The neurophysiology of childhood and adolescent bipolar disorder

Association of polygenic risk for bipolar disorder with resting-state network functional connectivity in youth with and without bipolar disorder

Little is known regarding the polygenic underpinnings of anomalous resting-state functional connectivity (rsFC) in youth bipolar disorder (BD). The current study examined the association of polygenic risk for BD (BD-PRS) with whole-brain rsFC at the large-scale network level in youth with and without BD. 99 youth of European ancestry (56 BD, 43 healthy controls [HC]), ages 13-20 years, completed resting-state fMRI scans. BD-PRS was calculated using summary statistics from the latest adult BD genome-wide association study. Data-driven independent component analyses of the resting-state fMRI data were implemented to examine the association of BD-PRS with rsFC in the overall sample, and separately in BD and HC. In the overall sample, higher BD-PRS was associated with lower rsFC of the salience network and higher rsFC of the frontoparietal network with frontal and parietal regions. Within the BD group, higher BD-PRS was associated with higher rsFC of the default mode network with orbitofrontal cortex, and altered rsFC of the visual network with frontal and occipital regions. Within the HC group, higher BD-PRS was associated with altered rsFC of the frontoparietal network with frontal, temporal and occipital regions. In conclusion, the current study found that BD-PRS generated based on adult genetic data was associated with altered rsFC patterns of brain networks in youth. Our findings support the usefulness of BD-PRS to investigate genetically influenced neuroimaging markers of vulnerability to BD, which can be observed in youth with BD early in their course of illness as well as in healthy youth.

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.

Morphological abnormalities in youth with bipolar disorder and their relationship to clinical characteristics

OBJECTIVES

To characterize the neuroanatomy of BD in youth and its correlation to clinical characteristics.

METHODS

The current study includes a sample of 105 unmedicated youth with first-episode BD, aged between 10.1 and 17.9 years, and 61 healthy comparison adolescents, aged between 10.1 and 17.7 years, who were matched for age, race, sex, socioeconomic status, intelligence quotient (IQ), and education level. T1-weighted magnetic resonance imaging (MRI) images were obtained using a 4 T MRI scanner. Freesurfer (V6.0) was used to preprocess and parcellate the structural data, and 68 cortical and 12 subcortical regions were considered for statistical comparisons. The relationship between morphological deficits and clinical and demographic characteristics were evaluated using linear models.

RESULTS

Compared with healthy youth, youth with BD had decreased cortical thickness in frontal, parietal, and anterior cingulate regions. These youth also showed decreased gray matter volumes in 6 of the 12 subcortical regions examined including thalamus, putamen, amygdala and caudate. In further subgroup analyses, we found that youth with BD with comorbid attention-deficit hyperactivity disorder (ADHD) or with psychotic symptoms had more significant deficits in subcortical gray matter volume.

LIMITATIONS

We cannot provide information about the course of structural changes and impact of treatment and illness progression.

CONCLUSIONS

Our findings indicate that youth with BD have significant neurostructural deficits in both cortical and subcortical regions mainly located in the regions related to emotion processing and regulation. Variability in clinical characteristics and comorbidities may contribute to the severity of anatomic alterations in this disorder.

Longitudinal proton spectroscopy study of the prefrontal cortex in youth at risk for bipolar disorder before and after their first mood episode

OBJECTIVES

To investigate neurochemical abnormalities in the left and right ventrolateral prefrontal cortex (VLPFC) and anterior cingulate cortex (ACC) of youth at risk for bipolar disorder using proton magnetic resonance spectroscopy before and after their first mood episode.

METHODS

Children and adolescents offspring of parents with bipolar I disorder (at-risk group, n = 117) and matched healthy controls (HC group, n = 61) were recruited at the University of Cincinnati. At-risk subjects had no lifetime major mood and psychotic disorders at baseline, and were followed up every 4 months to monitor for development of a major depressive, manic, hypomanic, or mixed mood episode. Levels of N-acetyl-aspartate (NAA), phosphocreatine plus creatine (PCr + Cr), choline-containing compounds, myo-inositol, and glutamate were determined using LCModel and corrected for partial volume effects.

RESULTS

There were no baseline differences in metabolite levels for any of the brain regions between at-risk and HC youth. Nineteen at-risk subjects developed a first mood episode during follow-up. Survival analyses showed that baseline PCr + Cr levels in the left VLPFC significantly predicted a mood episode during follow-up in the at-risk group (HR: 0.47, 95% CI: 0.27-0.82, P = 0.008). There were no longitudinal changes in metabolites levels in the VLPFC and ACC before and after a mood episode in at-risk subjects.

CONCLUSIONS

We found no evidence for abnormal proton spectroscopy metabolite levels in the VLPFC and ACC of at-risk youth, prior and after the development of their first mood episode. Preliminary findings of association between baseline PCr + Cr levels in the left VLPFC and risk to develop a mood episode warrant further investigation.

Increased prolidase activity and high blood monocyte counts in pediatric bipolar disorder

Various psychological, genetic, and biochemical factors are thought to be involved in the aetiology of pediatric bipolar disorder (PBD). However, few studies have evaluated the biochemical basis of PBD. The level of peripheral blood mononuclear cells and serum prolidase activity were determined in PBD and matched healthy comparison subjects. Blood from 38 (age range: 14-17) PBD-type I and 37 age- and gender-matched healthy comparison subjects was analyzed for numbers of neutrophils, lymphocytes, monocytes, lymphocyte-to-monocyte ratio (LMR), neutrophil-to-lymphocyte ratio (NLR) and serum prolidase activity. The prolidase activity and monocyte count were significantly higher in PBD than the control group. There were no significant differences in numbers of neutrophils, lymphocytes, LMR and NLR between the patient and control groups. These results suggest that the immune system and prolidase activity may be activated in PBD. There is a clinical benefit from the early detection of PBD using serum prolidase activity levels and monocyte counts. Especially, prolidase activity may be a trait marker for diagnosing PBD. However, further studies are needed to verify these findings.

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.

Chronic antipsychotic treatment differentially modulates protein kinase A- and glycogen synthase kinase 3 beta-dependent signaling pathways, N-methyl-D-aspartate receptor and γ-aminobutyric acid A receptors in nucleus accumbens of juvenile rats

BACKGROUND

Antipsychotics are developed to treat mental disorders in adults; however, the prescription (mostly "off-label") of antipsychotics for children/adolescents has been constantly increasing over years. The influences of antipsychotics on juveniles requires investigation to validate their clinic use. Antipsychotics mainly exert their effects via several receptors and signaling pathways.

AIMS

This study examined the effects of aripiprazole, olanzapine, and risperidone on selected signaling pathways, N-methyl-D-aspartate, and γ-aminobutyric acid A receptors in juveniles.

METHODS

Rats were orally administered aripiprazole (1 mg/kg), olanzapine (1 mg/kg), risperidone (0.3 mg/kg), or vehicle three times/day from postnatal day 23 (±1 day) for three weeks. The effects of antipsychotics in the nucleus accumbens and caudate putamen were measured by Western blots.

RESULTS

In the nucleus accumbens, all three drugs differentially increased N-methyl-D-aspartate and γ-aminobutyric acid A receptor expression. Additionally, all three antipsychotics differentially elevated the phosphorylation of glycogen synthase kinase 3 beta, β-catenin, and cAMP-responsive element-binding protein 1. In the caudate putamen, olanzapine increased β-catenin phosphorylation; and aripiprazole and olanzapine elevated γ-aminobutyric acid A receptor levels. Correlation analysis indicated that antipsychotics might modulate N-methyl-D-aspartate receptors via glycogen synthase kinase 3 beta-β-catenin signaling and/or cAMP-responsive element-binding protein 1 activation.

CONCLUSIONS

These findings suggest that antipsychotics can affect protein kinase A- and glycogen synthase kinase 3 beta-dependent signaling pathways in juveniles; and their modulation on N-methyl-D-aspartate and γ-aminobutyric acid A receptors is probably through glycogen synthase kinase 3 beta-β-catenin signaling and/or cAMP-responsive element-binding protein 1 activation.

Neutrophil-lymphocyte and platelet-lymphocyte ratios among adolescents with bipolar disorder: A preliminary study

We aimed to evaluate the neutrophil lymphocyte and platelet lymphocyte ratios among euthymic adolescents with bipolar disorder (BD) type I. Thirty-six adolescents with BD and 30 healthy controls were included in the study. The diagnosis was made by experienced physicians using the Kiddie and Young Adult Schedule for Affective Disorders and Schizophrenia Present and Lifetime Version and the affective module of Washington University in St. Louis Kiddie and Young Adult Schedule for Affective Disorders and Schizophrenia-Present State and Lifetime. Blood samples were taken during euthymia, which was defined as Young Mania Rating Scale and Hamilton Depression Rating Scale scores below 7. There was no significant difference in neutrophil lymphocyte ratio and platelet lymphocyte ratio between the patient and control group. Considering the literature, we may speculate that in the early stages, euthymia is associated with a lower inflammatory response, and prolongation of BD causes increased inflammatory processes predominant even in euthymia. In pediatric BD, further studies that assess neutrophil lymphocyte ratio and platelet lymphocyte ratio during different mood episodes and that identify neutrophil lymphocyte ratio and platelet lymphocyte ratio changes during the course of the disease will clarify the role of inflammation in the etiology of pediatric BD.

Serum Brain-derived Neurotrophic Factor Levels among Euthymic Adolescents with Bipolar Disorder Type I

INTRODUCTION

Bipolar disorder (BD) has been increasingly associated with abnormalities in neuroplasticity and cellular resilience in brain regions that are involved in mood and that affect regulation. Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family that regulates neuroplasticity. The aims of the current study were to compare serum BDNF levels in euthymic adolescents with BD type I with those in controls and to investigate the relationship between clinical variables and serum BDNF levels in adolescents with BD type I.

METHODS

Twenty-five adolescents diagnosed with BD type I and 17 healthy control subjects within the age range of 15-19 years were recruited. Diagnoses were made by two experienced research clinicians using the Kiddie and Young Adult Schedule for Affective Disorders and Schizophrenia Present and Lifetime Version and the affective module of Washington University in St. Louis Kiddie and Young Adult Schedule for Affective Disorders and Schizophrenia-Present State and Lifetime. Blood samples were taken during euthymia, which was defined as Young Mania Rating Scale and Hamilton Depression Rating Scale scores below 7.

RESULTS

The comparison of BDNF serum levels between the case and healthy control groups revealed no significant differences. In the case group, BDNF levels were significantly lower in patients being currently treated with lithium.

CONCLUSION

Similar to normal BDNF levels in adult patients with BD, the normal BDNF serum levels that we found in the euthymic state in adolescents and early adulthood may be related to the developmental brain stage in our study group. It may also show a common neurobiological basis of pediatric and adult BD. Further investigations evaluating BDNF levels in different mood states could help identify the role of BDNF in the underlying pathophysiology of BD.

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

BACKGROUND

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

METHODS

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

RESULTS

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

LIMITATIONS

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

CONCLUSIONS

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

Neurodevelopmental origins of bipolar disorder: iPSC models

Bipolar disorder (BP) is a chronic neuropsychiatric condition characterized by pathological fluctuations in mood from mania to depression. Adoption, twin and family studies have consistently identified a significant hereditary component to BP, yet there is no clear genetic event or consistent neuropathology. BP has been suggested to have a developmental origin, although this hypothesis has been difficult to test since there are no viable neurons or glial cells to analyze, and research has relied largely on postmortem brain, behavioral and imaging studies, or has examined proxy tissues including saliva, olfactory epithelium and blood cells. Neurodevelopmental factors, particularly pathways related to nervous system development, cell migration, extracellular matrix, H3K4 methylation, and calcium signaling have been identified in large gene expression and GWAS studies as altered in BP. Recent advances in stem cell biology, particularly the ability to reprogram adult somatic tissues to a pluripotent state, now make it possible to interrogate these pathways in viable cell models. A number of induced pluripotent stem cell (iPSC) lines from BP patient and healthy control (C) individuals have been derived in several laboratories, and their ability to form cortical neurons examined. Early studies suggest differences in activity, calcium signaling, blocks to neuronal differentiation, and changes in neuronal, and possibly glial, lineage specification. Initial observations suggest that differentiation of BP patient-derived neurons to dorsal telencephalic derivatives may be impaired, possibly due to alterations in WNT, Hedgehog or Nodal pathway signaling. These investigations strongly support a developmental contribution to BP and identify novel pathways, mechanisms and opportunities for improved treatments.

The Use of Cannabis as a Predictor of Early Onset of Bipolar Disorder and Suicide Attempts

Introduction. Bipolar disorder (BD) implies risk of suicide. The age at onset (AAO) of BD carries prognostic significance. Substance abuse may precede the onset of BD and cannabis is the most common illicit drug used. The main goal of this study is to review the association of cannabis use as a risk factor for early onset of BD and for suicide attempts. Materials and Methods. PubMed database was searched for articles using key words “bipolar disorder,” “suicide attempts,” “cannabis,” “marijuana,” “early age at onset,” and “early onset.” Results. The following percentages in bipolar patients were found: suicide attempts 3.6–42%; suicide attempts and substance use 5–60%; suicide attempts and cannabis use 15–42%. An early AAO was associated with cannabis misuse. The mean age of the first manic episode in individuals with and without BD and cannabis use disorder (CUD) was 19.5 and 25.1 years, respectively. The first depressive episode was at 18.5 and 24.4 years, respectively. Individuals misusing cannabis showed increased risk of suicide. Discussion. Cannabis use is associated with increased risk of suicide attempts and with early AAO. However, the effect of cannabis at the AAO and suicide attempts is not clear.

Influence of DGKH variants on amygdala volume in patients with bipolar affective disorder and schizophrenia

The diacylglycerol kinase eta (DGKH) gene, first identified in a genome-wide association study, is one of the few replicated risk genes of bipolar affective disorder (BD). Following initial positive studies, it not only was found to be associated with BD but also implicated in the etiology of other psychiatric disorders featuring affective symptoms, rendering DGKH a cross-disorder risk gene. However, the (patho-)physiological role of the encoded enzyme is still elusive. In the present study, we investigated primarily the influence of a risk haplotype on amygdala volume in patients suffering from schizophrenia or BD as well as healthy controls and four single nucleotide polymorphisms conveying risk. There was a significant association of the DGKH risk haplotype with increased amygdala volume in BD, but not in schizophrenia or healthy controls. These findings add to the notion of a role of DGKH in the pathogenesis of BD.

A review of MR spectroscopy studies of pediatric bipolar disorder

Pediatric bipolar disorder is a severe mental illness whose pathophysiology is poorly understood and for which there is an urgent need for improved diagnosis and treatment. MR spectroscopy is a neuroimaging method capable of in vivo measurement of neurochemicals relevant to bipolar disorder neurobiology. MR spectroscopy studies of adult bipolar disorder provide consistent evidence for alterations in the glutamate system and mitochondrial function. In bipolar disorder, these 2 phenomena may be linked because 85% of glucose in the brain is consumed by glutamatergic neurotransmission and the conversion of glutamate to glutamine. The purpose of this article is to review the MR spectroscopic imaging literature in pediatric bipolar disorder, at-risk samples, and severe mood dysregulation, with a focus on the published findings that are relevant to glutamatergic and mitochondrial functioning. Potential directions for future MR spectroscopy studies of the glutamate system and mitochondrial dysfunction in pediatric bipolar disorder are discussed.

Transcripts involved in calcium signaling and telencephalic neuronal fate are altered in induced pluripotent stem cells from bipolar disorder patients

Bipolar disorder (BP) is a chronic psychiatric condition characterized by dynamic, pathological mood fluctuations from mania to depression. To date, a major challenge in studying human neuropsychiatric conditions such as BP has been limited access to viable central nervous system tissue to examine disease progression. Patient-derived induced pluripotent stem cells (iPSCs) now offer an opportunity to analyze the full compliment of neural tissues and the prospect of identifying novel disease mechanisms. We have examined changes in gene expression as iPSC derived from well-characterized patients differentiate into neurons; there was little difference in the transcriptome of iPSC, but BP neurons were significantly different than controls in their transcriptional profile. Expression of transcripts for membrane bound receptors and ion channels was significantly increased in BP-derived neurons compared with controls, and we found that lithium pretreatment of BP neurons significantly altered their calcium transient and wave amplitude. The expression of transcription factors involved in the specification of telencephalic neuronal identity was also altered. Control neurons expressed transcripts that confer dorsal telencephalic fate, whereas BP neurons expressed genes involved in the differentiation of ventral (medial ganglionic eminence) regions. Cells were responsive to dorsal/ventral patterning cues, as addition of the Hedgehog (ventral) pathway activator purmorphamine or a dorsalizing agent (lithium) stimulated expression of NKX2-1 (ventral identity) or EMX2 (dorsal) in both groups. Cell-based models should have a significant impact on our understanding of the genesis and therefore treatment of BP; the iPSC cell lines themselves provide an important resource for comparison with other neurodevelopmental disorders.

Neural activity to intense positive versus negative stimuli can help differentiate bipolar disorder from unipolar major depressive disorder in depressed adolescents: a pilot fMRI study

Failure to distinguish bipolar depression (BDd) from the unipolar depression of major depressive disorder (UDd) in adolescents has significant clinical consequences. We aimed to identify differential patterns of functional neural activity in BDd versus UDd and employed two (fearful and happy) facial expression/ gender labeling functional magnetic resonance imaging (fMRI) experiments to study emotion processing in 10 BDd (8 females, mean age=15.1 ± 1.1) compared to age- and gender-matched 10 UDd and 10 healthy control (HC) adolescents who were age- and gender-matched to the BDd group. BDd adolescents, relative to UDd, showed significantly lower activity to both intense happy (e.g., insula and temporal cortex) and intense fearful faces (e.g., frontal precentral cortex). Although the neural regions recruited in each group were not the same, both BDd and UDd adolescents, relative to HC, showed significantly lower neural activity to intense happy and mild happy faces, but elevated neural activity to mild fearful faces. Our results indicated that patterns of neural activity to intense positive and negative emotional stimuli can help differentiate BDd from UDd in adolescents.

Progression of amygdala volumetric abnormalities in adolescents after their first manic episode

OBJECTIVE

Although previous neuroimaging studies suggest that adolescents with bipolar disorder exhibit smaller amygdala volumes compared with healthy adolescents, whether these abnormalities are present at illness onset or instead develop over time remains unclear. The aim of this study was to conduct a prospective longitudinal investigation comparing amygdala neurodevelopment among adolescents after their first manic episode, adolescents with attention-deficit/hyperactivity disorder (ADHD), and healthy adolescents.

METHOD

A total of 30 adolescents hospitalized for their first manic/mixed episode associated with bipolar disorder, 29 adolescents with ADHD, and 24 demographically matched healthy teens underwent magnetic resonance imaging scanning at index assessment and approximately 12 months later. Adolescents with bipolar disorder were prospectively evaluated using diagnostic interviews and with symptom rating scales.

RESULTS

Mixed models examining the group × time effect for both left (p = .005) and right (p = .002) amygdala volumes were statistically significant. Change in left (p = .01) and right (p = .0008) amygdala volumes from baseline to 12 months were significantly different among groups. Specifically, left amygdala volumes increased over time in healthy adolescents (p = .008) and adolescents with ADHD (p = .0009), but not in adolescents with bipolar disorder (p = .3). Right amygdala volume increased over time in adolescents with ADHD (p < .001), but not in healthy adolescents nor in adolescents with bipolar disorder (p = .1 and p = .3, respectively). In adolescents with bipolar disorder, baseline total amygdala volume was significantly greater in those who subsequently achieved symptomatic recovery as compared with those who did not achieve recovery (p = .02).

CONCLUSIONS

Adolescents with mania do not exhibit normal increases in amygdala volume that occur during healthy adolescent neurodevelopment.

Fronto-temporal spontaneous resting state functional connectivity in pediatric bipolar disorder

BACKGROUND

The recent upsurge in interest about pediatric bipolar disorder (BD) has spurred the need for greater understanding of its neurobiology. Structural and functional magnetic resonance imaging studies have implicated fronto-temporal dysfunction in pediatric BD. However, recent data suggest that task-dependent neural changes account for a small fraction of the brain's energy consumption. We now report the first use of task-independent spontaneous resting state functional connectivity (RSFC) to study the neural underpinnings of pediatric BD.

METHODS

We acquired task-independent RSFC blood oxygen level-dependent functional magnetic resonance imaging scans while participants were at rest and also a high-resolution anatomical image (both at three Tesla) in BD and control youths (n = 15 of each). We focused, on the basis of prior research, on the left dorsolateral prefrontal cortex (DLPFC), amygdala, and accumbens. Image processing and group-level analyses followed that of prior work.

RESULTS

Our primary analysis showed that pediatric BD participants had significantly greater negative RSFC between the left DLPFC and the right superior temporal gyrus versus control subjects. Secondary analyses using partial correlation showed that BD and control youths had opposite phase relationships between spontaneous RSFC fluctuations in the left DLPFC and right superior temporal gyrus.

CONCLUSIONS

Our data indicate that pediatric BD is characterized by altered task-independent functional connectivity in a fronto-temporal circuit that is also implicated in working memory and learning. Further study is warranted to determine the effects of age, gender, development, and treatment on this circuit in pediatric BD.

Pharmacotherapy of bipolar disorder in children and adolescents: recent progress

Child and adolescent bipolar disorder (BPD) is a serious psychiatric disorder that often causes significant impairment in functioning. Pharmacological intervention is the cornerstone of treatment for bipolar youth, although psychotherapeutic interventions may be beneficial as adjunctive treatment. Medications used for the treatment of BPD in adults are still commonly used for bipolar children and adolescents. With the recent US FDA indication of risperidone, aripiprazole, quetiapine and olanzapine for the treatment of bipolar youth, the atypical antipsychotics are rapidly becoming a first-line treatment option. However, these agents are associated with adverse effects such as increased appetite, weight gain and type II diabetes mellitus. Although several evidence-based medications are now available for the treatment of BPD in younger populations, additional studies to evaluate the short- and long-term efficacy and potential for adverse events of these and other medications are needed.

Midline brain abnormalities in established bipolar affective disorder

BACKGROUND

Morphologic changes of cortico-limbic regions have been reported in bipolar disorder, but it remains unclear whether midline brain abnormalities relevant to cortico-limbic connectivity are also present.

METHODS

We used magnetic resonance imaging to investigate the size of the adhesio interthalamica (AI) and cavum septi pellucidi (CSP), as well as third ventricular volume, in 26 patients with bipolar I disorder and 24 matched controls.

RESULTS

CSP length and prevalence of a large CSP did not differ between the groups, but bipolar patients had significantly shorter AI and larger third ventricles compared to controls.

LIMITATIONS

A comprehensive investigation of medication effects was not possible due to incomplete medication data.

CONCLUSIONS

These findings implicate a role for the AI and connected brain regions in the neurobiology of bipolar disorder.

Correlation between amygdala volume and age in bipolar disorder - a systematic review and meta-analysis of structural MRI studies

The amygdala has gained special interest regarding the neuropathology of bipolar disorder (BD). Structural magnetic resonance imaging (MRI) studies with patients suffering from BD have yielded quite inconsistent results with respect to amygdala volume. We performed a meta-analysis of structural MRI studies that investigated right and left amygdala volume in pediatric and adult patients with BD. The aim was to assess the heterogeneous findings and to investigate whether a correlation between amygdala volume and the patient's age exists. Studies were searched for in "Pub Med" (last search June 2007), and data for right and left amygdala volume in cm(3) were extracted and combined in a meta-analysis. Thirteen studies with 389 scans of patients and 488 scans of healthy control subjects (HC) were included. The impact of age on the difference in amygdala volume between patients and HC was assessed by meta-regression. The amygdala volume was bilaterally reduced in the overall sample of patients with BD and the pediatric subsample. The results of the adult studies were less homogeneous, and on average, no significant difference between adult patients and HC was found. A meta-regression analysis revealed a positive correlation between mean age and amygdala volume in patients with BD. We speculate that amygdala volume is reduced at the onset of the disease and increases with age.

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.

Motor function may differentiate attention deficit hyperactivity disorder from early onset bipolar disorder

BACKGROUND

Differentiating between bipolar spectrum disorder (BD) and attention deficit hyperactivity disorder (ADHD) in childhood and adolescence is difficult because the clinical presentation is influenced by ongoing neural development, causing considerable symptom overlap. Motor problems and neurological soft signs have been associated with ADHD for decades. Little is known about motor skills in BD. Here we assess the diagnostic accuracy of neuromotor deviations in differentiating ADHD from BD in clinical practice. We also investigate if these deviations exist in concurrent ADHD and BD, thus indicating true comorbidity

METHODS

64 patients 6-18 years (31 girls, 33 boys) fulfilling the diagnostic criteria of BD, ADHD combined subtype (ADHD-C) or comorbid BD and ADHD-C, were compared using an age-standardized neuromotor test; NUBU. Categorical variables were analyzed using cross table with two-tailed chi square test or Fisher's exact test when appropriate. Continuous variables were analyzed by Kruskal-Wallis test and, if significant, Mann-Whitney U test and ROC plots.

RESULTS

The ADHD-C group and the comorbid ADHD-C and BD group both showed significantly more neurological soft signs (p less than 0.01) and lower mean static coordination percentile (p less than 0.01) than the BD group. The positive predictive value of NUBU in the diagnosis of ADHD-C with or without concurrent BD was 89% (80-95) for total soft signs and 87% (79-95) for static coordination below the 7.5 percentile.

CONCLUSION

An age-standardized neuromotor test battery may promote diagnostic accuracy in differentiating ADHD from BD in clinical practice, and help evaluating whether symptoms of ADHD in children who have BD reflect symptom overlap or real comorbidity. This may have important implications for everyday diagnostic work.

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.

Retrospective age at onset of bipolar disorder and outcome during two-year follow-up: results from the STEP-BD study

OBJECTIVE

Symptoms of bipolar disorder are increasingly recognized among children and adolescents, but little is known about the course of bipolar disorder among adults who experience childhood onset of symptoms.

METHODS

We examined prospective outcomes during up to two years of naturalistic treatment among 3,658 adult bipolar I and II outpatients participating in a multicenter clinical effectiveness study, the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD). Age at illness onset was identified retrospectively by clinician assessment at study entry.

RESULTS

Compared to patients with onset of mood symptoms after age 18 years (n = 1,187), those with onset before age 13 years (n = 1,068) experienced earlier recurrence of mood episodes after initial remission, fewer days of euthymia, and greater impairment in functioning and quality of life over the two-year follow-up. Outcomes for those with onset between age 13 and 18 years (n = 1,403) were generally intermediate between these two groups.

CONCLUSION

Consistent with previous reports in smaller cohorts, adults with retrospectively obtained early-onset bipolar disorder appear to be at greater risk for recurrence, chronicity of mood symptoms, and functional impairment during prospective observation.

Clinical implications of current findings in neurodevelopment

Research in the last decade has advanced our knowledge about biological factors underlying neurodevelopmental processes in childhood. Genetic research has gone beyond mapping the human genome to identifying epigenetic factors and explicating gene-environment interactions. Biological markers of vulnerability to specific disorders have been identified. The functions of and interactions between neuroanatomic regions have been illuminated by new imaging and other noninvasive techniques, such as EEG, event-related potentials, and functional magnetic resonance imaging, that allow us to link earliest signs of disorders to neurological changes. This article provides an overview of current findings in neurodevelopment, and discusses diagnostic factors, prevention and intervention, and clinical implications.

Limbic changes identified by imaging in bipolar patients

The hippocampus and amygdala are key limbic regions for memory formation and emotion modulation that are potentially involved in the cognitive and affective symptoms of bipolar disorder. Here we discuss the most consistent MRI literature in bipolar disorder, focusing on the role of the hippocampus and amygdala. In child and adolescent patients, a unique pattern of abnormalities has begun to emerge, with volume deficits in the hippocampus and amygdala already detectable early in the illness course. In adults, it is unclear whether hippocampal volumes are abnormal, whereas the amygdala is reported to be larger and hyperactive to external emotional stimuli. However, available findings are often conflicting, and most studies suffer from limitations. Future longitudinal magnetic resonance studies should focus on juvenile patients; first-episode, drug-free patients; and unaffected family members. Jointly with genetic, postmortem, and neuropsychological studies, these studies will be extremely valuable in separating state from trait brain abnormalities and further characterizing the pathophysiology of bipolar disorder.

Neuroanatomic comparison of bipolar adolescents with and without cannabis use disorders

OBJECTIVE

Co-occurrence of substance use and bipolar disorders is both common and associated with poor treatment response and greater functional impairment than either disorder alone. The neurophysiological correlates of this co-morbidity however, remain unclear. In this pilot study, we compared brain morphometry between bipolar adolescents with co-occurring cannabis use disorders (CUD) and bipolar adolescents without any substance use disorder.

METHODS

Whole-brain structural magnetic resonance imaging (MRI) scans were obtained from 14 bipolar adolescents. Seven study participants were diagnosed with CUD before and/or shortly after their MR scan was obtained, and 7 subjects were free of any substance use disorder at the time of their MR scan as well as during longitudinal follow up. Morphologic differences were calculated using voxel-based morphometry implemented using statistical parametric mapping software (SPM2).

RESULTS

Bipolar adolescents with co-occurring CUD demonstrated decreased gray matter volume (GMV) in the left fusiform gyrus and increased GMV in the right caudate and precentral gyrus, as well as increased gray matter density in the right middle occipital and fusiform gyri and cerebellar vermis.

CONCLUSIONS

Bipolar adolescents with CUD demonstrate evidence of greater structural abnormalities than adolescents with bipolar disorder alone in frontal and temporal cortical regions, as well as in subcortical areas linked with emotion and motivational regulation. Although the limited prescan exposure to marijuana in these adolescents tentatively suggests that these findings may reflect underlying differences, the direct effect of cannabis exposure may also be involved.

Neurochemical alterations in adolescent bipolar depression: a proton magnetic resonance spectroscopy pilot study of the prefrontal cortex

OBJECTIVE

Identifying neurochemical alterations in adolescent bipolar depression may enhance our understanding of the neurophysiology of bipolar disorder across the age spectrum. The objective of this study was to compare in vivo neurometabolite concentrations in bipolar adolescents with a depressed episode and healthy adolescents using proton magnetic resonance spectroscopy ((1)H MRS).

METHOD

Bipolar adolescents with a depressed episode (n = 28) and healthy adolescents (n = 10) underwent a (1)H MRS scan. Anterior cingulate (ACC) and left and right ventral lateral prefrontal (LVLPFC, RVLPFC) metabolite concentrations were calculated and compared between groups using analysis of covariance (ANCOVA).

RESULTS

ANCOVA showed significant group differences in ACC N-acetyl-aspartate (NAA) (F(1,33) = 17.8, p = 0.0002), LVLPFC choline (Cho) (F(1,32) = 13.1, p = 0.001), creatine/phosphocreatine (Cr) (F(1,32) = 18.5, p = 0.0002), and NAA (F(1,32) = 13.6, p = 0.0008), and RVLPFC Cr (F(1,32) = 9.6, p = 0.004), mI (F(1,32) = 11.1, p = 0.002), and NAA (F(1,32) = 11.4, p = 0.002) concentrations. In general, the bipolar depressed group had higher neurometabolite concentrations than the healthy group.

CONCLUSIONS

There may be localized alterations in brain neurometabolites in adolescents with bipolar depression. Limitations include lack of bipolar adolescents in other mood states and potential confounding effects of prior psychotropic medication use. Confirmatory (1)H MRS studies in larger samples of youths with bipolar depression are needed.

Adjunctive psychotherapy for bipolar disorder: state of the evidence

OBJECTIVE

Psychotherapy has long been recommended as adjunctive to pharmacotherapy for bipolar disorder, but it is unclear which interventions are effective for which patients, over what intervals, and for what domains of outcome. This article reviews randomized trials of adjunctive psychotherapy for bipolar disorder.

METHOD

Eighteen trials of individual and group psychoeducation, systematic care, family therapy, interpersonal therapy, and cognitive-behavioral therapy are described. Relevant outcome variables include time to recovery, recurrence, duration of episodes, symptom severity, and psychosocial functioning.

RESULTS

The effects of the treatment modalities varied according to the clinical condition of patients at the time of random assignment and the polarity of symptoms at follow-up. Family therapy, interpersonal therapy, and systematic care appeared to be most effective in preventing recurrences when initiated after an acute episode, whereas cognitive-behavioral therapy and group psychoeducation appeared to be most effective when initiated during a period of recovery. Individual psychoeducational and systematic care programs were more effective for manic than depressive symptoms, whereas family therapy and cognitive-behavioral therapy were more effective for depressive than manic symptoms.

CONCLUSIONS

Adjunctive psychotherapy enhances the symptomatic and functional outcomes of bipolar disorder over 2-year periods. The various modalities differ in content, structure, and associated mediating mechanisms. Treatments that emphasize medication adherence and early recognition of mood symptoms have stronger effects on mania, whereas treatments that emphasize cognitive and interpersonal coping strategies have stronger effects on depression. The placement of psychotherapy within chronic care algorithms and its role as a preventative agent in the early stages of the disorder deserve investigation.

Meta-analysis of amygdala volumes in children and adolescents with bipolar disorder

OBJECTIVE

The neurophysiological basis of bipolar disorder in youths remains poorly understood. Neurofunctional and neuropathologic studies have implicated the amygdala as a primary brain structure involved in the regulation of emotion. Because one of the cardinal features of bipolar disorder is mood dysregulation, structural and functional amygdala abnormalities identified with neuroimaging may serve as useful disease and treatment response biomarker. Therefore, we conducted a meta-analysis summarizing the literature examining amygdala size obtained from magnetic resonance imaging in bipolar youths and adults.

METHOD

A literature search using the National Institutes of Health's PubMed was conducted to identify published peer-reviewed neuroimaging studies of amygdala size in children, adolescents, and adults with bipolar disorder. Eleven studies that met inclusion and exclusion criteria were identified.

RESULTS

Smaller amygdala volumes were found in children and adolescents with bipolar disorder compared with the control children and adolescents (standardized mean difference -0.74; 95% confidence interval -1.36 to -0.15). Amygdala volumes in bipolar adults were not significantly different from the control adults (standardized mean difference 0.20; 95% confidence interval -0.31 to 0.73).

CONCLUSIONS

The results of this meta-analysis suggest that structural amygdala abnormalities are present in bipolar youths but that these structural differences do not seem to be present in bipolar adults. Future studies examining whether structural, functional, and neurochemical amygdala differences between bipolar and control youths may be useful as age-specific biomarkers of illness and treatment response are needed.

Neuroanatomical characterization of child offspring of bipolar parents

OBJECTIVE

To examine structural differences in selected anterior limbic brain regions between at-risk children of parents with bipolar I disorder and children with healthy parents. We hypothesized that at-risk (AR) children would exhibit abnormalities in brain regions that are involved in mood regulation.

METHOD

Children (8-12 years old) of parents with bipolar I disorder (AR children, n = 21) and of parents without any DSM-IV Axis I disorder (healthy controls, n = 24) were evaluated using diagnostic assessments and brain magnetic resonance imaging. Morphometric analyses were used to examine group differences in the prefrontal cortical, thalamic, striatal, and amygdalar volumes.

RESULTS

Nine (43%) of the AR children met DSM-IV-TR criteria for a nonbipolar mood disorder at the time of assessment. AR and healthy control children did not demonstrate statistically significant differences across regions of interest (Wilks lambda =.86, F4,39 = 1.64, p = .18; effect size, f = 0.19). Post hoc analyses of covariance showed the largest relative effect size was contributed by the prefrontal cortex (f = 0.26).

CONCLUSIONS

Eight- to 12-year-old children with a familial risk for mania do not exhibit any statistically significant volumetric differences in the prefrontal cortex, thalamus, striatum, or amygdala as compared with age-matched children of parents without any psychopathology. Longitudinal studies examining whether structural changes over time may be associated with vulnerability for developing subsequent bipolar disorder are needed to clarify the underlying pathophysiology of this disorder.

Anxiety symptoms and syndromes in bipolar children and adolescents

Anxiety disorders are relatively common in children and adolescents with bipolar disorder. Research to date indicates they may impact the onset, course, and treatment response of bipolar illness in children. Anxiety disorders often precede the onset of pediatric bipolar disorder. Family studies suggest first-degree relatives of bipolar patients are at increased risk for developing mood and anxiety disorders compared with relatives of individuals without mood disorders. Childhood adversity has been associated with higher rates of comorbid anxiety disorders and more severe illness course in bipolar patients. Preliminary study of the neurobiology of bipolar disorder with comorbid anxiety disorders suggests it may be neurophysiologically distinct from bipolar disorder without comorbid anxiety. Bipolar disorder with comorbid anxiety disorders has been associated with greater functional impairment and slower recovery. Prospective, longitudinal studies are needed to help us better understand the relationship between bipolar disorder and comorbid anxiety disorders so that opportunities for early intervention and effective treatment can be realized.

Biologic basis of bipolar disorder in children and adolescents

Bipolar disorder is a serious and difficult-to-treat condition in any age group. In childhood and adolescence, diagnosis and treatment present specific challenges, as the disorder often manifests in atypical presentations, such as marked irritability and frequent alterations of mood states not typically seen in adults. The lack of double-blind, placebo-controlled studies in pediatric populations also leads to many difficult pharmacologic challenges. In this paper, we review available studies in neuroanatomy, neurochemistry, neurocognitive functioning, and genetics to further explore the underlying neurobiologic mechanisms of child and adolescent bipolar disorder. Future investigation should elicit distinct mechanisms for diagnosing and treating bipolar disorder from a neurobiologic perspective.

Morphometric magnetic resonance imaging in psychiatry

Although advances in the clinical criteria of various axis I psychiatric disorders are continually being made, there is still considerable overlap in the clinical features, and diagnosis is often challenging. As a result, there has been substantial interest in using morphometric magnetic resonance imaging to better characterize these diseases and inform diagnosis. Region of interest and voxel-based morphometry studies are reviewed herein to examine the extent to which these goals are being met across various psychiatric disorders. It is concluded based on the studies reviewed that specific patterns of regional loss, although present in certain axis I disorders, are not, as yet, diagnostically useful. However, advances in outcome and treatment monitoring show considerably more promise for rapid application in psychiatry.

Prevention of bipolar disorder in at-risk children: theoretical assumptions and empirical foundations

This article examines how bipolar symptoms emerge during development, and the potential role of psychosocial and pharmacological interventions in the prevention of the onset of the disorder. Early signs of bipolarity can be observed among children of bipolar parents and often take the form of subsyndromal presentations (e.g., mood lability, episodic elation or irritability, depression, inattention, and psychosocial impairment). However, many of these early presentations are diagnostically nonspecific. The few studies that have followed at-risk youth into adulthood find developmental discontinuities from childhood to adulthood. Biological markers (e.g., amygdalar volume) may ultimately increase our accuracy in identifying children who later develop bipolar I disorder, but few such markers have been identified. Stress, in the form of childhood adversity or highly conflictual families, is not a diagnostically specific causal agent but does place genetically and biologically vulnerable individuals at risk for a more pernicious course of illness. A preventative family-focused treatment for children with (a) at least one first-degree relative with bipolar disorder and (b) subsyndromal signs of bipolar disorder is described. This model attempts to address the multiple interactions of psychosocial and biological risk factors in the onset and course of bipolar disorder.

Increased rates of bipolar disorder diagnoses among U.S. child, adolescent, and adult inpatients, 1996-2004

BACKGROUND

Volatile, aggressive behavior is the chief complaint that brings children to inpatient psychiatric care. These difficulties are increasingly conceptualized as bipolar disorder (BD). The impact of doing so on clinical diagnoses in clinical care is uncertain.

METHODS

We extracted records from the annual National Hospital Discharge Survey (NHDS) for which a psychiatric diagnosis was primary and examined trends in the rates of hospitalization for BD.

RESULTS

Population-adjusted rates of hospital discharges of children with a primary diagnosis of BD increased linearly over survey years. The rate in 1996 was 1.3 per 10,000 U.S. children and climbed to 7.3 per 10,000 U.S. children in 2004. Bipolar disorder related discharges also increased fourfold among adolescents. Adults showed a more modest, though still marked, rise of 56%. Bipolar disorder related hospitalization was more prevalent among female adolescents and adults, while male children had larger risk than female children. Children's BD diagnoses tended not to specify a prevailing mood state, while depression and psychotic features were the most common codes for adults. Black individuals, especially men, had lower rates of BD diagnoses in early survey years, but more recently their rate of BD related hospitalizations has exceeded other NHDS race groups.

CONCLUSIONS

Higher rates of inpatient admissions among youth associated with BD may reflect greater appreciation of the importance of affective dysregulation in this patient group or "upcoding" to putatively more severe conditions for reimbursement or administrative reasons. Further study is warranted to examine this shift's causes and implications for treatments and outcomes.