Temporal change in N-acetyl-aspartate concentrations in adolescents with bipolar depression treated with lithium

Functional Connectivity of the Cerebellar Vermis in Bipolar Disorder and Associations with Mood

Purpose

Studies of the neural underpinnings of bipolar type I disorder have focused on the emotional control network. However, there is also growing evidence for cerebellar involvement, including abnormal structure, function, and metabolism. Here, we sought to assess functional connectivity of the cerebellum with the cerebrum in bipolar disorder and to assess whether any effects might depend on mood.

Methods

This cross-sectional study enrolled 128 participants with bipolar type I disorder and 83 control comparison participants who completed a 3T MRI scan, which included anatomical imaging as well as resting state BOLD imaging. Functional connectivity of the cerebellar vermis to all other brain regions was assessed. Based on quality control metrics of the fMRI data, 109 participants with bipolar disorder and 79 controls were used to in the statistical analysis comparing connectivity of the vermis as well as associations with mood. Potential impacts of medications were also explored.

Results

Functional connectivity of the cerebellar vermis in bipolar disorder was found to differ significantly between brain regions known to be involved in the control of emotion, motor function, and language. While connections with emotion and motor control areas were significantly stronger in bipolar disorder, connection to a region associated language production was significantly weaker. In the participants with bipolar disorder, ratings of depression and mania were inversely associated with vermis functional connectivity. No effect of medications on these connections were observed.

Conclusion

Together the findings suggest cerebellum may play a compensatory role in bipolar disorder and when it can no longer fulfill this role, depression and mania develop. The proximity of the cerebellar vermis to the skull may make this region a potential target for treatment with transcranial magnetic stimulation.

Anterior cingulate cortex neuro-metabolic changes underlying lithium-induced euthymia in bipolar depression: A longitudinal 1H-MRS study

The diagnosis and treatment of bipolar depression (BDep) poses complex clinical challenges for psychiatry. Proton magnetic resonance spectroscopy (¹H-MRS) is a useful imaging tool for investigating in vivo levels of brain neuro-metabolites, critical to understanding the process of mood dysregulation in Bipolar Disorder. Few studies have evaluated longitudinal clinical outcomes in BDep associated with ¹H-MRS metabolic changes. This study aimed to longitudinally assess brain ¹H-MRS metabolites in the anterior cingulate cortex (ACC) correlated with improvement in depression (from BDep to euthymia) after lithium treatment in BDep patients versus matched healthy controls (HC). Twenty-eight medication-free BDep patients and 28 HC, matched for age and gender, were included in this study. All subjects were submitted to a 3-Tesla brain ¹H-MRS scan in the ACC using a single-voxel (8cm³) PRESS sequence at baseline. At follow-up (6 weeks), 14 BDep patients repeated the exam in euthymia. Patients with current BDep had higher baseline Myo-inositol/Cr (mI/Cr) and Choline/Cr (Cho/Cr) compared to HC. After six weeks, mI/Cr or Cho/Cr levels in subjects that achieved euthymia no longer differed to levels in HC, while high Cho/Cr levels persisted in non-responders . Elevated ACC mI/Cr and Cho/Cr in BDep might indicate increased abnormal membrane phospholipid metabolism and phosphatidylinositol (PI) cycle activity. Return of mI/Cr and Cho/Cr to normal levels after lithium-induced euthymia suggests a critical regulatory effect of lithium targeting the PI cycle involved in mood regulation.

Lithium-associated anterior cingulate neurometabolic profile in euthymic Bipolar I disorder: A 1H-MRS study

OBJECTIVE

In the treatment of Bipolar disorder (BD), achieving euthymia is highly complex and usually requires a combination of mood stabilizers. The mechanism of action in stabilizing mood has not been fully elucidated, but alterations in N-Acetylaspartate (NAA), Myo-Inositol (mI) and Choline (Cho) have been implicated. Proton magnetic resonance spectroscopy (¹H-MRS) is the gold standard technique for measuring brain NAA, Cho and mI in vivo. The objective of this study was to investigate the association of lithium use in BD type I and brain levels of NAA, mI and Cho in the (anterior cingulate cortex) ACC.

METHODS

129 BD type I subjects and 79 healthy controls (HC) were submitted to a 3-Tesla brain magnetic resonance imaging scan (¹H-MRS) using a PRESS ACC single voxel (8cm³) sequence.

RESULTS

BD patients exhibited higher NAA and Cho levels compared to HC. Lithium prescription was associated with lower mI (combination + monotherapy) and higher NAA levels (monotherapy).

CONCLUSION

The results observed add to the knowledge about the mechanisms of action of mood stabilizers on brain metabolites during euthymia. Additionally, the observed decrease in mI levels associated with lithium monotherapy is an in vivo finding that supports the inositol-depletion hypothesis of lithium pharmacodynamics.

Lithium, Stress, and Resilience in Bipolar Disorder: Deciphering this key homeostatic synaptic plasticity regulator

BACKGROUND

Lithium is the lightest metal and the only mood stabilizer that has been used for over half a century for the treatment of bipolar disorder (BD). As a small ion, lithium is omnipresent, and consequently, its molecular mechanisms and targets are widespread. Currently, lithium is a crucial pharmacotherapy for the treatment of acute mood episodes, prophylactic therapy, and suicide prevention in BD. Besides, lithium blood level is the most widely used biomarker in clinical psychiatry. The concept of stress in BD characterizes short- and long-term deleterious effects at multiple levels (from genes to behaviors) and the ability to establish homeostatic regulatory mechanisms to either prevent or reverse these effects. Within this concept, lithium has consistently shown anti-stress effects, by normalizing components across several levels associated with BD-induced impairments in cellular resilience and plasticity.

METHODS

A literature search for biomarkers associated with lithium effects at multiple targets, with a particular focus on those related to clinical outcomes was performed. An extensive search of the published literature using PubMed, Medline and Google Scholar was performed. Example search terms included lithium, plasticity, stress, efficacy, and neuroimaging. Articles determined by the author to focus on lithium's impact on neural plasticity markers (central and periphery) and clinical outcomes were examined in greater depth. Relevant papers were evaluated, selected and included in this review.

RESULTS

Lithium induces neurotrophic and neuroprotective effects in a wide range of preclinical and translational models. Lithium's neurotrophic effects are related to the enhancement of cellular proliferation, differentiation, growth, and regeneration, whereas its neuroprotective effects limit the progression of neuronal atrophy or cell death following the onset of BD. Lithium's neurotrophic and neuroprotective effects seem most pronounced in the presence of pathology, which again supports its pivotal role as an active homeostatic regulator.

LIMITATIONS

Few studies associated with clinical outcomes. Due to space limitations, the author was unable to detail all findings, in special those originated from preclinical studies.

CONCLUSIONS

These results support a potential role for biomarkers involved in neuroprotection and activation of plasticity pathways in lithium's clinical response. Evidence supporting this model comes from results evaluating macroscopic and microscopic brain structure as well neurochemical findings in vivo from cellular to sub-synaptic (molecules and intracellular signaling) compartments using central and peripheral biomarkers. Challenges to precisely decipher lithium's biological mechanisms involved in its therapeutic profile include the complex nature of the illness and clinical subtypes, family history and comorbid conditions. In the context of personalized medicine, it is necessary to validate predictive biomarkers of response to lithium by designing longitudinal clinical studies during mood episodes and associated clinical dimensions in BD.

Proton magnetic resonance spectroscopy changes after lithium treatment. Systematic review

1H MRS is widely used in the research of mental disorders. It enables evaluation of concentration or ratios of several metabolites, which play important roles in brain metabolism: N-acetylaspartate (NAA), choline containing compounds, myo-inositol and glutamate, glutamine and GABA (together as Glx complex or separately). Specifically in bipolar disorder brain metabolite abnormalities include mostly NAA reduces and Glx increases in different brain regions. Bipolar disorder is associated with impairment in neurotrophic and cellular plasticity, resilience pathways and in neuroprotective processes. Lithium, which is commonly used in BD treatment, modulates neurotransmitter release, reduces oxidative stress and apoptosis, induces angiogenesis, neurogenesis and neurotrophic response. Thus brain metabolite abnormalities may elucidate the mechanisms of this processes. In the present article we systematically reviewed 26 studies - the majority of them investigated bipolar disorder ( 7 follow-up and all 11 cross-sectional studies). Moreover we dispute whether the influence of lithium on brain metabolites in bipolar disorder could explain the background of its potential neuroprotective action. The results of our literature review do not equivocally confirm Lithium's influence the metabolite changes in the brain. The majority of the follow-up studies do not support the initially assumed influence of Lithium on the increase of NAA level in various brain structures. The results of studies are inconclusive with regard to levels of Glx or Glu and Lithium intake, rather point a lack of relationship. The above results were reviewed according to the most recent theories in the field accounting for the impact of lithium (1)HMRS measures.

The International Society for Bipolar Disorders Task Force report on pediatric bipolar disorder: Knowledge to date and directions for future research

OBJECTIVES

Over the past two decades, there has been tremendous growth in research regarding bipolar disorder (BD) among children and adolescents (ie, pediatric BD [PBD]). The primary purpose of this article is to distill the extant literature, dispel myths or exaggerated assertions in the field, and disseminate clinically relevant findings.

METHODS

An international group of experts completed a selective review of the literature, emphasizing areas of consensus, identifying limitations and gaps in the literature, and highlighting future directions to mitigate these gaps.

RESULTS

Substantial, and increasingly international, research has accumulated regarding the phenomenology, differential diagnosis, course, treatment, and neurobiology of PBD. Prior division around the role of irritability and of screening tools in diagnosis has largely abated. Gold-standard pharmacologic trials inform treatment of manic/mixed episodes, whereas fewer data address bipolar depression and maintenance/continuation treatment. Adjunctive psychosocial treatment provides a forum for psychoeducation and targets primarily depressive symptoms. Numerous neurocognitive and neuroimaging studies, and increasing peripheral biomarker studies, largely converge with prior findings from adults with BD.

CONCLUSIONS

As data have accumulated and controversy has dissipated, the field has moved past existential questions about PBD toward defining and pursuing pressing clinical and scientific priorities that remain. The overall body of evidence supports the position that perceptions about marked international (US vs elsewhere) and developmental (pediatric vs adult) differences have been overstated, although additional research on these topics is warranted. Traction toward improved outcomes will be supported by continued emphasis on pathophysiology and novel therapeutics.

Clinical neuroimaging markers of response to treatment in mood disorders

Mood disorders (MD) are important and frequent psychiatric illness. The management of patients affected by these conditions represents an important factor of disability as well as a significant social and economic burden. The "in-vivo" studies can help researchers to understand the first developmental events of the pathology and to identify the molecular and non-molecular targets of therapies. However, they have strong limitations due to the fact that human brain circuitry can not be reproduced in animal models. In addition, these neural pathways are difficult to be selectively studied with the modern imaging (such as Magnetic Resonance and Positron Emitted Tomography/Computed Tomography) and non-imaging (such as electroencephalography, magnetoencephalography, transcranial magnetic stimulation and evoked potentials) methods. In comparison with other methods, the "in-vivo" imaging investigations have higher temporal and spatial resolution compared to the "in-vivo" non-imaging techniques. All these factors make difficult to fully understand the aetiology and pathophysiology of these disorders, and consequently hinder the analysis of the effects of pharmacological and non-pharmacological therapies, which have been demonstrated effective in clinical settings. In this review, we will focus our attention on the current state of the art of imaging in the assessment of treatment efficacy in MD. We will analyse briefly the actual classification of MD; then we will focus on the "in vivo" imaging methods used in research and clinical activity, the current knowledge about the neural models at the base of MD. Finally the last part of the review will focus on the analysis of the main markers of response to treatment.

A Longitudinal (6-week) 3T (1)H-MRS Study on the Effects of Lithium Treatment on Anterior Cingulate Cortex Metabolites in Bipolar Depression

The anterior cingulate cortex (ACC) is a key area in mood regulation. To date, no longitudinal study has specifically evaluated lithium׳s effects on ACC metabolites using (1)H-MRS, as well as its association with clinical improvement in bipolar depression. This (1)H-MRS (TE=35ms) study evaluated 24 drug-free BD patients during depressive episodes and after lithium treatment at therapeutic levels. Brain metabolite levels (N-acetyl aspartate (NAA), creatine (tCr), choline, myo-inositol, and glutamate levels) were measured in the ACC at baseline (week 0) and after lithium monotherapy (week 6). The present investigation showed that ACC glutamate (Glu/tCr) and glutamate+glutamine (Glx/tCr) significantly increased after six weeks of lithium therapy. Regarding the association with clinical improvement, remitters showed an increase in myoinositol levels (mI/tCr) after lithium treatment compared to non-remitters. The present findings reinforce a role for ACC glutamate-glutamine cycling and myoinositol pathway as key targets for lithium׳s therapeutic effects in BD.

Using neuroimaging to evaluate and guide pharmacological and psychotherapeutic treatments for mood disorders in children

Mood disorders are increasing in childhood, and often require multimodal and comprehensive treatment plans to address a complex array of symptoms and associated morbidities. Pharmacotherapy, in combination with psychotherapeutic interventions, is essential for treatment and stabilization. Current evidence supports the use of a number of interventions in children and adolescents diagnosed with DSM-5 mood spectrum disorders, which are associated with impairments in prefrontal-striatal-limbic networks, which are key for emotional functioning and regulation. Yet, little is known about the neurobiological effects of interventions on the developing brain. This chapter provides a synopsis of the literature demonstrating the neural effects of psychotropic medications and psychotherapy in youth with depressive or bipolar spectrum disorders. Additional longitudinal and biological studies are warranted to characterize the effects of these interventions on all phases and stages of mood illness development in children and adolescents.

Effects of lithium on cortical thickness and hippocampal subfield volumes in psychotic bipolar disorder

Relative to healthy controls, lithium free bipolar patients exhibit significant gray matter abnormalities. Lithium, the long-time reference standard medication treatment for bipolar disorder, has been proposed to be neuro-protective against these abnormalities. However, its effects on cortical thickness and hippocampal subfield (HSF) volumes remain unstudied and unclear, respectively, in bipolar disorder. This study included 342 healthy controls (HC), 51 lithium free PBD patients (NoLi), and 51 PBD patients taking lithium (Li). Regional gray matter thickness and HSF volume values were extracted from 3T MRI images. After matching NoLi and Li samples, regions where HC differed from either Li or NoLi were identified. In regions of significant or trending HC-NoLi difference, Li-NoLi comparisons were made. No significant HC-Li thickness or HSF volume differences were found. Significantly thinner occipital cortices were observed in NoLi compared to HC. In these regions, Li consistently exhibited non-significant trends for greater cortical thickness relative to NoLi. Significantly less volume was observed in NoLi compared to both HC and Li in right HSFs. Our results suggest that PBD in patients not treated with Li is associated with thinner occipital cortices and reduced HSF volumes compared with HC. Patients treated with Li exhibited significantly larger HSF volumes than NoLi, and those treated with Li were no different from HC in cortical thickness or hippocampal volumes. This evidence directly supports the hypothesis that Li may counteract the locally thinner and smaller gray matter structure found in PBD.

Clinical characteristics associated with lithium use among adolescents with bipolar disorder

OBJECTIVE

Little is known regarding demographic and/or clinical characteristics associated with the use of lithium among adolescents with bipolar disorder (BP) in naturalistic clinical settings. We therefore examined factors associated with lithium among adolescents with BP presenting to a tertiary outpatient clinic.

METHODS

Participants were 100 adolescents 13-19 years of age, with BP-I, BP-II, or BP not otherwise specified (BP-NOS). Diagnoses and lifetime medication exposure were determined using the Schedule for Affective Disorders and Schizophrenia for School Age Children, Present and Lifetime Version (KSADS-PL). Analyses examined for demographic and clinical correlates of lifetime lithium exposure.

RESULTS

Twenty percent of participants reported lifetime lithium use. Participants with, versus those without, lifetime lithium use were significantly older and significantly more likely to have BP-I, lifetime history of psychiatric hospitalization, and psychosis. Lithium-treated participants were significantly more likely to report use of second-generation antipsychotics (SGAs) and antimanic anticonvulsants. In contrast, participants with lithium exposure were significantly less likely to have BP-II, self-injurious behavior, and a family history of depression. Adolescents with lithium exposure had significantly less parent-reported family conflict and mood lability, and significantly less self-reported impulsivity, emotional dysregulation, identity confusion, and interpersonal problems. In multivariable analyses, lithium use was associated with greater lifetime SGA use, lower parent-reported family conflict, and lower adolescent-reported interpersonal problems.

CONCLUSIONS

Lithium was infrequently used among adolescents with BP in this sample. Although constrained by retrospective methodology and a single site, our findings suggest that clinicians may be deferring lithium use until late in treatment. The fact that there are lower rates of lithium use among adolescents with suicidal ideation, impulsivity, mood lability, and family history of depression suggests potential missed opportunities for use of lithium among high-risk adolescents with BP.

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.

(1)H-MRS of hippocampus in patients after first manic episode

OBJECTIVES

The investigation of the pathophysiology of bipolar disorder in patients at disease onset is a strategy to avoid the confounding effect of progression of disease or duration of treatment. Our purpose was to investigate in vivo neuronal metabolites in the hippocampus of bipolar disorder patients using proton magnetic resonance spectroscopy ((1)H-MRS) within 3 months after their first manic episode.

METHODS

Fifty-eight BD I patients meeting DSM-IV criteria following their first episode of mania and 27 healthy subjects were studied using (1)H-MRS with a 3.0 T Philips Achieva scanner. Voxels with 30 × 15 × 15 mm were placed in the hippocampus on both sides of the brain and the signal was collected using a PRESS sequence with TE = 35 ms and TR = 2000 ms. Data analysis was performed using the LC Model software.

RESULTS

N-Acetyl-aspartate (NAA), choline (Cho), myo-inositol (mI), creatine (Cre) and glutamine + glutamate (Glx) levels were compared between the groups and no statistically significant differences were found.

CONCLUSIONS

Our results suggest that early in the course of BD there are no alterations in neuronal metabolism or vulnerability in the hippocampus after the first manic episode.

Prospective neurochemical characterization of child offspring of parents with bipolar disorder

We wished to determine whether decreases in N-acetyl aspartate (NAA) and increases in myoinositol (mI) concentrations as a ratio of creatine (Cr) occurred in the dorsolateral prefrontal cortex (DLPFC) of pediatric offspring of parents with bipolar disorder (BD) and a healthy comparison group (HC) over a 5-year period using proton magnetic resonance spectroscopy ((1)H-MRS). Paticipants comprised 64 offspring (9-18 years old) of parents with BD (36 with established BD, and 28 offspring with symptoms subsyndromal to mania) and 28 HCs, who were examined for group differences in NAA/Cr and mI/Cr in the DLPFC at baseline and follow-up at either 8, 10, 12, 52, 104, 156, 208, or 260 weeks. No significant group differences were found in metabolite concentrations at baseline or over time. At baseline, BD offspring had trends for higher mI/Cr concentrations in the right DLPFC than the HC group. mI/Cr concentrations increased with age, but no statistically significant group differences were found between groups on follow-up. It may be the case that with intervention youth at risk for BD are normalizing otherwise potentially aberrant neurochemical trajectories in the DLPFC. A longer period of follow-up may be required before observing any group differences.

Biomarkers in bipolar disorder: a positional paper from the International Society for Bipolar Disorders Biomarkers Task Force

Although the etiology of bipolar disorder remains uncertain, multiple studies examining neuroimaging, peripheral markers and genetics have provided important insights into the pathophysiologic processes underlying bipolar disorder. Neuroimaging studies have consistently demonstrated loss of gray matter, as well as altered activation of subcortical, anterior temporal and ventral prefrontal regions in response to emotional stimuli in bipolar disorder. Genetics studies have identified several potential candidate genes associated with increased risk for developing bipolar disorder that involve circadian rhythm, neuronal development and calcium metabolism. Notably, several groups have found decreased levels of neurotrophic factors and increased pro-inflammatory cytokines and oxidative stress markers. Together these findings provide the background for the identification of potential biomarkers for vulnerability, disease expression and to help understand the course of illness and treatment response. In other areas of medicine, validated biomarkers now inform clinical decision-making. Although the findings reviewed herein hold promise, further research involving large collaborative studies is needed to validate these potential biomarkers prior to employing them for clinical purposes. Therefore, in this positional paper from the ISBD-BIONET (biomarkers network from the International Society for Bipolar Disorders), we will discuss our view of biomarkers for these three areas: neuroimaging, peripheral measurements and genetics; and conclude the paper with our position for the next steps in the search for biomarkers for bipolar disorder.

The Neural Effects of Psychotropic Medications in Children and Adolescents

Little is known about the neurobiological effects of psychotropic medications used in the treatment of children and adolescents diagnosed with a psychiatric disorder. This review provides a synopsis of the literature demonstrating the neural effects associated with exposure to psychotropic medication in youth using multimodal neuroimaging. The article concludes by illustrating how, taken together, these studies suggest that pharmacological interventions during childhood do indeed affect brain structure and function in a detectable manner, and the effects appear to be ameliorative.

Frontal lobe bioenergetic metabolism in depressed adolescents with bipolar disorder: a phosphorus-31 magnetic resonance spectroscopy study

OBJECTIVES

To compare the concentrations of high-energy phosphorus metabolites associated with mitochondrial function in the frontal lobe of depressed adolescents with bipolar disorder (BD) and healthy controls (HC).

METHODS

We used in vivo phosphorus-31 magnetic resonance spectroscopy ((31) P-MRS) at 3 Tesla to measure phosphocreatine (PCr), beta-nucleoside triphosphate (β-NTP), inorganic phosphate (Pi), and other neurometabolites in the frontal lobe of eight unmedicated and six medicated adolescents with bipolar depression and 24 adolescent HCs.

RESULTS

Analysis of covariance, including age as a covariate, revealed differences in PCr (p=0.037), Pi (p=0.017), and PCr/Pi (p=0.002) between participant groups. Percentage neurochemical differences were calculated with respect to mean metabolite concentrations in the HC group. Post-hoc Tukey-Kramer analysis showed that unmedicated BD participants had decreased Pi compared with both HC (17%; p=0.038) and medicated BD (24%; p=0.022). The unmedicated BD group had increased PCr compared with medicated BD (11%; p=0.032). The PCr/Pi ratio was increased in unmedicated BD compared with HC (24%; p=0.013) and with medicated BD (39%; p=0.002). No differences in β-NTP or pH were observed.

CONCLUSIONS

Our results support the view that frontal lobe mitochondrial function is altered in adolescent BD and may have implications for the use of Pi as a biomarker. These findings join volumetric studies of the amygdala, and proton MRS studies of n-acetyl aspartate in pointing to potential differences in neurobiology between pediatric and adult BD.

Smaller hippocampal volumes in patients with bipolar disorder are masked by exposure to lithium: a meta-analysis

BACKGROUND

Smaller hippocampal volumes relative to controls are among the most replicated neuroimaging findings in individuals with unipolar but not bipolar depression. Preserved hippocampal volumes in most studies of participants with bipolar disorder may reflect potential neuroprotective effects of lithium (Li).

METHODS

To investigate hippocampal volumes in patients with bipolar disorder while controlling for Li exposure, we performed a meta-analysis of neuroimaging studies that subdivided patients based on the presence or absence of current Li treatment. To achieve the best coverage of literature, we categorized studies based on whether all or a majority, or whether no or a minority of patients were treated with Li. Hippocampal volumes were compared by combining standardized differences between means (Cohen d) from individual studies using random-effects models.

RESULTS

Overall, we analyzed data from 101 patients with bipolar disorder in the Li group, 245 patients in the non-Li group and 456 control participants from 16 studies. Both the left and right hippocampal volumes were significantly larger in the Li group than in controls (Cohen d = 0.53, 95% confidence interval [CI] 0.18 to 0.88; Cohen d = 0.51, 95% CI 0.21 to 0.81, respectively) or the non-Li group (Cohen d = 0.93, 95% CI 0.56 to 1.31; Cohen d = 1.07, 95% CI 0.70 to 1.45, respectively), which had smaller left and right hippocampal volumes than the control group (Cohen d = -0.36, 95% CI -0.55 to -0.17; Cohen d = -0.38, 95% CI -0.63 to -0.13, respectively). There was no evidence of publication bias.

LIMITATIONS

Missing information about the illness burden or lifetime exposure to Li and polypharmacy in some studies may have contributed to statistical heterogeneity in some analyses.

CONCLUSION

When exposure to Li was minimized, patients with bipolar disorder showed smaller hippocampal volumes than controls or Li-treated patients. Our findings provide indirect support for the negative effects of bipolar disorder on hippocampal volumes and are consistent with the putative neuroprotective effects of Li. The preserved hippocampal volumes among patients with bipolar disorder in most individual studies and all previous meta-analyses may have been related to the inclusion of Li-treated participants.

Neurometabolite effects of response to quetiapine and placebo in adolescents with bipolar depression

OBJECTIVE

Mood stabilizers have been reported to affect brain concentrations of myo-inositol (mI) and N-acetylaspartate (NAA). We examined the effects of quetiapine (QUET), an atypical antipsychotic, on these neurochemicals, and potential predictors of response to QUET in adolescents with bipolar depression.

METHODS

Twenty-six adolescents with bipolar depression participated in an 8-week placebo-controlled trial of QUET monotherapy. Subjects were scanned at baseline and after 8 weeks with proton magnetic resonance spectroscopy (1H-MRS) at 3T and 4T at two sites, with 8 cm(3) voxels placed in the right and left dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC). LCModel was used to calculate absolute concentrations of NAA and mI.

RESULTS

Twenty-six subjects had pre- and posttreatment scans (mean age=15.6 years, 9 boys). Of these subjects, 5 out of 16 subjects receiving QUET and 5 out of 10 receiving placebo (PBO) were responders (50% decrease in Children's Depression Rating Scale [CDRS] score). Although baseline ACC mI did not predict responder status, responders had significantly lower posttreatment ACC mI values than did nonresponders (3.27±.71 vs. 4.23±.70; p=0.004). There were no significant differences in the changes in ACC and DLPFC NAA levels in the QUET group compared with the PBO group (ACC: -0.55±1.3 vs.+0.25±1.5, p=0.23; right-DLPFC: -0.55±1.3 vs. 0.33±0.89, p=0.13; left-DLPFC: -0.04±0.91 vs.+0.29±0.61, p=0.41).

CONCLUSION

We found that posttreatment, not baseline, ACC mI levels were associated with response to QUET in adolescents with bipolar depression. There were no differences in NAA concentration changes between the QUET and PBO groups. Larger studies including different brain regions would help to clarify the effects of QUET on neurochemistry in patients with bipolar disorder.

Large positive effect of lithium on prefrontal cortex N-acetylaspartate in patients with bipolar disorder: 2-centre study

BACKGROUND

Neuroprotective effects of lithium (Li) have been well documented in tissue cultures and animal models, whereas human data continue to be limited. Previous studies investigating the association between Li treatment and brain N-acetylaspartate (NAA), a putative neuronal marker, showed mixed results because of methodological heterogeneity.

METHODS

To investigate the effects of Li on prefrontal cortex NAA levels, we compared patients with bipolar disorder from specialized Li clinics in Berlin and Halifax with at least 2 years of ongoing Li treatment (Li group), patients with lifetime Li exposure of less than 3 months more than 2 years ago (non-Li group) and healthy controls. Participants in both patient groups had at least 10 years of illness and 5 episodes. We measured left prefrontal NAA levels using 1.5-T magnetic resonance spectroscopy.

RESULTS

We enrolled 27 participants in the Li, 16 in the non-Li and 21 in the healthy control groups. The non-Li group had lower prefrontal NAA levels than the Li group (t41 = -3.44, corrected p < 0.01) or control participants (t35 = -2.91, corrected p < 0.05), who did not differ from the Li group (t46 = -0.14, p = 0.89). The same pattern of prefrontal NAA differences was replicated in both sites. In addition, there was a negative correlation between prefrontal NAA and duration of illness in the non-Li group (r = -0.60, p = 0.019) but not in the Li group (r = 0.07, p = 0.74).

LIMITATIONS

Study limitations include the crosssectional design and exposure to other medications.

CONCLUSION

Whereas patients with bipolar disorder, substantial illness burden and limited lifetime Li exposure had significantly lower prefrontal NAA levels than controls, Li-treated patients with similar illness burden showed prefrontal NAA levels comparable to those of healthy controls. These findings provide indirect support for neuroprotective effects of Li and for negative effects of illness burden on prefrontal NAA levels in patients with bipolar disorder.

MR spectroscopic studies of the brain in psychiatric disorders

The measurement of brain metabolites with magnetic resonance spectroscopy (MRS) provides a unique perspective on the brain bases of neuropsychiatric disorders. As a context for interpreting MRS studies of neuropsychiatric disorders, we review the characteristic MRS signals, the metabolic dynamics,and the neurobiological significance of the major brain metabolites that can be measured using clinical MRS systems. These metabolites include N-acetylaspartate(NAA), creatine, choline-containing compounds, myo-inositol, glutamate and glutamine, lactate, and gamma-amino butyric acid (GABA). For the major adult neuropsychiatric disorders (schizophrenia, bipolar disorder, major depression, and the anxiety disorders), we highlight the most consistent MRS findings, with an emphasis on those with potential clinical or translational significance. Reduced NAA in specific brain regions in schizophrenia, bipolar disorder, post-traumatic stress disorder, and obsessive–compulsive disorder corroborate findings of reduced brain volumes in the same regions. Future MRS studies may help determine the extent to which the neuronal dysfunction suggested by these findings is reversible in these disorders. Elevated glutamate and glutamine (Glx) in patients with bipolar disorder and reduced Glx in patients with unipolar major depression support models of increased and decreased glutamatergic function, respectively, in those conditions. Reduced phosphomonoesters and intracellular pH in bipolar disorder and elevated dynamic lactate responses in panic disorder are consistent with metabolic models of pathogenesis in those disorders. Preliminary findings of an increased glutamine/glutamate ratio and decreased GABA in patients with schizophrenia are consistent with a model of NMDA hypofunction in that disorder. As MRS methods continue to improve, future studies may further advance our understanding of the natural history of psychiatric illnesses, improve our ability to test translational models of pathogenesis, clarify therapeutic mechanisms of action,and allow clinical monitoring of the effects of interventions on brain metabolicmarkers

Pediatric sports-related concussion produces cerebral blood flow alterations

OBJECTIVES

The pathophysiology of sports-related concussion (SRC) is incompletely understood. Human adult and experimental animal investigations have revealed structural axonal injuries, decreases in the neuronal metabolite N-acetyl aspartate, and reduced cerebral blood flow (CBF) after SRC and minor traumatic brain injury. The authors of this investigation explore these possibilities after pediatric SRC.

PATIENTS AND METHODS

Twelve children, ages 11 to 15 years, who experienced SRC were evaluated by ImPACT neurocognitive testing, T1 and susceptibility weighted MRI, diffusion tensor imaging, proton magnetic resonance spectroscopy, and phase contrast angiography at <72 hours, 14 days, and 30 days or greater after concussion. A similar number of age- and gender-matched controls were evaluated at a single time point.

RESULTS

ImPACT results confirmed statistically significant differences in initial total symptom score and reaction time between the SRC and control groups, resolving by 14 days for total symptom score and 30 days for reaction time. No evidence of structural injury was found on qualitative review of MRI. No decreases in neuronal metabolite N-acetyl aspartate or elevation of lactic acid were detected by proton magnetic resonance spectroscopy. Statistically significant alterations in CBF were documented in the SRC group, with reduction in CBF predominating (38 vs 48 mL/100 g per minute; P = .027). Improvement toward control values occurred in only 27% of the participants at 14 days and 64% at >30 days after SRC.

CONCLUSIONS

Pediatric SRC is primarily a physiologic injury, affecting CBF significantly without evidence of measurable structural, metabolic neuronal or axonal injury. Further study of CBF mechanisms is needed to explain patterns of recovery.

Abnormal cingulate and prefrontal cortical neurochemistry in major depression after electroconvulsive therapy

BACKGROUND

Metabolic changes after electroconvulsive therapy (ECT) have been described in depressed patients, but results are heterogeneous. To determine the concentrations of N-acetyl-aspartate (NAA), choline-containing compounds, creatine + phosphocreatine (tCr), and glutamate in the left dorsolateral prefrontal cortex (DLPFC) and left anterior cingulum of depressed patients before and after ECT, we used proton magnetic resonance spectroscopy.

METHODS

Metabolite concentrations in the DLPFC and anterior cingulum were determined in 25 patients with major depressive disorder (MDD) and 27 healthy control subjects using the point resolved spectroscopy sequence. Neuropsychological and clinical parameters were determined before and after nine sessions of right unilateral ultrabrief pulse ECT.

RESULTS

In the cingulum, baseline glutamate and NAA levels were decreased in depressed patients. High glutamate at baseline predicted a greater treatment response. After ECT, increased NAA levels were observed in responders to treatment and tCr levels were significantly decreased across all depressive patients. In the left DLPFC, NAA levels were significantly decreased in responders to ECT compared with nonresponders. Autobiographic memory was deteriorated in all patients after ECT.

CONCLUSIONS

Low glutamatergic state in depressive patients emphasizes the role of dysfunctional glutamatergic neurotransmission in the pathophysiology of MDD. The low NAA level at baseline in the patients supports neurodegenerative changes in MDD. N-acetyl-aspartate levels might serve as early surrogate marker for dynamic metabolic changes due to ECT, reflecting both neuroprotection and lowered neuronal viability. The tCr decrease in the cingulum suggests altered mitochondrial energy metabolism.

Lower N-acetyl-aspartate levels in prefrontal cortices in pediatric bipolar disorder: a ¹H magnetic resonance spectroscopy study

OBJECTIVE

The few studies applying single-voxel ¹H spectroscopy in children and adolescents with bipolar disorder (BD) have reported low N-acetyl-aspartate (NAA) levels in the dorsolateral prefrontal cortex (DLPFC), and high myo-inositol / phosphocreatine plus creatine (PCr+Cr) ratios in the anterior cingulate. The aim of this study was to evaluate NAA, glycerophosphocholine plus phosphocholine (GPC+PC) and PCr+Cr in various frontal cortical areas in children and adolescents with BD. We hypothesized that NAA levels within the prefrontal cortex are lower in BD patients than in healthy controls, indicating neurodevelopmental alterations in the former.

METHOD

We studied 43 pediatric patients with DSM-IV BD (19 female, mean age 13.2 ± 2.9 years) and 38 healthy controls (19 female, mean age 13.9 ± 2.7 years). We conducted multivoxel in vivo ¹H spectroscopy measurements at 1.5 Tesla using a long echo time of 272 ms to obtain bilateral metabolite levels from the medial prefrontal cortex (MPFC), DLPFC (white and gray matter), cingulate (anterior and posterior), and occipital lobes. We used the nonparametric Mann-Whitney U test to compare neurochemical levels between groups.

RESULTS

In pediatric BD patients, NAA and GPC+PC levels in the bilateral MPFC, and PCr+Cr levels in the left MPFC were lower than those seen in the controls. In the left DLPFC white matter, levels of NAA and PCr+Cr were also lower in BD patients than in controls.

CONCLUSIONS

Lower NAA and PCr+Cr levels in the PFC of children and adolescents with BD may be indicative of abnormal dendritic arborization and neuropil, suggesting neurodevelopmental abnormalities.

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.

Review: magnetic resonance spectroscopy studies of pediatric major depressive disorder

Introduction. This paper focuses on the application of Magnetic Resonance Spectroscopy (MRS) to the study of Major Depressive Disorder (MDD) in children and adolescents. Method. A literature search using the National Institutes of Health's PubMed database was conducted to identify indexed peer-reviewed MRS studies in pediatric patients with MDD. Results. The literature search yielded 18 articles reporting original MRS data in pediatric MDD. Neurochemical alterations in Choline, Glutamate, and N-Acetyl Aspartate are associated with pediatric MDD, suggesting pathophysiologic continuity with adult MDD. Conclusions. The MRS literature in pediatric MDD is modest but growing. In studies that are methodologically comparable, the results have been consistent. Because it offers a noninvasive and repeatable measurement of relevant in vivo brain chemistry, MRS has the potential to provide insights into the pathophysiology of MDD as well as the mediators and moderators of treatment response.

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.

Brain glutamatergic characteristics of pediatric offspring of parents with bipolar disorder

We wished to determine whether decreases in prefrontal glutamate concentrations occur in offspring of parents with bipolar disorder with and at high risk for mania. Sixty children and adolescents, 9-18 years old, of parents with bipolar I or II disorder (20 offspring with established history of mania, "BD", 20 offspring with symptoms subsyndromal to mania, "SS", and 20 healthy controls "HC") were examined using proton magnetic resonance spectroscopy at 3T to study glutamatergic metabolite concentrations in the anterior cingulate cortex (ACC). A signal for reductions in absolute glutamate concentrations in the ACC was seen in the BD compared with HC and SS groups. No other statistically significant differences among groups were found. Offspring of parents with BD with prior histories of mania may have disruptions in glutamatergic function compared with HC or children at risk for BD who have not yet developed mania. Longitudinal studies are necessary to confirm whether prefrontal glutamate decreases only after the onset of full mania.

Effect of divalproex on brain morphometry, chemistry, and function in youth at high-risk for bipolar disorder: a pilot study

OBJECTIVE

Divalproex has been found efficacious in treating adolescents with and at high risk for bipolar disorder (BD), but little is known about the effects of mood stabilizers on the brain itself. We sought to examine the effects of divalproex on the structure, chemistry, and function of specific brain regions in children at high-risk for BD.

METHODS

A total of 24 children with mood dysregulation but not full BD, all offspring of a parent with BD, were treated with divalproex monotherapy for 12 weeks. A subset of 11 subjects and 6 healthy controls were scanned with magnetic resonance imaging (MRI, magnetic resonance spectroscopy [MRS], and functional MRI [fMRI]) at baseline and after 12 weeks.

RESULTS

There were no significant changes in amygdalar or cortical volume found over 12 weeks. Furthermore, no changes in neurometabolite ratios were found. However, we found the degree of decrease in prefrontal brain activation to correlate with degree of decrease in depressive symptom severity.

CONCLUSIONS

Bipolar offspring at high risk for BD did not show gross morphometric, neurometabolite, or functional changes after 12 weeks of treatment with divalproex. Potential reasons include small sample size, short exposure to medications, or lack of significant neurobiological impact of divalproex in this particular population.

Randomized double-blind placebo-controlled trial of lithium in youths with severe mood dysregulation

OBJECTIVE

The diagnosis and treatment of youth with severe nonepisodic irritability and hyperarousal, a syndrome defined as severe mood dysregulation (SMD) by Leibenluft, has been the focus of increasing concern. We conducted the first randomized double-blind, placebo-controlled trial in SMD youth, choosing lithium on the basis of its potential in treating irritability and aggression and neuro-metabolic effects.

METHODS

SMD youths 7-17 years were tapered off their medications. Those who continued to meet SMD criteria after a 2-week, single-blind, placebo run-in were randomized to a 6-week double-blind trial of either lithium (n = 14) or placebo (n = 11). Clinical outcome measures were: (1) Clinical Global Impressions-Improvement (CGI-I) score less than 4 at trial's end and (2) the Positive and Negative Syndrome Scale (PANSS) factor 4 score. Magnetic resonance spectroscopy (MRS) outcome measures were myoinositol (mI), N-acetyl-aspartate (NAA), and combined glutamate/glutamine (GLX), all referenced to creatine (Cr).

RESULTS

In all, 45% (n = 20/45) of SMD youths were not randomized due to significant clinical improvement during the placebo run-in. Among randomized patients, there were no significant between-group differences in either clinical or MRS outcome measures.

CONCLUSION

Our study suggests that although lithium may not result in significant clinical or neurometabolic alterations in SMD youths, further SMD treatment trials are warranted given its prevalence.

Neuroimaging studies of normal brain development and their relevance for understanding childhood neuropsychiatric disorders

OBJECTIVE

To review the maturational events that occur during prenatal and postnatal brain development and to present neuroimaging findings from studies of healthy individuals that identify the trajectories of normal brain development.

METHOD

Histological and postmortem findings of early brain development are presented, followed by a discussion of anatomical, diffusion tensor, proton spectroscopy, and functional imaging findings from studies of healthy individuals, with special emphasis on longitudinal data.

RESULTS

Early brain development occurs through a sequence of major events, beginning with the formation of the neural tube and ending with myelination. Brain development at a macroscopic level typically proceeds first in sensorimotor areas, spreading subsequently and progressively into dorsal and parietal, superior temporal, and dorsolateral prefrontal cortices throughout later childhood and adolescence. These patterns of anatomical development parallel increasing activity in frontal cortices that subserves the development of higher-order cognitive functions during late childhood and adolescence. Disturbances in these developmental patterns seem to be involved centrally in the pathogenesis of various childhood psychiatric disorders including childhood-onset schizophrenia, attention-deficit/hyperactivity disorder, developmental dyslexia, Tourette's syndrome, and bipolar disorder.

CONCLUSIONS

Advances in imaging techniques have enhanced our understanding of normal developmental trajectories in the brain, which may improve insight into the abnormal patterns of development in various childhood psychiatric disorders.