Rumination in bipolar disorder: evidence for an unquiet mind

Sex differences in neural responses to emotional facial expressions are associated with lifetime depression and mania risk

INTRODUCTION

No studies systematically examined sex differences in neural mechanisms underlying depression and mania/hypomania risk.

METHOD

80 females and 35 males, n = 115(age21.6±1.90) were scanned using 3TfMRI during an implicit emotional-faces task. We examined neural activation to all emotional faces versus baseline, using an anatomical region-of-interest mask comprising regions supporting emotion and salience processing. Sex was a covariate. Extracted parameter estimates(FWE < 0.05,k > 15), age, IQ and their sex interactions were independent variables(IV) in two penalized regression models: dependent variable either MOODS-SR-lifetime, depressive or manic domain score as measures of mania and depression risk. Subsequent Poisson regression models included the non-zero variables identified in the penalized regression models. We tested each model in 2 independent samples. Test sample-I,n = 108(21.6 ± 2.09 years,males/females = 33/75); Test sample-II,n = 93(23.7 ± 2.9 years,males/females = 31/62).

RESULTS

Poisson regression models yielded significant relationships with depression and mania risk: Positive correlations were found between right fusiform activity and depression(beta = 0.610) and mania(beta = 0.690) risk. There was a significant interaction between sex and right fusiform activity(beta = -0.609) related to depression risk, where females had a positive relationship than; and a significant interaction(beta = 0.743) between sex and left precuneus activity related to mania risk, with a more negative relationship in females than males. All findings were replicated in the test samples(qs < 0.05,FDR).

LIMITATIONS

No longitudinal follow-up.

CONCLUSION

Greater visual attention to emotional faces might underlie greater depression and mania risk, and confer greater vulnerability to depression in females, because of heightened visual attention to emotional faces. Females have a more negative relationship between mania risk and left precuneus activity, suggesting heightened empathy might be associated with reduced mania/hypomania risk in females more than males.

Behavioral evidence of impaired self-referential processing in patients with affective disorders and first-episode schizophrenia

Despite the critical role of self-disturbance in psychiatric diagnosis and treatment, its diverse behavioral manifestations remain poorly understood. This investigation aimed to elucidate unique patterns of self-referential processing in affective disorders and first-episode schizophrenia. A total of 156 participants (41 first-episode schizophrenia [SZ], 33 bipolar disorder [BD], 44 major depressive disorder [MDD], and 38 healthy controls [HC]) engaged in a self-referential effect (SRE) task, assessing trait adjectives for self-descriptiveness, applicability to mother, or others, followed by an unexpected recognition test. All groups displayed preferential self- and mother-referential processing with no significant differences in recognition scores. However, MDD patients showed significantly enhanced self-referential recognition scores and increased bias compared to HC, first-episode SZ, and BD. The present study provides empirical evidence for increased self-focus in MDD and demonstrates that first-episode SZ and BD patients maintain intact self-referential processing abilities. These findings refine our understanding of self-referential processing impairments across psychiatric conditions, suggesting that it could serve as a supplementary measure for assessing treatment response in first-episode SZ and potentially function as a discriminative diagnostic criterion between MDD and BD.

Predictive Value of qEEG in Manic Switch of Depressed Patients

Backgrounds: More than half of the patients with bipolar disorder (BD) had depressive episodes at the onset of BD. Despite some suggested clinical predictors, there are no certain criteria for predicting which unipolar depression patient switch to manic episodes during the treatment course. Electrophysiological markers can address this issue. Methods: Pretreatment quantitative electroencephalography (qEEG) records of patients diagnosed with major depressive disorder (MDD) or BD at the first visit were included in the study. Patients with MDD were also grouped with manic switch (MS) or MDD based on the diagnosis of later visits. The qEEG spectral power was analyzed across 3 groups, that is, MS, MDD, and BD. Results: Compared to patients whose diagnosis did not change, patients with MS had accelerated high-frequency activities predominantly in the left hemisphere (central-parietal-occipital regions). In contrast, they showed increased slow wave activity predominantly in the right hemisphere (parietal-occipital regions). Conclusion: It can be concluded that searching for electrophysiological markers, which have distinct advantages of repeatability, noninvasiveness, and cost-effectiveness, can facilitate the prediction of the MS.

Rumination in bipolar disorder associated with brain network and behavioural measures of inhibitory executive control

OBJECTIVE

Rumination is a passive form of negative self-focused cognition that predicts depressive episodes for individuals with bipolar disorder (BD). Individuals with BD also have impaired inhibitory executive control; rumination in BD may therefore reflect executive dysfunction. We investigated the relationship between a neural measure of executive functioning (functional connectivity between the frontoparietal control network [FPCN] and the default mode network [DMN] during an effortful task), behavioural measures of executive functioning (the Behavior Rating Inventory of Executive Function) and rumination (the Ruminative Responses Scale).

METHODS

Fifteen individuals with BD and fifteen healthy controls underwent MRI scans during mental distraction. Using CONN toolbox, between-network FPCN-DMN connectivity values were calculated. We conducted Pearson's r bivariate correlations between connectivity values, BRIEF and RRS scores.

RESULTS

RRS scores were positively correlated with BRIEF Behavioral Regulation Index (BRI) scores. In individuals with BD, there was a positive correlation between FPCN-DMN functional connectivity during distraction and BRIEF BRI scores. FPCN-DMN functional connectivity was also positively correlated with RRS ruminative brooding scores. Healthy controls did not show significant correlations between these behavioural and neural measures of executive functioning and rumination.

CONCLUSION

For individuals with BD, the greater the tendency to ruminate and the higher the executive dysfunction, the stronger the connectivity between an executive control network and a network involved in rumination during an unrelated cognitive task. This could reflect continual attempts to inhibit ruminative thinking and shift back to the distraction task. Therefore, engagement in rumination may reflect failed inhibitory executive control.

Amygdala-based functional connectivity mediates the relationship between thought control ability and trait anxiety

Thought control ability (TCA) refers to the ability to exclude unwanted thoughts. There has been consistent evidence on the protective effect of TCA on anxiety, that higher TCA is associated with lower anxiety. However, the underlying neural mechanism remains unclear. In this study, with a large sample (N = 495), we investigated how seed-based resting-state functional connectivity (RSFC) mediates the relationship between TCA and anxiety. Our behaviour results replicated previous findings that TCA is negatively associated with trait anxiety after controlling for gender, age, and depression. More importantly, the RSFC results revealed that TCA is negatively associated with the left amygdala - left frontal pole (LA-LFP), left amygdala - left inferior temporal gyrus (LA-LITG), and left hippocampus - left inferior frontal gyrus (LH-LIFG) connectivity. In addition, a mediation analysis demonstrated that the LA-LFP and LA-LITG connectivity in particular mediated the influence of TCA on trait anxiety. Overall, our study extends previous research by revealing the neural bases underlying the protective effect of TCA on anxiety and pinpointing specific mediating RSFC pathways. Future studies could explore whether targeted TCA training (behavioural or neural) can help alleviate anxiety.

Differential patterns of default mode network activity associated with negative and positive rumination in bipolar disorder

BACKGROUND

Patients with bipolar disorder (BD) engage in both negative and positive rumination, defined as maladaptive self-focused thinking, and this tendency predicts depressive and manic episodes, respectively. Prior research in patients with major depression implicates regions of the default mode network (DMN) consistent with the self-focused nature of rumination. Little is known about the neural correlates of rumination in bipolar disorder.

METHODS

Fifteen euthymic patients with BD (twelve with Type I) and 17 healthy controls (HC) performed negative and positive rumination induction tasks, as well as a distraction task, followed by a self-related trait judgment task while undergoing functional magnetic resonance imaging (fMRI). Participants also underwent resting state scans. We examined functional connectivity at rest and during the induction tasks, as well as task-based activation during the trait judgment task, in core regions of the DMN.

RESULTS

Compared to HC, patients with BD showed greater functional connectivity between the posterior cingulate cortex (PCC) and medial prefrontal cortex (MPFC) at rest and during positive rumination, compared to distraction. They also showed greater activity in the PCC and MPFC during processing of positive traits, following positive rumination. At rest and during negative rumination compared to distraction, patients with BD showed greater functional connectivity between the PCC and inferior parietal lobule than HC.

CONCLUSIONS

These findings demonstrate that negative and positive rumination are subserved by different patterns of connectivity within the DMN in BD. Additionally, the PCC and MPFC are key regions involved in the processing of positive self-relevant traits following positive rumination.

Electrophysiological and behavioral effects of unilateral and bilateral rTMS; A randomized clinical trial on rumination and depression

BACKGROUND

Rumination is significantly frequent in major depressive disorder (MDD). However, not a lot of studies have investigated the effects of repetitive transcranial magnetic stimulation (rTMS) on rumination.

METHODS

61 participants with a minimum Hamilton Depression Rating Scale (HAM-D) score of 20 were randomly assigned to sham, bilateral stimulation (BS) or unilateral stimulation (US) groups. EEG, The Ruminative Response Scale (RRS), and HAM-D were administered before and after the 20 sessions of rTMS. Phase locked values (PLV) were calculated as a measure of connectivity.

RESULTS

There was a significant decrease in HAM-D scores in both BS and US. In responders, BS and US differed significantly in RRS total scores, with greater reduction in BS. PLV significantly changed in the default mode network (DMN) in delta, theta, alpha, and beta in BS, in responders of which PLV decreased in the DMN in beta and gamma. Positive correlations between PLV and brooding in delta and theta, and negative correlations between PLV and reflection were found in theta, alpha, and beta. In US, connectivity in the DMN increased in beta, and PLV increased in theta and beta, and decreased in alpha and beta in its responders. Positive correlations between PLV and brooding in the delta and theta, as well as negative correlations between PLV and reflection in theta were observed in the DMN.

CONCLUSION

US and BS resulted in different modulations in the DMN, however, both could alleviate both rumination and depression. Reductions in the beta and alpha frequency bands in the DMN can be considered as potential EEG-based markers of response to bilateral and unilateral rTMS, respectively.

Decreased Psychological Well-Being in Patients With Bipolar Disorder in Remission

BACKGROUND

The goals of this study were to introduce psychological well-being as an important subject of inquiry in bipolar disorder, to compare well-being in a cohort of patients with bipolar disorder with that of a normative sample, and to assess whether common measures of well-being and mood measure empirically distinct phenomena.

METHODS

Participants were outpatients with bipolar I disorder in remission (N=37) from the Enhancing Emotion Regulation in Bipolar Disorder (EERBD) study and a matched community normative sample from the Midlife in the United States (MIDUS) survey (N=6297). The Psychological Well-Being Scale (PWBS) was used to measure psychological well-being. We calculated means and SD of scores on the PWBS and evaluated the differences between the scores of the bipolar I and community samples. We also tested the association between raw and change scores in depression [Hamilton Rating Scale for Depression (HAM-D)] and eudaimonic well-being (PWBS) using Spearman correlation coefficients.

RESULTS

The MIDUS survey sample (N=6297) was 48% male, with a mean age of 47 years (SD=13 y). The EERBD sample (N=37) was 27% male, with a mean age of 41 years (SD=11 y). In the bipolar sample, the baseline mean score on the HAM-D was 12.7 (SD=6.0) and the mean score on the Young Mania Rating Scale was 6.1 (SD=6.2). The baseline mean sum score on the PWBS in the normative community MIDUS sample was 100 (SD=14), while that of the bipolar I EERBD sample was 79 (SD=15) at baseline, 84 (SD=13) posttreatment, and 84 (SD=12) at the 3-month follow-up assessment. The effect sizes of the differences at all timepoints were large (Hedges g=1.42 at baseline, 1.11 at the end of treatment, and 1.06 at the 3-mo follow-up). No association was found between the PWBS and depression scores.

CONCLUSIONS

Outpatients with bipolar disorder in remission demonstrated substantially impaired psychological well-being, despite low levels of depressive symptoms, compared with a normative community sample.

The effect of mindfulness-based cognitive therapy on rumination and a task-based measure of intrusive thoughts in patients with bipolar disorder

Background

Preliminary evidence suggests that Mindfulness-Based Cognitive Therapy (MBCT) is a promising treatment for bipolar disorder (BD). A proposed working mechanism of MBCT in attenuating depressive symptoms is reducing depressive rumination. The primary aim of this study was to investigate the effect of MBCT on self-reported trait depressive rumination and an experimental state measure of negative intrusive thoughts in BD patients. Exploratively, we investigated the effect of MBCT on positive rumination and positive intrusive thoughts.

Methods

The study population consisted of a subsample of bipolar type I or II patients participating in a multicenter randomized controlled trial comparing MBCT + treatment as usual (TAU) (N = 25) to TAU alone (N = 24). Trait depressive rumination (RRS brooding subscale) and intrusive thoughts (breathing focus task (BFT)) were assessed at baseline (full subsample) and post-treatment (MBCT + TAU; n = 15, TAU; n = 15). During the BFT, participants were asked to report negative, positive and neutral intrusive thoughts while focusing on their breathing.

Results

Compared to TAU alone, MBCT + TAU resulted in a significant pre- to post-treatment reduction of trait depressive rumination (R² = .16, F(1, 27) = 5.15, p = 0.031; medium effect size (f² = 0.19)) and negative intrusive thoughts on the BFT (R² = .15, F(1, 28) = 4.88, p = 0.036; medium effect size (f² = 0.17)). MBCT did not significantly change positive rumination or positive intrusive thoughts.

Conclusions

MBCT might be a helpful additional intervention to reduce depressive rumination in BD which might reduce risk of depressive relapse or recurrence. Considering the preliminary nature of our findings, future research should replicate our findings and explore whether this reduction in rumination following MBCT indeed mediates a reduction in depressive symptoms and relapse or recurrence in BD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40345-022-00269-1.

Mood disorders disrupt the functional dynamics, not spatial organization of brain resting state networks

Spontaneous fluctuations in the blood oxygenation level dependent signal measured through resting-state functional magnetic resonance imaging have been corroborated to aggregate into multiple functional networks. Abnormal resting brain activity is observed in mood disorder patients, however with inconsistent results. How do such alterations relate to clinical symptoms; e.g., level of depression and rumination tendencies? Here we recovered spatially and temporally overlapping functional networks from 31 mood disorder patients and healthy controls during rest, by applying novel methods that identify transient changes in spontaneous brain activity. Our unique approach disentangles the dynamic engagement of resting-state networks unconstrained by the slow hemodynamic response. This time-varying characterization provides moment-to-moment information about functional networks in terms of their durations and dynamic coupling, and offers novel evidence for selective contributionsto particular clinical symptoms. Patients showed increased duration of default-mode network (DMN), increased duration and occurrence of posterior DMN as well as insula- and amygdala-centered networks, but decreased occurrence of visual and anterior salience networks. Coupling between limbic (insula and amygdala) networks was also reduced. Depression level modulated DMN duration, whereas intrusive thoughts correlated with occurrence of insula and posterior DMN. Anatomical network organization was similar to controls. In sum, altered brain dynamics in mood disorder patients appear to mediate distinct clinical dimensions including increased self-processing, and decreased attention to external world.

Cognitive attentional syndrome and metacognitive beliefs as potential treatment targets for metacognitive therapy in bipolar disorder

Most treatment guidelines emphasize the use of psychotropic drugs for both the acute and maintenance treatment of bipolar disorder (BD). However, relying only on psychotropics without adjunctive psychosocial interventions may be insufficient in treating patients with BD. Given its unique view in the explanation of psychopathological states, metacognitive therapy (MCT) might be helpful for BD. Metacognitive theory posits that psychopathology is a result of the cognitive attentional syndrome (CAS) and that it is influenced and maintained by dysfunctional metacognitive beliefs, perseverative thinking, attentional biases, and dysfunctional coping strategies. In this review, literature data regarding these areas in BD are examined. Studies suggest that perseverative thinking might be among the emotion regulation strategies endorsed in individuals with BD. Regarding attentional biases, literature data show that state-dependent, mood-changing attentional biases and a ruminative self-focused attention are present. Studies also suggest that cognitive self-consciousness is higher in BD compared to controls. It is seen that maladaptive coping strategies are frequently reported in BD, and that these strategies are associated with depression severity, negative affect and relapse risk. Studies focusing on dysfunctional metacognitive beliefs in BD reported that individuals with BD had higher scores for negative metacognitive beliefs, self-consciousness, need to control thoughts, and a lack of cognitive confidence. Also, dysfunctional metacognitive beliefs were associated with depressive symptomatology. These findings suggest that the components of CAS and dysfunctional metacognitive beliefs are evident in BD. For a subgroup of patients with BD who fail to respond to evidence-based psychopharmacological and adjunctive psychotherapeutic interventions, MCT might be an alternative way to consider as a treatment option. In conclusion, taken the available data together, we propose a sequential treatment protocol for BD, mainly based on the MCT treatment plan of depressive disorders.

Perseverative Cognition in the Positive Valence Systems: An Experimental and Ecological Investigation

Perseverative cognition (PC) is a transdiagnostic risk factor that characterizes both hypo-motivational (e.g., depression) and hyper-motivational (e.g., addiction) disorders; however, it has been almost exclusively studied within the context of the negative valence systems. The present study aimed to fill this gap by combining laboratory-based, computational and ecological assessments. Healthy individuals performed the Probabilistic Reward Task (PRT) before and after the induction of PC or a waiting period. Computational modeling was applied to dissociate the effects of PC on reward sensitivity and learning rate. Afterwards, participants underwent a one-week ecological momentary assessment of daily PC occurrence, as well as anticipatory and consummatory reward-related behavior. Induction of PC led to increased response bias on the PRT compared to waiting, likely due to an increase in learning rate but not in reward sensitivity, as suggested by computational modeling. In daily-life, PC increased the discrepancy between expected and obtained rewards (i.e., prediction error). Current converging experimental and ecological evidence suggests that PC is associated with abnormalities in the functionality of positive valence systems. Given the role of PC in the prediction, maintenance, and recurrence of psychopathology, it would be clinically valuable to extend research on this topic beyond the negative valence systems.

Global and reflective rumination are related to suicide attempts among patients experiencing major depressive episodes

BACKGROUND

Recent attention has focused on the role of rumination in suicidality, with evidence indicating that rumination may be positively related to suicidal ideation. There remains disagreement on the nature of the relationship between rumination and suicide attempts, especially in major affective disorders. This study was designed to identify whether rumination is a risk factor for attempted suicide.

METHODS

A total of 309 patients with major depressive episodes were recruited for this study, including 170 patients with major depression and 139 patients with bipolar disorder. All participants were categorized into two groups based on a series of clinical assessments: suicide attempters (n = 87) and non-suicide attempters (n = 222). Rumination was evaluated with the Ruminative Responses Scale. A binary logistic regression analysis was carried out to evaluate the relationship between rumination and suicide attempts.

RESULTS

Both global ruminative levels and the two subtypes of rumination, brooding and reflection, were significantly higher in the suicide attempters than the non-suicide attempters. After controlling for age, current depression and anxiety symptoms, and episode frequency, it was found that global rumination and reflection (but not brooding) were positively associated with suicide attempts.

CONCLUSION

These results suggest that rumination may be a risk factor for suicide attempts and highlight the maladaptive nature of reflection in patients with major depressive episodes.

Ruminations and their correlates in depressive episodes: Between-group comparison in patients with unipolar or bipolar depression and healthy controls

BACKGROUND

Rumination is an important feature of affective disorders. Relationships between rumination, cognitive function, emotion regulation, and psychological resilience have been examined in unipolar depression; but few studies have determined whether unipolar and bipolar depressive episodes are distinguishable in terms of these variables. This study examined rumination in relation to clinical and cognitive variables in patients with unipolar depression or bipolar depression, and healthy controls.

METHODS

In total, 150 participants (50 bipolar, 50 unipolar, 50 controls) were included. Assessments comprised the Ruminative Response Scale-Short Form, Positive Beliefs about Rumination Scale, Negative Beliefs about Rumination Scale, Brief Resilience Scale, Emotion Regulation Questionnaire, Stroop Test, and Trail Making Test A and B.

RESULTS

The unipolar group had significantly higher scores in ruminative response and performed better in a neuropsychological test (Trail Making Test Part A) than the bipolar group. When duration of illness was controlled, no significant difference was found between depression groups in terms of rumination. There was a negative relationship between rumination and emotion regulation (cognitive reappraisal subscale), and rumination and psychological resilience in both patient groups, but no significant relationship was found in healthy controls.

LIMITATIONS

Relatively small sample size: future studies in larger clinical samples would increase knowledge of rumination in both unipolar and bipolar depression.

CONCLUSIONS

Patients experiencing unipolar or bipolar depressive episodes are potentially distinguishable in terms of ruminative response levels and cognitive functions. This differentiation may help in developing targeted interventions for unipolar and bipolar depression.

Rumination in major depressive and bipolar disorder - a meta-analysis

BACKGROUND

rumination, defined as repetitive thoughts about emotionally relevant experiences, has been linked extensively with mood disorders, especially major depressive disorder (MDD).¹ However, there is a growing body of evidence suggesting the importance of rumination in bipolar disorder (BD)² as well.

METHODS

we searched for studies that investigated rumination in both BD and MDD in four databases. Our systematic search identified 12 studies with an overall sample size of 2071 clinical patients.

RESULTS

results demonstrated no significant difference in the ruminative tendencies of the two patient groups when all rumination measures were included. We tested for the effect of rumination subtype, BD subgroups, and the current mood state of BD and MDD patients. There were no significant differences in terms of depressive rumination, however, BD patients reported more rumination on positive affect. This difference remained significant when examining in BD-I³ and BD-II⁴ patient groups, with similar effect sizes.

LIMITATIONS

due to the lack of sufficient data in the literature, only a few self-report studies qualified to be included in our analysis. Thus additional moderating factors, such as the current mood state of the two patient groups could not be analyzed.

CONCLUSIONS

this review demonstrates that rumination is a significant process in both MDD and BD, highlighting the importance of interventions to reduce rumination in mood disorders. The two patient groups share several commonalities in terms of rumination, however, rumination subtype was found to be an important moderating variable underlining a difference in rumination on positive affect.

Personality Structure and Attachment in Bipolar Disorder

BACKGROUND

An impairment of self and interpersonal functioning has an impact on coping strategies, regulation of affect and stress. Little is known so far about the impairment of personality functioning in patients with bipolar disorder (BD). The aim of this study is to assess the effects of personality structure and attachment in BD patients on the symptom burden.

METHODS

Forty-six patients with the diagnosis of BD were assessed by the 12-item Operationalized Psychodynamic Diagnosis Structure Questionnaire (OPD-SQS), the short version of Experience in Close Relationship-revised (ECR-R-D), and the Brief Symptom Inventory-18 (BSI 18) to determine the level of personality functioning, attachment patterns, and symptom load.

RESULTS

We observed positive correlations between personality difficulties, insecure attachment, and symptom load in patients with BD. A low level of structural integration and an insecure attachment style in patients with BD were accompanied by a significantly higher symptom load (r = 0.66, p ≤ 0.01). Interestingly, there were no significant differences in the structural integration (T(1.44) = -0.93, p = 0.357) and in the attachment style attachment related avoidance: (T(1,44) = 1.50, p = 0.140); attachment related anxiety (T(1,44) = -0.781, p = 0.439) of study participants with BD when compared to the normative value of the general population.

LIMITATIONS

Our limitations are the small sample size of our group and the lack of a control group.

CONCLUSION

In general, our results suggest that there is a link between personality structure and affective dynamics including depressive, anxiety, and somatization symptoms in BD. These findings underline the increasing importance of assessing personality structure and attachment for diagnosis and treatment planning of BD.

Resting-state functional connectivity of emotion regulation networks in euthymic and non-euthymic bipolar disorder patients

Background

Previous functional magnetic resonance imaging studies in bipolar disorder (BD) have evidenced changes in functional connectivity (FC) in brain areas associated with emotion processing, but how these changes vary with mood state and specific clinical symptoms is not fully understood.

Methods

We investigated resting-state FC between a priori regions of interest (ROIs) from the default-mode network and key structures for emotion processing and regulation in 27 BD patients and 27 matched healthy controls. We further compared connectivity patterns in subgroups of 15 euthymic and 12 non-euthymic patients and tested for correlations of the connectivity strength with measures of mood, anxiety, and rumination tendency. No correction for multiple comparisons was applied given the small population sample and pre-defined target ROIs.

Results

Overall, regardless of mood state, BD patients exhibited increased FC of the left amygdala with left sgACC and PCC, relative to controls. In addition, non-euthymic BD patients showed distinctive decrease in FC between right amygdala and sgACC, whereas euthymic patients showed lower FC between PCC and sgACC. Euthymic patients also displayed increased FC between sgACC and right VLPFC. The sgACC–PCC and sgACC–left amygdala connections were modulated by rumination tendency in non-euthymic patients, whereas the sgACC-VLPFC connection was modulated by both the current mood and tendency to ruminate.

Conclusions

Our results suggest that sgACC-amygdala coupling is critically affected during mood episodes, and that FC of sgACC play a pivotal role in mood normalization through its interactions with the VLPFC and PCC. However, these preliminary findings require replication with larger samples of patients.

Decoding rumination: A machine learning approach to a transdiagnostic sample of outpatients with anxiety, mood and psychotic disorders

OBJECTIVE

To employ machine learning algorithms to examine patterns of rumination from RDoC perspective and to determine which variables predict high levels of maladaptive rumination across a transdiagnostic sample.

METHOD

Sample of 200 consecutive, consenting outpatient referrals with clinical diagnoses of schizophrenia, schizoaffective, bipolar, depression, anxiety disorders, obsessive compulsive and post-traumatic stress. Machine learning algorithms used a range of variables including sociodemographics, serum levels of immune markers (IL-6, IL-1β, IL-10, TNF-α and CCL11) and BDNF, psychiatric symptoms and disorders, history of suicide and hospitalizations, functionality, medication use and comorbidities.

RESULTS

The best model (with recursive feature elimination) included the following variables: socioeconomic status, illness severity, worry, generalized anxiety and depressive symptoms, and current diagnosis of panic disorder. Linear support vector machine learning differentiated individuals with high levels of rumination from those ones with low (AUC = 0.83, sensitivity = 75, specificity = 71).

CONCLUSIONS

Rumination is known to be associated with poor prognosis in mental health. This study suggests that rumination is a maladaptive coping style associated not only with worry, distress and illness severity, but also with socioeconomic status. Also, rumination demonstrated a specific association with panic disorder.

Rumination related activity in brain networks mediating attentional switching in euthymic bipolar patients

Introduction

Mood disorder patients have a tendency to be more internally oriented, with difficulties in switching attentional focus, which might result in the generation of negative thoughts, such as rumination. The present study explored self-referential neural activity correlating with rumination tendency and attentional switching capacity in bipolar disorder.

Methods

Twenty euthymic bipolar patients and twenty matched healthy controls underwent a novel introspection task of switching between internally and externally focused attention during a word processing task, while their brain activity was assessed using functional MRI.

Results

During internal focus, higher activity in self-related regions (mPFC, PCC) was found in euthymic bipolar patients as compared to controls, verifying the hypothesis of exaggerated recruitment of self-referential processes in bipolar subjects. Switching from internal to external focus revealed higher parahippocampal activity in patients as compared to controls, additionally more pronounced when switching away from negative as compared to positive self-referential information. Furthermore, rumination traits correlated with activity in PCC, subgenual and pregenual ACC, and bilateral anterior insula during repetition of internal focus, specifically when evaluating negative words. Finally, we used ACC subregions that correlated with tendency to ruminate as seeds for a whole brain connectivity analysis. Patients showed stronger connectivity between sgACC (seed), pgACC, dPFC, and anterior insula during internal focus, whereas pgACC (seed) was more strongly connected to parahippocampal gyrus when switching from internal to external focus.

Conclusions

These findings reveal an overactive rumination-related network whose activity is enhanced by negative information in euthymic bipolar patients, which could possibly contribute to impaired switching of thoughts away from internal attention.

Electronic supplementary material

The online version of this article (10.1186/s40345-018-0137-5) contains supplementary material, which is available to authorized users.

The Neuroanatomical Basis of Two Subcomponents of Rumination: A VBM Study

Rumination is a trait that includes two subcomponents, namely brooding and reflective pondering, respectively construed as maladaptive and adaptive response styles to negative experiences. Existing evidence indicates that rumination in general is associated with structural and functional differences in the anterior cingulate cortex (ACC) and the dorsal lateral prefrontal cortex (DLPFC). However, conclusive evidence on the specific neural structural basis of each of the two subcomponents is lacking. In this voxel-based morphometry study, we investigated the independent and specific neural structural basis of brooding and reflective pondering in 30 healthy young adults, who belonged to high or low brooding or reflective pondering groups. Consistent with past research, modest but significant positive correlation was found between brooding and reflective pondering. When controlling for reflective pondering, high-brooding group showed increased gray matter volumes in the left DLPFC and ACC. Further analysis on extracted gray matter values showed that gray matter of the same DLPFC and ACC regions also showed significant negative effects of reflective pondering. Taken together, our findings indicate that the two subcomponents of rumination might share some common processes yet also have distinct neural basis. In view of the significant roles of the left DLPFC and ACC in attention and self-related emotional processing/regulation, our findings provide insight into how the potentially shared and distinct cognitive, affective and neural processes of brooding and reflective pondering can be extended to clinical populations to further elucidate the neurobehavioral relationships between rumination and prefrontal abnormality.

Transdiagnostic assessment of repetitive negative thinking and responses to positive affect: Structure and predictive utility for depression, anxiety, and mania symptoms

BACKGROUND

Repetitive negative thinking (RNT) is a cognitive process that is repetitive, passive, relatively uncontrollable, and focused on negative content, and is elevated in emotional disorders including depression and anxiety disorders. Repetitive positive thinking is associated with bipolar disorder symptoms. The unique contributions of positive versus negative repetitive thinking to emotional symptoms are unknown. The first aim of this study was to use confirmatory factor analyses to evaluate the psychometrics of two transdiagnostic measures of RNT, the Repetitive Thinking Questionnaire (RTQ-10) and Perseverative Thinking Questionnaire (PTQ), and a measure of repetitive positive thinking, the Responses to Positive Affect (RPA) Questionnaire. The second aim was to determine incremental predictive utility of these measures.

METHOD

All measures were administered to a sample of 2088 undergraduate students from the Netherlands (n = 992), Australia (n = 698), and America (n = 398).

RESULTS

Unidimensional, bifactor, and three-factor models were supported for the RTQ-10, PTQ, and RPA, respectively. A common factor measured by all PTQ items explained most variance in PTQ scores suggesting that this measure is essentially unidimensional. The RNT factor of the RTQ-10 demonstrated the strongest predictive utility, although the PTQ was also uniquely although weakly associated with anxiety, depression, and mania symptoms. The RPA dampening factor uniquely predicted anxiety and depression symptoms, suggesting that this scale is a separable process to RNT as measured by the RTQ-10 and PTQ.

LIMITATIONS

Findings were cross-sectional and need to be replicated in clinical samples.

CONCLUSIONS

Transdiagnostic measures of RNT are essentially unidimensional, whereas RPA is multidimensional. RNT and RPA have unique predictive utility.

Cognitive deficits in bipolar disorders: Implications for emotion

Prominent cognitive deficits have been documented in bipolar disorder, and multiple studies suggest that these deficits can be observed among non-affected first-degree relatives of those with bipolar disorder. Although there is variability in the degree of cognitive deficits, these deficits are robustly relevant for functional outcomes. A separate literature documents clear difficulties in emotionality, emotion regulation, and emotion-relevant impulsivity within bipolar disorder, and demonstrates that these emotion-relevant variables are also central to outcome. Although cognitive and emotion domains are typically studied independently, basic research and emergent findings in bipolar disorder suggest that there are important ties between cognitive deficits and the emotion disturbances observed in bipolar disorder. Understanding these relationships has relevance for fostering more integrative research, for clarifying relevant aspects related to functionality and vulnerability within bipolar disorder, and for the development of novel treatment interventions. Bipolar disorder (BD) is a severe psychiatric illness that has been ranked as one of the 20 leading medical causes of disability (WHO, 2011). BD has been shown to be the psychiatric disorder with the highest rates of completed suicide across two major cohort studies (Ilgen et al., 2010; Nordentoft, Mortensen, & Pedersen, 2011). In a cross-national representative sample, one in four persons diagnosed with bipolar I disorder reported a suicide attempt (Merikangas et al., 2011). Rates of relapse remain high despite available treatments (Gitlin, Swendsen, Heller, & Hammen, 1995), and in the year after hospitalization for manic episode, two-thirds of patients do not return to work (Strakowski et al., 1998). Poverty, homelessness, and incarceration are all too common (Copeland et al., 2009). Despite the often poor outcomes, there is also evidence for outstanding accomplishments and creativity among those with milder forms of the disorder and their family members (Coryell et al., 1989; Jamison, 1993; Murray & Johnson, 2010). Some individuals appear to achieve more than the general population, suggesting the importance of understanding the variables that predict differential outcome within bipolar disorder. Within this paper, we focus on two key predictors of outcomes within bipolar disorder: cognition and emotionality. We review evidence that problems in cognition and emotionality are prominent among those diagnosed with the disorder, are not artifacts of symptom state, and relate substantively to poorer outcomes. Although traditionally studied separately, new work points toward the idea that cognition and emotionality are intricately linked within bipolar disorder. Drawing from research within bipolar disorder as well as outside of bipolar disorder, we build a model of how cognition and emotionality might be tied within bipolar disorder. We then provide suggestions for future research. Before considering findings, it is worth noting that there are several forms of the disorder, defined by varying degrees and duration of manic symptoms (APA, 2013; WHO, 1993). Manic episodes are defined by abnormally elevated or irritable mood, accompanied by increased activity and at least three symptoms (four if mood is only irritable) such as decreased need for sleep, increased self-confidence, racing thoughts or flight of ideas, rapid speech, distractibility, goal-directed activity, and engagement in pleasurable activities without regard to potential negative consequences. To meet criteria for mania, these symptoms must persist for at least one week or require hospitalization, and must lead to difficulties with functioning. If functional impairment is not more than mild and duration is between 4 and 6 days, the episode is considered a hypomanic episode. Bipolar I disorder (BD I) is diagnosed on the basis of at least one lifetime manic episode within the DSM-5 and by at least two episodes within the ICD, whereas bipolar II disorder is diagnosed on the basis of at least one hypomanic episode (and no manic episodes) as well as major depressive episodes. Cyclothymic disorder is defined by chronic but milder fluctuations between manic and depressive symptoms. Most research focuses on BD I. In addition to diagnosed samples, research has focused on those at high risk for bipolar disorder, including first-degree relatives of those with BD. This work draws on the evidence for extremely high heritability of BD I, with estimates from community-based twin studies of 0.85 (Kieseppä, Partonen, Haukka, Kaprio, & Lönnqvist, 2014). Other research has considered high risk for BD by virtue of lifetime subsyndromal symptoms, as measured by scales such as the Hypomanic Personality Scale (Eckblad & Chapman, 1986) or the General Behavior Inventory (Depue, Krauss, Spoont, & Arbisi, 1989). The study of high-risk individuals provides a way to decipher whether deficits are present before the onset of the disorder, of importance given models suggesting that episodes of the disorder may change brain function (Chang, Steiner, & Ketter, 2000; Strakowski, 2012) as well as individuals' perceptions of their emotion regulation. Beyond defining BD, it is worth defining some of the many different neuropsychological tasks that have been widely studied in BD. Perhaps no area has received more attention than executive function. Executive function is related to three core functions: 1) inhibition, the ability to suppress irrelevant information in working memory in order to accomplish an established goal; 2) working memory, the ability to hold and manipulate information in mind; and 3) cognitive flexibility, the ability to shift strategies in response to feedback (Diamond, 2013; Miyake et al., 2000). Attention (defined as the process of selecting information reception from internal or external cues) is implicated in all three of these aspects of executive function. Much of the literature we will discuss focuses on response inhibition, or the ability to suppress a prepotent response, which is considered a subtype of inhibition. Some tests measure multiple facets of executive function; for example the Trails B test likely requires working memory and cognitive flexibility (Sánchez-Cubillo et al., 2009). Aside from executive function, multiple other facets of cognition have been widely studied in bipolar disorder. Verbal and non-verbal memory are related to the ability to register, store and retrieve verbal or visual information (Lezak, 1995). Verbal fluency is measured as the number of verbal responses a person can generate to a given target, such as a specific semantic category (e.g., animals, furniture) or phonetic category (e.g., words that begin with letter F) (Diamond, 2013). Although cognitive tasks have been designed to evaluate these specific functions, it is important to note that most measures are highly inter-correlated and may assess multiple overlapping functions to some extent (for example, the Trails B test is often described as an "executive function" task, although this task likely involves both working memory and cognitive flexibility. Not surprisingly, then, some authors label the function of certain tests differently, and this is particularly evident in meta-analyses of cognition. As we describe findings in this paper, we will use the terms proposed by the authors but will also identify key tests used to define a cognitive construct. With this background in mind, we turn to a discussion of cognitive deficits, then of emotion-related traits. Our hope is that those concise summaries provide evidence for the importance of both domains, but also specificity regarding the facets of emotion and cognition that are most impaired in BD. This specificity then guides our consideration of models that integrate cognition and emotion.

Improving functional outcome in bipolar disorder: A pilot study on metacognitive training

BACKGROUND

Effective group psychological interventions in bipolar disorder are rare. In this study, we present "metacognitive training (MCT) for bipolar disorder"-an adaption of a group intervention that has proven effective in other severe psychiatric disorders. MCT is a structured, interactive approach that addresses cognitive biases, social cognition, and self-esteem. In this pilot study, we investigated psychosocial functioning as primary outcome measure, as well as the feasibility of MCT and its acceptance among bipolar patients.

METHODS

Thirty-four outpatients with bipolar disorder were recruited. Inclusion criteria were euthymia and psychosocial functioning with a score >11 assessed by the Functional Assessment Short Test. The subjects received eight weekly MCT sessions. Before and after the intervention, psychosocial functioning, quality of life (QoL), and patient views were assessed.

RESULTS

Patients improved significantly in global psychosocial functioning, with a large effect size from baseline to post-treatment. Over the intervention period, patient QoL improved significantly in terms of their physical health, however not for other QoL subdomains. Treatment adherence was 80%, and patients' appraisal of the training was positive.

LIMITATIONS

As this study lacks a control group, it is not possible to ascertain whether the positive treatment effects are attributable to MCT. Additionally, it is unclear whether gains in psychosocial functioning would have been maintained long term.

CONCLUSIONS

This pilot trial conclusively shows that MCT is feasible and provides preliminary evidence for both the acceptance and efficacy of MCT. Further studies with larger samples and control condition will be necessary to build on these findings.

The role of rumination in illness trajectories in youth: linking trans-diagnostic processes with clinical staging models

Research in developmental psychopathology and clinical staging models has increasingly sought to identify trans-diagnostic biomarkers or neurocognitive deficits that may play a role in the onset and trajectory of mental disorders and could represent modifiable treatment targets. Less attention has been directed at the potential role of cognitive-emotional regulation processes such as ruminative response style. Maladaptive rumination (toxic brooding) is a known mediator of the association between gender and internalizing disorders in adolescents and is increased in individuals with a history of early adversity. Furthermore, rumination shows moderate levels of genetic heritability and is linked to abnormalities in neural networks associated with emotional regulation and executive functioning. This review explores the potential role of rumination in exacerbating the symptoms of alcohol and substance misuse, and bipolar and psychotic disorders during the peak age range for illness onset. Evidence shows that rumination not only amplifies levels of distress and suicidal ideation, but also extends physiological responses to stress, which may partly explain the high prevalence of physical and mental co-morbidity in youth presenting to mental health services. In summary, the normative developmental trajectory of rumination and its role in the evolution of mental disorders and physical illness demonstrates that rumination presents a detectable, modifiable trans-diagnostic risk factor in youth.

Electrophysiological correlates of bilateral and unilateral repetitive transcranial magnetic stimulation in patients with bipolar depression

Repetitive transcranial magnetic stimulation (rTMS) has been demonstrated to have efficacy in the treatment of unipolar depression but limited research has explored the efficacy of rTMS in bipolar depression. Therefore, we conducted a comparative clinical trial evaluating clinical responses to prefrontal bilateral and unilateral rTMS in patients suffering from bipolar depression. We hypothesized that, 1) the response to the treatment would be associated with a decrease in the frequency of beta waves, 2) bilateral stimulation of the cortex would bring about more extensive changes in brain activity than unilateral stimulation, and 3) bilateral stimulation is more effective than unilateral. Thirty patients with bipolar depression were divided into two groups. Bilateral Group (n=15) who received rTMS in the left DLPFC (10Hz) and right DLPFC (1-Hz), and unilateral group (n=15) who received the stimulation only in the right DLPFC (1-Hz) during 20 treatment sessions. The proportion of responders in the bilateral stimulation group was significantly higher than that in the unilateral group [80% versus 47%]. The remission rate was 40% in the bilateral group and 40% in the unilateral group (not significant). In the responders to bilateral rTMS treatment, a significant reduction of alpha1-2, beta 1-3, and gamma frequencies were observed in medial and superior frontal and cingulate gyrus . Responders to the unilateral treatment showed decrease of gamma frequency in postcentral gyrus, precuneus, superior and inferior parietal lobule, Cuneus and angular gyrus. In conclusion, we found that bilateral stimulation was more effective than the unilateral stimulation and evidence that beta frequency activity could possibly be used as a marker for response to rTMS.

Rumination in bipolar disorder: a systematic review

OBJECTIVE

To conduct a systematic review of the literature about the symptom of rumination in bipolar disorder (BD).

METHODS

We searched the MEDLINE (PubMed), ISI Web of Knowledge, PsycINFO, and SciELO databases using the descriptors "rumination" and "bipolar disorder" and no time limits. This strategy yielded 105 references, of which 74 were selected. Inclusion criteria were studies involving patients with BD and the use of at least one validated scale for the assessment of rumination. Review articles were excluded. Seventeen articles were ultimately analyzed and included in the review.

RESULTS

Rumination is present in all BD phases, is a stable interepisodic symptom, is associated with symptoms of depression, anxiety, and hypomania, and may occur in response to both positive and negative affect. There is no research on rumination and neurobiological findings in patients with BD.

CONCLUSIONS

Rumination seems to be independent of mood state, but shows close relationship with it. It is possible that rumination has a negative impact on cognitive and executive functions, particularly inhibitory control. Finally, rumination is an important symptom in both phases of BD, and, therefore, may be a useful target for further exploration as a dimensional domain and a transdiagnostic phenomenon in Research Domain Criteria (RDoC) projects.

Nature experience reduces rumination and subgenual prefrontal cortex activation

Urbanization has many benefits, but it also is associated with increased levels of mental illness, including depression. It has been suggested that decreased nature experience may help to explain the link between urbanization and mental illness. This suggestion is supported by a growing body of correlational and experimental evidence, which raises a further question: what mechanism(s) link decreased nature experience to the development of mental illness? One such mechanism might be the impact of nature exposure on rumination, a maladaptive pattern of self-referential thought that is associated with heightened risk for depression and other mental illnesses. We show in healthy participants that a brief nature experience, a 90-min walk in a natural setting, decreases both self-reported rumination and neural activity in the subgenual prefrontal cortex (sgPFC), whereas a 90-min walk in an urban setting has no such effects on self-reported rumination or neural activity. In other studies, the sgPFC has been associated with a self-focused behavioral withdrawal linked to rumination in both depressed and healthy individuals. This study reveals a pathway by which nature experience may improve mental well-being and suggests that accessible natural areas within urban contexts may be a critical resource for mental health in our rapidly urbanizing world.

Emotion regulation in bipolar disorder: profile and utility in predicting trait mania and depression propensity

Current emotion regulation research in BD has tended to focus on the extent to which patients control their emotions using different cognitive strategies. Fewer studies have investigated whether patients with BD have difficulties in regulating other dimensions of emotion that serve a functional purpose and are thereby more amenable to change. To overcome this paucity of research we utilised a multi-dimensional measure of emotion regulation to characterise the emotion regulation profile of BD, and examine its utility in predicting trait mania and depression propensity. Fifty BD patients and 52 healthy controls completed the Difficulties in Emotion Regulation Scale (DERS) and the General Behaviour Inventory (GBI). Results indicated that patients had difficulties in emotion regulation across a range of dimensions. Impulse control difficulties most parsimoniously predicted trait (hypo)mania propensity in BD patients, whilst poor access to mood regulation strategies predicted depressive propensity. Predictors of the propensity to experience these moods differed in the control group. These findings represent an important step toward informing the development of new treatment strategies to remediate emotion regulation difficulties and improve BD symptomatology.

Brain electrical source imaging in manic and depressive episodes of bipolar disorder

OBJECTIVE

Bipolar disorder (BD) electroencephalographic (EEG) studies have reported varying results. The present study compared EEG in BD during manic and depressive episodes, using brain electrical source imaging [standardized low-resolution electromagnetic tomography (sLORETA)] to assess the cortical spatial distribution of the sources of EEG oscillation frequencies.

METHODS

Two independent datasets (a total of 95 patients with bipolar I disorder, of whom 59 were female) were analyzed. Dataset #1 comprised 14 patients in a manic as well as a depressive episode. Dataset #2 comprised 26 patients in a manic episode and 55 patients in a depressive episode. From the head surface-recorded EEG, sLORETA cortical activity was computed in eight EEG frequency bands, and compared between mood states in both datasets. The results from the two datasets were combined using conjunction analysis.

RESULTS

Conjunction analysis yielded significant differences between mood states: In manic compared to depressive states, patients had lesser theta frequency band activity (right-hemispheric lateral lower prefrontal and anterior temporal, mainly Brodmann areas 13, 38, and 47), and greater beta-2 and beta-3 frequency band activity (extended bilateral prefrontal-to-parietal, mainly Brodmann area 6, and the cingulate).

CONCLUSIONS

The spatial organization of the brain's electrical oscillations differed in patients with BD between manic and depressive mood states. The brain areas implementing the main functions that show opposing abnormalities during manic and depressive episodes were affected by unduly increased or decreased activity (beta or theta). The discussion considers that facilitating (beta) or inhibiting (theta) electrical activity can in either case result in behavioral facilitation or inhibition, depending on the function of the brain area.

Social stimulation and corticolimbic reactivity in premenstrual dysphoric disorder: a preliminary study

BACKGROUND

Premenstrual dysphoric disorder (PMDD), characterized by luteal phase-induced negative affect and loss of impulse control, often results in compromised social interactions. Although amygdala activation is generally linked to negative affect, increased amygdala reactivity to aversive stimuli in the luteal phase has not been consistently reported in PMDD. We tested the hypothesis that amygdala hyper-reactivity in PMDD is symptom specific, rather than generalized, and linked to socially relevant stimuli. Blood oxygenation level dependent signal changes during exposure to negative images with social and non-social content were evaluated in the mid-follicular and late luteal phase of the menstrual cycle. Fourteen women with PMDD and 13 healthy controls participated.

RESULTS

When compared with healthy controls, women with PMDD in the luteal phase had enhanced reactivity to social stimuli compared to non-social stimuli in the amygdala and insula, but attenuated reactivity in the anterior cingulate cortex. Functional couplings between emotion processing and controlling areas were significantly different, being positive in women with PMDD and negative in healthy controls. Changes in progesterone levels in women with PMDD correlated positively with altered amygdala reactivity.

CONCLUSIONS

Socially relevant aversive stimulation elicited enhanced activity in affective processing brain regions that were functionally coupled to compromised activity in cognitive control areas. Because increased reactivity correlated positively with alterations in ovarian steroid levels, data preliminary support the hypothesis that enhanced progesterone sensitivity in PMDD affects corticolimbic processing of social emotions.

Possible beneficial effects of lithium chloride on cerulein-induced acute pancreatitis in mice

One of the most important and serious disorders of gastrointestinal tract is acute pancreatitis which in severe form is associated with high mortality rate particularly in the presence of systemic inflammatory response and multiple organ failure. Apoptosis linked to oxidative stress has been shown in the pancreas of the patients with acute pancreatitis. Lithium, one of the most effective drugs for the treatment of bipolar disorder, also has dramatic effects on preventing cell damage and apoptosis. Also lithium has shown anti-inflammatory effects in some animal studies. This study was designed to investigate the possible effect of lithium chloride in acute pancreatitis. Induction of acute pancreatitis was performed in male mice (25-30 g) by five intraperitoneal (i.p.) injection of cerulein (50 μg/kg) with 1 h intervals. Lithium chloride (10, 20 and 30 mg/kg) was administered i.p. 15 min before the induction of pancreatitis. Six h after the last injection of cerulein, the animals were sacrificed and biochemical as well as histopathological analysis was performed. Pretreatment with 20 mg/kg i.p. of lithium chloride reduced significantly the inflammatory response in cerulein-induced acute pancreatitis by ameliorating pancreatic edema and leukocyte infiltration, attenuating amylase and lipase serum levels, and myeloperoxidase activity compared to control group (p<0.05). Two other administered doses namely 10 and 30 mg/kg were found ineffective. In this study our findings demonstrate that lithium can dose dependently exhibit protective effect against cerulein-induced acute pancreatitis.

Assessing the roles of stimulants/stimulant-like drugs and dopamine-agonists in the treatment of bipolar depression

Bipolar depression is considered the most difficult-to-treat phase of bipolar disorder, in relation to its pervasiveness and efficacy and/or tolerability limitations of available treatments. Indeed, most mood stabilizers and atypical antipsychotics are not as effective in ameliorating depressive compared with manic symptoms, and entail substantial tolerability limitations. However, the use of antidepressants is highly controversial, as their efficacy appears less robust in bipolar compared with unipolar depression. In addition, antidepressants, in spite of generally having adequate somatic tolerability, in BD may be associated with a higher risk of manic/hypomanic switch, suicidality and rapid cycling. Among alternative pharmacological strategies, compounds with stimulant and pro-dopaminergic effects, such as methylphenidate, modafinil, armodafinil and pramipexole, have showed potential antidepressant activity, even though their use in clinical practice has been limited by the paucity of controlled evidence. This article seeks to review available evidence about the use of the aforementioned compounds in the treatment of bipolar depression. Findings from reviewed studies suggested that pro-dopaminergic compounds, such as pramipexole and stimulants/stimulant-like agents, deserve consideration as adjunctive therapies in bipolar depressed patients, at least in some subgroups of patients. Nevertheless, caution regarding their use is recommended as further clinical trials with larger samples and longer follow-up periods are necessary to clarify the roles of these medications in bipolar depression.

Investigating brain community structure abnormalities in bipolar disorder using path length associated community estimation

In this article, we present path length associated community estimation (PLACE), a comprehensive framework for studying node-level community structure. Instead of the well-known Q modularity metric, PLACE utilizes a novel metric, Ψ(PL), which measures the difference between intercommunity versus intracommunity path lengths. We compared community structures in human healthy brain networks generated using these two metrics and argued that Ψ(PL) may have theoretical advantages. PLACE consists of the following: (1) extracting community structure using top-down hierarchical binary trees, where a branch at each bifurcation denotes a collection of nodes that form a community at that level, (2) constructing and assessing mean group community structure, and (3) detecting node-level changes in community between groups. We applied PLACE and investigated the structural brain networks obtained from a sample of 25 euthymic bipolar I subjects versus 25 gender- and age-matched healthy controls. Results showed community structural differences in posterior default mode network regions, with the bipolar group exhibiting left-right decoupling.