Magnetic resonance imaging studies in early-onset bipolar disorder: a critical review

Aberrant Hippocampal Development in Early-onset Mental Disorders and Promising Interventions: Evidence from a Translational Study

Early-onset mental disorders are associated with disrupted neurodevelopmental processes during adolescence. The methylazoxymethanol acetate (MAM) animal model, in which disruption in neurodevelopmental processes is induced, mimics the abnormal neurodevelopment associated with early-onset mental disorders from an etiological perspective. We conducted longitudinal structural magnetic resonance imaging (MRI) scans during childhood, adolescence, and adulthood in MAM rats to identify specific brain regions and critical windows for intervention. Then, the effect of repetitive transcranial magnetic stimulation (rTMS) intervention on the target brain region during the critical window was investigated. In addition, the efficacy of this intervention paradigm was tested in a group of adolescent patients with early-onset mental disorders (diagnosed with major depressive disorder or bipolar disorder) to evaluate its clinical translational potential. The results demonstrated that, compared to the control group, the MAM rats exhibited significantly lower striatal volume from childhood to adulthood (all P <0.001). In contrast, the volume of the hippocampus did not show significant differences during childhood (P >0.05) but was significantly lower than the control group from adolescence to adulthood (both P <0.001). Subsequently, rTMS was applied to the occipital cortex, which is anatomically connected to the hippocampus, in the MAM models during adolescence. The MAM-rTMS group showed a significant increase in hippocampal volume compared to the MAM-sham group (P <0.01), while the volume of the striatum remained unchanged (P >0.05). In the clinical trial, adolescents with early-onset mental disorders showed a significant increase in hippocampal volume after rTMS treatment compared to baseline (P <0.01), and these volumetric changes were associated with improvement in depressive symptoms (r = - 0.524, P = 0.018). These findings highlight the potential of targeting aberrant hippocampal development during adolescence as a viable intervention for early-onset mental disorders with neurodevelopmental etiology as well as the promise of rTMS as a therapeutic approach for mitigating aberrant neurodevelopmental processes and alleviating clinical symptoms.

Neural markers of mania that distinguish inpatient adolescents with bipolar disorder from those with other psychopathology

Pediatric bipolar disorder (BD) is difficult to distinguish from other psychiatric disorders, a challenge which can result in delayed or incorrect interventions. Using neuroimaging we aimed to identify neural measures differentiating a rarified sample of inpatient adolescents with BD from other inpatient psychopathology (OP) and healthy adolescents (HC) during a reward task. We hypothesized reduced subcortical and elevated cortical activation in BD relative to other groups, and that these markers will be related to self-reported mania scores. We examined inpatient adolescents with diagnosis of BD-I/II (n = 29), OP (n = 43), and HC (n = 20) from the Inpatient Child and Adolescent Bipolar Spectrum Imaging study. Inpatient adolescents with BD showed reduced activity in right thalamus, left thalamus, and left amygdala, relative to inpatient adolescents with OP and HC. This reduced neural function explained 21% of the variance in past month and 23% of the variance in lifetime mania scores. Lower activity in regions associated with the reward network, during reward processing, differentiates BD from OP in inpatient adolescents and explains >20% of the variance in mania scores. These findings highlight potential targets to aid earlier identification of, and guide new treatment developments for, pediatric BD.

Association of polygenic risk for bipolar disorder with grey matter structure and white matter integrity in youth

There is a gap in knowledge regarding the polygenic underpinnings of brain anomalies observed in youth bipolar disorder (BD). This study examined the association of a polygenic risk score for BD (BD-PRS) with grey matter structure and white matter integrity in youth with and without BD. 113 participants were included in the analyses, including 78 participants with both T1-weighted and diffusion-weighted MRI images, 32 participants with T1-weighted images only, and 3 participants with diffusion-weighted images only. BD-PRS was calculated using PRS-CS-auto and was based on independent adult genome-wide summary statistics. Vertex- and voxel-wise analyses examined the associations of BD-PRS with grey matter metrics (cortical volume [CV], cortical surface area [CSA], cortical thickness [CTh]) and fractional anisotropy [FA] in the combined sample, and separately in BD and HC. In the combined sample of participants with T1-weighted images (n = 110, 66 BD, 44 HC), higher BD-PRS was associated with smaller grey matter metrics in frontal and temporal regions. In within-group analyses, higher BD-PRS was associated with lower CTh of frontal, temporal, and fusiform gyrus in BD, and with lower CV and CSA of superior frontal gyrus in HC. In the combined sample of participants with diffusion-weighted images (n = 81, 49 BD, 32 HC), higher BD-PRS was associated with lower FA in widespread white matter regions. In summary, BD-PRS calculated based on adult genetic data was negatively associated with grey matter structure and FA in youth in regions implicated in BD, which may suggest neuroimaging markers of vulnerability to BD. Future longitudinal studies are needed to examine whether BD-PRS predicts neurodevelopmental changes in BD vs. HC and its interaction with course of illness and long-term medication use.

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

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

Neural Correlates of Positive Emotion Processing That Distinguish Healthy Youths at Familial Risk for Bipolar Versus Major Depressive Disorder

OBJECTIVE

Familial risk for bipolar disorder (BD) or major depressive disorder (MDD) may lead to differential emotion processing signatures, resulting in unique neural vulnerability.

METHOD

Healthy offspring of a parent with BD (n = 29, "BD-risk") or MDD (n = 44, "MDD-risk") and healthy control youths without any personal or family psychopathology (n = 28, "HC") aged 8 to 17 years (13.64 ± 2.59 years) completed an implicit emotion-perception functional magnetic resonance imaging task. Whole-brain voxelwise and psychophysiological interaction analyses examined neural differences in activation and connectivity during emotion processing. Regression modeling tested for neural associations with behavioral strengths and difficulties and conversion to psychopathology at follow-up (3.71 ± 1.91 years).

RESULTS

BD-risk youth showed significantly reduced bilateral putamen activation, and decreased connectivity between the left putamen and the left ventral anterior cingulate cortex (vACC) and the right posterior cingulate cortex (PCC) during positive-valence emotion processing compared to MDD-risk and HC (Z >2.3; p <.001). Decreased left putamen-right PCC connectivity correlated with subsequent peer problems in BD-risk (β = -2.90; p <.05) and MDD-risk (β = -3.64; p < .05) groups. Decreased left (β = -0.09; p < .05) and right putamen activation (β = -0.07; p = .04) were associated with conversion to a mood or anxiety disorder in BD-risk youths. Decreased left putamen-right PCC connectivity was associated with a higher risk of conversion in BD-risk (HR = 8.28 , p < .01) and MDD-risk (HR = 2.31, p = .02) groups.

CONCLUSION

Reduced putamen activation and connectivity during positive emotion processing appear to distinguish BD-risk youths from MDD-risk and HC youths, and may represent a marker of vulnerability.

Gray matter voxel-based morphometry in mania and remission states of children with bipolar disorder

BACKGROUND

It has been found by many studies that gray matter (GM) abnormalities exist in both adults and children with bipolar disorder (PBD) which is a serious mental illness characterized by alternating episodes of mania and depression. However, there are few studies on the comparison between brain imaging of different mood states shown by patients with bipolar disorder. This study is aimed at exploring the differences existing in brain structures between children with bipolar disorder and that of healthy controls, and then it tries to further explore whether there is a structural difference between the states of mania and remission in children with bipolar disorder.

METHODS

21 PBD-mania subjects, 19 PBD-remission subjects and 18 control subjects aged 12-17 years old were engaged in this study. In the present study, magnetic resonance imaging was obtained by employing a Siemens 3.0 T scanner. With regard to the volumes of gray matter in the mania group, remission group and healthy control group, analysis was carried out by using voxel-based morphometry (VBM). Further analysis was conducted on the correlation between MRI data and clinical features of patients with PBD.

RESULTS

In comparison with the healthy control subjects, the gray matter volume measured from the left hippocampus, parahippocampal gyrus and amygdala in both manic and euthymic groups showed a decreasing trend, while the volume of left orbitofrontal cortex increased. However, no significant difference in volumes was found between BD manic and euthymic groups. It was observed that the volume of orbitofrontal cortex had a positive correlation with onset age in PBD euthymic group.

CONCLUSIONS

Our study came to the conclusion that extensive brain structural changes are available in patients with PBD. The brain regions with structural changes are distributed in the anterior limbic network (ALN), which has been proved to have been involved in the abnormal emotional and cognitive regulation of PBD. However, there is no difference in the volumes of gray matter between mania and remission in PBD .

Odor-related brain hyper-reactivity in euthymic bipolar disorder: An fMRI and ERP study

Previous studies on olfactory function in patients with bipolar disorder (BD) are limited and contradictory. The current study aimed to comprehensively analyze the olfactory function of patients with euthymic BD using psychophysical, electrophysiological and neuroimaging techniques. Twenty-one patients with BD in remission and 20 healthy controls were tested with the "Sniffin' Sticks" olfactory test. Block-design fMRI data to a pleasant and an unpleasant stimulus were acquired while recording intensity and hedonic ratings. Olfactory event-related potentials (OERP) to the same stimuli were additionally recorded. Results show no differences between patients and healthy controls in terms of self-rated olfactory function and tested olfactory domains (odor threshold, discrimination or identification) (p>0.05). Compared to healthy controls, patients showed an increased fMRI activation in multiple cortical and subcortical regions as a response to olfactory stimulation, as well as larger amplitudes of OERPs regardless of the hedonic valence of the odor. All in all, patients with euthymic BD showed a stronger central responsiveness to odorous stimuli in fMRI and OERPs despite of normal psychophysical results, indicating the probable existence of an odor-related over-reactive brain network in the remission phase of BD.

Relationship of executive functioning deficits to N-acetyl aspartate (NAA) and gamma-aminobutyric acid (GABA) in youth with bipolar disorder

BACKGROUND

Although cognitive deficits in bipolar disorder (BD) have been repeatedly observed, our understanding of these impairments at a mechanistic level remains limited. Few studies that investigated cognitive impairments in bipolar illness have examined the association with brain biochemistry. This pilot study utilized proton magnetic resonance spectroscopy (¹H-MRS) to evaluate the relationship between neurocognitive performance and brain metabolites in youth with BD.

METHODS

Thirty participants, twenty depressed BD participants and ten healthy comparison participants, ages 13-21, completed mood and executive function measures. ¹H-MRS data were also acquired from the anterior cingulate cortex (ACC) using two-dimensional (2D) J-resolved ¹H-MRS sequence. Proton metabolites including N-acetyl aspartate (NAA) and gamma-aminobutyric acid (GABA) were quantified for both groups.

RESULTS

Participants with BD performed significantly lower on executive functioning measures than comparison participants. There were significant positive correlations between Wisconsin Card Sorting Test (WCST) performance and NAA (p < .001) and GABA (p < .01) in the ACC in bipolar youth, such that as WCST performance increased, both NAA and GABA levels increased.

LIMITATIONS

Small sample size and lack of control for medications.

CONCLUSIONS

These findings build on previous observations of biochemical alterations associated with BD and indicate that executive functioning deficits in bipolar youth are correlated with NAA and GABA. These results suggest that cognitive deficits occur early in the course of illness and may reflect risk factors associated with altered neurochemistry. Further investigation of the relationship between brain metabolites and cognition in BD may lead to important information for developing novel, targeted interventions.

Paediatric population neuroimaging and the Generation R Study: the second wave

Paediatric population neuroimaging is an emerging field that falls at the intersection between developmental neuroscience and epidemiology. A key feature of population neuroimaging studies involves large-scale recruitment that is representative of the general population. One successful approach for population neuroimaging is to embed neuroimaging studies within large epidemiological cohorts. The Generation R Study is a large, prospective population-based birth-cohort in which nearly 10,000 pregnant mothers were recruited between 2002 and 2006 with repeated measurements in the children and their parents over time. Magnetic resonance imaging was included in 2009 with the scanning of 1070 6-to-9-year-old children. The second neuroimaging wave was initiated in April 2013 with a total of 4245 visiting the MRI suite and 4087 9-to-11-year-old children being scanned. The sequences included high-resolution structural MRI, 35-direction diffusion weighted imaging, and a 6 min and 2 s resting-state functional MRI scan. The goal of this paper is to provide an overview of the imaging protocol and the overlap between the neuroimaging data and metadata. We conclude by providing a brief overview of results from our first wave of neuroimaging, which highlights a diverse array of questions that can be addressed by merging the fields of developmental neuroscience and epidemiology.

Quantitative analysis of the amygdala, thalamus and hippocampus on magnetic resonance images in paediatric bipolar disorders and compared with the children of bipolar parents and healthy control

MR imaging studies in paediatric bipolar disorder have particularly focused on the amygdala and hippocampus, subcortical structures, and to a lesser extent on the thalamus. The purpose of this study was to perform structural analysis of the regions of interest (ROI) associated with mood regulation. In this study 18 children (between the ages of 12-18) were matched according to their age and sex and were divided into three groups. These were: a paediatric bipolar disorder group, risk group and a healthy control group. The structured diagnostic interviews were performed with children and their parents. T1 weighted MR images in the sagittal plane with a thickness of 1mm were taken from the subjects. Automatic structural brain analysis was performed, and the volume and volume fraction (VF) of the ROIs were obtained. Brain size in the patients with paediatric bipolar disorder (742.4 ± 110.1cm³) was significantly smaller than the healthy control group (880.7 ± 73.8cm³) (p≤0.05). MRI analysis between the paediatric bipolar disorder, risk group and healthy control group revealed no difference between them in terms of amygdala, thalamus or hippocampal volumes. In this study, there was no difference between the volumes of amygdala, thalamus or hippocampus.

Decreased right hippocampal volumes and neuroprogression markers in adolescents with bipolar disorder

OBJECTIVES

The aim of the present study was to assess differences and correlations between the hippocampal volumes (HCVs), serum nerve growth factor (NGF), and brain-derived neurotrophic factor (BDNF) levels in adolescents with bipolar disorder (BP) compared to healthy controls.

METHODS

Using structural magnetic resonance imaging, we compared HCVs of 30 patients with euthymic BP who were already enrolled in a naturalistic clinical follow-up. For comparison, we enrolled 23 healthy controls between the ages of 13 and 19. The boundaries of the hippocampus were outlined manually. The BDNF and NGF serum levels were measured with the sandwich ELISA.

RESULTS

The groups did not differ in the right or left HCVs or in the NGF or BDNF serum levels. However, negative correlations were found between the right HCVs and the duration of the disorder and medication and positive correlations were found between the duration of the medications and the NGF and BDNF levels in the patient group. Additionally, positive correlations were found between the follow-up period and left normalized HCVs in both the BP and lithium-treated groups.

CONCLUSIONS

The right HCVs may vary with illness duration and the medication used to treat BP; NGF and BDNF levels may be affected by long-term usage. Further research is needed to determine whether these variables and their structural correlates are associated with clinical or functional differences between adolescents with BP and healthy controls.

Hippocampal structure and function in individuals with bipolar disorder: a systematic review

INTRODUCTION

Bipolar disorder (BD) is a psychiatric disorder accompanied by deficits in declarative memory. Given the importance of the hippocampus in declarative memory, it is not surprising that BD patients have been reported to show hippocampal abnormalities.

OBJECTIVES

Review evidence about structural and functional hippocampal abnormalities in BD.

METHODS

Systematic review of studies comparing BD patients and healthy controls with respect to hippocampal structure or function.

RESULTS

Twenty-five studies were included, together involving 1043 patients, 21 of which compared patients to controls. Decrease in hippocampal volume was found in four of 18 studies using adult samples, and two of three samples using adolescents. Four studies revealed localized hippocampal deficits. Meta-analysis revealed a significant but small effect with lower hippocampal volumes when comparing all BD patients with controls. Lithium treatment was associated with larger hippocampal volumes across studies. The three functional studies yielded contradictory evidence.

LIMITATIONS

Studies were only cross-sectional in nature and all used MRI or fMRI to investigate hippocampal volume or function. Heterogeneous patients groups and different methodologies for hippocampal segmentation, may have contributed to difficulties when comparing the different studies.

CONCLUSIONS

There seems to be a small reduction in hippocampal volume in BD, which perhaps is more pronounced in early-onset BD and is counteracted by a neuroprotective effect of lithium treatment. However, how these structural abnormalities relate to functional deficits is largely unclear. Given the few functional neuroimaging studies and given the lack of congruence in these results, further investigation of especially hippocampal function in BD is recommended.

Changes in brain activation following psychotherapy for youth with mood dysregulation at familial risk for bipolar disorder

BACKGROUND

Psychotherapy for youth with mood dysregulation can help stabilize mood and improve functioning, but the neural mechanisms of this improvement are not known. In this study we investigated the changes in brain activation underlying improvement in mood symptoms.

METHODS

Twenty-four subjects (ages 13-17) participated: 12 patients with clinically significant symptoms of depression and/or mania, and 12 healthy comparison subjects (HC) matched for age and sex. All subjects completed functional magnetic resonance imaging while viewing facial expressions. The patients then received up to 4 months of psychotherapy and were rescanned at end of treatment. Whole brain differences between patient and control groups were assessed with a voxel-wise analysis. Changes in activation from pre- to post-treatment within the patient group were tested for correlation with changes in mood symptoms.

RESULTS

At baseline the patient group had hypoactivation in the dorsolateral prefrontal cortex (DLPFC) and hyperactivation in the posterior cingulate cortex compared to the HC group. Between pre- and post-treatment activation increased in the DLPFC and decreased in the amygdala. Increases in DLPFC activation were significantly correlated with improvement in mania symptoms.

DISCUSSION

Enhancement of frontal executive control brain regions may underlie improvement in mood dysregulation in pediatric patients at familial risk for bipolar disorder.

Brain changes in early-onset bipolar and unipolar depressive disorders: a systematic review in children and adolescents

Pediatric bipolar disorder (BD) and unipolar disorder (UD) share common symptomatic and functional impairments. Various brain imaging techniques have been used to investigate the integrity of brain white matter (WM) and gray matter (GM) in these disorders. Despite promising preliminary findings, it is still unclear whether these alterations may be considered as common trait markers or may be used to distinguish BD from UD. A systematic literature search of studies between 1980 and September 2013 which reported WM/GM changes in pediatric and adolescent BD/UD, as detected by diffusion tensor imaging and voxel-based analysis was conducted. Of the 34 articles judged as eligible, 17 fulfilled our inclusion criteria and were finally retained in this review. More abnormalities have been documented in the brains of children and adolescents with BD than UD. Reductions in the volume of basal ganglia and the hippocampus appeared more specific for pediatric UD, whereas reduced corpus callosum volume and increased rates of deep WM hyperintensities were more specific for pediatric BD. Seminal papers failed to address the possibility that the differences between unipolar and bipolar samples might be related to illness severity, medication status, comorbidity or diagnosis. UD and BD present both shared and distinctive impairments in the WM and GM compartments. More WM abnormalities have been reported in children and adolescents with bipolar disease than in those with unipolar disease, maybe as a result of a low number of DTI studies in pediatric UD. Future longitudinal studies should investigate whether neurodevelopmental changes are diagnosis-specific.

Neurocognitive impairments among youth with pediatric bipolar disorder: a systematic review of neuropsychological research

BACKGROUND

Pediatric bipolar disorder (PBD) has emerged as a field of research in which neuropsychological studies are continuously providing new empirical findings. Despite this, a comprehensive framework for neurocognitive impairments is still lacking, and most of the evidence remains unconnected. We addressed this question through a systematic review of neuropsychological research, with the aim of elucidating the main issues concerning this topic.

METHOD

A comprehensive search of databases (PubMed, PsycINFO) was performed. Published manuscripts between 1990 and January 2014 were identified. Overall, 124 studies fulfilled inclusion criteria. Methodological differences between studies required a descriptive review of findings.

RESULTS

Evidence indicates that verbal/visual-spatial memory, processing speed, working memory, and social cognition are neurocognitive domains impaired in PBD youth. Furthermore, these deficits are greater among those who suffer acute affective symptoms, PBD type I, and/or attention deficit hyperactivity disorder (ADHD) comorbidity. In addition, several neurocognitive deficits imply certain changes in prefrontal cortex activity and are somewhat associated with psychosocial and academic disabilities. Strikingly, these deficits are consistently similar to those encountered in ADHD as well as severe mood dysregulation (SMD). Besides, some neurocognitive impairments appear before the onset of the illness and tend to maintain stable across adolescence. Finally, any therapy has not yet demonstrated to be effective on diminishing these neurocognitive impairments.

LIMITATIONS

More prolonged follow-up studies aimed at delineating the course of treatment and the response to it are warranted.

CONCLUSIONS

Despite noteworthy research on the neurocognitive profile of PBD, our knowledge is still lagging behind evidence from adult counterparts.

G protein-linked signaling pathways in bipolar and major depressive disorders

The G-protein linked signaling system (GPLS) comprises a large number of G-proteins, G protein-coupled receptors (GPCRs), GPCR ligands, and downstream effector molecules. G-proteins interact with both GPCRs and downstream effectors such as cyclic adenosine monophosphate (cAMP), phosphatidylinositols, and ion channels. The GPLS is implicated in the pathophysiology and pharmacology of both major depressive disorder (MDD) and bipolar disorder (BPD). This study evaluated whether GPLS is altered at the transcript level. The gene expression in the dorsolateral prefrontal (DLPFC) and anterior cingulate (ACC) were compared from MDD, BPD, and control subjects using Affymetrix Gene Chips and real time quantitative PCR. High quality brain tissue was used in the study to control for confounding effects of agonal events, tissue pH, RNA integrity, gender, and age. GPLS signaling transcripts were altered especially in the ACC of BPD and MDD subjects. Transcript levels of molecules which repress cAMP activity were increased in BPD and decreased in MDD. Two orphan GPCRs, GPRC5B and GPR37, showed significantly decreased expression levels in MDD, and significantly increased expression levels in BPD. Our results suggest opposite changes in BPD and MDD in the GPLS, “activated” cAMP signaling activity in BPD and “blunted” cAMP signaling activity in MDD. GPRC5B and GPR37 both appear to have behavioral effects, and are also candidate genes for neurodegenerative disorders. In the context of the opposite changes observed in BPD and MDD, these GPCRs warrant further study of their brain effects.

Combined analyses of gray matter voxel-based morphometry and white matter tract-based spatial statistics in pediatric bipolar mania

BACKGROUND

Ample evidence has suggested the presence of gray matter (GM) and white matter (WM) abnormalities in bipolar disorder (BD) patients, including pediatric bipolar disorder (PBD). However, little research has been done in PBD patients that carefully classify the mood states. The aim of the present study is to investigate the brain structural changes in PBD-mania children and adolescents.

METHODS

Eighteen children and adolescents with bipolar mania (male/female, 6/12) aged 10-18 years old and 18 age- and sex-matched healthy controls were included in the present study. The 3D T1-weighted magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) data were obtained on a Siemens 3.0 T scanner. Voxel-based morphometry (VBM) analysis and tract-based spatial statistics (TBSS) analysis were conducted to compare the gray matter volume and white matter fractional anisotropy (FA) value between patients and controls. Correlations of the MRI data of each survived area with clinical characteristics in PBD patients were further analyzed.

RESULTS

As compared with the control group, PBD-mania children showed decreased gray matter volume in the left hippocampus. Meanwhile, significant lower FA value was detected in the right anterior cingulate (AC) in the patient group. No region of increased gray matter volume or FA value was observed in PBD-mania. The hippocampal volume was negatively associated with the Young Mania Rating Scale (YMRS) score when controlling for clinical characteristics in PBD-mania patients, however, there was no significant correlation of FA value of the survived area with illness duration, the onset age, number of episodes, or the YMRS score in PBD-mania patients.

LIMITATION

The present outcomes require replication in larger samples and verification in medication free subjects.

CONCLUSIONS

Our findings highlighted that extensive brain structural lesions (including GM and WM) were existed in PBD-mania. The widespread occurrence of structural abnormalities mainly located in the anterior limbic network (ALN) which suggested that this network might contribute to emotional and cognitive dysregulations in PBD.

Nutrient-based therapies for bipolar disorder: a systematic review

BACKGROUND

Pharmacotherapy is the first line of treatment for bipolar disorder, but many patients continue to experience persistent subthreshold symptoms. Alternative adjunct treatments, including nutritional therapies, may have the potential to alleviate residual symptoms and improve the outcomes of standard pharmacotherapy. The aim of this paper is to critically review the current clinical evidence and mechanisms of action of nutrient-based therapies alone or in combination with commonly used pharmacotherapies for mania and bipolar depression.

METHODS

We conducted a Medline search for clinical trials conducted with humans, published in English from 1960 to 2012 using nutritional supplements such as n-3, chromium, inositol, choline, magnesium, folate and tryptophan alone or in combination with pharmacotherapies for the treatment of bipolar disorder.

RESULTS

Preliminary data yields conflicting but mainly positive evidence for the use of n-3 fatty acids and chromium in the treatment of bipolar depression. Limited evidence found that inositol may be helpful for bipolar depression, but larger sample sizes are needed. Preliminary randomized, controlled trials suggest that choline, magnesium, folate and tryptophan may be beneficial for reducing symptoms of mania.

CONCLUSIONS

Given the potential public health impact of identifying adjunct treatments that improve psychiatric as well as physical health outcomes, nutritional treatments appear promising for the management of bipolar disorder but require further study.

Organic bases of late-life depression: a critical update

Late-life depression (LLD) is frequently associated with cognitive impairment and increases the risk of subsequent dementia. Cerebrovascular disease, deep white matter lesions, Alzheimer disease (AD) and dementia with Lewy bodies (DLB) have all been hypothesized to contribute to this increased risk, and a host of studies have looked at the interplay between cerebrovascular disease and LLD. This has resulted in new concepts of LLD, such as "vascular depression", but despite multiple magnetic resonance imaging (MRI) studies in this field, the relationship between structural changes in human brain and LLD is still controversial. While pathological findings of suicide in some elderly persons revealed multiple lacunes, small vessel cerebrovascular disease, AD-related lesions or multiple neurodegenerative pathologies, recent autopsy data challenged the role of subcortical lacunes and white matter lesions as major morphological substrates of depressive symptoms as well as poorer executive function and memory. Several neuropathological studies, including a personal clinico-pathological study in a small cohort of elderly persons with LLD and age-matched controls confirmed that lacunes, periventricular and deep white matter demyelination as well as AD-related lesions are usually unrelated to the occurrence of LLD. In the same line, neuropathological data show that early-onset depression is not associated with an acceleration of age-related neurodegenerative changes. Very recent data on the critical role of glia-modulating neuronal dysfunction and degeneration in depression are discussed.

Reduced functional connectivity of prefrontal regions and amygdala within affect and working memory networks in pediatric bipolar disorder

This study examined whether adolescents with pediatric bipolar disorder (PBD) have abnormal regional functional connectivity in distributed brain networks during an affective working memory task. Adolescents with PBD (n=41) and healthy controls (HC; n=16) performed a two-back functional magnetic resonance imaging working memory task with blocks of either angry or neutral faces. Independent component analysis methodology identified two temporally independent and functionally connected brain networks that showed differential functional connectivity in PBD and HC. Within a network for "affect evaluation and regulation," PBD showed decreased functional connectivity relative to HC in regions involved in emotion processing such as the right amygdala, and in emotion regulation regions such as the right ventrolateral prefrontal cortex (VLPFC), while functional connectivity was increased in emotion evaluation regions such as the bilateral medial PFC. Furthermore, in an "Affective Working Memory Network," PBD exhibited greater connectivity relative to HC in left dorsolateral PFC (DLPFC), caudate, and right VLPFC; and simultaneously reduced connectivity in emotion processing regions, such as the right amygdala, bilateral temporal regions, and the junction of DLPFC/VLPFC, which interfaces affective and cognitive processes. Dysfunction in network engagement in PBD patients illustrates that they are expending greater effort in face emotion evaluation, while being less able to engage affect regulation regions.

Neurobiological correlates of illness progression in the recurrent affective disorders

Some clinical aspects of affective illness progression, such as episode-, stress-, and substance-induced sensitization, have been well documented in the literature, but others have received less attention. These include cognitive deficits, treatment-refractoriness, and neurobiological correlates of illness progression, which are the primary focus of this paper. We review the evidence that cognitive dysfunction, treatment resistance, medical comorbidities, and neurobiological abnormalities increase as a function of the number of prior episodes or duration of illness in the recurrent unipolar and bipolar disorders. Substantial evidence supports the view that cognitive dysfunction and vulnerability to a diagnosis of dementia in old age increases as a function of number of prior mood episodes as does non-response to many therapeutic interventions as well as naturalistic treatment. Neurobiological abnormalities that correlate with the number of mood episodes or duration of illness include: anatomical, functional, and biochemical deficits in the prefrontal cortex and hippocampus, as well as amygdala hyperactivity and cortisol hyper-secretion. Some neurotrophic factors and inflammatory markers may also change with greater illness burden. Causality cannot be inferred from these correlative relationships. Nonetheless, given the potentially grave consequences of episode recurrence and progression for morbidity and treatment non-responsiveness, it is clinically wise to assume episodes are causing some of the progressive cognitive and neurobiological abnormalities. As such, earlier and more sustained long-term prophylaxis to attempt to reduce these adverse outcomes is indicated.

Amygdalar, hippocampal, and thalamic volumes in youth at high risk for development of bipolar disorder

Children of parents with bipolar disorder (BD), especially those with attention deficit hyperactivity disorder (ADHD) and symptoms of depression or mania, are at significantly high risk for developing BD. As we have previously shown amygdalar reductions in pediatric BD, the current study examined amygdalar volumes in offspring of parents (BD offspring) who have not yet developed a full manic episode. Youth participating in the study included 22 BD offspring and 22 healthy controls of comparable age, gender, handedness, and IQ. Subjects had no history of a manic episode, but met criteria for ADHD and moderate mood symptoms. MRI was performed on a 3T GE scanner, using a 3D volumetric spoiled gradient echo series. Amygdalae were manually traced using BrainImage Java software on positionally normalized brain stacks. Bipolar offspring had similar amygdalar volumes compared to the control group. Exploratory analyses yielded no differences in hippocampal or thalamic volumes. Bipolar offspring do not show decreased amygdalar volume, possibly because these abnormalities occur after more prolonged illness rather than as a preexisting risk factor. Longitudinal studies are needed to determine whether amygdalar volumes change during and after the development of BD.

Longitudinal analysis of cognitive performances and structural brain changes in late-life bipolar disorder

OBJECTIVES

Cross-sectional studies in bipolar disorder (BD) suggested the presence of cognitive deficits and subtle magnetic resonance imaging (MRI) changes in limbic areas that may persist at euthymic stages. Whether or not cognitive and MRI changes represent stable attributes of BD or evolve with time is still matter of debate. To address this issue, we performed a 2-year longitudinal study including detailed neuropsychological and magnetic resonance imaging (MRI) analyses of 15 euthymic older BD patients and 15 controls.

METHODS

Neuropsychological evaluation concerned working memory, episodic memory, processing speed, and executive functions. MRI analyses included voxel-based morphometry (VBM) analysis of gray matter including region of interest (ROI) analysis and tract-based spatial statistics (TBSS) analysis of white matter of diffusion tensor imaging derived fractional anisotropy (FA).

RESULTS

BD patients displayed significantly lower performances in processing speed and episodic memory but not in working memory and executive functions compared to controls. However, BD patients did not differ from controls in the mean trajectory of cognitive changes during the 2 years follow-up. In the same line, longitudinal gray matter (VBM, ROI) and white matter (TBSS FA) changes did not differ between BD patients and controls.

CONCLUSION

The lack of distinction between BD patients and controls in respect to the 2-year changes in cognition and MRI findings supports the notion that this disorder does not have a significant adverse impact on cognitive and brain aging. From this point of view, the present results convey a message of hope for patients suffering from BD.

Combined analysis of grey matter voxel-based morphometry and white matter tract-based spatial statistics in late-life bipolar disorder

BACKGROUND

Previous magnetic resonance imaging (MRI) studies in young patients with bipolar disorder indicated the presence of grey matter concentration changes as well as microstructural alterations in white matter in various neocortical areas and the corpus callosum. Whether these structural changes are also present in elderly patients with bipolar disorder with long-lasting clinical evolution remains unclear.

METHODS

We performed a prospective MRI study of consecutive elderly, euthymic patients with bipolar disorder and healthy, elderly controls. We conducted a voxel-based morphometry (VBM) analysis and a tract-based spatial statistics (TBSS) analysis to assess fractional anisotropy and longitudinal, radial and mean diffusivity derived by diffusion tensor imaging (DTI).

RESULTS

We included 19 patients with bipolar disorder and 47 controls in our study. Fractional anisotropy was the most sensitive DTI marker and decreased significantly in the ventral part of the corpus callosum in patients with bipolar disorder. Longitudinal, radial and mean diffusivity showed no significant between-group differences. Grey matter concentration was reduced in patients with bipolar disorder in the right anterior insula, head of the caudate nucleus, nucleus accumbens, ventral putamen and frontal orbital cortex. Conversely, there was no grey matter concentration or fractional anisotropy increase in any brain region in patients with bipolar disorder compared with controls.

LIMITATIONS

The major limitation of our study is the small number of patients with bipolar disorder.

CONCLUSION

Our data document the concomitant presence of grey matter concentration decreases in the anterior limbic areas and the reduced fibre tract coherence in the corpus callosum of elderly patients with long-lasting bipolar disorder.

Pharmacotherapy impacts functional connectivity among affective circuits during response inhibition in pediatric mania

OBJECTIVE

The aim of the current study was to determine the influence of implicated affective circuitry disturbance in pediatric bipolar disorder (PBD) on behavioral inhibition. The differential influence of an antipsychotic and an anti-epileptic medication on the functional connectivity across affective and cognitive neural operations in PBD was examined.

METHODS

This was a six-week double blind randomized fMRI trial of risperidone plus placebo vs. divalproex plus placebo for patients with mania (n=22; 13.6 ± 2.5 years). Healthy controls (HC; n=14, 14.5 ± 2.8 years) were also scanned for normative comparison. Participants performed a response inhibition fMRI task where a motor response, already 'on the way' to execution, had to be voluntarily inhibited on trials where a stop signal was presented. Independent component analysis was used to map functional connectivity across the whole brain.

RESULTS

While there were no behavioral differences between the groups at pre- or post-drug trial, there was significant improvement on manic symptoms in the patient groups. All participants engaged an evaluative affective circuit (EAC: bilateral inferior frontal gyrus, middle frontal gyrus, anterior cingulate cortex (ACC), middle temporal gyrus, insulae, caudate and putamen) and a reactive affective circuit (RAC: bilateral occipital cortex, amygdala, medial frontal gyrus and insula) during task performance. Within the EAC, post-treatment and relative to HC, greater engagement was seen in left insula in risperidone group and left subgenual ACC in divalproex group. Within the RAC, greater baseline amygdala connectivity in patients did not alter with treatment.

CONCLUSION

EAC and RAC are two key circuits that moderate emotional influence on response inhibition in PBD. Risperidone and divalproex differentially engage the EAC. Limited change in amygdala activity with treatment in all patients indicates a likely trait deficit in PBD.

Toward a functional neuroanatomical signature of bipolar disorder: quantitative evidence from the neuroimaging literature

The present meta-analysis quantitatively reviewed the functional neuroimaging literature on bipolar disorder (BPD) to better characterize its neuroanatomical signature with respect to the influence of mood state, test conditions, and clinical demographics on regional brain activation. Fifty-five functional neuroimaging studies published between 1987 and 2010 met criteria for inclusion, encompassing a total of 774 adult patients with BPD and 810 healthy adult controls. A meta-analysis was conducted comparing the activation states of multiple brain regions in BPD patients and control subjects. Despite heterogeneity across studies, our findings support the view that limbic hyperactivity and frontal hypoactivity are neurobiological correlates of BPD. Our findings also highlight the involvement of many brain regions and circuits, as well as the critical role of mood state and test conditions in the functional impairments of BPD. This review represents the first attempt to quantitatively articulate the magnitude of functional brain abnormality in BPD, and, in so doing, provides a synthesis of evidence in line with current network models of the disorder. Overall, this review offers support for, and seeks to help guide, the continued use of functional neuroimaging as an informative probe into the complex neurobiology of BPD.

Structural brain and neuropsychometric changes associated with pediatric bipolar disorder with psychosis

OBJECTIVES

To identify neuropsychological and structural brain changes using a combination of high-resolution structural and diffusion tensor imaging in pediatric bipolar disorder (PBD) with psychosis (presence of delusions and or hallucinations).

METHODS

We recruited 15 patients and 20 euthymic age- and gender-matched healthy controls. All subjects underwent high-resolution structural and diffusion tensor imaging. Voxel-based morphometry (VBM), tract-based spatial statistics (TBSS), and probabilistic tractography were used to analyse magnetic resonance imaging data.

RESULTS

The PBD subjects had normal overall intelligence with specific impairments in working memory, executive function, language function, and verbal memory. Reduced gray matter (GM) density was found in the left orbitofrontal cortex, left pars triangularis, right premotor cortex, occipital cortex, right occipital fusiform gyrus, and right crus of the cerebellum. TBSS analysis showed reduced fractional anisotropy (FA) in the anterior corpus callosum. Probabilistic tractography from this cluster showed that this region of the corpus callosum is connected with the prefrontal cortices, including those regions whose density is decreased in PBD. In addition, FA change was correlated with verbal memory and working memory, while more widespread reductions in GM density correlated with working memory, executive function, language function, and verbal memory.

CONCLUSIONS

The findings suggest widespread cortical changes as well as specific involvement of interhemispheric prefrontal tracts in PBD, which may reflect delayed myelination in these tracts.

Effects of early intervention on the course of bipolar disorder: theories and realities

Given the severity and early onset of pediatric bipolar disorder, early intervention is important to bring about recovery and alter the course of the illness. There is a new and burgeoning body of literature on the biological basis of early signs of the illness and the mechanistic understanding of treatment interventions. Biological findings based on multimodal imaging, genomic studies of cellular proteins, and performance-based findings of neurocognitive studies are beginning to assemble a cohesive and interlinked model of systems neuroscience. This offers the promise of identifying biomarkers, predictors of illness, and treatment outcomes. In complement, at the tier of clinical application is a multitude of efficacy trials, yet neither a single medication nor a combination of choices seems to suffice in reality. The current review develops a point of view bridging scientific developments to where comprehensive, multipronged treatment strategies find their clinical application-a model that is similarly applicable in adult bipolar disorder.

Combined diffusion tensor imaging and transverse relaxometry in early-onset bipolar disorder

OBJECTIVE

Transverse relaxation time (T2) imaging provides the opportunity to examine membrane fluidity, which can affect a number of cellular functions. The objective of the present work was to examine T2 abnormalities in children with unmodified DSM-IV-TR bipolar disorder (BD) in bilateral cingulate-paracingulate (CPC) white matter.

METHOD

A total of 21 children and adolescents with BD and 16 healthy control subjects underwent magnetic resonance imaging at 1.5 Tesla and were compared using a region-of-interest analysis. A post hoc diffusion tensor imaging (DTI) analysis was also performed on selected subjects.

RESULTS

The T2 values were significantly decreased on the right-side of the subjects with BD compared with that of the control subjects. Hemispheric difference was also observed in the BD group, with decreased T2 on the right side compared with the left side. No significant difference was observed between left and right CPC T2 in control subjects. For participants who had both T2 and DTI measurements, significant DTI differences were observed: On the left side, fractional anisotropy was reduced and trace and radial diffusivity were increased, whereas on the right side, trace was increased and T2 was decreased in subjects with BD compared with control subjects.

CONCLUSIONS

Our findings suggest that the observed T2 difference is a reflection of cerebral blood flow rather than an alteration of the fluidity of cell membranes. It is possible that myelin damage occurs on the left side in early-onset BD, in addition to changes in the blood flow. Prospective studies with larger numbers of subjects are warranted to further explore the relevance of the presented results.

Abnormal structure or function of the amygdala is a common component of neurodevelopmental disorders

The amygdala, perhaps more than any other brain region, has been implicated in numerous neuropsychiatric and neurodevelopmental disorders. It is part of a system initially evolved to detect dangers in the environment and modulate subsequent responses, which can profoundly influence human behavior. If its threshold is set too low, normally benign aspects of the environment are perceived as dangers, interactions are limited, and anxiety may arise. If set too high, risk taking increases and inappropriate sociality may occur. Given that many neurodevelopmental disorders involve too little or too much anxiety or too little of too much social interaction, it is not surprising that the amygdala has been implicated in many of them. In this chapter, we begin by providing a brief overview of the phylogeny, ontogeny, and function of the amygdala and then appraise data from neurodevelopmental disorders which suggest amygdala dysregulation. We focus on neurodevelopmental disorders where there is evidence of amygdala dysregulation from postmortem studies, structural MRI analyses or functional MRI. However, the results are often disparate and it is not totally clear whether this is due to inherent heterogeneity or differences in methodology. Nonetheless, the amygdala is a common site for neuropathology in neurodevelopmental disorders and is therefore a potential target for therapeutics to alleviate associated symptoms.

The structural neuroimaging of bipolar disorder

There is an increasing body of literature fuelled by advances in high-resolution structural MRI acquisition and image processing techniques which implicates subtle neuroanatomical abnormalities in the aetiopathogenesis of bipolar disorder. This account reviews the main findings from structural neuroimaging research into regional brain abnormalities, the impact of genetic liability and mood stabilizing medication on brain structure in bipolar disorder, and the overlapping structural deviations found in the allied disorders of schizophrenia and depression. The manifold challenges extant within neuroimaging research are highlighted with accompanying recommendations for future studies. The most consistent findings include preservation of total cerebral volume with regional grey and white matter structural changes in prefrontal, midline and anterior limbic networks, non-contingent ventriculomegaly and increased rates of white matter hyperintensities, with more pronounced deficits in juveniles suffering from the illness. There is increasing evidence that medication has observable effects on brain structure, whereby lithium status is associated with volumetric increase in the medial temporal lobe and anterior cingulate gyrus. However, research continues to be confounded by the use of highly heterogeneous methodology and clinical populations, in studies employing small scale, low-powered, cross-sectional designs. Future work should investigate larger, clinically homogenous groups of patients and unaffected relatives, combining both categorical and dimensional approaches to illness classification in cross-sectional and longitudinal designs in order to elucidate trait versus state mechanisms, genetic effects and medication/illness progression effects over time.

Pediatric bipolar disorder: evidence for prodromal states and early markers

BACKGROUND

Childhood bipolar disorder remains a controversial but increasingly diagnosed disorder that is associated with significant impairment, chronic course and treatment resistance. Therefore, the search for prodromes or early markers of risk for later childhood bipolar disorder may be of great importance for prevention and/or early identification.

METHODS

Literature searches were conducted to identify reviews, case reports and empirical papers addressing the issue of prodromes of childhood bipolar disorder.

RESULTS

A total of 54 articles were found that related to bipolar prodromes, risk factors for later childhood bipolar disorder, childhood risk for adult bipolar disorder, mania manifestations in early childhood, and neuropsychological and biological markers of childhood bipolar disorder. A review of articles suggest (a) childhood bipolar prodromes may be detectable prior to the onset of the disorder, (b) prodromal symptoms may display episodicity during childhood, (c) there is evidence of possible endophenotypic markers such as deficits in executive function, sustained attention, and emotion labeling, (d) there is a potential association with functional, structural, and biochemical alterations evident in brain structures involved in mood regulation, (e) a link between childhood bipolar disorder with early tempermental markers, such as emotional regulation and behavioral disinhibition and (f) there is some early but promising evidence of effective psychotherapeutic preventions.

CONCLUSIONS

There has been very limited investigation of early prodromes of childhood bipolar disorder. Based on the promising findings of prodromes as well as high-risk states and possible endophenotypic markers, more controlled and targeted investigations into the early markers of bipolar disorder appear warranted and potentially fruitful. Until such longitudinal studies with appropriate controls are conducted, specific markers for bipolar prodromes will remain elusive, although evidence suggests they are manifest in at least some subgroups. The finding of promising psychotherapeutic prevention programs underscores the need to find specific and sensitive markers of bipolar prodromes in childhood.

Subcortical volumetric correlates of anxiety in familial pediatric bipolar disorder: a preliminary investigation

Anxiety is a common comorbid condition in pediatric bipolar disorder (BD). However, there is little known about the effects of comorbidity on brain morphometry in this population. The aim of the present study was to examine subcortical correlates of anxiety in familial pediatric BD. The subject group comprised 120 children (mean age=12+/-3.3 years) with at least one parent diagnosed with BD. Bipolar offspring with BD were compared with bipolar offspring without BD on a measure of overall lifetime anxiety. A sub-sample of 20 bipolar offspring with BD (mean age=14.6+/-2.8 years) underwent magnetic resonance imaging (MRI) with a 3-T scanner. Correlational analyses were conducted between hippocampal and amygdalar volumes, and anxiety scores. The results showed significantly higher anxiety in bipolar offspring with BD compared to bipolar offspring without BD. There was a significant negative association between total hippocampal volume and anxiety scores. No significant association was found between total amygdalar volume and anxiety scores. Clinically, these findings suggest that anxiety comorbidity needs to be properly assessed and treated in the management of pediatric BD. This is the first study to show a negative association between hippocampal volume and anxiety in this population. The overlap between anxiety and familial pediatric BD suggests that anxiety may be one important area of future research in parsing out the heterogeneous nature and complex etiology of early-onset BD.

Magnetic resonance imaging studies in early onset bipolar disorder: an updated review

Over the past 5-10 years, advances in neuroimaging methods and study designs have begun to appear in the literature of early-onset bipolar disorder (onset before 18 years of age). This article contains an updated review of the literature regarding neuroimaging in youths with bipolar disorder (BPD), highlighting important new study designs and techniques. Overall, structural, functional (fMRI) and magnetic resonance spectroscopy (MRS) report consistent abnormalities in regions of the frontal lobe and limbic structures. Functional MRI and MRS studies also frequently report striatal and thalamic abnormalities in early-onset BPD. Future neuroimaging studies in youths with BPD should include longitudinal studies incorporating multimodal neuroimaging techniques.

An fMRI study of the neural correlates of incidental versus directed emotion processing in pediatric bipolar disorder

OBJECTIVE

To use functional neuroimaging to probe the affective circuitry dysfunctions underlying disturbances in emotion processing and emotional reactivity in pediatric bipolar disorder (PBD).

METHOD

Equal numbers of controls (HC) and unmedicated patients with euthymia and PBD were matched for age, sex, race, socioeconomic status, and IQ (n = 10 per group; mean age 14.2 years [SD 2.0 years]). The task consisted of a "directed" emotion processing condition where subjects judged whether emotion in facial expression was positive or negative and an "incidental" condition where subjects judged whether faces expressing similar affect were older or younger than 35 years.

RESULTS

Relative to the directed condition, the incidental condition elicited greater activation in the right amygdala and the right insula, the left middle frontal gyrus, and the left posterior cingulate cortex in patients with PBD, in contrast to the HC that showed greater activation in the right superior frontal gyrus. In both incidental and directed conditions, relative to visual fixation, patients with PBD showed less activation in the right prefrontal cortex (superior, middle, and inferior frontal gyri) and the pregenual anterior cingulate cortex and greater activation in the posterior visual and face-processing regions (i.e., right precuneus/cuneus, fusiform gyrus).

CONCLUSIONS

Increased amygdala activation observed in patients with PBD elicited by incidental emotional processing relative to directed emotional processing may indicate more intense automatic emotional reactivity. Furthermore, the right prefrontal systems that are believed to modulate affect seem to be less engaged in patients with PBD regardless of whether the emotion processing is incidental or directed, which may signify reduced top-down control of emotional reactivity in PBD.

The role of the amygdala in bipolar disorder development

The amygdala has received great interest as a possible neurophysiological substrate of bipolar disorder (BD). This review summarizes information about the structure and function of the amygdala with attention to its role in experienced emotion and mood. We review the evidence for amygdala pathology in psychiatric conditions and discuss the role of the amygdala in BD during development. There appear to be consistent findings in the neuroimaging literature that suggest an etiological model for BD that involves abnormalities in the structure and function of the amygdala, but also depends on the failure of prefrontal cortical regions to modulate amygdala activity. In addition, evidence is accumulating to suggest that this model has flexible outcomes, depending on factors intrinsic and extrinsic to BD, and may follow several possible paths across the course of maturational development.

Eyeblink conditioning anomalies in bipolar disorder suggest cerebellar dysfunction

OBJECTIVES

Accumulating research implicates the cerebellum in non-motor psychological processes and psychiatric diseases, including bipolar disorder (BD). Despite recent evidence that cerebellar lesions have been documented to trigger bipolar-like symptoms, few studies have directly examined the functional integrity of the cerebellum in those afflicted with BD.

METHODS

Using a single-cue delay eyeblink conditioning procedure, the functional integrity of the cerebellum was examined in 28 individuals with BD (9 manic, 8 mixed, and 11 euthymic) and 28 age-matched healthy controls.

RESULTS

Analysis of the bipolar group as a whole indicated a conditioned response acquisition and timing deficit compared to controls. However, when the bipolar group was categorized according to mood state (mixed, manic, euthymic), individuals tested during mixed episodes were strikingly impaired, performing significantly worse than all other groups on both the acquisition and timing of conditioned responses.

CONCLUSIONS

These findings extend prior research implicating cerebellar functional abnormalities in BD and suggest that cerebellar dysfunction may be associated with mood state and course of illness.

A quantitative and qualitative review of neurocognitive performance in pediatric bipolar disorder

Bipolar disorder (BD) is an increasingly prevalent diagnosis in youth. As a result, there has been a corresponding increase in interest about neuropsychological and cognitive profiles in children and adolescents diagnosed with BD. Meta-analysis of the existing literature comparing individuals with BD to healthy controls indicated that the largest differences are observed for measures of verbal memory (d = 0.77). Moderate differences were found in the areas of attention (d = 0.62), executive functioning (d = 0.62), working memory (d = 0.60), visual memory (d = 0.51), visual perceptual skills (d = 0.48), and verbal fluency (d = 0.45). Small differences were found for measures of reading (d = 0.40), motor speed (d = 0.33), and full-scale intelligence quotient (IQ) (d = 0.32). Often, few studies have provided relevant information for a particular neurocognitive domain. Despite this, several domains displayed heterogeneity of effect sizes across studies. Methodological factors explained the variance in effect sizes to different extents depending upon the cognitive domain. The changing influence of method artifacts is likely due to variable coverage of cognitive domains across studies and the use of different measures across studies. Findings are consistent with previous meta-analyses of the adult BD neurocognitive literature, suggesting that many of the deficits observed in adults are present earlier in the course of the illness. Study reporting guidelines are offered that may help clarify the impact of illness definitions, mood state, medication status, and other methodological variables on neurocognition in pediatric BD.

Increased rates of white matter hyperintensities in late-onset bipolar disorder

OBJECTIVES

Magnetic resonance imaging (MRI) studies have reported an increased frequency of white matter hyperintensities (WMH) in association with late-onset (LO) depression, and this has supported the notion that vascular-related mechanisms may be implicated in the pathophysiology of LO mood disorders. Recent clinical studies have also suggested a link between LO bipolar disorder (LO-BD) and cerebrovascular risk factors, but this has been little investigated with neuroimaging techniques. In order to ascertain whether there could be a specific association between WMH and LO-BD, we directly compared WMH rates between LO-BD subjects (illness onset >or= 60 years), early-onset BD subjects (EO-BD, illness onset <60 years), and elderly healthy volunteers.

METHODS

T2-weighted MRI data were acquired in LO-BD subjects (n = 10, age = 73.60 +/- 4.09), EO-BD patients (n = 49, age = 67.78 +/- 4.44), and healthy subjects (n = 24, age = 69.00 +/- 7.22). WMH rates were assessed using the Scheltens scale.

RESULTS

There was a greater prevalence of WMH in LO-BD patients relative to the two other groups in the deep parietal region (p = 0.018) and basal ganglia (p < 0.045). When between-group comparisons of mean WMH scores were conducted taking account of age differences (ANCOVA), there were more severe scores in LO-BD patients relative to the two other groups in deep frontal and parietal regions, as well as in the putamen (p < 0.05).

CONCLUSIONS

Our results provide empirical support to the proposed link between vascular risk factors and LO-BD. If extended in future studies with larger samples, these findings may help to clarify the pathophysiological distinctions between bipolar disorder emerging at early and late stages of life.

Three-dimensional mapping of hippocampal anatomy in adolescents with bipolar disorder

OBJECTIVE

Early-onset bipolar disorder is thought to be a particularly severe variant of the illness. Continuity with the adult form of illness remains unresolved, but preliminary evidence suggests similar biological underpinnings. Recently, we observed localized hippocampal decreases in unmedicated adults with bipolar disorder that were not detectable with conventional volumetric measures. Using the same three-dimensional mapping methods, we sought to investigate whether a similar pattern exists in adolescents with bipolar disorder.

METHOD

High-resolution brain magnetic resonance images were acquired from 16 adolescents meeting DSM-IV criteria for bipolar disorder (mean age 15.5 +/- 3.4 years, 50% female) and 20 demographically matched, typically developing control subjects. Three-dimensional parametric mesh models of the hippocampus were created from manual tracings of the hippocampal formation.

RESULTS

Controlling for total brain volume, total hippocampal volume was significantly smaller in adolescent patients with bipolar disorder relative to controls (by 9.2%). Statistical mapping results, confirmed by permutation testing, revealed significant localized deformations in the head and tail of the left hippocampus in adolescents with bipolar disorder, relative to normal controls. In addition, there was a significant positive correlation between hippocampal size and age in patients with bipolar disorder, whereas healthy controls showed an inverse relation.

DISCUSSION

Localized hippocampal deficits in adolescent patients with bipolar disorder suggest a possible neural correlate for memory deficits observed in this illness. Moreover, age-related increases in hippocampal size in patients with bipolar disorder, not observed in healthy controls, may reflect abnormal developmental mechanisms in bipolar disorder. This possibility must be confirmed by longitudinal studies.

Subcortical gray matter volume abnormalities in healthy bipolar offspring: potential neuroanatomical risk marker for bipolar disorder?

OBJECTIVE

A growing number of structural neuroimaging studies have shown that bipolar disorder (BD) is associated with gray matter (GM) volume abnormalities in brain regions known to support affect regulation. The goal of this study was to examine whole-brain regional GM volume in healthy bipolar offspring (HBO) relative to age-matched controls to identify possible structural abnormalities that may be associated with risk for BD.

METHOD

Participants were 20 youths (8-17 years old) with at least one parent diagnosed with BD, and 22 age-matched healthy individuals. All of them were free of Axis I diagnoses. High-resolution magnetic resonance imaging structural images were acquired using a 3-T Siemens scanner. Voxel-based morphometric analyses were conducted using SPM5.

RESULTS

Relative to controls, HBO had significantly increased GM volume in left parahippocampal/hippocampal gyrus (p <.05 corrected), following whole-brain analyses. This increase was correlated with puberty but not age in HBO. Region-of-interest analyses on the amygdala and orbitomedial prefrontal cortex did not yield any significant group differences after conducting small volume correction.

CONCLUSIONS

The pattern of increased GM volume in parahippocampal/hippocampal gyrus in HBO suggests a potential marker for risk for BD. It can also be considered as a potential neuroprotective marker for the disorder because HBO were free of current psychopathology. Prospective studies examining the relationship between changes in GM volume in these regions and subsequent development of BD in HBO will allow us to elucidate further the role of this region in either conferring risk for or protecting against the development of BD.

Assessing the role of cingulate cortex in bipolar disorder: neuropathological, structural and functional imaging data

OBJECTIVES

Most of the neuroanatomical models of bipolar disorder (BD) propose a key role for the anterior cingulate cortex (ACC). We provide here a review of currently available data regarding the CC neuroimaging and neuropathological alterations in BD.

MATERIALS AND METHODS

After an exploratory search of the MEDLINE, we first identified all English-written articles that provide separate data for BD patients and report original experimental data on cingulate gyrus. Subsequently, we selected those including neuroimaging or neuropathological data. Among the 161 articles updated through June 2007, 81 articles were retained using this procedure.

RESULTS

The review of in vivo volumetric imaging data, as well as ex vivo morphometric and histological studies indicates that BD patients show volume changes of the subgenual ACC (sgACC-BA 25 and part of 24) during the early stages of the disease. Whether this phenomenon is due to neuronal and glial depletion or damage of corticocortical connections is still a matter of debate. The resting state activity in the left BA 25 appears to be state dependent showing significant increase during mania and decrease during depressive phases. The presence of a deficient GABAergic activity in ACC is also documented. Pharmacological treatment partly restores BD-related functional imaging changes.

CONCLUSION

The present review reveals the striking discrepancies of the experimental results present both for functional and structural imaging studies but also for neuropathological analyses. Methodological and conceptual limitations are addressed with particular reference to the heterogeneity of BD clinical patterns. We also critically discuss the validity of CC changes as possible trait- or state-markers of the disease.

Diagnostic and sex effects on limbic volumes in early-onset bipolar disorder and schizophrenia

OBJECTIVE

The limbic structures in early-onset schizophrenia-spectrum illness (SZ) and bipolar disorder (BPD) were studied to discern patterns associated with diagnosis and sex.

METHODS

Thirty-five youths with DSM-IV BPD without psychosis, 19 with BPD with psychosis, 20 with SZ, and 29 healthy controls (HC), similar in age (6-17 years) and sex, underwent structured and clinical interviews, neurological examination, and cognitive testing. Structural magnetic resonance images (MRIs) were acquired on a 1.5 Tesla, General Electric Signa Scanner. Differences in subcortical brain volumes, including the amygdala and hippocampus, were evaluated using two-way (diagnosis, sex) univariate analyses covarying for total cerebral volume and age.

RESULTS

Youth with SZ and BPD showed no differences in amygdala and hippocampal volumes. However, boys with SZ had smallest left amygdala and girls with BPD had the smallest left hippocampal volumes. In exploratory analyses, SZ showed reduced thalamic volumes bilaterally and both BPD groups had larger right nucleus accumbens (NA) volumes relative to HC.

CONCLUSION

There were no limbic volumetric differences between BPD and SZ. However, there were diagnosis-by-sex interactions in the amygdala and hippocampus, structures that are rich in sex hormone receptors. In addition, smaller thalamus was associated with SZ while larger right NA volumes were most related to BPD. This study underscores the importance of assessing diagnostic effects and sex effects on the brain in future studies and provides evidence that boys and girls with SZ and BPD may have differential patterns of neuropathology associated with disease expression.

Cellular plasticity cascades in the pathophysiology and treatment of bipolar disorder

Bipolar disorder (BPD) is characterized by recurrent episodes of disturbed affect including mania and depression as well as changes in psychovegetative function, cognitive performance, and general health. A growing body of data suggests that BPD arises from abnormalities in synaptic and neuronal plasticity cascades, leading to aberrant information processing in critical synapses and circuits. Thus, these illnesses can best be conceptualized as genetically influenced disorders of synapses and circuits rather than simply as deficits or excesses in individual neurotransmitters. In addition, commonly used mood-stabilizing drugs that are effective in treating BPD have been shown to target intracellular signaling pathways that control synaptic plasticity and cellular resilience. In this article we draw on clinical, preclinical, neuroimaging, and post-mortem data to discuss the neurobiology of BPD within a conceptual framework while highlighting the role of neuroplasticity in the pathophysiology and treatment of this disorder.

Anterior cingulate volume in pediatric bipolar disorder and autism

BACKGROUND

An increasing number of studies indicate the anterior cingulate gyrus (ACG) may play a role in the attention deficits associated with pediatric bipolar disorder (BD). Age, medications, and intelligence quotient (IQ) may affect ACG volume; few studies have controlled for these effects.

METHODS

We recruited 16 children with BD and 24 children with autism spectrum disorder (ASD); 15 children with no psychiatric diagnosis (NP) were also included. All participants were evaluated with the K-SADS and a DSM-IV Autism/Asperger's Checklist; the ADI-R was also administered to ASD participants shortly after the study began. The participants completed a brain MRI scan on a 1.5Tesla Signa GE scanner. We segmented the ACG and compared left and right ACG volumes between groups. The influence of medications on the ACG volume was assessed while controlling for the effects of age and IQ.

RESULTS

The left ACG volume was significantly smaller in the BD group compared to the NP (p=0.004) and ASD (p=0.006) groups. No significant differences were found in the right ACG volume. These differences do not appear to be attributable to medication use or IQ.

CONCLUSIONS

Pediatric BD patients have a smaller left ACG volume compared to NP children and children diagnosed with ASD. This replication and extension of previous studies suggest that the ACG volume abnormality may be a biomarker for BD.

White matter abnormalities in children with and at risk for bipolar disorder

OBJECTIVES

Diffusion tensor magnetic resonance imaging (DT-MRI) assesses the integrity of white matter (WM) tracts in the brain. Children with bipolar disorder (BPD) may have WM abnormalities that precede illness onset. To more fully examine this possibility, we scanned children with DSM-IV BPD and compared them to healthy peers and children at risk for BPD (AR-BPD), defined as having a first-degree relative with the disorder.

METHODS

Ten children with BPD, eight healthy controls (HC), and seven AR-BPD, similar in age, had MRI scans on a 1.5 Tesla GE scanner, including a standard DT-MRI sequence (T2-EPI) with 25 axial slices. Fractional anisotropy (FA) values were compared between groups to determine regions of significant difference (p < 0.05).

RESULTS

Compared to HC, children with BPD had decreased FA in right and left superior frontal tracts, including the superior longitudinal fasciculus I (SLF I) and the cingulate-paracingulate WM (CG-PAC(WM)). In addition, the BPD group had reduced FA in left orbital frontal WM and the right corpus callosum body. Compared to AR-BPD, children with BPD showed reduced FA in the right and left CG-PAC(WM). Both the BPD and AR-BPD groups showed reduced FA relative to HC in bilateral SLF I.

CONCLUSIONS

The bilateral SLF I finding in both the BPD and AR-BPD groups may represent a trait-based marker or endophenotype of the disorder. The finding of decreased FA in the right and left CG-PAC(WM) in children with BPD compared to the other two groups may represent a disease-state related finding.

Update on pediatric bipolar disorder

Children and adolescents with a bipolar disorder experience mood dysregulation that is often chronic with little interepisodic recovery. Although bipolar disorder in youth is recognized by more and more clinicians, much is still not known regarding how best to accurately diagnose and effectively treat it. As a result, children and adolescents with bipolar disorder are often symptomatic for long periods of time before receiving appropriate treatment. In this review of the pediatric bipolar disorder literature, the phenomenology, longitudinal course, and risk factors associated with the illness' development are discussed. Also, recent research pertaining to neuroimaging and pharmacologic and psychological treatments are considered. Because pediatric bipolar disorder is such a pernicious condition, it is recommended that clinicians complete a careful assessment of mood symptoms and comorbid conditions when this illness is suspected so that they can provide treatments with the best chance of benefit in a timely manner.