Relation between amygdala structure and function in adolescents with bipolar disorder

Towards a neurodevelopmental model of bipolar disorder: a critical review of trait- and state-related functional neuroimaging in adolescents and young adults

Neurodevelopmental mechanisms are increasingly implicated in bipolar disorder (BD), highlighting the importance of their study in young persons. Neuroimaging studies have demonstrated a central role for frontotemporal corticolimbic brain systems that subserve processing and regulation of emotions, and processing of reward in adults with BD. As adolescence and young adulthood (AYA) is a time when fully syndromal BD often emerges, and when these brain systems undergo dynamic maturational changes, the AYA epoch is implicated as a critical period in the neurodevelopment of BD. Functional magnetic resonance imaging (fMRI) studies can be especially informative in identifying the functional neuroanatomy in adolescents and young adults with BD (BDAYA) and at high risk for BD (HR-BDAYA) that is related to acute mood states and trait vulnerability to the disorder. The identification of early emerging brain differences, trait- and state-based, can contribute to the elucidation of the developmental neuropathophysiology of BD, and to the generation of treatment and prevention targets. In this critical review, fMRI studies of BDAYA and HR-BDAYA are discussed, and a preliminary neurodevelopmental model is presented based on a convergence of literature that suggests early emerging dysfunction in subcortical (e.g., amygdalar, striatal, thalamic) and caudal and ventral cortical regions, especially ventral prefrontal cortex (vPFC) and insula, and connections among them, persisting as trait-related features. More rostral and dorsal cortical alterations, and bilaterality progress later, with lateralization, and direction of functional imaging findings differing by mood state. Altered functioning of these brain regions, and regions they are strongly connected to, are implicated in the range of symptoms seen in BD, such as the insula in interoception, precentral gyrus in motor changes, and prefrontal cortex in cognition. Current limitations, and outlook on the future use of neuroimaging evidence to inform interventions and prevent the onset of mood episodes in BDAYA, are outlined.

Mapping Structural Neuroimaging Trajectories in Bipolar Disorder: Neurobiological and Clinical Implications

Neuroimaging is a powerful noninvasive method for studying brain alterations in bipolar disorder (BD). To date, most neuroimaging studies of BD have included smaller cross-sectional samples reporting case versus control comparisons, revealing small to moderate effect sizes. In this narrative review, we discuss the current state of structural neuroimaging studies using magnetic resonance imaging, which inform our understanding of altered brain trajectories in BD across the lifespan. Alternative methodologies such as those that model patient deviations from age-specific norms are discussed, which may help derive new markers of BD pathophysiology. We discuss evidence from neuroimaging genetics and transcriptomics studies, which attempt to bridge the gap between macroscale brain variations and underlying microscale neurodevelopmental mechanisms. We conclude with a look toward the future and how ambitious investments in longitudinal, deeply phenotyped, population-based cohorts can improve modeling of complex clinical factors and provide more clinically actionable brain markers for BD.

Resting-state functional magnetic resonance imaging alterations in first-degree relatives of individuals with bipolar disorder: A systematic review

BACKGROUND

Relatives of individuals with bipolar disorder (BD) are at higher risk of developing the disorder. Identifying brain alterations associated with familial vulnerability in BD can help discover endophenotypes, which are quantifiable biological traits more prevalent in unaffected relatives of BD (BD-RELs) than the general population. This review aimed at expanding our knowledge on endophenotypes of BD by providing an overview of resting-state functional magnetic resonance imaging (rs-fMRI) alterations in BD-RELs.

METHODS

A systematic search of PubMed, Scopus, and Web of Science was performed to identify all available rs-fMRI studies conducted in BD-RELs up to January 2024. A total of 18 studies were selected. Six included BD-RELs with no history of psychiatric disorders and 10 included BD-RELs that presented psychiatric disorders. Two investigations examined rs-fMRI alterations in BD-RELs with and without subthreshold symptoms for BD.

RESULTS

BD-RELs presented rs-fMRI alterations in the cortico-limbic network, fronto-thalamic-striatal circuit, fronto-occipital network, and, to a lesser extent, in the default mode network. This was true both for BD-RELs with no history of psychopathology and for BD-RELs that presented psychiatric disorders. The direct comparison of rs-fMRI alterations in BD-RELs with and without psychiatric symptoms displayed largely non-overlapping patterns of rs-fMRI abnormalities.

LIMITATIONS

Small sample sizes and the clinical heterogeneity of BD-RELs limit the generalizability of our findings.

CONCLUSIONS

The current literature suggests that first-degree BD-RELs exhibit rs-fMRI alterations in brain circuits involved in emotion regulation, cognition, reward processing, and psychosis susceptibility. Future studies are needed to validate these findings and to explore their potential as biomarkers for early detection and intervention.

Network dysfunction of sadness facial expression processing and morphometry in euthymic bipolar disorder

Facial emotion recognition (FER), including sadness, is altered in bipolar disorder (BD). However, the relationship between this impairment and the brain structure in BD is relatively unexplored. Furthermore, its association with clinical variables and with the subtypes of BD remains to be clarified. Twenty euthymic patients with BD type I (BD-I), 28 BD type II (BD-II), and 45 healthy controls completed a FER test and a 3D-T1-weighted magnetic resonance imaging. Gray matter volume (GMV) of the cortico-limbic regions implicated in emotional processing was estimated and their relationship with FER performance was investigated using network analysis. Patients with BD-I had worse total and sadness-related FER performance relative to the other groups. Total FER performance was significantly negatively associated with illness duration and positively associated with global functioning in patients with BD-I. Sadness-related FER performance was also significantly negatively associated with the number of previous manic episodes. Network analysis showed a reduced association of the GMV of the frontal-insular-occipital areas in patients with BD-I, with a greater edge strength between sadness-related FER performance and amygdala GMV relative to controls. Our results suggest that FER performance, particularly for facial sadness, may be distinctively impaired in patients with BD-I. The pattern of reduced interrelationship in the frontal-insular-occipital regions and a stronger positive relationship between facial sadness recognition and the amygdala GMV in BD may reflect altered cortical modulation of limbic structures that ultimately predisposes to emotional dysregulation. Future longitudinal studies investigating the effect of mood state on FER performance in BD are warranted.

Early longitudinal changes in brain structure and cognitive functioning in remitted patients with recently diagnosed bipolar disorder

BACKGROUND

Patients with bipolar disorder (BD) who are presenting with cognitive impairment and associated structural brain abnormalities have generally a poorer clinical outcome. This study aims to map the early longitudinal trajectories in brain structure and cognition in patients with recently diagnosed BD.

METHODS

Fully or partially remitted patients with a recent diagnosis of BD and matched healthy controls (HC) underwent structural MRI and neuropsychological testing at baseline (BD n = 97; HC n = 66) and again following an average of 16 (range 6-27) months (BD n = 50; HC n = 38). We investigated the differential trajectories in BD vs. HC in cortical gray matter volume and thickness, total cerebral white matter, hippocampal and amygdala volumes, estimated brain age, and cognitive functioning using linear mixed models. Within patients, we further investigated whether brain structural abnormalities detected at baseline were associated with subsequent mood episodes.

RESULTS

Compared to HC, patients showed a decline in total white matter volume over time and they had a larger amygdala volume, both at baseline and at follow-up time. Patients further showed lower cognitive performance at both times of investigation with no significant change over time. There were no differences between patients and HC in cortical gray matter volume or thickness, hippocampal volume, or brain-aging patterns.

CONCLUSIONS

Cognitive impairment and amygdala enlargement may represent stable markers of BD early in the course of illness, whereas subtle white matter decline may result from illness progression.

Four attachment-based categories of emotion regulation in adolescent psychic troubles

Introduction

Emotion regulation is altered in many psychiatric disorders in adolescence, but the understanding of mechanisms that underlie this alteration is still poor.

Methods

The PERCEPT study explores alexithymia, empathy, facial emotion recognition (FER) and defence mechanisms in a sample of adolescents in psychiatric care (n = 61, 74% of girls, mean age = 15.03 y.o.), in relation with participants' attachment styles.

Results

Results revealed correlations between attachment dimensions and all of the emotion regulation variables, suggesting that attachment modalities have functional links with emotional regulation at its different levels: FER accuracy was inversely correlated with avoidant attachment, while affective empathy, difficulty in identifying feelings (alexithymia) and immature as well as neurotic defence mechanisms were positively correlated with anxious attachment. Moreover, attachment categories delineated distinct emotional perception profiles. In particular, preoccupied attachment included adolescents with the highest levels of facial emotion perception (sensitivity and accuracy) and of affective empathy, whereas detached attachment included adolescents with the lowest levels of these variables. Neurotic defence mechanisms and difficulty to identify feelings were correlated with preoccupied attachment; immature defence mechanisms and difficulty to describe feelings to others characterized fearful attachment.

Discussion

These results suggest that attachment categories underlie emotion regulation processes in psychiatric disorders in adolescence. Theoretical and clinical implications are discussed.

Gray matter alterations in adolescent major depressive disorder and adolescent bipolar disorder

BACKGROUND

Gray matter volume (GMV) alterations in several emotion-related brain areas are implicated in mood disorders, but findings have been inconsistent in adolescents with major depressive disorder (MDD) or bipolar disorder (BD).

METHODS

We conducted a comprehensive meta-analysis of 35 region-of-interest (ROI) and 18 whole-brain voxel-based morphometry (VBM) MRI studies in adolescent MDD and adolescent BD, and indirectly compared the results in the two groups. The effects of age, sex, and other demographic and clinical scale scores were explored using meta-regression analysis.

RESULTS

In the ROI meta-analysis, right putamen volume was decreased in adolescents with MDD, while bilateral amygdala volume was decreased in adolescents with BD compared to healthy controls (HC). In the whole-brain VBM meta-analysis, GMV was increased in right middle frontal gyrus and decreased in left caudate in adolescents with MDD compared to HC, while in adolescents with BD, GMV was increased in left superior frontal gyrus and decreased in limbic regions compared with HC. MDD vs BD comparison revealed volume alteration in the prefrontal-limbic system.

LIMITATION

Different clinical features limit the comparability of the samples, and small sample size and insufficient clinical details precluded subgroup analysis or meta-regression analyses of these variables.

CONCLUSIONS

Distinct patterns of GMV alterations in adolescent MDD and adolescent BD could help to differentiate these two populations and provide potential diagnostic biomarkers.

Effects of short-term quetiapine and lithium therapy for acute manic or mixed episodes on the limbic system and emotion regulation circuitry in youth with bipolar disorder

Disruptions in the limbic system, and in emotion regulation circuitry that supports affect modulation, have been reported during acute manic episodes of bipolar disorder (BD). The impact of pharmacological treatment on these deficits, especially in youth, remains poorly characterized. 107 youths with acute manic or mixed episodes of bipolar I disorder and 60 group-matched healthy controls were recruited. Youth with bipolar disorder were randomized to double-blind treatment with quetiapine or lithium and assessed weekly. Task-based fMRI studies were performed using an identical pairs continuous performance task (CPT-IP) at pre-treatment baseline and post-treatment weeks one and six. Region of interest analyses focused on the limbic system and ventral PFC - basal ganglia - thalamocortical loop structures known to be involved in emotion regulation. Changes in regional activation were compared between the two treatment groups, and pretreatment regional activation was used to predict treatment outcome. Mania treatment scores improved more rapidly in the quetiapine than lithium treated group, as did significant normalization of neural activation toward that of healthy individuals in left amygdala (p = 0.007), right putamen (p < 0.001), and right globus pallidus (p = 0.003). Activation changes in the right putamen were correlated with reduction of mania symptoms. The limbic and emotion regulation system activation at baseline and week one predicted treatment outcome in youth with bipolar disorder with significant accuracy (up to 87.5%). Our findings document more rapid functional brain changes associated with quetiapine than lithium treatment in youth with bipolar disorder, with most notable changes in the limbic system and emotion regulation circuitry. Pretreatment alterations in these regions predicted treatment response. These findings advance understanding of regional brain alterations in youth with bipolar disorder, and show that fMRI data can predict treatment outcome before it can be determined clinically, highlighting the potential utility of fMRI biomarkers for early prediction of treatment outcomes in bipolar disorder.Clinical Trials Registration: Name: Multimodal Neuroimaging of Treatment Effects in Adolescent Mania. URL: https://clinicaltrials.gov/ . Registration number: NCT00893581.

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.

Is abnormal metabolism in the olfactory bulb and amygdala associated with bipolar disorder?

Accumulated evidence has demonstrated abnormal amygdala activation in bipolar disorder (BD). The olfactory bulb (OB) has vigorous connections with the amygdala. Although odor-related functions of the OB decreased during the evolutionary process, we hypothesized that an evolved OB with increased activation in emotion regulation may be one of the main factors affecting amygdala functions in BD. Our aim was to investigate metabolism in the OB and amygdala in patients with BD. Twenty-six patients diagnosed with BD according to DSM-5 diagnostic criteria were included in this cross-sectional study. Metabolism in the OB and amygdala was assessed using fluorodeoxyglucose positron emission tomography/CT in patients with BD. The OB and amygdala metabolism was compared with the patients' Z scores. Both OB and amygdala metabolic activities were significantly higher than in the controls. A positive correlation was detected between right/left amygdala metabolism and right OB metabolism (p < 0.05, r:467 and r:662, respectively). This study increased our understanding of the etiopathogenesis of BD. In BD, the main cause of hypermetabolism in the amygdala may be increased metabolism in the OB. During evolution, the OB may have assumed a dominant role in emotional processing rather than olfactory functions.

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.

DNA methylation patterns and gene expression from amygdala tissue of mature Brahman cows exposed to prenatal stress

Prenatal stress can alter postnatal performance and temperament of cattle. These phenotypic effects may result from changes in gene expression caused by stress-induced epigenetic alterations. Specifically, shifts in gene expression caused by DNA methylation within the brain’s amygdala can result in altered behavior because it regulates fear, stress response and aggression in mammals Thus, the objective of this experiment was to identify DNA methylation and gene expression differences in the amygdala tissue of 5-year-old prenatally stressed (PNS) Brahman cows compared to control cows. Pregnant Brahman cows (n = 48) were transported for 2-h periods at 60 ± 5, 80 ± 5, 100 ± 5, 120 ± 5, and 140 ± 5 days of gestation. A non-transported group (n = 48) were controls (Control). Amygdala tissue was harvested from 6 PNS and 8 Control cows at 5 years of age. Overall methylation of gene body regions, promoter regions, and cytosine-phosphate-guanine (CpG) islands were compared between the two groups. In total, 202 genes, 134 promoter regions, and 133 CpG islands exhibited differential methylation (FDR ≤ 0.15). Following comparison of gene expression in the amygdala between the PNS and Control cows, 2 differentially expressed genes were identified (FDR ≤ 0.15). The minimal differences observed could be the result of natural changes of DNA methylation and gene expression as an animal ages, or because this degree of transportation stress was not severe enough to cause lasting effects on the offspring. A younger age may be a more appropriate time to assess methylation and gene expression differences produced by prenatal stress.

Thyroid hormones disturbances, cognitive deficits and abnormal dynamic functional connectivity variability of the amygdala in unmedicated bipolar disorder

OBJECTIVE

Accumulating evidence suggests that hypothalamus-pituitary-thyroid (HPT) axis dysfunction is relevant to the neuropsychological and pathophysiology functions of bipolar disorder (BD). However, no research has investigated the inter-relationships among thyroid hormones disturbance, neurocognitive deficits, and aberrant brain function (particularly in the amygdala) in patients with BD.

MATERIALS AND METHODS

Data of dynamic resting-state functional connectivity (rs-dFC) were gathered from 59 patients with unmedicated BD II during depressive episodes and 52 healthy controls (HCs). Four seeds were selected (the bilateral lateral amygdala and the bilateral medial amygdala). The sliding-window analysis was applied to investigate dynamic functional connectivity (dFC). Additionally, the serum thyroid hormone (free tri-iodothyronine (FT3), total tri-iodothyronine (TT3), free thyroxin (FT4), total thyroxin (TT4) and thyroid-stimulating hormone (TSH)) levels, and cognitive scores on the MATRICS Consensus Cognitive Battery (MCCB) in patients and HCs were detected.

RESULTS

The BD group exhibited increased dFC variability between the left medial amygdala and right medial prefrontal cortex (mPFC) when compared with the HC group. Additionally, the BD group showed lower FT3, TT3, and TSH level, higher FT4 level, and poorer cognitive score. Moreover, a significant negative correlation was observed between the dFC variability of the left medial amygdala-right mPFC and TSH level, or reasoning and problem solving of MCCB score in BD group. Multiple regression analysis showed that the TSH level × dFC variability of the medial amygdala-mPFC was an independent predictor for cognitive processing speed in BD group.

CONCLUSIONS

This study revealed patients with BD II depression had excessive variability in dFC between the medial amygdala and mPFC. Moreover, both HPT axis dysfunction and abnormal dFC of the amygdala-mPFC might be implicated in cognitive impairment in the early stages of BD.

Adversity, attachment and emotion recognition in BPD adolescents: the distinct roles of disengaged and controlling environment

Background

Literature data about emotion perception in patients with borderline personality disorders (BPD) revealed some discrepancies between some patients that are vigilant and accurate to detect their emotional environment and others that are impaired at identifying emotions of others. Even if some links between childhood adversity and facial affect recognition have been established, there is a need to understand the heterogeneous psychobiological mechanisms underlying this association. The aim is to distinguish in a BPD sample, the links between facial emotion recognition (FER) and adversity types (maltreatment and parental bonding), by evaluating two dimensions of disengaged and controlling environment.

Method

The study includes BPD adolescents (n = 45) and healthy controls (HC, n = 44): two scores of disengaged environment (parental low care; emotional and physical neglect) and controlling environment (high level of parenting control; emotional, physical and sexual abuse) were established and correlated to FER, as well as to attachment dimensions. Multiple linear regression analyzes were conducted to evaluate the effect of disengaged and controlling dimensions, on FER scores of sensitivity and accuracy, including anxious and avoidant attachment as covariables.

Results

Analyzes revealed that a disengaged environment was positively correlated to sensitivity in BPD patients, and the correlation was negative in the HC group. Controlling environment was negatively associated to accuracy of emotion in BPD. Avoidant and anxious attachment did not influence these associations.

Conclusions

These results suggest that distinct adverse experiences account for the heterogeneity observed in emotion regulation in BPD patients.

Associations between testosterone, estradiol, and androgen receptor genotype with amygdala subregions in adolescents

Much is known about the development of the whole amygdala, but less is known about its structurally and functionally diverse subregions. One notable distinguishing feature is their wide range of androgen and estrogen receptor densities. Given the rise in pubertal hormones during adolescence, sex steroid levels as well as receptor sensitivity could influence age-related subregion volumes. Therefore, our goal was to evaluate the associations between the total amygdala and its subregion volumes in relation to sex hormones - estradiol and free testosterone (FT) - as a function of age and genetic differences in androgen receptor (AR) sensitivity in a sample of 297 adolescents (46% female). In males, we found small effects of FT-by-age interactions in the total amygdala, portions of the basolateral complex, and the cortical and medial nuclei (CMN), with the CMN effects being moderated by AR sensitivity. For females, small effects were seen with increased genetic AR sensitivity relating to smaller basolateral complexes. However, none of these small effects passed multiple comparisons. Future larger studies are necessary to replicate these small, yet possibly meaningful effects of FT-by-age associations and modulation by AR sensitivity on amygdala development to ultimately determine if they contribute to known sex differences in emotional neurodevelopment.

Amygdala structure and function in paediatric bipolar disorder and high-risk youth: A systematic review of magnetic resonance imaging findings

OBJECTIVE

Converging evidence from structural and functional magnetic resonance imaging (MRI) studies points to amygdala alteration as crucial in the development of paediatric bipolar disorder (pBP). The high number of recent studies prompted us to comprehensively evaluate findings. We aimed to systematically review structural and functional MRI studies investigating the amygdala in patients with pBP and in youth at high-risk (HR) for developing pBP.

METHODS

We searched PubMed from any time to 25 September 2020 using: 'amygdala AND (MRI OR magnetic resonance imaging) AND bipolar AND (pediatr* OR child OR children OR childhood OR adolescent OR adolescents OR adolescence OR young OR familial OR at-risk OR sibling* OR offspring OR high risk)'. In this review, we adhered to the PRISMA statement.

RESULTS

Amygdala hyperactivity to emotional stimuli is the most commonly reported finding in youth with pBP and HR compared to healthy peers (HC), whereas findings from structural MRI studies are inconsistent.

CONCLUSIONS

Hyperactivation of the amygdala might be an endophenotype of pBP.

Longitudinal grey matter changes following first episode mania in bipolar I disorder: A systematic review

BACKGROUND

While widespread grey matter (GM) changes are seen in bipolar I disorder (BD-I), it is unclear how early in the illness such changes emerge. To date there has been little synthesis of findings regarding longitudinal grey matter changes early in the course of BD-I. We conducted a systematic review to examine the evolution of GM changes in BD-I patients following the first episode of mania (FEM).

METHODS

Following PRISMA guidelines, we conducted a systematic review of studies examining longitudinal changes in GM volume (GMV), cortical thickness and/or surface area in BD-I patients following FEM. We qualitatively synthesized results regarding longitudinal GM changes in BD-I patients.

RESULTS

Fifteen studies met inclusion criteria, all examining GMV changes. Longitudinal ACC volume decrease following FEM was the most replicated finding, but was only reported in 4 out of 7 studies that examined this region as part of a whole brain/region of interest analysis, with 2 of these positive studies using an overlapping patient sample. The impact of episode recurrence, medications, and other clinical factors was inconsistently examined.

LIMITATIONS

The literature regarding GM changes early in BD-I is highly inconsistent, likely due to heterogeneity in participant characteristics, imaging methodology/analysis and duration of follow up.

CONCLUSIONS

Though there was some suggestion that structural ACC changes may represent a marker for neuroprogression following FEM, results were too inconsistent to draw any conclusions. Larger longitudinal studies examining cortical thickness/surface area, and the influence of relevant clinical factors, are needed to better understand neuroprogression in early BD-I.

Hormonal Contraception and Violent Death: The Physiological and Psychological Links

In the past decade, two large prospective cohort studies of British and American women have been conducted which found a statistically significant increase in the risk of violent death in ever-users of hormonal contraceptives. Research on the effects of hormonal contraceptives upon the behaviors of intimate partners and on the physiology of women using hormonal contraceptives has provided insight into the possible basis for the resulting increase in violent death. This review examines the changes that are potential contributors to the reported increase.

Cognitive correlates of impulsive aggression in youth with pediatric bipolar disorder and bipolar offspring

BACKGROUND

Youth with bipolar disorder (BD) and offspring of individuals with BD (BD-OFF) are characterized by higher levels of impulsive and overt aggression. The cognitive basis underlying these aggressive behaviors are not clarified in this population. The aim of this study was to investigate the relationship between cognitive alterations and aggressive behavior in youth with BD and BD-OFF.

METHODS

Forty-two youth with BD, 17 BD-OFF and 57 healthy controls (HCs) were administered the Modified Overt Aggression Scale (MOAS), the Cambridge Neuropsychological Test Automated Battery (CANTAB), the Young Mania Rating Scale (YMRS) and the Children's Depression Rating Scale (CDRS). Multiple linear regression analyses were performed in the three groups separately. In each group, tests scores from the CANTAB were predictors. MOAS subscale scores and MOAS total scores were dependent variables. Results are corrected for age, IQ and mood state.

RESULTS

Both youth with BD and BD-OFF showed positive correlations between impairment in executive functions and levels of verbal aggression. In youth with BD, altered processing of either positive and negative stimuli positively correlated with MOAS total scores, whereas in BD-OFF, such relationship was negative.

CONCLUSIONS

Impulsive aggressive behaviors in youth with BD arise from a combination of altered affective processing and executive dysfunction. The negative relationship between affective processing and aggression in BD-OFF suggested the presence of possible mechanisms of resilience in this population.

Altered frontal cortex functioning in emotion regulation and hopelessness in bipolar disorder

OBJECTIVES

Emotion regulation difficulties precipitate and exacerbate acute mood symptoms in individuals with bipolar disorder (BD), and contribute to suicidal behavior. However, few studies have examined regional brain responses in explicit emotion regulation during acute BD mood states, or hopelessness, a major suicide risk factor. We assessed brain responses during explicit emotion regulation, and their relationship with hopelessness, in acutely symptomatic and euthymic individuals with BD.

METHODS

Functional MRI data were obtained from individuals with BD who were either in acute negative (BD-A; n = 24) or euthymic (BD-E; n = 24) mood states, and from healthy volunteers (HV; n = 55), while participants performed a paradigm that instructed them to downregulate their responses to fearful (EmReg-Fear) and happy (EmReg-Happy) facial stimuli. Emotion regulation-related differences in brain responses during negative and euthymic BD states, as well as their associations with negative affective symptoms (hopelessness and depression), were examined.

RESULTS

Decreased responses were observed in ventral and dorsal frontal regions, including medial orbitofrontal (mOFC) and dorsal anterior cingulate cortices, during EmReg-Fear across symptomatic and euthymic states in participants with BD relative to HVs. The lowest responses were observed in the BD-A group. Across BD participants, negative associations were observed between mOFC responses and hopelessness, particularly due to loss of motivation. Differences were not significant during EmReg-Happy.

CONCLUSIONS

Lesser emotion regulation-related ventral and dorsal frontal engagement in BD could represent a trait abnormality that worsens during acute negative states. The reduced mOFC engagement in BD during explicit regulation of negative emotions may contribute to hopelessness particularly in the context of diminished motivation.

Research Review: Pediatric anxiety disorders - what have we learnt in the last 10 years?

BACKGROUND

Anxiety disorders first emerge during the critical developmental periods of childhood and adolescence. This review synthesizes recent findings on the prevalence, risk factors, and course of the anxiety disorders; and their neurobiology and treatment.

METHODS

For this review, searches were conducted using PubMed, PsycINFO, and clinicaltrials.gov. Findings related to the epidemiology, neurobiology, risk factors, and treatment of pediatric anxiety disorders were then summarized.

FINDINGS

Anxiety disorders are high prevalence, and early-onset conditions associated with multiple risk factors including early inhibited temperament, environment stress, and structural and functional abnormalities in the prefrontal-amygdala circuitry as well as the default mode and salience networks. The anxiety disorders are effectively treated with cognitive behavioral therapy (CBT), selective serotonin reuptake inhibitors (SSRIs), and serotonin-norepinephrine reuptake inhibitors (SNRIs).

CONCLUSIONS

Anxiety disorders are high prevalence, early-onset conditions associated with a distinct neurobiological fingerprint, and are consistently responsive to treatment. Questions remain regarding who is at risk of developing anxiety disorders as well as the way in which neurobiology predicts treatment response.

The amygdala in adolescents with attention-deficit/hyperactivity disorder: Structural and functional correlates of delay aversion

OBJECTIVES

Recent magnetic resonance imaging (MRI) studies implicate structural alterations of amygdala, a brain region responsible for processing and experiencing negative emotions, in adolescents with attention-deficit/hyperactivity disorder (ADHD). Here we examined ADHD-related structural correlates of amygdala functional activity elicited during a functional MRI task designed to test behavioural and brain responses to the imposition of delay - an event known to both elicit amygdala hyperactivation and aversity in ADHD.

METHODS

Structural MRI scans from 28 right-handed male adolescents with combined type ADHD and 32 age-matched controls were analysed. Regional grey matter volumes of ADHD and control participants (P[FWE] < 0.05) were correlated with delay aversion self-ratings and neural activity in response to delay-related cues on the Escape Delay Incentive fMRI task.

RESULTS

ADHD was associated with significantly reduced volumes in bilateral amygdala, parahippocampal and temporal gyrus (P[FWE] < 0.05), greater basolateral amygdala activation to delay-related cues (P[FWE] < 0.05) and higher delay aversion self-ratings. Amygdala volume reductions were significantly correlated with, and statistically mediated the pathway from ADHD to, delay-cue-related amygdala hyperactivity (P < 0.01) and self-reported delay aversion (P < 0.01).

CONCLUSIONS

We provide the first evidence of the functional significance of reduced amygdala volumes in adolescents with ADHD by highlighting its relation to delay-induced brain activity that is linked to delay aversion.

Material hardship, prefrontal cortex-amygdala structure, and internalizing symptoms in children

Material hardship, or difficulty affording basic resources such as food, housing, utilities, and health care, increases children's risk for internalizing problems. The uncinate fasciculus (UNC) and two of the gray matter regions it connects-the orbitofrontal cortex (OFC) and amygdala-may play important roles in the neural mechanisms underlying these associations. We investigated associations among material hardship, UNC microstructure, OFC and amygdala structure, and internalizing symptoms in children. Participants were 5-9-year-old children (N = 94, 61% female) from socioeconomically diverse families. Parents completed questionnaires assessing material hardship and children's internalizing symptoms. High-resolution, T1-weighted magnetic resonance imaging (n = 51), and diffusion tensor imaging (n = 58) data were acquired. UNC fractional anisotropy (FA), medial OFC surface area, and amygdala gray matter volume were extracted. Greater material hardship was significantly associated with lower UNC FA, smaller amygdala volume, and higher internalizing symptoms in children, after controlling for age, sex, and family income-to-needs ratio. Lower UNC FA significantly mediated the association between material hardship and internalizing symptoms in girls but not boys. These findings are consistent with the notion that material hardship may lead to altered white matter microstructure and gray matter structure in neural networks critical to emotion processing and regulation.

The Amygdala in Schizophrenia and Bipolar Disorder: A Synthesis of Structural MRI, Diffusion Tensor Imaging, and Resting-State Functional Connectivity Findings

Frequently implicated in psychotic spectrum disorders, the amygdala serves as an important hub for elucidating the convergent and divergent neural substrates in schizophrenia and bipolar disorder, the two most studied groups of psychotic spectrum conditions. A systematic search of electronic databases through December 2017 was conducted to identify neuroimaging studies of the amygdala in schizophrenia and bipolar disorder, focusing on structural MRI, diffusion tensor imaging (DTI), and resting-state functional connectivity studies, with an emphasis on cross-diagnostic studies. Ninety-four independent studies were selected for the present review (49 structural MRI, 27 DTI, and 18 resting-state functional MRI studies). Also selected, and analyzed in a separate meta-analysis, were 33 volumetric studies with the amygdala as the region-of-interest. Reduced left, right, and total amygdala volumes were found in schizophrenia, relative to both healthy controls and bipolar subjects, even when restricted to cohorts in the early stages of illness. No volume abnormalities were observed in bipolar subjects relative to healthy controls. Shape morphometry studies showed either amygdala deformity or no differences in schizophrenia, and no abnormalities in bipolar disorder. In contrast to the volumetric findings, DTI studies of the uncinate fasciculus tract (connecting the amygdala with the medial- and orbitofrontal cortices) largely showed reduced fractional anisotropy (a marker of white matter microstructure abnormality) in both schizophrenia and bipolar patients, with no cross-diagnostic differences. While decreased amygdalar-orbitofrontal functional connectivity was generally observed in schizophrenia, varying patterns of amygdalar-orbitofrontal connectivity in bipolar disorder were found. Future studies can consider adopting longitudinal approaches with multimodal imaging and more extensive clinical subtyping to probe amygdalar subregional changes and their relationship to the sequelae of psychotic disorders.

Correlation Between Decreased Amygdala Subnuclei Volumes and Impaired Cognitive Functions in Pediatric Bipolar Disorder

BACKGROUND

The amygdala has been proposed to be involved in the pathophysiology of pediatric and adult bipolar disorder (BD). The goal of this structural magnetic resonance imaging (sMRI) study was to investigate the morphometric characteristics of amygdala subnuclei in patients with pediatric bipolar disorder (PBD) compared to healthy controls (HCs). Simultaneously, we examined correlation between amygdala subnuclei volumes and cognitive dysfunction.

MATERIALS AND METHODS

We assessed 40 adolescent outpatients, diagnosed with manic or euthymic PBD according to the DSM-5 criteria for BD and 19 HCs. Cognitive functions were evaluated using a Stroop color-word test (SCWT), trail making test (TMT), visual reproduction immediate recall subtest (VR I), and digit span subtest (DST). Amygdala and its subnuclei structures were automated segmented using FreeSurfer software and the volumes of them were compared between groups and correlation with clinical and cognitive outcomes was conducted.

RESULTS

Manic patients exhibited significantly decreased volumes in the bilateral whole amygdala and its basal nucleus, cortico-amygdaloid transition (CAT), and accessory basal nucleus (ABN) compared with HCs. Euthymic patients had decreased volume in the bilateral ABN and left CAT. In addition, we found significant positive associations between VR I scores and the right whole amygdala and its bilateral basal, right lateral, and ABN volumes in the manic group.

CONCLUSION

These findings support previous reports of smaller amygdala volumes and cognitive dysfunctions in PBD, and further mapping abnormalities to specific amygdala subnuclei. Correlation between basolateral volume and VR I of PBD may expand our understanding of neural abnormalities that could be targeted by treatment.

Association of Prepubertal and Postpubertal Exposure to Childhood Maltreatment With Adult Amygdala Function

IMPORTANCE

Abnormalities in amygdala response to threatening faces have been observed in anxiety disorders, autism, bipolar disorder, depression, posttraumatic stress disorder, and schizophrenia. Abnormally hyperactive and hypoactive responses have typically been associated with anxiety and inhibition vs risk taking and inappropriate social behaviors. Maltreatment is a major risk factor for most of these disorders and is associated with abnormal amygdala function.

OBJECTIVE

To identify the type and age of exposure to childhood maltreatment that are associated with hyperactive and hypoactive amygdala responses in young adulthood.

DESIGN, SETTING, AND PARTICIPANTS

Data collection for this retrospective cohort study took place from November 8, 2010, to August 23, 2012. Data analyses were conducted from September 20, 2012, to June 27, 2018. Participants were recruited from the urban and suburban Boston vicinity without diagnostic restrictions based on exposure history.

EXPOSURES

The Maltreatment and Abuse Chronology of Exposure (MACE) scale was used to retrospectively assess type and age of exposure to childhood maltreatment.

MAIN OUTCOMES AND MEASURES

Activation and pattern information functional magnetic resonance imaging were used to assess bilateral amygdala response to angry and fearful faces vs neutral faces or shapes, and sensitive exposure periods were identified using cross-validated artificial intelligence predictive analytics (50 averaged randomized iterations with training on 63.3% and testing on 36.7% of the sample).

RESULTS

Of the 202 participants (mean [SD] age, 23.2 [1.7] years; 118 [58.4%] female), 52 (25.7%) reported no exposure to maltreatment and 150 (74.3%) reported exposure to 1 or more maltreatment types. Eight participants (15.1%) with a MACE score of 0 and 51 (34.2%) with a MACE score of 1 or higher had a history of major depression (odds ratio, 2.40; 95% CI, 1.05-6.06; P = .03); 8 unexposed participants (15.1%) and 46 with MACE scores of 1 or higher (30.9%) had a history of 1 or more anxiety disorders (odds ratio, 2.45; 95% CI, 1.03-6.50; P = .03). Retrospective self-report of physical maltreatment between 3 and 6 years of age and peer emotional abuse at 13 and 15 years were associated with amygdala activation to emotional faces vs shapes. Early exposure was associated with blunted response (β = -0.17, P < .001), whereas later exposure was associated with augmented response (β = 0.16, P < .001). Prepubertal vs postpubertal maltreatment was associated with an opposite response on the voxelwise response pattern in clustering stimuli of the same type (eg, mean [SD] emotional ellipse areas for physical maltreatment at age 4 years vs nonverbal emotional abuse at 13 years: 1.41 [1.05] vs 0.25 [0.10], P < .001) and in distinguishing between stimuli of different types (eg, mean [SD] emotional vs neutral faces distance for peer emotional abuse at age 6 years vs 13 years: 1.89 [0.75] vs 0.80 [0.39], P < .001).

CONCLUSIONS AND RELEVANCE

The findings suggest that prepubertal vs postpubertal developmental differences in the association between maltreatment and amygdala response to threatening or salient stimuli exist. Understanding the role of adversity in different sensitive exposure periods and the potential adaptive significance of attenuated vs enhanced amygdala response may help explain why maltreatment may be a risk factor for many different disorders and foster creation of targeted interventions to preempt the emergence of psychopathology in at-risk youths.

Early and late cortical reactivity to passively viewed emotional faces in pediatric bipolar disorder

BACKGROUND

We studied emotional information processing in youth with pediatric bipolar disorder (pBD) using the late positive potential (LPP), assessing automatic allocation of attentional resources to emotionally salient stimuli, and the occipital P1, assessing early sensory processing.

METHODS

Participants were 20 youth with pBD and 26 healthy controls (HC). Participants passively viewed faces with a fearful, neutral or happy expressions. Group differences were tested with general linear models. P1 was included to examine modulating effects on LPP. We calculated Bayes factor (BF) values to express strength of evidence for choosing one hypothesis over another.

RESULTS

A significant emotion by group interaction for LPP amplitude was associated with a larger amplitude for happy faces for pBD than HC (F[1,40] = 6.04, p = .018); this was not modulated by P1 amplitude or latency. P1 amplitude did not differ between groups, although P1 peaked earlier for HC (F[1,40] = 5.45, p = .025). BF for LPP was 2.93, suggesting moderate evidence favoring H₁. BF for P1 latency of 14.58 suggests strong evidence favoring H₁.

LIMITATIONS

Inclusion of children and adolescents prohibited careful control for neurodevelopmental effects.

CONCLUSIONS

Larger LPP amplitude for happy faces without change in P1 suggests enhanced automatic allocation of attentional resources to positive information in pBD. Delayed P1 latency in pBD suggests slower early processing of emotional information.

Abnormal Degree Centrality Associated With Cognitive Dysfunctions in Early Bipolar Disorder

Delayed diagnosis of bipolar disorder (BD) is common. However, diagnostic validity may be enhanced using reliable neurobiological markers for BD. Degree centrality (DC) is one such potential marker that enables researchers to visualize neuronal network abnormalities in the early stages of some neuropsychiatric disorders. In the present study, we measured resting-state DC abnormalities and cognitive deficits in order to identify early neurobiological markers for BD. We recruited 23 patients with BD who had recently experienced manic episodes (duration of illness <2 years) and 46 matched healthy controls. Our findings indicated that patients with BD exhibited DC abnormalities in frontal areas, temporal areas, the right postcentral gyrus, and the posterior lobe of the cerebellum. Moreover, correlation analysis revealed that psychomotor speed indicators were associated with DC in the superior temporal and inferior temporal gyri, while attention indicators were associated with DC in the inferior temporal gyrus, in patients with early BD. Our findings suggest that DC abnormalities in neural emotion regulation circuits are present in patients with early BD, and that correlations between attention/psychomotor speed deficits and temporal DC abnormalities may represent early markers of BD.

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

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

Biobehavioral threat sensitivity and amygdala volume: A twin neuroimaging study

Current literature on the relationship between dispositional fear (or threat sensitivity) and amygdala gray matter volume (GMV) is heterogeneous, with findings including positive, negative, and null correlations. A clearer understanding of this relationship would help to determine the potential utility of amygdala volume as a biomarker of anxious/depressive (internalizing) disorders and contribute to understanding of neural mechanisms for variations in fearfulness. The study reported here used voxel-based morphometry to quantify amygdala GMV scores from structural neuroimaging data in a sample of 44 monozygotic twins (i.e., 22 pairs). Dispositional threat sensitivity (THT) was quantified using a biobehavioral cross-domain score that combined neurophysiological indicators with a psychological scale measure. Analyses revealed expected high concordance for amygdala GMV between co-twins. With respect to the major question of the study, a negative correlation was found between biobehavioral THT scores and amygdala volume - with individuals higher in THT showing smaller amygdala GMV scores. More modest associations of amygdala GMV with symptoms of social phobia, and fear disorder symptomology more broadly, were mediated by THT. These results provide insight into prior mixed findings and support the combined use of biological and behavioral measures to quantify characteristics relevant to mental health problems.

Preliminary mapping of the structural effects of age in pediatric bipolar disorder with multimodal MR imaging

This study investigates multimodal structural MR imaging biomarkers of development trajectories in pediatric bipolar disorder. T1-weighted and diffusion-weighted MR imaging was conducted to investigate cross-sectional group differences with age between typically developing controls (N = 26) and youths diagnosed with bipolar disorder (N = 26). Region-based analysis was used to examine cortical thickness of gray matter and diffusion tensor parameters in superficial white matter, and tractography-based analysis was used to examine deep white matter fiber bundles. Patients and controls showed significantly different maturation trajectories across brain areas; however, the magnitude of differences varied by region. The rate of cortical thinning with age was greater in patients than controls in the left frontal pole. While controls showed increasing fractional anisotropy (FA) and axial diffusivity (AD) with age, patients showed an opposite trend of decreasing FA and AD with age in fronto-temporal-striatal regions located in both superficial and deep white matter. The findings support fronto-temporal-striatal alterations in the developmental trajectories of youths diagnosed with bipolar disorder, and further, show the value of multimodal computational techniques in the assessment of neuropsychiatric disorders. These preliminary results warrant further investigation into longitudinal changes and the effects of treatment in the brain areas identified in this study.

Reliability of neural activation and connectivity during implicit face emotion processing in youth

Face emotion imaging paradigms are widely used in both healthy and psychiatric populations. Here, in children and adolescents, we evaluate the test-retest reliability of blood oxygenation-level dependent (BOLD) activation and task-based functional connectivity on a widely used implicit face emotion processing task (i.e., gender labeling). Twenty-five healthy youth (M age = 13.97 year s; 60% female) completed two functional magnetic resonance imaging (fMRI) scan sessions approximately two months apart. Participants identified the gender of faces displaying angry, fearful, happy, and neutral emotions. A Bayesian adaptation of the intraclass correlation (ICC) assessed reliability of evoked BOLD activation and amygdala seed-based functional connectivity on task events vs. baseline as well as contrasts between face emotions. For each face emotion vs. baseline, good reliability of activation was demonstrated across key emotion processing regions including middle, medial, and inferior frontal gyri. However, contrasts between face emotions yielded variable results. Contrasts of angry to neutral or happy faces exhibited good reliability of amygdala connectivity to prefrontal regions. Contrasts of fearful to happy faces exhibited good reliability of activation in the anterior cingulate. Findings inform the reproducibility literature and emphasize the need for continued evaluation of task reliability.

Longitudinal Diffusion Tensor Imaging Study of Adolescents and Young Adults With Bipolar Disorder

OBJECTIVE

Longitudinal neuroimaging during adolescence/young adulthood, when bipolar disorder (BD) commonly emerges, can help elucidate the neurodevelopmental pathophysiology of BD. Adults with BD have shown reduced structural integrity in the uncinate fasciculus (UF), a white matter (WM) tract providing major connections between the amygdala and ventral prefrontal cortex (vPFC), important in emotion regulation. In this longitudinal diffusion tensor imaging (DTI) study of adolescents/young adults, we hypothesized differences in age- and time-related changes in UF integrity in BD compared to healthy controls (HC).

METHOD

Two DTI scans were obtained in 27 adolescents/young adults with BD and 37 HC adolescents/young adults, on average approximately 2.5 years apart. Interactions between diagnosis with age and with time for UF fractional anisotropy (FA) were assessed. Exploratory analyses were performed including euthymic-only participants with BD, and for potential influences of demographic and clinical factors. Whole-brain analyses were performed to explore for interactions in other regions.

RESULTS

There were significant interactions between diagnosis with age and with time for UF FA (p < .05). Healthy control adolescents/young adults showed significant UF FA increases with age and over time (p < .05), whereas no significant changes with age or over time were observed in the adolescents/young adults with BD. Significant interactions with age and time were also observed in analyses including euthymic-only participants with BD (p < .05).

CONCLUSION

These findings provide neuroimaging evidence supporting differences in UF WM structural development during adolescence/young adulthood, suggesting that differences in the development of an amygdala-vPFC system subserving emotion regulation may be a trait feature of BD neurodevelopment.

Developmental relations between amygdala volume and anxiety traits: Effects of informant, sex, and age

Although substantial human and animal evidence suggests a role for the amygdala in anxiety, literature linking amygdala volume to anxiety symptomatology is inconclusive, with studies finding positive, negative, and null results. Clarifying this brain–behavior relation in middle to late childhood is especially important, as this is a time both of amygdala structural maturation and the emergence of many anxiety disorders. The goal of the current study was to clarify inconsistent findings in previous literature by identifying factors moderating the relation between amygdala volume and anxiety traits in a large sample of typically developing children aged 6–13 years (N = 72). In particular, we investigated the moderating effects of informant (parent vs. child), age, and sex. We found that children's reports (i.e., self-reports) were related to amygdala volume; children who reported higher anxiety levels had smaller amygdalae. This negative relation between amygdala volume and anxiety weakened with age. There was also an independent effect of sex, such that relations were stronger in males than in females. These results indicate the importance of considering sample and informant characteristics when charting the neurobiological mechanisms underlying developmental anxiety.

Effects of ANK3 variation on gray and white matter in bipolar disorder

The single-nucleotide polymorphism rs9804190 in the Ankyrin G (ANK3) gene has been reported in genome-wide association studies to be associated with bipolar disorder (BD). However, the neural system effects of rs9804190 in BD are not known. We investigated associations between rs9804190 and gray and white matter (GM and WM, respectively) structure within a frontotemporal neural system implicated in BD. A total of 187 adolescent and adult European Americans were studied: a group homozygous for the C allele (52 individuals with BD and 56 controls) and a T-carrier group, carrying the high-risk T allele (38 BD and 41 controls). Subjects participated in high-resolution structural magnetic resonance imaging and diffusion tensor imaging (DTI) scanning. Frontotemporal region of interest (ROI) and whole-brain exploratory analyses were conducted. DTI ROI-based analysis revealed a significant diagnosis by genotype interaction within the uncinate fasciculus (P⩽0.05), with BD subjects carrying the T (risk) allele showing decreased fractional anisotropy compared with other subgroups, independent of age. Genotype effects were not observed in frontotemporal GM volume. These findings support effects of rs9804190 on frontotemporal WM in adolescents and adults with BD and suggest a mechanism contributing to WM pathology in BD.

Variants in calcium voltage-gated channel subunit Alpha1 C-gene (CACNA1C) are associated with sleep latency in infants

Genetic variants in CACNA1C (calcium voltage-gated channel subunit alpha1 C) are associated with bipolar disorder and schizophrenia where sleep disturbances are common. In an experimental model, Cacna1c has been found to modulate the electrophysiological architecture of sleep. There are strong genetic influences for consolidation of sleep in infancy, but only a few studies have thus far researched the genetic factors underlying the process. We hypothesized that genetic variants in CACNA1C affect the regulation of sleep in early development. Seven variants that were earlier associated (genome-wide significantly) with psychiatric disorders at CACNA1C were selected for analyses. The study sample consists of 1086 infants (520 girls and 566 boys) from the Finnish CHILD-SLEEP birth cohort (genotyped by Illumina Infinium PsychArray BeadChip). Sleep length, latency, and nightly awakenings were reported by the parents of the infants with a home-delivered questionnaire at 8 months of age. The genetic influence of CACNA1C variants on sleep in infants was examined by using PLINK software. Three of the examined CACNA1C variants, rs4765913, rs4765914, and rs2239063, were associated with sleep latency (permuted P<0.05). There was no significant association between studied variants and night awakenings or sleep duration. CACNA1C variants for psychiatric disorders were found to be associated with long sleep latency among 8-month-old infants. It remains to be clarified whether the findings refer to defective regulation of sleep, or to distractibility of sleep under external influences.

Subcortical volumetric abnormalities in bipolar disorder

Considerable uncertainty exists about the defining brain changes associated with bipolar disorder (BD). Understanding and quantifying the sources of uncertainty can help generate novel clinical hypotheses about etiology and assist in the development of biomarkers for indexing disease progression and prognosis. Here we were interested in quantifying case-control differences in intracranial volume (ICV) and each of eight subcortical brain measures: nucleus accumbens, amygdala, caudate, hippocampus, globus pallidus, putamen, thalamus, lateral ventricles. In a large study of 1710 BD patients and 2594 healthy controls, we found consistent volumetric reductions in BD patients for mean hippocampus (Cohen's d=-0.232; P=3.50 × 10-7) and thalamus (d=-0.148; P=4.27 × 10-3) and enlarged lateral ventricles (d=-0.260; P=3.93 × 10-5) in patients. No significant effect of age at illness onset was detected. Stratifying patients based on clinical subtype (BD type I or type II) revealed that BDI patients had significantly larger lateral ventricles and smaller hippocampus and amygdala than controls. However, when comparing BDI and BDII patients directly, we did not detect any significant differences in brain volume. This likely represents similar etiology between BD subtype classifications. Exploratory analyses revealed significantly larger thalamic volumes in patients taking lithium compared with patients not taking lithium. We detected no significant differences between BDII patients and controls in the largest such comparison to date. Findings in this study should be interpreted with caution and with careful consideration of the limitations inherent to meta-analyzed neuroimaging comparisons.

Brain functional effects of psychopharmacological treatments in bipolar disorder

Functional magnetic resonance imaging (fMRI) studies have contributed to the understanding of bipolar disorder. However the effect of medication on brain activation remains poorly understood. We conducted an extensive literature review on PubMed and ScienceDirect to investigate the influence of medication in fMRI studies, including both longitudinal and cross-sectional studies, which aimed at assessing this influence. Although we reported all reviewed studies, we gave greater emphasis to studies with the most robust methodology. One hundred and forty studies matched our inclusion criteria and forty-seven studies demonstrated an effect of pharmacological treatment on fMRI blood oxygen level dependent (BOLD) signal in adults and children with bipolar disorder. Out of these studies, nineteen were longitudinal. Most of cross-sectional studies suffered from methodological bias, due to post-hoc analyses performed on a limited number of patients and did not find any effect of medication. However, both longitudinal and cross-sectional studies showing an impact of treatment tend to suggest that medication prescribed to patients with bipolar disorder mostly influenced brain activation in prefrontal regions, when measured by tasks involving emotional regulation and processing as well as non-emotional cognitive tasks. FMRI promises to elucidate potential new biomarkers in bipolar disorder and could be used to evaluate the effect of new therapeutic compounds. Further research is needed to disentangle the effect of medication and the influence of the changes in mood state on brain activation in patients with bipolar disorder.

Anterior Cortical Development During Adolescence in Bipolar Disorder

BACKGROUND

Increasing evidence supports a neurodevelopmental model for bipolar disorder (BD), with adolescence as a critical period in its development. Developmental abnormalities of anterior paralimbic and heteromodal frontal cortices, key structures in emotional regulation processes and central in BD, are implicated. However, few longitudinal studies have been conducted, limiting understanding of trajectory alterations in BD. In this study, we performed longitudinal neuroimaging of adolescents with and without BD and assessed volume changes over time, including changes in tissue overall and within gray and white matter. Larger decreases over time in anterior cortical volumes in the adolescents with BD were hypothesized. Gray matter decreases and white matter increases are typically observed during adolescence in anterior cortices. It was hypothesized that volume decreases over time in BD would reflect alterations in those processes, showing larger gray matter contraction and decreased white matter expansion.

METHODS

Two high-resolution magnetic resonance imaging scans were obtained approximately 2 years apart for 35 adolescents with bipolar I disorder (BDI) and 37 healthy adolescents. Differences over time between groups were investigated for volume overall and specifically for gray and white matter.

RESULTS

Relative to healthy adolescents, adolescents with BDI showed greater volume contraction over time in a region including insula and orbitofrontal, rostral, and dorsolateral prefrontal cortices (p < .05, corrected), including greater gray matter contraction and decreased white matter expansion over time, in the BD compared with the healthy group.

CONCLUSIONS

The findings support neurodevelopmental abnormalities during adolescence in BDI in anterior cortices, including altered developmental trajectories of anterior gray and white matter.

Variation in CACNA1C is Associated with Amygdala Structure and Function in Adolescents

OBJECTIVE

Genome-wide association studies have identified allelic variation in CACNA1C as a risk factor for multiple psychiatric disorders associated with limbic system dysfunction, including bipolar disorder, schizophrenia, and depression. The CACNA1C gene codes for a subunit of L-type voltage-gated calcium channels, which modulate amygdala function. Although CACNA1C genotype appears to be associated with amygdala morphology and function in adults with and without psychopathology, whether genetic variation influences amygdala structure and function earlier in development has not been examined.

METHODS

In this first investigation of the neural correlates of CACNA1C in young individuals, we examined associations between two single nucleotide polymorphisms in CACNA1C (rs1006737 and rs4765914) with amygdala volume and activation during an emotional processing task in 58 adolescents and young adults 13-20 years of age.

RESULTS

Minor (T) allele carriers of rs4765914 exhibited smaller amygdala volume than major (C) allele homozygotes (β=-0.33, p=0.006). Furthermore, minor (A) allele homozygotes of rs1006737 exhibited increased blood-oxygen-level-dependent (BOLD) signal in the amygdala when viewing negative (vs. neutral) stimuli (β=0.29, p=0.040) and decreased BOLD signal in the amygdala when instructed to downregulate their emotional response to negative stimuli (β=-0.38, p=0.009). Follow-up analyses indicated that childhood trauma did not moderate the associations of CACNA1C variation with amygdala structure and function (ps>0.170).

CONCLUSIONS

Findings indicate that CACNA1C-related differences in amygdala structure and function are present by adolescence. However, population stratification is a concern, given the racial/ethnic heterogeneity of our sample, and our findings do not have direct clinical implications currently. Nevertheless, these results suggest that developmentally informed research can begin to shed light on the time course by which genetic liability may translate into neural differences associated with vulnerability to psychopathology.

Correlations between amygdala volumes and serum levels of BDNF and NGF as a neurobiological markerin adolescents with bipolar disorder

BACKGROUND

The amygdala is repeatedly implicated as a critical component of the neurocircuitry regulating emotional valence. Studies have frequently reported reduced amygdala volumes in children and adolescents with bipolar disorder (BD). Brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF) play critical roles in growth, differentiation, maintenance, and synaptic plasticity of neuronal systems in adolescent brain development. The aim of the present study was to assess amygdala volumesand its correlation with serum levels of NGF and BDNF in euthymic adolescents with BD and healthy controls.

METHODS

Using structural MRI, we compared the amygdala volumes of 30 euthymic subjects with BD with 23 healthy control subjects aged between 13 and 19 years during a naturalistic clinical follow-up. The boundaries of the amygdala were outlined manually. Serum BDNF and NGF levels were measured using sandwich-ELISA and compared between the study groups.

RESULTS

The right or left amygdala volume did not differ between the study groups.The right and left amygdala volumes were highly correlated with levels of BDNF in the combined BD group and the valproate-treated group.Both R and L amygdala volumes were correlated with BDNF levels in healthy controls. The left amygdala volumes were correlated with BDNF levels in the lithium-treated group.

LIMITATIONS

This cross-sectional study cannot inform longitudinal changes in brain structure. Further studies with larger sample sizes are needed to improve reliability.

CONCLUSIONS

The correlations between amygdala volumes and BDNF levels might be an early neuromarker for diagnosis and/or treatment response in adolescents with BD.

Cognitive remediation: potential novel brain-based treatment for bipolar disorder in children and adolescents

Bipolar disorder (BD) is among the most impairing psychiatric disorders affecting children and adolescents, despite our best psychopharmacological and psychotherapeutic treatments. Cognitive remediation, defined as a behavioral intervention designed to improve cognitive functions so as to reduce psychiatric illness, is an emerging brain-based treatment approach that has thus far not been studied in pediatric BD. The present article reviews the basic principles of cognitive remediation, describes what is known about cognitive remediation in psychiatric disorders, and delineates potential brain/behavior alterations implicated in pediatric BD that might be targets for cognitive remediation. Emerging data show that cognitive remediation may be useful in children and adults with schizophrenia, ADHD, and anxiety disorders, and in adults with BD. Potential targets for cognitive remediation in pediatric BD include face processing, response inhibition, frustration, and cognitive flexibility. Further study is warranted to determine if cognitive remediation for these targets, or others, may serve as a novel, brain-based treatment for pediatric BD.

Widespread white matter tract aberrations in youth with familial risk for bipolar disorder

Few studies have examined multiple measures of white matter (WM) differences in youth with familial risk for bipolar disorder (FR-BD). To investigate WM in the FR-BD group, we used three measures of WM structure and two methods of analysis. We used fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) to analyze diffusion tensor imaging (DTI) findings in 25 youth with familial risk for bipolar disorder, defined as having both a parent with BD and mood dysregulation, and 16 sex-, age-, and IQ-matched healthy controls. We conducted a whole brain voxelwise analysis using tract based spatial statistics (TBSS). Subsequently, we conducted a complementary atlas-based, region-of-interest analysis using Diffeomap to confirm results seen in TBSS. When TBSS was used, significant widespread between-group differences were found showing increased FA, increased AD, and decreased RD in the FR-BD group in the bilateral uncinate fasciculus, cingulum, cingulate, superior fronto-occipital fasciculus (SFOF), superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus, and corpus callosum. Atlas-based analysis confirmed significant between-group differences, with increased FA and decreased RD in the FR-BD group in the SLF, cingulum, and SFOF. We found significant widespread WM tract aberrations in youth with familial risk for BD using two complementary methods of DTI analysis.

Histone deacetylase inhibitors reverse manic-like behaviors and protect the rat brain from energetic metabolic alterations induced by ouabain

Studies have revealed alterations in mitochondrial complexes in the brains of bipolar patients. However, few studies have examined changes in the enzymes of the tricarboxylic acid cycle. Several preclinical studies have suggested that histone deacetylase inhibitors may have antimanic effects. The present study aims to investigate the effects of lithium, valproate and sodium butyrate, a histone deacetylase inhibitor, on the activity of tricarboxylic acid cycle enzymes in the brains of rats subjected to an animal model of mania induced by ouabain. Wistar rats received a single intracerebroventricular injection of ouabain or cerebrospinal fluid. Starting on the day following the intracerebroventricular injection, the rats were treated for 7days with intraperitoneal injections of saline, lithium, valproate or sodium butyrate. Risk-taking behavior, locomotor and exploratory activities were measured using the open-field test. Citrate synthase, succinate dehydrogenase, and malate dehydrogenase were examined in the frontal cortex and hippocampus. All treatments reversed ouabain-related risk-taking behavior and hyperactivity in the open-field test. Ouabain inhibited tricarboxylic acid cycle enzymes in the brain, and valproate and sodium butyrate but not lithium reversed this ouabain-induced dysfunction. Thus, protecting the tricarboxylic acid cycle may contribute to the therapeutic effects of histone deacetylase inhibitors.

A critical appraisal of neuroimaging studies of bipolar disorder: toward a new conceptualization of underlying neural circuitry and a road map for future research

OBJECTIVE

In this critical review, the authors appraise neuroimaging findings in bipolar disorder in emotion-processing, emotion-regulation, and reward-processing neural circuitry in order to synthesize the current knowledge of the neural underpinnings of bipolar disorder and provide a neuroimaging research road map for future studies.

METHOD

The authors examined findings from all major studies in bipolar disorder that used functional MRI, volumetric analysis, diffusion imaging, and resting-state techniques, integrating findings to provide a better understanding of larger-scale neural circuitry abnormalities in bipolar disorder.

RESULTS

Bipolar disorder can be conceptualized, in neural circuitry terms, as parallel dysfunction in prefrontal cortical (especially ventrolateral prefrontal cortical)-hippocampal-amygdala emotion-processing and emotion-regulation circuits bilaterally, together with an "overactive" left-sided ventral striatal-ventrolateral and orbitofrontal cortical reward-processing circuitry, resulting in characteristic behavioral abnormalities associated with bipolar disorder: emotional lability, emotional dysregulation, and heightened reward sensitivity. A potential structural basis for these functional abnormalities is gray matter volume decreases in the prefrontal and temporal cortices, the amygdala, and the hippocampus and fractional anisotropy decreases in white matter tracts connecting prefrontal and subcortical regions.

CONCLUSIONS

Neuroimaging studies of bipolar disorder clearly demonstrate abnormalities in neural circuits supporting emotion processing, emotion regulation, and reward processing, although there are several limitations to these studies. Future neuroimaging research in bipolar disorder should include studies adopting dimensional approaches; larger studies examining neurodevelopmental trajectories in youths with bipolar disorder or at risk for bipolar disorder; multimodal neuroimaging studies using integrated systems approaches; and studies using pattern recognition approaches to provide clinically useful individual-level data. Such studies will help identify clinically relevant biomarkers to guide diagnosis and treatment decision making for individuals with bipolar disorder.

Fronto-limbic-striatal dysfunction in pediatric and adult patients with bipolar disorder: impact of face emotion and attentional demands

BACKGROUND

Research in bipolar disorder (BD) implicates fronto-limbic-striatal dysfunction during face emotion processing but it is unknown how such dysfunction varies by task demands, face emotion and patient age.

METHOD

During functional magnetic resonance imaging (fMRI), 181 participants, including 62 BD (36 children and 26 adults) and 119 healthy comparison (HC) subjects (57 children and 62 adults), engaged in constrained and unconstrained processing of emotional (angry, fearful, happy) and non-emotional (neutral) faces. During constrained processing, subjects answered questions focusing their attention on the face; this was processed either implicitly (nose width rating) or explicitly (hostility; subjective fear ratings). Unconstrained processing consisted of passive viewing.

RESULTS

Pediatric BD rated neutral faces as more hostile than did other groups. In BD patients, family-wise error (FWE)-corrected region of interest (ROI) analyses revealed dysfunction in the amygdala, inferior frontal gyrus (IFG), anterior cingulate cortex (ACC) and putamen. Patients with BD showed amygdala hyperactivation during explicit processing (hostility ratings) of fearful faces and passive viewing of angry and neutral faces but IFG hypoactivation during implicit processing of neutral and happy faces. In the ACC and striatum, the direction of dysfunction varied by task demand: BD demonstrated hyperactivation during unconstrained processing of angry or neutral faces but hypoactivation during constrained processing (implicit or explicit) of angry, neutral or happy faces.

CONCLUSIONS

Findings suggest amygdala hyperactivation in BD while processing negatively valenced and neutral faces, regardless of attentional condition, and BD IFG hypoactivation during implicit processing. In the cognitive control circuit involving the ACC and putamen, BD neural dysfunction was sensitive to task demands.