volume in the left middle temporal gyrus, right postcentral gyrus, and right cuneus. BD patients with multiple episodes had lower cortical measures while those with single episode had cortical measures comparable to HV. Findings indicate that the pathophysiological processes in BD are possibly progressive in nature. Our findings underscore the potential importance of early diagnosis and intervention in preventing deterioration and improving functional recovery.

Fusion analysis of gray matter and white matter in bipolar disorder by multimodal CCA-joint ICA

BACKGROUND

Bipolar disorder (BD) patients show morphological abnormalities in gray matter (GM) and white matter (WM), which can be revealed by structure MRI (sMRI) and diffusion tensor imaging (DTI) respectively. However, previous studies on BD mainly relied on separated analysis of single neuroimaging modality, and it remains unclear how GM and WM covary to the abnormal brain structures of BD patients.

METHODS

We recorded multimodal sMRI-DTI data of 35 BD patients and 30 healthy controls (HC) and used multimodal canonical component analysis and joint independent component analysis (mCCA-jICA) to identify altered covariant structures in GM and WM of BD. Group-discriminative and joint group-discriminative independent components (ICs) were identified between BD and HC. Correlation analysis was performed between the mixing coefficients and behavioral index.

RESULTS

For BD patients, experiments results revealed that the GM atrophy in inferior frontal gyrus, right anterior cingulate gyrus and left superior frontal gyrus are associated with the WM integrity reduction in corticospinal tract and superior longitudinal fasciculus. Further, compared with HC, different correlation between mixing coefficients of ICs and age was observed for BD patients.

LIMITATIONS

The number of participants needs to be increased to more rigorously validate the results of this study, ideally from multiple sites. Functional imaging data could be utilized to explore structural-functional covariant pattern in BD. Possible confounding effect of medication.

CONCLUSIONS

We performed fusion analysis of sMRI and DTI and revealed covariant (GM-WM) structural patterns of BD patients. This study could be useful for developing more reliable neural biomarkers of BD.

Personalized and precision medicine as informants for treatment management of bipolar disorder

DSM-5 diagnostic categories, defined by a set of psychopathological symptoms are heterogeneous conditions that may include different biological entities, with distinct etiopathogenesis, different courses and requiring different treatment management. For bipolar disorder the major evidences for this lack of validity are the long paths before a proper diagnosis, the inconsistence of treatment guidelines, the long phases of pharmacological adjustment and the low average of long-term treatment response rates. Personalized medicine for mental disorders aims to couple established clinical-pathological indexes with new molecular profiling to create diagnostic, prognostic and therapeutic strategies precisely tailored to each patient. Regarding bipolar disorder, the clinical history and presentation are still the most reliable markers in stratifying patients and guiding therapeutic management, despite the research goes to great lengths to develop new neuropsychological or biological markers that can reliably predict individual therapy effectiveness. We provide an overview of the advancements in personalized medicine in bipolar disorder, with particular attention to how psychopathology, age at onset, comorbidity, course and staging, genetic and epigenetic, imaging and biomarkers can influence treatment management and provide an integration to the conventional treatment guidelines. This approach may offer a new and rational path for the development of treatments for targeted subgroups of patients with bipolar disorder.

From cerebellar alterations to mood disorders: A systematic review

BACKGROUND

Several studies have shown cerebellar abnormalities during depressive and manic states, although the specific cerebellar role in mood fluctuations remains poorly defined. Therefore, the study of pathologies characterized by frequent mood swings, such as bipolar disorder, is of great interest to investigate the relationship between the cerebellum and mood alterations.

METHODS

A systematic literature search on the occurrence of mood disorders in patients with cerebellar pathologies (1^st research strategy) and on the presence of cerebellar alterations in mood disorders (2^nd research strategy) was conducted using the PubMed electronic Internet database. For this systematic review all information was written based on the PRISMA-P statement.

RESULTS

The results of the 1^st research strategy generated 9 articles, and in one of these, a direct correlation between cerebellar damage and the onset of mood disorder was reported. The 2^nd research strategy generated 14 articles that were grouped according to the patient's mood phase (manic or depressive) or diagnosis (bipolar I or bipolar II).

CONCLUSIONS

The present review suggests that the cerebellum should be considered a key structure involved in the regulation of mood.

Cortical Volume and Thickness Across Bipolar Disorder Subtypes in Adolescents: A Preliminary Study

OBJECTIVES

Neuroimaging studies of adults with bipolar disorder (BD) have identified several BD subtype distinctions, including greater deficits in prefrontal gray matter volumes in BD-I (bipolar I disorder) compared to BD-II (bipolar II disorder). We sought to investigate BD subtype differences in brain structure among adolescents and young adults.

METHODS

Forty-four youth with BD (14 BD-I, 16 BD-II, and 14 BD-not otherwise specified [NOS], mean age 17) underwent 3T-MRI and images were analyzed using FreeSurfer software. Cortical volume and thickness were analyzed for region of interest (ROI): ventrolateral prefrontal cortex, ventromedial prefrontal cortex, anterior cingulate cortex (ACC), subgenual cingulate cortex, and amygdala, controlling for age, sex, and total intracranial volume. ROIs were selected as found to be implicated in BD in prior studies. A whole brain vertex-wise exploratory analysis was also performed. Uncorrected results are presented.

RESULTS

There were group differences in ACC thickness (F = 3.88, p = 0.03, η² = 0.173 uncorrected), which was reduced in BD-II in comparison to BD-I (p = 0.027 uncorrected) and BD-NOS (p = 0.019 uncorrected). These results did not survive correction for multiple comparisons and no other group differences were observed. The exploratory vertex-wise analysis found a similar pattern of lower cortical thickness in BD-II in the left and right superior frontal gyrus and left caudal middle frontal gyrus.

CONCLUSIONS

This study found reduced cortical thickness for youth with BD-II, relative to BD-I, in regions associated with cognitive control. Further neurostructural differences between subtypes may emerge later during the course of illness.

Abnormal cerebellum-DMN regions connectivity in unmedicated bipolar II disorder

OBJECTIVE

Bipolar disorder (BD) is a common psychiatric disease. Previous studies have found abnormalities in structural and functional brain connectivity in BD patients. However, few studies have focused on the functional connectivity (FC) of the cerebellum and its sub-regions in patients with BD. The present study aimed to examine the FC of cerebellum-default mode network (DMN) regions in patients with BD II.

METHOD

Ninety patients with unmedicated BD II depression and 100 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging. We selected three pairs of subregions of the cerebellum that are DMN-related (the bilateral Crus I, Crus II, and lobule IX) as seed regions and calculated the whole brain FC for each subregion.

RESULTS

Compared with the HCs, the patients with BD II depression showed increased connectivity between the right Crus I and bilateral precuneus and decreased connectivity between the left Crus II and bilateral medial prefrontal cortex (mPFC) and between the left Crus II and right medial frontal gyrus (MFG). There was no significant difference in the whole FC of the left Crus I and bilateral lobule IX between the BD II depression group and the HCs group.

LIMITATIONS

This study was cross-sectional and did not examine data from euthymic BD patients.

CONCLUSIONS

The findings showed impaired FC of cerebellum-DMN regions in BD; partial FC between the Crus I and precuneus and the Crus II and prefrontal cortex suggests the importance of abnormal cerebellum-DMN regions FC in the pathophysiology of BD.

Correlation between Intrinsic Brain Activity and Thyroid-Stimulating Hormone Level in Unmedicated Bipolar II Depression

BACKGROUND/AIMS

Although abnormalities of amplitude of low-frequency fluctuations (ALFF) and hormone levels of hypothalamus-pituitary-thyroid axis have been reported in patients with bipolar disorder (BD), the association between abnormal ALFF and serum thyroid hormone levels remains unknown.

METHOD

A total of 90 patients with unmedicated BD II depression and 100 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging, and then routine band (0.01-0.1 Hz), slow-5 band (0.01-0.027 Hz), and slow-4 band (0.027-0.073 Hz) ALFF analysis were performed. Additionally, serum thyroid hormone levels including free tri-iodothyronine (FT3), total tri-iodothyronine (TT3), free thyroxin (FT4), total thyroxin (TT4), and thyroid-stimulating hormone (TSH) were detected. The correlation between abnormal serum thyroid hormone levels and ALFF values in patients with BD II depression was calculated.

RESULTS

Compared with the HCs, patients with BD II depression showed decreased ALFF in bilateral precuneus (PCu)/posterior cingulate cortex (PCC) in routine and slow-4 frequency bands, decreased ALFF in the right PCu, and increased ALFF in the right middle occipital gyrus (MOG) in the slow-5 frequency band. Additionally, patients with BD II depression showed lower TSH level than HCs, and TSH level was positively correlated with ALFF values in the bilateral PCu/PCC in the routine frequency band.

CONCLUSIONS

These findings suggest that patients with BD II depression display intrinsic activity abnormalities, mainly in the PCu/PCC and MOG, which are associated with specific frequency bands. Moreover, altered intrinsic activity in the PCu/PCC may be related to TSH levels in bipolar II depression.

Altered cerebellar functional connectivity in remitted bipolar disorder: A resting-state functional magnetic resonance imaging study

OBJECTIVES

Several recent studies have reported a strong association between the cerebellar structural and functional abnormalities and psychiatric disorders. However, there are no studies to investigate possible changes in cerebellar functional connectivity in bipolar disorder. This study aimed to examine the whole-brain functional connectivity pattern of patients with remitted bipolar disorder II, in particular in the cerebellum.

METHODS

A total of 25 patients with remitted bipolar disorder II and 25 controls underwent resting-state functional magnetic resonance imaging and neuropsychological tests. Voxel-wise whole-brain connectivity was analyzed using a graph theory approach: functional connectivity strength. A seed-based resting-state functional connectivity analysis was further performed to investigate abnormal functional connectivity pattern of those regions with changed functional connectivity strength.

RESULTS

Remitted bipolar disorder II patients had significantly decreased functional connectivity strength in the bilateral posterior lobes of cerebellum (mainly lobules VIIb/VIIIa). The seed-based functional connectivity analyses revealed decreased functional connectivity between the right posterior cerebellum and the default mode network (i.e. right posterior cingulate cortex/precuneus and right superior temporal gyrus), bilateral hippocampus, right putamen, left paracentral lobule and bilateral posterior cerebellum and decreased functional connectivity between the left posterior cerebellum and the right inferior parietal lobule and bilateral posterior cerebellum in patients with remitted bipolar disorder II.

CONCLUSION

Our results suggest that cerebellar dysconnectivity, in particular distributed cerebellar-cerebral functional connectivity, might be associated with the pathogenesis of bipolar disorder.

Potential Gender-Related Aging Processes Occur Earlier and Faster in the Vermis of Patients with Bipolar Disorder: An MRI Study

BACKGROUND

In the last decades, there has been increasing interest in investigating the role of the vermis in bipolar disorder (BD), especially because of its involvement in cognitive processes. The main aims of this study were to explore the integrity of the vermis and elucidate the role of demographic and clinical variables on vermis volumes in BD patients, stratified according to gender.

METHODS

T1-weighted images were obtained for 38 BD patients and 38 healthy controls using a 1.5-T MRI scanner. Images were analyzed with a PC workstation with BRAINS2 software on a Linux system. Anatomical regions were traced manually from a blinded operator, with respect to subject identity and other clinical variables.

RESULTS

The direct comparison between the 2 groups showed no significant gray matter differences in vermis volumes. Interestingly, vermis volumes were significantly inversely associated with chronological age and age of BD onset, particularly in male subjects.

CONCLUSIONS

Our study provides evidence of the impact of aging on the vermis in BD, potentially related to earlier and faster gender-related neurodegenerative phenomena occurring during the progression of the disease.

Factors affecting time to remission for inpatients with bipolar mania - A naturalistic Taiwanese study

BACKGROUND

Bipolar disorder is a complicated and chronic mental disorder. This study investigated factors affecting time to remission for inpatients with bipolar mania after 4 weeks of acute treatment.

METHODS

This naturalistic study recruited inpatients with bipolar mania for acute treatment. Symptom severity was assessed using the Young Mania Rating Scale (YMRS) at weeks 0, 1, 2, 3, and 4. Patients were included if they had had assessments at weeks 0 and 1 Remission was defined as an YMRS score ≤ 12. The Cox regression analysis was used to analyze factors associated with time to remission after 4 weeks of acute treatment.

RESULTS

Four hundred and forty-nine patients entered the analysis. Seventy-one of the 449 subjects (15.8%) reached symptomatic remission within 4 weeks of acute treatment. Using forward multivariate Cox regression analysis, comorbid substance use disorders, earlier age at onset, and greater manic symptom severity at baseline found to be statistically significant predictors of a longer time to reach remission after 4 weeks of treatment.

LIMITATIONS

As a retrospective chart review and naturalistic design, placebo effect and potentially confounding factors such as the possibility of missing records may have limited our results.

CONCLUSIONS

Early identification and intervention with integrated therapy is considered to shorten time to remission for patients at high risk of poor treatment outcome. More studies are needed in other real-world settings to generalize our results.

Pathophysiology in the comorbidity of Bipolar Disorder and Alzheimer's Disease: pharmacological and stem cell approaches

Neuropsychiatric disorders involve various pathological mechanisms, resulting in neurodegeneration and brain atrophy. Neurodevelopmental processes have shown to be critical for the progression of those disorders, which are based on genetic and epigenetic mechanisms as well as on extrinsic factors. We review here common mechanisms underlying the comorbidity of Bipolar Disorders and Alzheimer's Disease, such as aberrant neurogenesis and neurotoxicity, reporting current therapeutic approaches. The understanding of these mechanisms precedes stem cell-based strategies as a new therapeutic possibility for treatment and prevention of Bipolar and Alzheimer's Disease progression. Taking into account the difficulty of studying the molecular basis of disease progression directly in patients, we also discuss the importance of stem cells for effective drug screening, modeling and treating psychiatric diseases, once in vitro differentiation of patient-induced pluripotent stem cells provides relevant information about embryonic origins, intracellular pathways and molecular mechanisms.

Meta-analysis of regional white matter volume in bipolar disorder with replication in an independent sample using coordinates, T-maps, and individual MRI data

Converging evidence suggests that bipolar disorder (BD) is associated with white matter (WM) abnormalities. Meta-analyses of voxel based morphometry (VBM) data is commonly performed using published coordinates, however this method is limited since it ignores non-significant data. Obtaining statistical maps from studies (T-maps) as well as raw MRI datasets increases accuracy and allows for a comprehensive analysis of clinical variables. We obtained coordinate data (7-studies), T-Maps (12-studies, including unpublished data) and raw MRI datasets (5-studies) and analysed the 24 studies using Seed-based d Mapping (SDM). A VBM analysis was conducted to verify the results in an independent sample. The meta-analysis revealed decreased WM volume in the posterior corpus callosum extending to WM in the posterior cingulate cortex. This region was significantly reduced in volume in BD patients in the independent dataset (p=0.003) but there was no association with clinical variables. We identified a robust WM volume abnormality in BD patients that may represent a trait marker of the disease and used a novel methodology to validate the findings.

The regulation of tetraspanin 8 gene expression-A potential new mechanism in the pathogenesis of bipolar disorder

In a previous study, we identified the single nucleotide polymorphism (SNP) rs4500567, located in the upstream region of tetraspanin 8 (TSPAN8), to be associated with bipolar disorder (BD). Due to its proximal position, the SNP might have an impact on promoter activity, thus on TSPAN8 gene expression. We investigated the impact of rs4500567 on TSPAN8 expression in vitro with luciferase-based promoter assays in human embryonic kidney (HEK293) and neuroblastoma cells (SH-SY5Y), and its effect on expression of downstream associated genes by microarray-based transcriptome analyses. Immunohistochemical localization studies on murine brain slices served to identify possible target regions of altered TSPAN8 expression in the brain. Promoter assays revealed decreased TSPAN8 expression in presence of the minor allele. Transcriptome analyses of TSPAN8-knockdown cells, mirroring the effects of putatively reduced TSPAN8 expression in minor allele carriers, resulted in 231 differentially expressed genes with enrichments of relevant signaling pathways for psychiatric disorders and neuronal development. Finally, we demonstrate Tspan8 abundance in mouse cerebellum and hippocampus. These findings point to a role of TSPAN8 in neuronal function or development. Considering a rather protective effect of the minor allele of rs4500567, our findings reveal a possible novel mechanism that contributes to the development of BD.

Elucidating the aberrant brain regions in bipolar disorder using T1-weighted/T2-weighted magnetic resonance ratio images

Although diffusion tensor imaging (DTI) have revealed brain abnormalities in bipolar disorder (BD) subjects, DTI methods might not detect disease-related abnormalities in the white matter (WM) where nerve fibers are crossing. We investigated BD myelin-related abnormal brain regions in both gray matter and WM for 29 BD and 33 healthy control (HC) participants using T1-weighted (T1w)/T2-weighted (T2w) ratio images that increase myelin-related contrast irrespective of nerve fiber orientation. To check effect of the brain volume, the results were compared with those of voxel-based morphometry (VBM). We found significantly lower T1w/T2w signal intensity in broad WM regions in BD subjects, including the corpus callosum, corona radiata, internal capsule, middle cerebellar peduncle and cerebellum. Regional volume reduction was found in the WM bilateral posterior thalami and retrolenticular part of the internal capsules of BD subjects. We also performed tract-based spatial statistics (TBSS) in 25 BD and 24 HC participants and compared those for the T1w/T2w ratio images. Both methods detected the BD corpus callosum abnormality. Further, the ratio images detected the corona radiata and the cerebellar abnormality in BD. These results suggest that T1w/T2w ratio image analysis could take a complementary role with the DTI method in elucidating myelin-related abnormalities in BD.

Structural and metabolic differentiation between bipolar disorder with psychosis and substance-induced psychosis: An integrated MRI/PET study

BACKGROUND

Bipolar disorder (BD) may be characterized by the presence of psychotic symptoms and comorbid substance abuse. In this context, structural and metabolic dysfunctions have been reported in both BD with psychosis and addiction, separately. In this study, we aimed at identifying neural substrates differentiating psychotic BD, with or without substance abuse, versus substance-induced psychosis (SIP) by coupling, for the first time, magnetic resonance imaging (MRI) and positron emission tomography (PET).

METHODS

Twenty-seven BD type I psychotic patients with (n=10) or without (n=17) substance abuse, 16 SIP patients and 54 healthy controls were enrolled in this study. 3T MRI and 18-FDG-PET scanning were acquired.

RESULTS

Gray matter (GM) volume and cerebral metabolism reductions in temporal cortices were observed in all patients compared to healthy controls. Moreover, a distinct pattern of fronto-limbic alterations were found in patients with substance abuse. Specifically, BD patients with substance abuse showed volume reductions in ventrolateral prefrontal cortex, anterior cingulate, insula and thalamus, whereas SIP patients in dorsolateral prefrontal cortex and posterior cingulate. Common alterations in cerebellum, parahippocampus and posterior cingulate were found in both BD with substance abuse and SIP. Finally, a unique pattern of GM volumes reduction, with concomitant increased of striatal metabolism, were observed in SIP patients.

CONCLUSIONS

These findings contribute to shed light on the identification of common and distinct neural markers associated with bipolar psychosis and substance abuse. Future longitudinal studies should explore the effect of single substances of abuse in patients at the first-episode of BD and substance-induced psychosis.