Lateralized caudate metabolic abnormalities in adolescent major depressive disorder: a proton MR spectroscopy study

Testosterone synthesis was inhibited in the testis metabolomics of a depression mouse model

INTRODUCTION

Depression is a common emotional disorder. Previous studies have suggested that depression is associated with the central nervous system. Recent studies have suggested that reduced testosterone level is the core inducement of depression. Testis is the vital organ for the synthesis of testosterone. How does testis mediate depression is still unknown.

OBJECTIVES

We adopted a classical depression model of mouse caused through chronic mild stress (CMS). The metabolomics liquid chromatography-mass spectrometry was adopted to analyse the influence of CMS on testis metabolism. Then we confirmed the possible abnormal metabolism of the testis in depression mice by pathway analysis and molecular biological technique.

RESULTS

Compared with control mice, 16 differential metabolites were found in CMS mice by multivariate statistical analysis. In comparison with control mice, CMS mice showed higher levels for campesterol, ribitol, citric acid, platelet activating factor, guanosine, cytosine and xanthine and lower levels for docosahexaenoic acid, hippuric acid, creatine, testosterone, dehydroepiandrosterone, progesterone, l-carnitine, acetyl carnitine and propionyl carnitine. The pathway analysis indicated that these differential metabolites are associated with steroid hormone synthesis, purine metabolism and phenylalanine metabolism. In addition, we also first discovered that testicular morphology in depression mice was damaged and steroid hormone synthetases (including steroidogenic acute regulatory protein and P450 cholesterol side chain cleavage) were inhibited.

CONCLUSION

These findings may be helpful to parse molecular mechanisms of pathophysiology of depression. It also pointed out the direction to search for potential therapy schedules for male depression and provide novel insights into exploring the pathogenesis of male depression.

In vivo Human MR Spectroscopy Using a Clinical Scanner: Development, Applications, and Future Prospects

MR spectroscopy (MRS) is a unique and useful method for noninvasively evaluating biochemical metabolism in human organs and tissues, but its clinical dissemination has been slow and often limited to specialized institutions or hospitals with experts in MRS technology. The number of 3-T clinical MR scanners is now increasing, representing a major opportunity to promote the use of clinical MRS. In this review, we summarize the theoretical background and basic knowledge required to understand the results obtained with MRS and introduce the general consensus on the clinical utility of proton MRS in routine clinical practice. In addition, we present updates to the consensus guidelines on proton MRS published by the members of a working committee of the Japan Society of Magnetic Resonance in Medicine in 2013. Recent research into multinuclear MRS equipped in clinical MR scanners is explained with an eye toward future development. This article seeks to provide an overview of the current status of clinical MRS and to promote the understanding of when it can be useful. In the coming years, MRS-mediated biochemical evaluation is expected to become available for even routine clinical practice.

Correlations between facial emotion processing and biochemical abnormalities in untreated adolescent patients with major depressive disorder: A proton magnetic resonance spectroscopy study

BACKGROUND

Studies show that disturbances of the fronto-striato-thalamic-cerebellar circuit could be correlated to facial emotion processing (FEP) biases in major depressive disorder (MDD). Nevertheless, the underlying mechanism of natural metabolism-emotion relationships in adolescent MDD remains unclear.

METHODS

Thirty-seven adolescent patients with MDD and 30 healthy controls completed FEP tasks using the Chinese Facial Affective Picture System (CAFPS). Proton magnetic resonance spectroscopy (¹H-MRS) was also used to obtain ratios of N-acetylaspartate (NAA) /creatine (Cr) and choline (Cho) /Cr ratios in the prefrontal cortex (PFC), anterior cingulate cortex (ACC), putamen, thalamus and cerebellum. Correlations between abnormal neurometabolic ratios and FEP were also computed.

RESULTS

Compared with the control group, the MDD group had significantly lower accuracy and perception intensity of happiness, and significantly higher accuracy of disgust and perception intensity of sad and fearful faces in FEP tasks. Compared to healthy controls, adolescent patients with MDD showed significantly lower NAA/Cr ratios in the left PFC, higher NAA/Cr ratios in the right thalamus, and higher Cho/Cr ratios in the right putamen, although there were no significant differences in metabolites in the ACC and cerebellum between two groups. In the MDD group, NAA/Cr ratios of the right thalamus were negatively correlated with happy reaction time and positively correlated with sad, anger, and fear intensity; Cho/Cr ratios in the right putamen were positively correlated with fear reaction time.

CONCLUSIONS

Our findings suggest that FEP bias may exist in adolescents with MDD, while the impairment of FEP may be associated with abnormal metabolites in the fronto-striato-thalamic circuit.

Interaction of Serum Copper and Neurometabolites on Executive Dysfunction in Unmedicated Patients With Major Depressive Disorder

Objective: The mechanism of executive function (EF) impairment in major depressive disorder (MDD) remains unclear. Previous studies have demonstrated that altered serum copper levels and neurometabolic alterations may be associated with the psychopathology and cognitive impairment of MDD. While, their inter-relationships in MDD remain uncertain. The present study aims to assess whether the interaction between serum copper levels and neurometabolic alterations is involved in the deficit of executive function (EF) in patients with unmedicated MDD. Methods: Serum copper levels and EFs were measured in 41 MDD patients and 50 control subjects. EFs were evaluated by Trail Making Test, Part-B (TMT-B), Digit Symbol Substitution Test (DSST), Wisconsin Card Sorting Task (WCST), and Semantic Verbal Fluency testing (SVFT). Additionally, 41 patients and 41 healthy controls underwent proton magnetic resonance spectroscopy (¹H-MRS) to obtain ratios of N-acetyl aspartate to creatine (NAA/Cr) and choline-containing compounds to creatine (Cho/Cr) in the lenticular nucleus (LN) of basal ganglia (BG). Finally, association and interaction analysis were conducted to investigate their inter-relationships. Results: The results showed that patients performed worse in the DSST, WCST, TMT-B time and SVFT. Moreover, patients had higher serum copper levels, but lower NAA/Cr ratios in left LN of BG than healthy controls. In patients, serum copper levels were found to significantly negative associated with Categories Completed (CC) number of WCST (r = -0.408, p = 0.008), and positive associated with the Total Errors (TE) and Nonperseverative Errors (PE) number of WCST (r = 0.356, p = 0.023; r = -0.356, p = 0.022). In addition, the NAA/Cr ratios of left LN were found to significantly negative associated with VFS (r = -0.401, p = 0.009), as well as negative associated with serum copper levels (r = -0.365, p = 0.019). Finally, the interaction between copper and NAA may as influencing factors for SVFT and CC number of WCST in patients. Conclusion: Our results indicated that the interaction of abnormal copper levels and NAA/Cr neurometabolic disruption of the LN may impact executive dysfunction, and this may relevant to the pathophysiology of executive impairment in MDD patients.

Metabolomic analysis of the hippocampus in a rat model of chronic mild unpredictable stress-induced depression based on a pathway crosstalk and network module approach

BACKGROUND

The molecular alterations underlying the pathogenesis of depression have not been systematically defined. Increasing evidence suggests that hippocampus metabolism is strongly involved in the pathogenesis of chronic mild unpredictable stress (CUMS)-induced depression. The principal objective of this study was to reveal important information concerning the pathogenesis of depression through a comprehensive analysis of metabolites in the hippocampus in a CUMS rat model.

METHODS

Metabolites related to metabolic changes in the hippocampus in the CUMS model were collected from a depression-specific database and published literature. Potential metabolite pathways were identified by the Omicsolution tool. Then, crosstalk analysis was carried out to investigate the relationship between different important pathways. In addition, MetaboAnalyst was used to analyze potential metabolites for drug-related metabolite enrichment analysis, which was used to study hippocampus metabolite-related drug pathways in a CUMS model. Then, a metabolite-protein interaction (MPI) network was constructed and analyzed to identify important metabolites and proteins. The functional modules were extracted using the CNM network decomposition algorithm. Finally, neurotransmitters in the hippocampus of rats with CUMS depression were detected to verify the important pathways.

RESULTS

In the current study, 53 significantly enriched pathways related to the 107 identified metabolites were selected, and the top ranked enriched pathways included arginine and proline metabolism, neuroactive ligand-receptor interaction, phenylalanine metabolism, bile secretion, and glutathione metabolism. Pathway crosstalk analysis showed that the significantly enriched pathways were divided into two interrelated modules, which were mainly involved in metabolism, signal transduction, neurotransmitters, and the endocrine system. Enrichment analysis of drug-related metabolic KEGG pathways identified the antibiotic pathways as the most important pathways. In the MPI network, the hub metabolites were phosphate, arachidonic acid, oxoglutaric acid, l-glutamic acid, and glutathione, and the hub proteins were Got1, Got2, Tat, Ccbl1, Ccbl2, Il4i1. A total of 16 functional modules were extracted from the MPI network by using the CNM algorithm. Finally, metabolites related to serotonergic synapses, dopaminergic synapses, and glutamatergic synapses were found to be involved in the pathology of depression.

CONCLUSION

We found that neurotransmitter pathways (serotonergic synapses, dopaminergic synapses and glutamatergic synapses) in the hippocampus play a crucial role in the underlying molecular mechanism of depression, which provides useful clues for identifying the detailed depression-associated metabolic profiles.

Transcranial magnetic stimulation and magnetic resonance spectroscopy: Opportunities for a bimodal approach in human neuroscience

Over the last decade, there has been an increasing number of studies combining transcranial magnetic stimulation (TMS) and magnetic resonance spectroscopy (MRS). MRS provides a manner to non-invasively investigate molecular concentrations in the living brain and thus identify metabolites involved in physiological and pathological processes. Particularly the MRS-detectable metabolites glutamate, the major excitatory neurotransmitter, and gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter, are of interest when combining TMS and MRS. TMS is a non-invasive brain stimulation technique that can be applied either as a neuromodulation or neurostimulation tool, specifically targeting glutamatergic and GABAergic mechanisms. The combination of TMS and MRS can be used to evaluate alterations in brain metabolite levels following an interventional TMS protocol such as repetitive TMS (rTMS) or paired associative stimulation (PAS). MRS can also be combined with a variety of non-interventional TMS protocols to identify the interplay between brain metabolite levels and measures of excitability or receptor-mediated inhibition and facilitation. In this review, we provide an overview of studies performed in healthy and patient populations combining MRS and TMS, both as a measurement tool and as an intervention. TMS and MRS may reveal complementary and comprehensive information on glutamatergic and GABAergic neurotransmission. Potentially, connectivity changes and dedicated network interactions can be probed using the combined TMS-MRS approach. Considering the ongoing technical developments in both fields, combined studies hold future promise for investigations of brain network interactions and neurotransmission.

Altered anterior cingulate glutamatergic metabolism in depressed adolescents with current suicidal ideation

The anterior cingulate cortex (ACC) is involved in emotion regulation and salience processing. Prior research has implicated ACC dysfunction in suicidal ideation (SI) and suicidal behavior. This study aimed to quantify ACC glutamatergic concentrations and to examine relationships with SI in a sample of healthy and depressed adolescents. Forty adolescents underwent clinical evaluation and proton magnetic resonance spectroscopy (1H-MRS) at 3 T, utilizing a 2-dimensional J-averaged PRESS sequence sampling a medial pregenual ACC voxel. Cerebrospinal fluid-corrected ACC metabolite concentrations were compared between healthy control (HC, n = 16), depressed without SI (Dep/SI-, n = 13), and depressed with SI (Dep/SI+, n = 11) youth using general linear models covarying for age, sex, and psychotropic medication use. Relationships between ACC metabolites and continuous measures of SI were examined using multiple linear regressions. ROC analysis was used to determine the ability of glutamate+glutamine (Glx) and the N-acetylaspartate (NAA)/Glx ratio to discriminate Dep/SI- and Dep/SI+ adolescents. Dep/SI+ adolescents had higher Glx than Dep/SI- participants (padj = 0.012) and had lower NAA/Glx than both Dep/SI- (padj = 0.002) and HC adolescents (padj = 0.039). There were significant relationships between SI intensity and Glx (pFDR = 0.026), SI severity and NAA/Glx (pFDR = 0.012), and SI intensity and NAA/Glx (pFDR = 0.004). ACC Glx and NAA/Glx discriminated Dep/SI- from Dep/SI+ participants. Uncoupled NAA-glutamatergic metabolism in the ACC may play a role in suicidal ideation and behavior. Longitudinal studies are needed to establish whether aberrant glutamatergic metabolism corresponds to acute or chronic suicide risk. Glutamatergic biomarkers may be promising targets for novel risk assessment and interventional strategies for suicidal ideation and behavior.

Brain imaging findings in children and adolescents with mental disorders: A cross-sectional review

Background

While brain imaging studies of juvenile patients has expanded in recent years to investigate the cerebral neurophysiologic correlates of psychiatric disorders, this research field remains scarce. The aim of the present review was to cluster the main mental disorders according to the differential brain location of the imaging findings recently reported in children and adolescents reports. A second objective was to describe the worldwide distribution and the main directions of the recent magnetic resonance imaging (MRI) and positron tomography (PET) studies in these patients.

Methods

A survey of 423 MRI and PET articles published between 2005 and 2008 was performed. A principal component analysis (PCA), then an activation likelihood estimate (ALE) meta-analysis, were applied on brain regional information retrieved from articles in order to cluster the various disorders with respect to the cerebral structures where alterations were reported. Furthermore, descriptive analysis characterized the literature production.

Results

Two hundred and seventy-four articles involving children and adolescent patients were analyzed. Both the PCA and ALE methods clustered, three groups of diagnosed psychiatric disorders, according to the brain structural and functional locations: one group of affective disorders characterized by abnormalities of the frontal-limbic regions; a group of mental disorders with “cognition deficits” mainly related to cortex abnormalities; and one psychomotor condition associated with abnormalities in the basal ganglia. The descriptive analysis indicates a focus on attention deficit hyperactivity disorders and autism spectrum disorders, a general steady rise in the number of annual reports, and lead of US research.

Conclusion

This cross-sectional review of child and adolescent mental disorders based on neuroimaging findings suggests overlaps of brain locations that allow to cluster the diagnosed disorders into three sets with respectively marked affective, cognitive, and psychomotor phenomenology. Furthermore, the brain imaging research effort was unequally distributed across disorders, and did not reflect their prevalence.

Creatine for the Treatment of Depression

Depressed mood, which can occur in the context of major depressive disorder, bipolar disorder, and other conditions, represents a serious threat to public health and wellness. Conventional treatments are not effective for a significant proportion of patients and interventions that are often beneficial for treatment-refractory depression are not widely available. There is, therefore, an immense need to identify novel antidepressant strategies, particularly strategies that target physiological pathways that are distinct from those addressed by conventional treatments. There is growing evidence from human neuroimaging, genetics, epidemiology, and animal studies that disruptions in brain energy production, storage, and utilization are implicated in the development and maintenance of depression. Creatine, a widely available nutritional supplement, has the potential to improve these disruptions in some patients, and early clinical trials indicate that it may have efficacy as an antidepressant agent.

MENDA: a comprehensive curated resource of metabolic characterization in depression

Depression is a seriously disabling psychiatric disorder with a significant burden of disease. Metabolic abnormalities have been widely reported in depressed patients and animal models. However, there are few systematic efforts that integrate meaningful biological insights from these studies. Herein, available metabolic knowledge in the context of depression was integrated to provide a systematic and panoramic view of metabolic characterization. After screening more than 10 000 citations from five electronic literature databases and five metabolomics databases, we manually curated 5675 metabolite entries from 464 studies, including human, rat, mouse and non-human primate, to develop a new metabolite-disease association database, called MENDA (http://menda.cqmu.edu.cn:8080/index.php). The standardized data extraction process was used for data collection, a multi-faceted annotation scheme was developed, and a user-friendly search engine and web interface were integrated for database access. To facilitate data analysis and interpretation based on MENDA, we also proposed a systematic analytical framework, including data integration and biological function analysis. Case studies were provided that identified the consistently altered metabolites using the vote-counting method, and that captured the underlying molecular mechanism using pathway and network analyses. Collectively, we provided a comprehensive curation of metabolic characterization in depression. Our model of a specific psychiatry disorder may be replicated to study other complex diseases.

The possible beneficial effects of creatine for the management of depression

Depression, a highly prevalent neuropsychiatric disorder worldwide, causes a heavy burden for the society and is associated with suicide risk. The treatment of this disorder remains a challenge, since currently available antidepressants provide a slow and, often, incomplete response and cause several side effects that contribute to diminish the adhesion of patients to treatment. In this context, several nutraceuticals have been investigated regarding their possible beneficial effects for the management of this neuropsychiatric disorder. Creatine stands out as a supplement frequently used for ergogenic purpose, but it also is a neuroprotective compound with potential to treat or mitigate a broad range of central nervous systems diseases, including depression. This review presents preclinical and clinical evidence that creatine may exhibit antidepressant properties. The focus is given on the possible molecular mechanisms underlying its effects based on the results obtained with different animal models of depression. Finally, evidence obtained in animal models of depression addressing the possibility that creatine may produce rapid antidepressant effect, similar to ketamine, are also presented and discussed.

Altered resting-state cerebral blood flow and functional connectivity of striatum in bipolar disorder and major depressive disorder

BACKGROUND

Clinically distinguishing bipolar disorder (BD) from major depressive disorder (MDD) during depressive states is difficult. Neuroimaging findings suggested that patients with BD and those with MDD differed with respect to the gray matter volumes of their subcortical structures, especially in their striatum. However, whether these disorders have different effects on functionally striatal neuronal activity and connectivity is unclear.

METHODS

Arterial spin labeling and resting-state functional MRI was performed on 25 currently depressive patients with BD, 25 depressive patients with MDD, and 34 healthy controls (HCs). The functional properties of striatal neuronal activity (cerebral blood flow, CBF) and its functional connectivity (FC) were analyzed, and the results from the three groups were compared. The result of the multiple comparisons was corrected on the basis of the Gaussian Random Field theory.

RESULTS

The patients with BD and those with MDD both had higher CBF values than the HCs in the right caudate and right putamen. The hyper-metabolism of right striatum in BD patients was associated with increased average duration per depressive episode. The two disorders showed commonly increased FC between the striatum and dorsolateral prefrontal cortex, whereas the altered FC of the striatum with precuneus/cuneus was observed only in patients with BD.

CONCLUSIONS

Patients with BD and those with MDD had a common deficit in their prefrontal-limbic-striatal circuits. The altered striato-precuneus FC can be considered as a marker for the differentiation of patients with BD from those with MDD.

Polyunsaturated fatty acids metabolism, purine metabolism and inosine as potential independent diagnostic biomarkers for major depressive disorder in children and adolescents

Major depressive disorder (MDD) in children and adolescents is a recurrent and disabling condition globally but its pathophysiology remains poorly elucidated and there are limited effective treatments available. We performed metabolic profiling of plasma samples based on ultra-high-performance liquid chromatography equipped with quadrupole time-offlight mass spectrometry to explore the potential biomarkers of depression in children and adolescents with MDD. We identified several perturbed pathways, including fatty acid metabolism-particularly the polyunsaturated fatty acids metabolism, and purine metabolism-that were associated with MDD in these young patients. In addition, inosine was shown as a potential independent diagnostic biomarker for MDD, achieving an area under the ROC curve of 0.999 in discriminating drug-naive MDD patients and 0.866 in discriminating drug-treated MDD from healthy controls. Moreover, we found evidence for differences in the pathophysiology of MDD in children and adolescents to that of adult MDD, specifically with tryptophan metabolism. Through metabolomic analysis, we have identified links between a framework of metabolic perturbations and the pathophysiology and diagnostic biomarker of child and adolescent MDD.

Brain choline in major depression: A review of the literature

The focus of this review is to provide a synthesis of the current literature on the role of brain choline, as measured by proton magnetic resonance spectroscopy (1H-MRS), in major depressive disorder (MDD). The most recent ¹H-MRS literature review took place over 10 years ago and, reflecting the high level of research on this topic, much has been learned since then. Higher brain choline levels have been linked to an increase in depression, and a cholinergic model for MDD development has been postulated. However, current ¹H-MRS studies have been inconclusive regarding the role of choline in depression. Data from eighty-six peer-reviewed studies were analyzed for a random-effects model meta-analysis. Two significant findings are reported. Papers that did not report segmentation had a significant, moderate effect size. Higher choline concentrations in the frontal lobe were found in depressed patients, both in those who responded to treatment and those who did not, after treatment with psychiatric medication, repetitive transcranial magnetic stimulation, or electroconvulsive therapy. Findings from this review may add to existing information regarding the role of brain choline in MDD. This may provide a future target for treatment and drug development. It also may serve as a biomarker for treatment progress.

Elevated Choline-Containing Compound Levels in Rapid Cycling Bipolar Disorder

Previous studies have found increased levels of choline-containing compounds (ie, glycerophosphocholine plus phosphocholine (GPC+PC)) in bipolar disorder using in vivo proton magnetic resonance spectroscopy (¹H MRS), especially in bipolar I disorder (BD-I). Increased levels of GPC+PC suggest alterations in the membrane phospholipids metabolism in bipolar disorder. Rapid cycling (RC) bipolar disorder is considered as a severe course of bipolar disorder, but it is unclear whether rapid cycling bipolar disorder is linked to highly altered membrane phospholipid metabolism. The purpose of this study was to investigate whether the regional extent of elevated GPC+PC were greater in BD-I patients with rapid cycling compared to BD-I patients without rapid cycling and healthy controls. Using a multi-voxel ¹H MRS approach at 3 Tesla with high spatial resolution and absolute quantification, GPC+PC levels from the anterior cingulate cortex (ACC), caudate and putamen of 16 RC BD-I, 34 non-RC BD-I and 44 healthy controls were assessed. We found significantly elevated GPC+PC levels in ACC, putamen and caudate of RC BD-I patients compared to healthy controls (P<0.005) and in ACC compared to non-RC BD-I patients (P<0.05). These results suggest greater alteration of membrane phospholipid metabolisms in rapid cycling BD-I compared to non-rapid-cycling BD-I.

Ketamine changes the local resting-state functional properties of anesthetized-monkey brain

OBJECTIVE

Ketamine is a well-known anesthetic. 'Recreational' use of ketamine common induces psychosis-like symptoms and cognitive impairments. The acute and chronic effects of ketamine on relevant brain circuits have been studied, but the effects of single-dose ketamine administration on the local resting-state functional properties of the brain remain unknown. In this study, we aimed to assess the effects of single-dose ketamine administration on the brain local intrinsic properties.

METHODS

We used resting-state functional magnetic resonance imaging (rs-fMRI) to explore the ketamine-induced alterations of brain intrinsic properties. Seven adult rhesus monkeys were imaged with rs-fMRI to examine the fractional amplitude of low-frequency fluctuation (fALFF) and regional homogeneity (ReHo) in the brain before and after ketamine injection. Paired comparisons were used to detect the significantly altered regions.

RESULTS

Results showed that the fALFF of the prefrontal cortex (p=0.046), caudate nucleus (left side, p=0.018; right side, p=0.025), and putamen (p=0.020) in post-injection stage significantly increased compared with those in pre-injection period. The ReHo of nucleus accumbens (p=0.049), caudate nucleus (p=0.037), and hippocampus (p=0.025) increased after ketamine injection, but that of prefrontal cortex decreased (p<0.05).

CONCLUSIONS

These findings demonstrated that single-dose ketamine administration can change the regional intensity and synchronism of brain activity, thereby providing evidence of ketamine-induced abnormal resting-state functional properties in primates. This evidence may help further elucidate the effects of ketamine on the cerebral resting status.

DTI-based connectome analysis of adolescents with major depressive disorder reveals hypoconnectivity of the right caudate

BACKGROUND

Adolescence is a vulnerable period for the onset of major depressive disorder (MDD). While some studies have shown white matter alterations in adolescent MDD, there is still a gap in understanding how the brain is affected at a network level.

METHODS

We compared diffusion tensor imaging (DTI)-based brain networks in a cohort of 57 adolescents with MDD and 41 well-matched healthy controls who completed self-reports of depression symptoms and stressful life events. Using atlas-based brain regions as network nodes and tractography streamline count or mean fractional anisotropy (FA) as edge weights, we examined weighted local and global network properties and performed Network-Based Statistic (NBS) analysis.

RESULTS

While there were no significant group differences in the global network properties, the FA-weighted node strength of the right caudate was significantly lower in depressed adolescents and correlated positively with age across both groups. The NBS analysis revealed a cluster of lower FA-based connectivity in depressed subjects centered on the right caudate, including connections to frontal gyri, insula, and anterior cingulate. Within this cluster, the most robust difference between groups was the connection between the right caudate and middle frontal gyrus. This connection showed a significant diagnosis by stress interaction and a negative correlation with total stress in depressed adolescents.

LIMITATIONS

Use of DTI-based tractography, one atlas-based parcellation, and FA values to characterize brain networks represent this study's limitations.

CONCLUSIONS

Our results allowed us to suggest caudate-centric models of dysfunctional processes underlying adolescent depression, which might guide future studies and help better understand and treat this disorder.

An Exploratory Study of Spectroscopic Glutamatergic Correlates of Cortical Excitability in Depressed Adolescents

Introduction: Transcranial magnetic stimulation (TMS) research has suggested dysfunction in cortical glutamatergic systems in adolescent depression, while proton magnetic resonance spectroscopy (¹H-MRS) studies have demonstrated deficits in concentrations of glutamatergic metabolites in depressed individuals in several cortical regions, including the anterior cingulate cortex (ACC). However, few studies have combined TMS and MRS methods to examine relationships between glutamatergic neurochemistry and excitatory and inhibitory neural functions, and none have utilized TMS-MRS methodology in clinical populations or in youth. This exploratory study aimed to examine relationships between TMS measures of cortical excitability and inhibition and concentrations of glutamatergic metabolites as measured by ¹H-MRS in depressed adolescents. Methods: Twenty-four adolescents (aged 11-18 years) with depressive symptoms underwent TMS testing, which included measures of the resting motor threshold (RMT), cortical silent period (CSP), short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF). Fourteen participants from the same sample also completed ¹H-MRS in a 3 T MRI scanner after TMS testing. Glutamate + glutamine (Glx) concentrations were measured in medial ACC and left primary motor cortex voxels with a TE-optimized PRESS sequence. Metabolite concentrations were corrected for cerebrospinal fluid (CSF) after tissue segmentation. Pearson product-moment and Spearman rank-order correlations were calculated to assess relationships between TMS measures and [Glx]. Results: In the left primary motor cortex voxel, [Glx] had a significant positive correlation with the RMT. In the medial ACC voxel, [Glx] had significant positive correlations with ICF at the 10-ms and 20-ms interstimulus intervals (ISIs). Conclusion: These preliminary data implicate glutamate in cortical excitatory processes measured by TMS. Limitations included small sample size, lack of healthy control comparators, possible age- and sex-related effects, and observational nature of the study. Further research aimed at examining the relationship between glutamatergic metabolite concentrations measured through MRS and the excitatory and inhibitory physiology measured through TMS is warranted. Combined TMS-MRS methods show promise for future investigations of the pathophysiology of depression in adults as well as in children and adolescents.

Creatine in the central nervous system: From magnetic resonance spectroscopy to creatine deficiencies

Creatine (Cr) is an important organic compound acting as intracellular high-energy phosphate shuttle and in energy storage. While located in most cells where it plays its main roles in energy metabolism and cytoprotection, Cr is highly concentrated in muscle and brain tissues, in which Cr also appears to act in osmoregulation and neurotransmission. This review discusses the basis of Cr metabolism, synthesis and transport within brain cells. The importance of Cr in brain function and the consequences of its impaired metabolism in primary and secondary Cr deficiencies are also discussed. Cr and phosphocreatine (PCr) in living systems can be well characterized using in vivo magnetic resonance spectroscopy (MRS). This review describes how ¹H MRS allows the measurement of Cr and PCr, and how ³¹P MRS makes it possible to estimate the creatine kinase (CK) rate constant and so detect dynamic changes in the Cr/PCr/CK system. Absolute quantification by MRS using creatine as internal reference is also debated. The use of in vivo MRS to study brain Cr in a non-invasive way is presented, as well as its use in clinical and preclinical studies, including diagnosis and treatment follow-up in patients.

Evidence of altered membrane phospholipid metabolism in the anterior cingulate cortex and striatum of patients with bipolar disorder I: A multi-voxel (1)H MRS study

BACKGROUND

Previous proton magnetic resonance spectroscopy ((1)H MRS) studies have reported elevated glycerophosphocholine plus phosphocholine (GPC+PC) in the basal ganglia of patients with bipolar disorders (BD), which implicates an imbalance between synthesis and degradation activity of neuronal and glia membrane phospholipids (MPLs). However, the full extent of altered metabolites of MPLs in subareas within the basal ganglia, such as caudate and putamen, as well as anterior cingulate cortex (ACC) of BD patients is poorly understood.

METHODS

Multi-voxel (1)H MRS measurements were acquired in 50 type-one BD (BD-I) and 44 healthy controls (HC) on a 3-T MRI scanner. Four different anatomically defined voxels covering ACC, caudate and putamen were systematically extracted and quantified using LCModel. Group differences in absolute GPC+PC and other metabolites were tested with age and gender as covariates.

RESULTS

BD-I patients had higher GPC+PC levels in the anterior-dorsal ACC (p = 0.037), caudate (p = 0.005) and putamen (p = 0.004) compared to HC. GPC+PC levels in the caudate were elevated most significantly in currently unmediated BD-I patients (p = 0.022) and were positively correlated with HAM-D scores (r = 0.51, p = 0.005). PCr+Cr and myo-inositol levels were also significantly higher in the caudate head (F(1,45) = 6.010, p = 0.018) of patients compared to HC. NAA and glutamate levels were not significantly different between BD-I and HC in these regions (p > 0.05).

CONCLUSION

The increased GPC+PC in BD-I patients may reflect an imbalance in the MPL metabolism. Caudate GPC+PC levels may be a potential biomarker for depressive symptoms in BD.

Proton spectroscopy study of the dorsolateral prefrontal cortex in youth with familial depression

AIM

Structural, functional, and metabolic changes in the dorsolateral prefrontal cortex (DLPFC) are implicated in the pathogenesis of major depressive disorder (MDD). We used proton magnetic resonance spectroscopy ((1) H-MRS) to examine the metabolite choline (glycerophosphocholine plus phosphocholine), which is used as an index of membrane integrity in the left DLPFC, in adolescents and young adults with MDD who were treatment-resistant and had a positive family history compared to healthy controls. Differences in the choline resonance indicate an imbalance between synthesis and degradation activity of neuronal and glia membrane phospholipids.

METHODS

Seventeen adolescents with MDD and 11 healthy controls underwent (1) H-MRS. A short echo point-resolved spectroscopy (echo time = 30 ms, repetition time = 2000 ms) protocol was used with a voxel (4.5cm(3) , 128 averages) placed within the left DLPFC.

RESULTS

There were significantly increased choline (P = 0.04) and creatine concentrations (P = 0.005) in the left DLPFC of the MDD group compared to controls. In MDD participants, choline concentration correlated with scores on the Beck Depression Inventory (r = 0.41, P = 0.03).

CONCLUSION

Increased left DLPFC choline and creatine levels in depressed adolescents may be biomarkers for the disorder. The increased choline levels may indicate abnormalities in neuronal membrane integrity, and the increased creatine could be reflective of altered energy demands and metabolism.

Increased ventricular cerebrospinal fluid lactate in depressed adolescents

BACKGROUND

Mitochondrial dysfunction has been increasingly examined as a potential pathogenic event in psychiatric disorders, although its role early in the course of major depressive disorder (MDD) is unclear. Therefore, the purpose of this study was to investigate mitochondrial dysfunction in medication-free adolescents with MDD through in vivo measurements of neurometabolites using high-spatial resolution multislice/multivoxel proton magnetic resonance spectroscopy.

METHODS

Twenty-three adolescents with MDD and 29 healthy controls, ages 12-20, were scanned at 3T and concentrations of ventricular cerebrospinal fluid lactate, as well as N-acetyl-aspartate (NAA), total creatine (tCr), and total choline (tCho) in the bilateral caudate, putamen, and thalamus were reported.

RESULTS

Adolescents with MDD exhibited increased ventricular lactate compared to healthy controls [F(1,41)=6.98, P=0.01]. However, there were no group differences in the other neurometabolites. Dimensional analyses in the depressed group showed no relation between any of the neurometabolites and symptomatology, including anhedonia and fatigue.

CONCLUSIONS

Increased ventricular lactate in depressed adolescents suggests mitochondrial dysfunction may be present early in the course of MDD; however it is still not known whether the presence of mitochondrial dysfunction is a trait vulnerability of individuals predisposed to psychopathology or a state feature of the disorder. Therefore, there is a need for larger multimodal studies to clarify these chemical findings in the context of network function.

Relationship between the catechol-O-methyl transferase Val108/158Met genotype and brain volume in treatment-naive major depressive disorder: Voxel-based morphometry analysis

Catechol-O-methyltransferase (COMT) is a methylation enzyme engaged in the degradation of dopamine and noradrenaline by catalyzing the transfer of a methyl group from S-adenosylmethionine. An association was found between the Valine (Val) 108/158Methionine (Met) COMT polymorphism (rs4680) and major depressive disorder (MDD). The authors prospectively investigated the relationship between the Val108/158Met COMT genotype and voxel-based morphometry (VBM) findings for patients with first-episode and treatment-naïve MDD and healthy subjects (HS). Participants comprised 30 MDD patients and 48 age- and sex-matched HS who were divided according to the COMT genotype. Effects of diagnosis, COMT genotype, and the genotype-diagnosis interaction in relation to brain morphology in the Val/Met and Val/Val individuals were evaluated using a VBM analysis of high-resolution magnetic resonance imaging findings. Among the Val/Met individuals, the volume of the bilateral caudate was significantly smaller for MDD patients than for HS. In the Val/Val individuals, the caudate volume was comparable between MDD patients and HS. Significant genotype-diagnosis interaction effects on brain morphology were noted in the right caudate.

Decreased thalamic glutamate level in unmedicated adult obsessive-compulsive disorder patients detected by proton magnetic resonance spectroscopy

BACKGROUND

Previous neuroimaging studies implied that the dysfunction of cortico-striato-thalamo-cortical (CSTC) circuit served as the neural basis for the pathophysiology of obsessive-compulsive disorder (OCD). The imbalances in neuronal metabolite and neurotransmitter within CSTC circuit have been shown as the leading reasons of the OCD onset. The aim of this study is to investigate the metabolic alterations, especially the glutamatergic signal dysfunction within CSTC circuit, and the relationships between neural metabolites and the symptom severity of OCD patients.

METHODS

Single voxel magnetic resonance spectroscopy (MRS) was conducted in medial prefrontal cortex (mPFC) and bilateral thalamus areas for thirteen unmedicated adult OCD patients with age-, gender-, and education-matched healthy controls. Quantification and multivariate analysis were performed to identify vital metabolic biomarkers for patients and healthy controls group differentiation. Moreover, we performed Spearman׳s rank correlation analysis for OCD patients to examine the relationship between the metabolite concentration level and OCD symptomatology.

RESULTS

Patients with OCD showed significantly decreased glutamate level in mPFC (p=0.021) and right thalamus (p=0.039), and significantly increased choline compounds in left thalamus (p=0.044).The glutamate in right thalamus was shown as the most important metabolite for group separation from multivariate analysis (Q(2)=0.134) and was significantly correlated with the patients׳ compulsion scores (Spearman r=-0.674, p=0.016).

LIMITATIONS

Limited sample size, the use of creatine and phosphocreatine (Cr) ratios rather than absolute concentrations and unresolved glutamine (Gln) are limitations of the present study.

CONCLUSION

Our study results consolidated the hypothesis about glutamatergic signaling dysfunction in OCD. To our knowledge, it is the first finding about a reduced thalamic glutamate level in adult unmedicated OCD patients. The dysregulation of glutamate serves as a potential target for the OCD pharmacotherapy and the detailed mechanisms underlying the glutamate alterations within CSTC circuits merit further investigations.

Depression, neuroimaging and connectomics: a selective overview

Depression is a multifactorial disorder with clinically heterogeneous features involving disturbances of mood and cognitive function. Noninvasive neuroimaging studies have provided rich evidence that these behavioral deficits in depression are associated with structural and functional abnormalities in specific regions and connections. Recent advances in brain connectomics through the use of graph theory highlight disrupted topological organization of large-scale functional and structural brain networks in depression, involving global topology (e.g., local clustering, shortest-path lengths, and global and local efficiencies), modular structure, and network hubs. These system-level disruptions show important correlates with genetic and environmental factors, which provide an integrative perspective on mood and cognitive deficits in depressive syndrome. Moreover, research suggests that the pathologic networks associated with depression represent potentially valuable biomarkers for early detection of this disorder and they are likely to be regulated and recalibrated by using pharmacologic, psychological, and brain stimulation therapies. These connectome-based imaging studies present new opportunities to reconceptualize the pathogenesis of depression, improve our knowledge of the biological mechanisms of therapeutic effects, and identify appropriate stimulation targets to optimize the clinical response in depression treatment. Here, we summarize the current findings and historical understanding of structural and functional connectomes in depression, focusing on graph analyses of depressive brain networks. We also consider methodological factors such as sample heterogeneity and poor test-retest reliability of recordings due to physiological, head motion, and imaging artifacts to discuss result inconsistencies among studies. We conclude with suggestions for future research directions on the emerging field of imaging connectomics in depression.

Similarities of biochemical abnormalities between major depressive disorder and bipolar depression: a proton magnetic resonance spectroscopy study

BACKGROUND

Depression in the context of bipolar disorder (BD) is often misdiagnosed as major depressive disorder (MDD), leading to mistreatments and poor clinical outcomes for many bipolar patients. Previous neuroimaging studies found mixed results on brain structure, and biochemical metabolism of the two disorders. To eliminate the compounding effects of medication, and aging, this study sought to investigate the brain biochemical changes of treatment-naïve, non-late-life patients with MDD and BD in white matter in prefrontal (WMP) lobe, anterior cingulate cortex (ACC) and hippocampus by using proton magnetic resonance spectroscopy ((1)H-MRS).

METHODS

Three groups of participants were recruited: 26 MDD patients, 20 depressed BD patients, and 13 healthy controls. The multi-voxel (1)H-MRS [repetition time (TR)=1000ms; echo-time (TE)=144ms] was used for the measurement of N-acetylaspartate(NAA), choline containg compounds (Cho), and creatine (Cr) in three brain locations: white matter in prefrontal (WMP) lobe, anterior cingulate cortex (ACC), and hippocampus. Two ratios of NAA/Cr and Cho/Cr as a measure of brain biochemical changes were compared among three experimental groups.

RESULTS

On the comparison of brain biochemical changes, both MDD patients and BD patients showed many similarities compared to the controls. They both had a significantly lower NAA/Cr ratio in the left WMP lobe. There were no significant differences among three experimental groups for Cho/Cr ratio in the WMP lobe, and for the ratios of NAA/Cr and Cho/Cr in the bilateral ACC and hippocampus. The only difference between MDD and BD patients existed for the NAA/Cr ratio in the right WMP lobe. While MDD patients had a significantly lower NAA/Cr ratio than controls, BD patients showed no such differences. On the comparison of correlation of medical variables and brain biochemical changes, all participants demonstrated no significant correlations.

CONCLUSION

Reduced NAA/Cr ratio at the left WMP lobe indicated the dysfunction of neuronal viability in deep white matter, in both MDD and BD patients who shared similarities of brain biochemical abnormalities, which might imply an overlap in neuropathology of depression.

The development of an RDoC-based treatment program for adolescent depression: "Training for Awareness, Resilience, and Action" (TARA)

Major depressive disorder (MDD) is one of the current leading causes of disability worldwide. Adolescence is a vulnerable period for the onset of depression, with MDD affecting 8–20% of all youth. Traditional treatment methods have not been sufficiently effective to slow the increasing prevalence of adolescent depression. We therefore propose a new model for the treatment of adolescent depression – Training for Awareness, Resilience, and Action (TARA) – that is based on current understanding of developmental and depression neurobiology. The TARA model is aligned with the Research Domain Criteria (RDoC) of the National Institute of Mental Health. In this article, we first address the relevance of RDoC to adolescent depression. Second, we identify the major RDoC domains of function involved in adolescent depression and organize them in a way that gives priority to domains thought to be driving the psychopathology. Third, we select therapeutic training strategies for TARA based on current scientific evidence of efficacy for the prioritized domains of function in a manner that maximizes time, resources, and feasibility. The TARA model takes into consideration the developmental limitation in top-down cognitive control in adolescence and promotes bottom-up strategies such as vagal afference to decrease limbic hyperactivation and its secondary effects. The program has been informed by mindfulness-based therapy and yoga, as well as modern psychotherapeutic techniques. The treatment program is semi-manualized, progressive, and applied in a module-based approach designed for a group setting that is to be conducted one session per week for 12 weeks. We hope that this work may form the basis for a novel and more effective treatment strategy for adolescent depression, as well as broaden the discussion on how to address this challenge.

Subcortical biophysical abnormalities in patients with mood disorders

Cortical-subcortical circuits have been implicated in the pathophysiology of mood disorders. Structural and biochemical abnormalities have been identified in patients diagnosed with mood disorders using magnetic resonance imaging-related approaches. In this study, we used magnetization transfer (MT), an innovative magnetic resonance approach, to study biophysical changes in both gray and white matter regions in cortical-subcortical circuits implicated in emotional regulation and behavior. Our study samples comprised 28 patients clinically diagnosed with major depressive disorder (MDD) and 31 non-depressed subjects of comparable age and gender. MT ratio (MTR), representing the biophysical integrity of macromolecular proteins within key components of cortical-subcortical circuits-the caudate, thalamic, striatal, orbitofrontal, anterior cingulate and dorsolateral regions-was the primary outcome measure. In our study, the MTR in the head of the right caudate nucleus was significantly lower in the MDD group when compared with the comparison group. MTR values showed an inverse relationship with age in both groups, with more widespread relationships observed in the MDD group. These data indicate that focal biophysical abnormalities in the caudate nucleus may be central to the pathophysiology of depression and critical to the cortical-subcortical abnormalities that underlie mood disorders. Depression may also accentuate age-related changes in the biophysical properties of cortical and subcortical regions. These observations have broad implications for the neuronal circuitry underlying mood disorders across the lifespan.

Anterior cingulate cortex and cerebellar hemisphere neurometabolite changes in depression treatment: A 1H magnetic resonance spectroscopy study

AIM

We utilized single-voxel 1H magnetic resonance spectroscopy to determine biochemical abnormalities related to major depressive disorder (MDD) in the bilateral dorsolateral prefrontal cortex, anterior cingulate cortex (ACC), and cerebellar hemisphere before and after antidepressant treatment.

METHODS

Fifteen adult MDD patients and 15 age- and sex-matched healthy controls were involved. Magnetic resonance spectroscopy of the brain was conducted in all subjects at the beginning of the study and the depressed subjects were reassessed after 8 weeks of antidepressant treatment.

RESULTS

At baseline, N-acetyl aspartate (NAA), total glutamine plus glutamate (Glx) and myo-inositol (MI) levels in the bilateral ACC were significantly lower in MDD patients than in controls (P < 0.05/3). MI in the bilateral cerebellar hemisphere were also decreased in patients compared with controls. After the treatment, the lower NAA, Glx and MI in ACC were normalized in MDD patients and the NAA and Glx increased compared to baseline values. The MI levels in the bilateral cerebellar hemisphere were also normalized in patients. MI and choline levels in the right cerebellar hemisphere were elevated compared to those at baseline.

CONCLUSION

Our study suggests that metabolic abnormalities in the ACC and cerebellar hemisphere are implicated in MDD. Antidepressants may alter the local metabolic abnormalities in these areas.

Depressive symptoms in Parkinson's disease are related to reduced [123I]FP-CIT binding in the caudate nucleus

BACKGROUND

Depression is a common neuropsychiatric symptom in Parkinson's disease (PD). In previous research, PD-related depression was associated with striatal dopaminergic deficits, presumably due to degeneration of brainstem dopaminergic projections. Segregated areas of the striatum are crucially involved in various parallelly arranged cortical-striatal-thalamocortical circuits and serve functions in, among others, motor control or emotion. This suggests regional specificity of dopaminergic deficits in the striatum in motor and depressive symptoms in PD.

METHODS

In this cross-sectional retrospective study, we correlated severity scores of depressive and motor symptoms in 100 non-demented PD patients (median Hoehn & Yahr stage: 2) with dopamine loss in specific regions of the striatum as measured by [(123)I]FP-CIT SPECT tracer binding to the dopamine transporter (DaT).

RESULTS

Depressive symptoms were related to lower DaT binding in the right caudate nucleus, while motor symptoms were associated with decreased DaT binding in the right putamen. This double dissociation was most pronounced in early-stage PD patients.

CONCLUSIONS

These results suggest that depressive symptoms in PD are associated with dopamine loss in the caudate nucleus, possibly related to degeneration of dopaminergic projections from the ventral tegmental area, while motor symptoms are associated with low dopamine signalling to the putamen and loss of nigrostriatal projections. This is consistent with the neuroanatomy of partially segregated cortical-striatal-thalamocortical circuits and supports the role of dysfunctional associative and motivational circuits in PD-related depression.

Reduced anterior cingulate gray matter volume in treatment-naïve clinically depressed adolescents

Adolescent depression is associated with increased risk for suicidality, social and educational impairment, smoking, substance use, obesity, and depression in adulthood. It is of relevance to further our insight in the neurobiological mechanisms underlying this disorder in the developing brain, as this may be essential to optimize treatment and prevention of adolescent depression and its negative clinical trajectories. The equivocal findings of the limited number of studies on neural abnormalities in depressed youth stress the need for further neurobiological investigation of adolescent depression. We therefore performed a voxel-based morphometry study of the hippocampus, amygdala, superior temporal gyrus, and anterior cingulate cortex (ACC) in 26 treatment-naïve, clinically depressed adolescents and 26 pair-wise matched healthy controls. Additionally, an exploratory whole-brain analysis was performed. Clinically depressed adolescents showed a volume reduction of the bilateral dorsal ACC compared to healthy controls. However, no association was found between gray matter volume of the ACC and clinical severity scores for depression or anxiety. Our finding of a smaller ACC in clinically depressed adolescents is consistent with literature on depressed adults. Future research is needed to investigate if gray matter abnormalities precede or follow clinical depression in adolescents.

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Voxel-based morphometry ROI and exploratory whole-brain analyses were performed

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Depressed adolescents showed a smaller anterior cingulate cortex compared to healthy controls

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No association found between gray matter volume of the effect and clinical scores for depression

Anterior cingulate cortex choline levels in female adolescents with unipolar versus bipolar depression: a potential new tool for diagnosis

BACKGROUND

Delayed diagnosis in bipolar disorder (BD) due to misdiagnosis as major depressive disorder (MDD) is a significant public health concern. Thus, identification of relevant diagnostic biomarkers is a critical unmet need, particularly early in the course of illness. The anterior cingulate cortex (ACC) is thought to play an important role in mood disorder pathophysiology. Case-control studies utilizing proton-1 magnetic resonance spectroscopy ((1)H-MRS) have found increased total choline levels in several brain regions in MDD. However, there are no published (1)H-MRS reports directly comparing adolescents with MDD and BD. We hypothesized that ACC choline levels would be increased in adolescents with unipolar versus bipolar depression.

METHODS

We studied depressed adolescents with MDD (n=28; mean age 17.0±2.1 years) and BD (n=9; 17.3±3.1 years). A Siemens Verio 3-Tesla clinical MRI system was used to acquire scans, using a single-voxel PRESS sequence. The voxel (18.75 cm(3)) was positioned on the ACC in the midsagittal plane. To remove potential gender effects, only female adolescent participants were included. Data were analyzed using the ANOVA and post-hoc Tukey tests.

RESULTS

A significantly increased ACC choline/creatine ratio was observed in participants with MDD (mean=0.253±0.021) compared to BD (mean=0.219±0.020) (p=0.0002). There were no significant differences in the other (1)H-MRS metabolites.

LIMITATIONS

Cross sectional design, single gender sample, limited sample size.

CONCLUSIONS

The present findings suggest that ACC total choline may have the potential to serve as a diagnostic biomarker in adolescent mood disorders.

Regional homogeneity abnormalities affected by depressive symptoms in migraine patients without aura: a resting state study

Background

Bidirectional relationship between migraine and depression suggests that there might be some etiological risk factors shared. However, few studies investigated resting state abnormalities affected by depressive symptoms in migraine patients without aura (MWoA).

Materials and Methods

According to their self-rating depression scale (SDS) score, MWoA were divided into twenty in the SDS (+) (SDS > 49) group and 20 in the SDS (−) (SDS ≤ 49) group. Regional homogeneity (ReHo) method were employed to assess local features of spontaneous brain activity between 1) all MWoA and healthy controls, 2) each subgroup and healthy controls, and 3) SDS (−) group and SDS (+) group.

Results

Compared with healthy controls, decreased ReHo in similar regions were shown in the MWoA group and subgroups. It is noteworthy that the caudate showed increased ReHo in the SDS (−) group compared with healthy controls and the SDS (+) group. Moreover, the average ReHo values of the caudate in SDS (−) group were significantly positively correlated with duration of migraine.

Conclusions

Our results suggested that ReHo patterns in migraine patients may be affected by depressive symptoms and serve as a biomarker to reflect depression severity in MWoA.

Creatine supplementation associated or not with strength training upon emotional and cognitive measures in older women: a randomized double-blind study

Purpose

To assess the effects of creatine supplementation, associated or not with strength training, upon emotional and cognitive measures in older woman.

Methods

This is a 24-week, parallel-group, double-blind, randomized, placebo-controlled trial. The individuals were randomly allocated into one of the following groups (n=14 each): 1) placebo, 2) creatine supplementation, 3) placebo associated with strength training or 4) creatine supplementation associated with strength training. According to their allocation, the participants were given creatine (4 x 5 g/d for 5 days followed by 5 g/d) or placebo (dextrose at the same dosage) and were strength trained or not. Cognitive function, assessed by a comprehensive battery of tests involving memory, selective attention, and inhibitory control, and emotional measures, assessed by the Geriatric Depression Scale, were evaluated at baseline, after 12 and 24 weeks of the intervention. Muscle strength and food intake were evaluated at baseline and after 24 weeks.

Results

After the 24-week intervention, both training groups (ingesting creatine supplementation and placebo) had significant reductions on the Geriatric Depression Scale scores when compared with the non-trained placebo group (p = 0.001 and p = 0.01, respectively) and the non-trained creatine group (p < 0.001 for both comparison). However, no significant differences were observed between the non-trained placebo and creatine (p = 0.60) groups, or between the trained placebo and creatine groups (p = 0.83). Both trained groups, irrespective of creatine supplementation, had better muscle strength performance than the non-trained groups. Neither strength training nor creatine supplementation altered any parameter of cognitive performance. Food intake remained unchanged.

Conclusion

Creatine supplementation did not promote any significant change in cognitive function and emotional parameters in apparently healthy older individuals. In addition, strength training perse improved emotional state and muscle strength, but not cognition, with no additive effects of creatine supplementation.

Trial Registration

Clinicaltrials.gov NCT01164020

Striatum-based circuitry of adolescent depression and anhedonia

OBJECTIVE

Striatum-based circuits have been implicated in both major depressive disorder (MDD) and anhedonia, a symptom that reflects deficits of reward processing. Yet adolescents with MDD often exhibit a wide range of anhedonia severity. Addressing this clinical phenomenon, we aimed to use intrinsic functional connectivity (iFC) to study striatum-based circuitry in relation to categorical diagnosis of MDD and anhedonia severity.

METHOD

A total of 21 psychotropic medication-free adolescents with MDD and 21 healthy controls (HC), group-matched for age and sex, underwent resting-state functional magnetic resonance imagining (fMRI) scans. Voxelwise maps indicating correlation strengths of spontaneous blood-oxygenation-level-dependent (BOLD) signals among 6 bilateral striatal seeds (dorsal caudate, ventral caudate, nucleus accumbens, dorsal-rostral putamen, dorsal-caudal putamen, ventral-rostral putamen) and the remaining brain regions were compared between groups. Relationships between striatal iFC and severity of MDD and anhedonia were examined in the MDD group. Analyses were corrected for multiple comparisons.

RESULTS

Adolescents with MDD manifested increased iFC between all striatal regions bilaterally and the dorsomedial prefrontal cortex (dmPFC), as well as between the right ventral caudate and the anterior cingulate cortex (ACC). MDD severity was associated with iFC between the striatum and midline structures including the precuneus, posterior cingulate cortex, and dmPFC. However, distinct striatal iFC patterns involving the pregenual ACC, subgenual ACC, supplementary motor area, and supramarginal gyrus were associated with anhedonia severity.

CONCLUSIONS

Although MDD diagnosis and severity were related to striatal networks involving midline cortical structures, distinct circuits within the reward system were associated with anhedonia. Findings support the incorporation of both categorical and dimensional approaches in neuropsychiatric research.

The neurobiology of depression and antidepressant action

We present a comprehensive overview of the neurobiology of unipolar major depression and antidepressant drug action, integrating data from affective neuroscience, neuro- and psychopharmacology, neuroendocrinology, neuroanatomy, and molecular biology. We suggest that the problem of depression comprises three sub-problems: first episodes in people with low vulnerability ('simple' depressions), which are strongly stress-dependent; an increase in vulnerability and autonomy from stress that develops over episodes of depression (kindling); and factors that confer vulnerability to a first episode (a depressive diathesis). We describe key processes in the onset of a 'simple' depression and show that kindling and depressive diatheses reproduce many of the neurobiological features of depression. We also review the neurobiological mechanisms of antidepressant drug action, and show that resistance to antidepressant treatment is associated with genetic and other factors that are largely similar to those implicated in vulnerability to depression. We discuss the implications of these conclusions for the understanding and treatment of depression, and make some strategic recommendations for future research.

Creatine metabolism and psychiatric disorders: Does creatine supplementation have therapeutic value?

Athletes, body builders, and military personnel use dietary creatine as an ergogenic aid to boost physical performance in sports involving short bursts of high-intensity muscle activity. Lesser known is the essential role creatine, a natural regulator of energy homeostasis, plays in brain function and development. Creatine supplementation has shown promise as a safe, effective, and tolerable adjunct to medication for the treatment of brain-related disorders linked with dysfunctional energy metabolism, such as Huntington's Disease and Parkinson's Disease. Impairments in creatine metabolism have also been implicated in the pathogenesis of psychiatric disorders, leaving clinicians, researchers and patients alike wondering if dietary creatine has therapeutic value for treating mental illness. The present review summarizes the neurobiology of the creatine-phosphocreatine circuit and its relation to psychological stress, schizophrenia, mood and anxiety disorders. While present knowledge of the role of creatine in cognitive and emotional processing is in its infancy, further research on this endogenous metabolite has the potential to advance our understanding of the biological bases of psychopathology and improve current therapeutic strategies.

Neurobiological circuits regulating attention, cognitive control, motivation, and emotion: disruptions in neurodevelopmental psychiatric disorders

OBJECTIVE

This article aims to review basic and clinical studies outlining the roles of prefrontal cortical (PFC) networks in the behavior and cognitive functions that are compromised in childhood neurodevelopmental disorders and how these map into the neuroimaging evidence of circuit abnormalities in these disorders.

METHOD

Studies of animals, normally developing children, and patients with neurodevelopmental disorders were reviewed, with focus on neuroimaging studies.

RESULTS

The PFC provides "top-down" regulation of attention, inhibition/cognitive control, motivation, and emotion through connections with posterior cortical and subcortical structures. Dorsolateral and inferior PFC regulate attention and cognitive/inhibitory control, whereas orbital and ventromedial structures regulate motivation and affect. PFC circuitries are very sensitive to their neurochemical environment, and small changes in the underlying neurotransmitter systems, e.g. by medications, can produce large effects on mediated function. Neuroimaging studies of children with neurodevelopmental disorders show altered brain structure and function in distinctive circuits respecting this organization. Children with attention-deficit/hyperactivity disorder show prominent abnormalities in the inferior PFC and its connections to striatal, cerebellar, and parietal regions, whereas children with conduct disorder show alterations in the paralimbic system, comprising ventromedial, lateral orbitofrontal, and superior temporal cortices together with specific underlying limbic regions, regulating motivation and emotion control. Children with major depressive disorder show alterations in ventral orbital and limbic activity, particularly in the left hemisphere, mediating emotions. Finally, children with obsessive-compulsive disorder appear to have a dysregulation in orbito-fronto-striatal inhibitory control pathways, but also deficits in dorsolateral fronto-parietal systems of attention.

CONCLUSIONS

Altogether, there is a good correspondence between anatomical circuitry mediating compromised functions and patterns of brain structure and function changes in children with neuropsychiatric disorders. Medications may optimize the neurochemical environment in PFC and associated circuitries, and improve structure and function.

Sex-specific antidepressant effects of dietary creatine with and without sub-acute fluoxetine in rats

The potential role of metabolic impairments in the pathophysiology of depression is motivating researchers to evaluate the treatment efficacy of creatine, a naturally occurring energetic and neuroprotective compound found in brain and muscle tissues. Growing evidence is demonstrating the benefit of oral creatine supplements for reducing depressive symptoms in humans and animals. A novel question is whether dietary creatine, when combined with antidepressant drug therapy, would be more effective than either compound alone. To answer this question, four studies were conducted to investigate the behavioral effects of combined creatine and low-dose fluoxetine treatment using the forced swim test in male and female rats. Sprague-Dawley rats were fed powdered rodent chow supplemented with 0%, 2% or 4% w/w creatine monohydrate for 5 weeks. Rats were injected with fluoxetine (5.0 or 10.0 mg/kg) or saline according to a sub-acute dosing schedule. Female rats maintained on a 4% creatine diet displayed antidepressant-like effects compared to non-supplemented females prior to fluoxetine treatment. In contrast, creatine did not alter behavior reliably in males. Following drug treatment and a second forced swim trial, the antidepressant-like profile of creatine remained significant only in females co-administered 5.0 mg/kg fluoxetine. Moreover, in females only, supplementation with 4% creatine produced a more robust antidepressant-like behavioral profile compared to either dose of fluoxetine alone. Estrous cycle data indicated that ovarian hormones influenced the antidepressant-like effects of creatine. Addressing the issue of sex differences in response to treatment may affect our understanding of creatine, its relationship with depressive behavior, and may lead to sex-specific therapeutic strategies.

Toward dysfunctional connectivity: a review of neuroimaging findings in pediatric major depressive disorder

Child and adolescent psychiatric neuroimaging research typically lags behind similar advances in adult disorders. While the pediatric depression imaging literature is less developed, a recent surge in interest has created the need for a synthetic review of this work. Major findings from pediatric volumetric and functional magnetic resonance imaging (fMRI), magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI) and resting state functional connectivity studies converge to implicate a corticolimbic network of key areas that work together to mediate the task of emotion regulation. Imaging the brain of children and adolescents with unipolar depression began with volumetric studies of isolated brain regions that served to identify key prefrontal, cingulate and limbic nodes of depression-related circuitry elucidated from more recent advances in DTI and functional connectivity imaging. Systematic review of these studies preliminarily suggests developmental differences between findings in youth and adults, including prodromal neurobiological features, along with some continuity across development.

Anti-depressant effects of Xiaoyaosan on rat model of chronic unpredictable mild stress: a plasma metabonomics study based on NMR spectroscopy

OBJECTIVES

To investigate the antidepressant effects of Xiaoyaosan (XYS) in a chronic unpredictable mild stress (CUMS) depression model.

METHODS

The changes in behaviour and plasma metabolic profiles were investigated after four-week CUMS exposure and treatment. Drugs were administered during the four-week period of CUMS, with the healthy group serving as negative controls, and the fluoxetine and venlafaxine groups serving as positive controls. Plasma samples were collected at 28th day, and the plasma metabolic profiling was measured using NMR, followed by multivariate analysis.

KEY FINDINGS

Exposure to CUMS for four weeks caused depression-like behaviour in rats, as indicated by significant decreases in weight gain, sucrose consumption and locomotor activity. Eleven potential biomarkers, including seven in the Carr-Purcell-Meiboom-Gill spectra, five in the diffusion-edited spectra, and one in both were identified. It was found that trimethylamine-N-oxide, alanine, β-hydroxybutyrate, valine, leucine/isoleucine, low-density lipoprotein/very low-density lipoprotein and lipids were lower and phosphatidylcholine, high-density lipoprotein, choline and N-acetyl glycoproteins were higher in CUMS-treated rats, as compared with controls. XYS significantly suppressed behavioural changes and attenuated plasma metabolite changes.

CONCLUSIONS

XYS produced an obvious antidepressant effect, and the metabonomic approach benefits estimation of the pharmacodynamic action of traditional Chinese medicine prescriptions.

Acute restraint-mediated increases in glutamate levels in the rat brain: an in vivo ¹H-MRS study at 4.7 T

It is well known that a variety of stressors induces a significant alteration in various putative neurotransmitters in the mammalian CNS. However, relatively little attention has been paid on the alteration of central glutamate neurotransmission, which is a major excitatory neurotransmitter in the brain. The present study aimed to determine whether acute restraint stress induces the changes in neurotransmitter level, especially glutamate, in rat brain and to examine whether 1-h recovery time after the termination of stress can revert to its pre-stress state. In vivo ¹H-NMR spectra were acquired from the cerebral cortex and hippocampus (control: N = 10, stress: N = 10, stress + 1 h rest: N = 10) immediately or after 1 h rest from restraint stress. All in vivo proton spectra were automatically analyzed using LCModel. We found that acute restraint stress induced significant increase in glutamate concentrations in the cerebral cortex and the hippocampus of rat. However, the level could not revert to its pre-stress state by the end of 1-h recovery period in cerebral cortex of rats. In addition, glutamine/glutamate ratio, which may function as an index of the glutamatergic neurotransmission, was significantly lower in the cerebral cortex of both stress and 1 h stress + 1 h recovery groups, as compared to control. Our finding may provide important evidence for altered glutamatergic activity after the stress and suggest a potential biochemical marker for eventual diagnosis and/or therapy monitoring in mood disorder.

Proton magnetic resonance spectroscopy in depression

Magnetic Resonance Spectroscopy (MRS) is a unique technique that can directly assess the concentration of various biochemical metabolites in the brain. Thus, it is used in the study of molecular pathophysiology of different neuropsychiatric disorders, such as, the major depressive disorder and has been an area of active research. We conducted a computer-based literature search using the Pubmed database with 'magnetic resonance spectroscopy', 'MRS', 'depression', and 'major depressive disorder' as the key words, supplemented by a manual search of bibliographic cross-referencing. Studies in depression report abnormalities in the frontal cortex, basal ganglia, hippocampus, anterior cingulate cortex, and the occipital cortex. These abnormalities improve after treatment with selective serotonin reuptake inhibitor, electroconvulsive therapy, and yoga, and thus, are possibly state-dependent. The findings are consistent with other morphometric and clinical studies and support the proposed pathophysiological theory of dysfunction in the neuronal circuits involving the frontal cortex, limbic cortex, and basal ganglia. Spectroscopy also has potential implications in predicting the response to treatment and formulating individualized pharmacotherapy.

Disrupted brain connectivity networks in drug-naive, first-episode major depressive disorder

BACKGROUND

Neuroimaging studies have shown that major depressive disorder (MDD) is accompanied by structural and functional abnormalities in specific brain regions and connections; yet, little is known about alterations of the topological organization of whole-brain networks in MDD patients.

METHODS

Thirty drug-naive, first-episode MDD patients and 63 healthy control subjects underwent a resting-state functional magnetic resonance imaging scan. The whole-brain functional networks were constructed by thresholding partial correlation matrices of 90 brain regions, and their topological properties (e.g., small-world, efficiency, and nodal centrality) were analyzed using graph theory-based approaches. Nonparametric permutation tests were further used for group comparisons of topological metrics.

RESULTS

Both the MDD and control groups showed small-world architecture in brain functional networks, suggesting a balance between functional segregation and integration. However, compared with control subjects, the MDD patients showed altered quantitative values in the global properties, characterized by lower path length and higher global efficiency, implying a shift toward randomization in their brain networks. The MDD patients exhibited increased nodal centralities, predominately in the caudate nucleus and default-mode regions, including the hippocampus, inferior parietal, medial frontal, and parietal regions, and reduced nodal centralities in the occipital, frontal (orbital part), and temporal regions. The altered nodal centralities in the left hippocampus and the left caudate nucleus were correlated with disease duration and severity.

CONCLUSIONS

These results suggest that depressive disorder is associated with disruptions in the topological organization of functional brain networks and that this disruption may contribute to disturbances in mood and cognition in MDD patients.

Stability of fMRI striatal response to alcohol cues: a hierarchical linear modeling approach

In functional magnetic resonance imaging (fMRI) studies of alcohol-dependent individuals, alcohol cues elicit activation of the ventral and dorsal aspects of the striatum (VS and DS), which are believed to underlie aspects of reward learning critical to the initiation and maintenance of alcohol dependence. Cue-elicited striatal activation may represent a biological substrate through which treatment efficacy may be measured. However, to be useful for this purpose, VS or DS activation must first demonstrate stability across time. Using hierarchical linear modeling (HLM), this study tested the stability of cue-elicited activation in anatomically and functionally defined regions of interest in bilateral VS and DS. Nine non-treatment-seeking alcohol-dependent participants twice completed an alcohol cue reactivity task during two fMRI scans separated by 14 days. HLM analyses demonstrated that, across all participants, alcohol cues elicited significant activation in each of the regions of interest. At the group level, these activations attenuated slightly between scans, but session-wise differences were not significant. Within-participants stability was best in the anatomically defined right VS and DS and in a functionally defined region that encompassed right caudate and putamen (intraclass correlation coefficients of .75, .81, and .76, respectively). Thus, within this small sample, alcohol cue-elicited fMRI activation had good reliability in the right striatum, though a larger sample is necessary to ensure generalizability and further evaluate stability. This study also demonstrates the utility of HLM analytic techniques for serial fMRI studies, in which separating within-participants variance (individual changes in activation) from between-participants factors (time or treatment) is critical.