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

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.

Effect of icariin on depressive behaviour in rat pups. Evidences for its mechanism of action by integrating network pharmacology, metabolomics and gut microbiota composition

BACKGROUND

Prenatal stress (PS) can cause cognitive disorder and a range of psychological illnesses, including anxiety and depression. Icariin (ICA) has shown promising effects in improving PS-induced depressive behaviour. However, its mechanism of action remains unclear.

PURPOSE

This study was performed to reveal the key targets, metabolites and gut microbiota for ICA in improving depressive behaviour in PS rat pups.

METHODS

A prenatal restraint stress animal model was established for Sprague-Dawley (SD) rats in late pregnancy. Male pups were randomly divided into six groups: no stress group (NS), PS group, PS + saline group (PS_S), PS + high-dose ICA group (ICAH, 80 mg/kg*day), PS + low-dose ICA group (ICAL, 40 mg/kg*day) and PS + fluoxetine group (FLU, 10 mg/kg*day). The depressive behaviour of each group of rat pups was evaluated using open field test, forced swimming test and sucrose preference test. Different metabolites were identified using untargeted metabolomics of serum and faeces, and metabolic pathways were analyzed through MetaboAnalyst. Targets for ICA acting on depression were determined after network pharmacology was applied. An integrated network of network pharmacology and metabolomics were constructed using Cytoscape software, and molecular docking were performed to verify the interactions between ICA and key targets. Finally, gut microbiota of rat pups in each group were analyzed after 16S rDNA sequencing.

RESULTS

PS could cause rat pups to exhibit depressive behaviour, and ICA could significantly improve this depressive behaviour. A total of 49 differential metabolites were found in serum and 23 differential metabolites were found in faeces, and 24 metabolites in serum and 6 metabolites in faeces could be reversed following ICA administration. Integrated analysis focused on five key targets (i.e. adenosyl homocysteinase; medium-chain specific acyl-CoA dehydrogenase, mitochondrial; thymidine phosphorylase; cGMP-specific 3',5'-cyclic phosphodiesterase and xanthine dehydrogenase/oxidase) and three metabolites (i.e. palmitoylcarnitine, methionine and hypoxanthine). Molecular docking indicated that ICA combined well with key targets. Gut microbiota analysis showed that g_Bacteroides, f_Bacteroidaceae and s_Lactobacillus reuteri were required for ICA to improve depressive behaviour.

CONCLUSION

In this study, the antidepressant mechanism of ICA was clarified with a strategy of integrating metabolomics, network pharmacology and gut microbiota. ICA has a good effect on improving metabolism and increasing the abundance of probiotics in the intestine. The present research provided new insights into the anti-depressant mechanism of ICA.

Imaging of nerve injury in neonatal acute bilirubin encephalopathy using 1H-MRS and Glu-CEST techniques

Objectives

To investigate the significance of proton magnetic resonance spectroscopy (1H-MRS) and glutamate chemical exchange saturation transfer (Glu-CEST) techniques in assessing the condition and prognosis of acute bilirubin encephalopathy patients and to understand the mechanism of nerve injury in this disease.

Materials and methods

From September 2019 to February 2021, 31 neonates with acute bilirubin encephalopathy and 16 healthy neonates were enrolled in this study. All the quantitative results of 1H-MRS, Glu-CEST, and conventional magnetic resonance imaging (MRI) of all neonates were analyzed. The associations between statistically significant indicators of imaging and developmental quotients (DQ) were analyzed.

Results

The 31 cases were assigned to the mild subgroup (n = 21) and moderate and severe subgroup (n = 10) according to the bilirubin-induced neurologic dysfunction (BIND) scores. The case group had elevated Cho and GABA absolute concentrations compared to the normal control group (all p < 0.05). Compared with the normal control group, the absolute concentration of GABA of the moderate and severe subgroup was significantly larger (p < 0.05). Compared with the normal control group, the Glu-CEST% values in the left basal ganglia, right thalamus, left frontal cortex and bilateral medial geniculate body of the case group was significantly larger (all p < 0.05). The moderate and severe subgroup had higher Glu-CEST% values in the left basal ganglia, right thalamus, and bilateral medial geniculate body than the normal control group (all p < 0.05). A negative association was revealed between the DQ scores and the Glu-CEST% values in the left basal ganglia (r = −0.888, p < 0.05).

Conclusion

The combination of 1H-MRS and Glu-CEST techniques can monitor the intracerebral metabolite level of acute bilirubin encephalopathy and evaluate the illness severity.

Neurochemical and microstructural alterations in bipolar and depressive disorders: A multimodal magnetic resonance imaging study

AIMS

Depression in bipolar disorder (BD) is often misdiagnosed as unipolar depression (UD), leading to mistreatments and poor clinical outcomes in many bipolar patients. Herein, we report direct comparisons between medication-free patients with BD and those with UD in terms of the microstructure and neurometabolites in eight brain regions.

METHODS

A total of 20 patients with BD, 30 with UD patients, and 20 matched healthy controls (HCs) underwent 3.0T magnetic resonance imaging with chemical exchange saturation transfer (CEST) for glutamate (Glu; GluCEST) imaging, multivoxel magnetic resonance spectroscopy, and diffusion kurtosis imaging.

RESULTS

Compared with HCs, patients with UD showed significantly lower levels of multiple metabolites, GluCEST% values, and diffusional kurtosis [mean kurtosis (MK)] values in most brain regions. In contrast, patients with BD presented significantly higher levels of Glu in their bilateral ventral prefrontal white matter (VPFWM), higher choline (Cho)-containing compounds in their left VPFWM and anterior cingulate cortex (ACC), and higher GluCEST% values in their bilateral VPFWM and ACC; moreover, reduced MK in these patients was more prominent in the left VPFWM and left thalamus.

CONCLUSION

The findings demonstrated that both patients with UD and BD have abnormal microstructure and metabolic alterations, and the changes are not completely consistent in the prefrontal lobe region. Elevated Glu, Cho, and GluCEST% in the ACC and VPFWM of patients with UD and BD may help in differentiating between these two disorders. Our findings support the significance for the microstructural integrity and brain metabolic changes of the prefrontal lobe region in BD and UD.

Effects of Repetitive Transcranial Magnetic Stimulation on Cognitive Function in Patients With Stress-Related Depression: A Randomized Double-Blind fMRI and 1H-MRS Study

Objectives

To reveal the effects of repetitive transcranial magnetic stimulation (rTMS) on the improvement of cognitive function in patients with stress-related depression, and to enrich the neural mechanism(s) underlying rTMS so as to improve cognitive function in patients with stress-related depression.

Methods

We conducted a randomized, double-blind, placebo-controlled study of rTMS in patients with stress-related depression who were 18–40 years of age. Patients were randomly allocated to either a sham or experimental group in a 1:1 ratio. A 10-session rTMS protocol was used with 10-Hz stimulation over the left dorsolateral prefrontal cortex (DLPFC). Clinical assessments (HAMD, HAMA, DASS, MoCA), neuropsychologic (Stroop, WCST), and resting state fMRI and ¹H-MRS assessments were executed at two time points—baseline and after the 10th rTMS session.

Results

rTMS relieved the mental symptoms of patients in both groups. The MoCA score of patients in the experimental group increased; the number of correct answers increased significantly in Stroop testing, and the number of errors and omissions decreased significantly; the number of persistent errors decreased significantly; and the time used to complete the test decreased to an even greater extent in the WCST experimental group. The ReHo value in the lingual gyrus of the right hemisphere and the cuneus of the left and right hemispheres in the experimental group decreased after treatment. The DC value in the left and right hemispheric cuneus and postcentral gyrus of the left hemisphere in the experimental group diminished after treatment. The functional connections of these brain regions also changed as the Cho and NAA/Cr of the left DLPFC changed, with alterations related to the improvement in cognitive function. The level of choline (Cho) in the left DLPFC of the experimental group was significantly lower than that of the control group, and the level of N-acetylaspartate/creatine (NAA/Cr) in the left DLPFC of the control group was significantly higher than that of the experimental group. These changes were related to the overall improvement in cognitive function.

Conclusions

Ten-Hz rTMS over the left DLPFC improved the cognitive function of patients with stress-related depression. The governing mechanism for this phenomenon may be via rTMS effects on multiple visual-related brain regions and their functional connections, and on the somatosensory cortex and its functional connection with visual and auditory cortex, reducing the level of Cho and stabilizing the level of NAA/Cr in the left DLPFC.

Associations between executive function impairment and biochemical abnormalities in depressed adolescents with non-suicidal self-injury

BACKGROUND

H protons magnetic resonance spectroscopy (¹H-MRS) has been used to detect the biochemical metabolism changes and the mechanism of executive dysfunction in major depressive disorder (MDD). While, finding information associated with non-suicidal self-injury (NSSI) among adolescents with MDD is challenging. The present study aimed to examine the executive function and biochemical metabolism alterations, as well as to elucidate their associations in depressed adolescents with NSSI.

METHODS

A total of 86 adolescents with MDD (40 with NSSI, and 46 without NSSI) and 28 healthy controls were recruited in the current study. The executive function was assessed by Digital symbol test (DST), Wisconsin Card Sorting Test (WCST), Trail Making Test, part B (TMT-B), and Verbal fluency (VF). Bilateral metabolite levels of the prefrontal cortex (PFC), anterior cingulated cortex (ACC), lenticular nucleus (LN) of basal ganglia and thalamus were obtained by ¹H-MRS at 3.0 T, and then the ratios of N-acetyl aspartate (NAA) and choline-containing compounds (Cho) to creatine (Cr) were determined, respectively. Finally, association analysis was conducted to investigate their relationships.

RESULTS

The depressed adolescents with NSSI showed significantly lower VF scores than those without NSSI and healthy controls. We also found significantly higher NAA/Cr ratios in the right thalamus, while significantly lower Cho/Cr ratios in the right thalamus of NSSI group than the MDD without NSSI group and healthy controls. And NSSI group also showed lower NAA/Cr ratio in the right LN than the MDD without NSSI group. For MDD with NSSI, the NAA/Cr ratios of the left thalamus were positively correlated with the time of TMTB and the Cho/Cr ratios of the left ACC were positively correlated with the VF scores.

CONCLUSIONS

Depressed adolescents with NSSI may have executive dysfunction and NAA and Cho metabolism abnormalities in the thalamus. And the NAA/Cr ratios of the right LN could distinguish NSSI from depressed adolescents. Further, the executive dysfunction may be associated with the abnormal NAA metabolism in the left thalamus and ACC.

Body mass index and variability in hippocampal volume in youth with major depressive disorder

BACKGROUND

The hippocampus has been implicated in major depressive disorder (MDD), in both adults and youth. However, possible sources of variability for the hippocampus have not been well delineated. Here, we explored the relationship between body mass index (BMI) and hippocampal volume in youth with MDD.

METHODS

Twenty-two controls (9 male, 13 female, 12-24 years), 24 youth with MDD and normal BMI (12 male, 12 female, 14-24 years), and 20 youth with MDD and high BMI (14 male, 6 female, 13-22 years) underwent magnetic resonance (MR) imaging and spectroscopy (1H-MRS). Hippocampal volume was determined through manual tracing of high-resolution anatomical T1 scans, and LCModel quantified neurochemical concentrations. Intracranial volume was used as a covariate in analysis to control for effects of brain volume on hippocampus.

RESULTS

In youth with MDD and normal BMI, right hippocampal volume was reduced (p = 0.006, Bonferroni) and a trend for reduced left hippocampal volume was noted when compared to healthy controls (p = 0.054, Bonferroni). Left hippocampal volumes were negatively associated with BMI in youth with MDD and high BMI group (r = -0.593, p = 0.006). No associations were found between the right hippocampus and BMI and there were no group differences for metabolite concentrations.

LIMITATIONS

Larger sample sizes would enable researchers to explore overweight vs obese groups and effect of sex in MDD-BMI groups.

CONCLUSIONS

BMI may account for some of the variability observed in previous studies of hippocampal volume in MDD, and therefore BMI impacts should be considered in future analyses.

Functional connectivity patterns of the subgenual anterior cingulate cortex in first-episode refractory major depressive disorder

Although accumulating evidence has been elucidating the neuronal basis of refractory/nonrefractory major depressive disorder (rMDD/nrMDD), the results are inconsistent, and little is known about the distinct neural mechanisms underlying rMDD. Here, we explored the convergent/divergent brain networks between first-episode MDD subtypes using the resting-state functional connectivity (RSFC) approach. In total, 33 healthy controls (HCs), 31 first-episode rMDD patients and 33 first-episode nrMDD patients were enrolled and underwent MRI scanning. The left subgenual anterior cingulate cortex (sgACC) was selected as the seed region, and RSFC was employed to evaluate associations between the seed and other regions in the whole brain. Both MDD subtypes exhibited convergent left sgACC-based neural networks, including increased RSFC with the dorsal prefrontal cortex (DPFC) and decreased RSFC with the bilateral orbitofrontal cortex (OFC) and right parahippocampus. rMDD patients exhibited increased left sgACC-OFC RSFC relative to nrMDD patients, and RSFC with the bilateral OFC in rMDD patients was negatively correlated with HAMD scores. These findings confirmed our speculation that convergent and divergent neural networks exist between rMDD and nrMDD. Cortical-limbic circuits, especially the prefrontal-limbic circuit, may serve as the convergent dysfunctional neural circuitry in MDD subtypes. As an important biomarker, a unique OFC-sgACC circuit abnormality was identified in rMDD patients, which might help elucidate the underlying mechanism regarding treatment responses in rMDD patients.

Immunological Disturbances and Neuroimaging Findings in Major Depressive Disorder (MDD) and Alcohol Use Disorder (AUD) Comorbid Patients

Mood disorders and Major Depressive Disorder, in particular, appear to be some of the most common psychiatric disorders with a high rate of comorbidity most frequently of anxiety or substance abuse disorders (alcohol use disorder). In both cases - MDD and AUD, a number of immunological disturbances are observed, such as chronic mild inflammation response, increased level of cytokines, hypercortisolaemia, which lead to specific changes in brain neurotransmitter functions. Some of the contemporary brain imaging techniques are functional magnetic resonance imaging (fMRI) and magnetic spectroscopy which are most commonly used to assess the brain metabolism and functional connectivity changes such as altered responses to emotional stimuli in MDD or overactivation of ventromedial prefrontal areas during delayed and underactivation of dorsolateral prefrontal regions during impulsive reward decisions in AUD and dysfunction of gamma-aminobutyric acid (GABA) and/or glutamate neurotransmitter systems, low NAA and myo-Inositol in both MDD and AUD.

Plasma Neuronal and Glial Markers and Anterior Cingulate Metabolite Levels in Major Depressive Disorder: A Pilot Study

INTRODUCTION

Neuroglial functions may be deteriorated in major depressive disorder (MDD).

OBJECTIVE

To evaluate the markers of glial and neuronal cell turnover and to explore their associations with brain metabolites.

METHODS

In 10 participants with MDD and 10 healthy controls (HC) we investigated neuronal and glial plasma markers (the neuron-specific enolase, NSE; and S100beta, S100B) and brain metabolites (N-acetyl aspartate, NAA; total choline, Cho; and total creatine, Cr). Blood was collected for NSE and S100B. NAA, Cho, and Cr metabolite levels were measured in the anterior cingulate cortex (ACC) with proton magnetic resonance spectroscopy (1H-MRS) at 3T.

RESULTS

NSE and S100B levels were significantly higher in MDD subjects than in HC. The Cr level was significantly higher in MDD subjects than in HC, but the NAA and Cho levels did not differ between groups. NAA/Cr and Cho/Cr ratios were significantly lower in patients with MDD versus HC. S100B was negatively correlated with the Cho levels.

CONCLUSIONS

These results provide supporting evidence of neuronal and glial distress in MDD. Neuronal viability appears decreased, whereas glial regenerative activity and energy metabolism in the ACC increase in acute major depressive episode. Since low concentrations of S100B have neuroplastic effects, these changes may indicate a possible compensatory mechanism.

Left Dorsolateral Prefrontal Cortex Glx/tCr Predicts Efficacy of High Frequency 4- to 6-Week rTMS Treatment and Is Associated With Symptom Improvement in Adults With Major Depressive Disorder: Findings From a Pilot Study

About 20-40% of estimated 121 million patients with major depressive disorder (MDD) are not adequately responsive to medication treatment. Repetitive transcranial magnetic stimulation (rTMS), a non-invasive, non-convulsive neuromodulation/neurostimulation method, has gained popularity in treatment of MDD. Because of the high cost involved in rTMS therapy, ability to predict the therapy effectiveness is both clinically and cost wise significant. This study seeks an imaging biomarker to predict efficacy of rTMS treatment using a standard high frequency 10-Hz 4- to 6-week protocol in adult population. Given the significance of excitatory and inhibitory neurotransmitters glutamate (Glu) and gamma aminobutyric acid (GABA) in the pathophysiology of MDD, and the involvement of the site of rTMS application, left dorsolateral prefrontal cortex (lDLPFC), in MDD, we explored lDLPFC Glx (Glu + glutamine) and GABA levels, measured by single voxel magnetic resonance spectroscopy (MRS) with total creatine (tCr; sum of creatine and phosphocreatine) as reference, as possible biomarkers of rTMS response prediction. Mescher-Garwood point-resolved spectroscopy (MEGA-PRESS) MRS data from 7 patients (40-74 y) were used in the study; 6 of these patients were scanned before and after 6 weeks of rTMS therapy. Findings from this study show inverse correlation between pretreatment lDLPFC Glx/tCr and (i) posttreatment depression score and (ii) change in depression score, suggesting higher Glx/tCr as a predictor of treatment efficacy. In addition association was observed between changes in depression scores and changes in Glx/tCr ratio. The preliminary findings did not show any such association between GABA/tCr and depression score.

Glutamatergic neurometabolite levels in major depressive disorder: a systematic review and meta-analysis of proton magnetic resonance spectroscopy studies

Alterations in glutamatergic neurotransmission are implicated in the pathophysiology of depression, and the glutamatergic system represents a treatment target for depression. To summarize the nature of glutamatergic alterations in patients with depression, we conducted a meta-analysis of proton magnetic resonance (¹H-MRS) spectroscopy studies examining levels of glutamate. We used the search terms: depress* AND (MRS OR "magnetic resonance spectroscopy"). The search was performed with MEDLINE, Embase, and PsycINFO. The inclusion criteria were ¹H-MRS studies comparing levels of glutamate + glutamine (Glx), glutamate, or glutamine between patients with depression and healthy controls. Standardized mean differences (SMD) were calculated to assess group differences in the levels of glutamatergic neurometabolites. Forty-nine studies met the eligibility criteria, which included 1180 patients and 1066 healthy controls. There were significant decreases in Glx within the medial frontal cortex (SMD = -0.38; 95% CI, -0.69 to -0.07) in patients with depression compared with controls. Subanalyses revealed that there was a significant decrease in Glx in the medial frontal cortex in medicated patients with depression (SMD = -0.50; 95% CI, -0.80 to -0.20), but not in unmedicated patients (SMD = -0.27; 95% CI, -0.76 to 0.21) compared with controls. Overall, decreased levels of glutamatergic metabolites in the medial frontal cortex are linked with the pathophysiology of depression. These findings are in line with the hypothesis that depression may be associated with abnormal glutamatergic neurotransmission.

Frontal Cortex Myo-Inositol Is Associated with Sleep and Depression in Adolescents: A Proton Magnetic Resonance Spectroscopy Study

AIM

This study used proton magnetic resonance spectroscopy (1H MRS) to evaluate the neurochemistry of the frontal cortex in adolescents with symptoms of sleep and depression.

METHODS

Nineteen non-medicated adolescent boys (mean age 16.0 years; 9 clinical cases with depression/sleep symptoms and 10 healthy controls) underwent 1H MRS at 3 T. MR spectra were acquired from the anterior cingulate cortex (ACC), the dorsolateral prefrontal cortex, and frontal white matter. Concentrations of N-acetyl aspartate, total creatine, choline-containing compounds, total glutamine plus glutamate, and myo-inositol (mI) were compared in the 2 subgroups, and correlated with sleep and clinical measures in the total sample. Sleep was assessed with self-report questionnaires and ambulatory polysomnography recordings.

RESULTS

Concentrations of mI were lower in both frontal cortical regions among the depressed adolescents than in controls. No statistically significant differences in other metabolite concentrations were observed between the subgroups. Frontal cortex mI concentrations correlated negatively with depression severity, subjective daytime sleepiness, insomnia symptoms, and the level of anxiety, and correlated positively with total sleep time and overall psychosocial functioning. The correlations between mI in the ACC and total sleep time as well as daytime sleepiness remained statistically significant when depression severity was controlled in the analyses.

CONCLUSION

Lower frontal cortex mI may indicate a disturbed second messenger system. Frontal cortical mI may thus be linked to the pathophysiology of depression and concomitant sleep symptoms among maturing adolescents. Short sleep and daytime sleepiness may be associated with frontal cortex mI independently from depression.

Investigating the metabolic alterations in a depressive-like rat model of chronic forced swim stress: An in vivo proton magnetic resonance spectroscopy study at 7T

Although recent investigations of major depressive disorder (MDD) have focused on the monoaminergic system, accumulating evidences suggest that alternative pathophysiological models of MDD and treatment options for patients with MDD are needed. Animals subjected to chronic forced swim stress (CFSS) develop behavioral despair. The purpose of this study was to investigate the in vivo effects of CFSS on systems other than the monoamine system in the rat prefrontal cortex (PFC) with 7T and short-echo-time (16.3 ms) proton magnetic resonance spectroscopy (¹H MRS). Ten male Wistar rats underwent 14 days of CFSS, and in vivo¹H MRS and forced swim tests were performed before and after CFSS. Point-resolved spectroscopy was used to quantify metabolite levels in the rat PFC. To investigate spectral overlap in glutamate and glutamine, spectral analyses in the spectra obtained in the in vivo¹H MRS, parametrically matched spectral simulation, and in vitro experiments were performed. The results of the spectral analyses showed that the glutamate/glutamine spectral overlap was not critical, which suggested that in vivo¹H MRS can be used to reliably assess the glutamate system. The rats showed significantly increased immobility times and decreased climbing times in the FST after CFSS, which suggested that the rats developed behavioral despair. The pre-CFSS and post-CFSS glutamate and glutamine levels did not significantly differ (p > 0.050). The levels of myo-inositol, total choline, and N-acetylaspartate, myo-inositol/creatine, and total choline/creatine increased significantly (p < 0.050). Similar findings have been reported in patients with MDD. Taken together, these results suggest that the CFSS-induced metabolic alterations were similar to those found in patients and that high-field and short-echo-time in vivo¹H MRS can be used to investigate depression-induced metabolic alterations. Such investigations might provide alternative insights into the nonmonoaminergic pathophysiology and treatment of depression.

Effects of a 72 hours fasting on brain metabolism in healthy women studied in vivo with magnetic resonance spectroscopic imaging

Adaptive response of human brain to stress plays a key role in maintaining health. Knowledge about how stress affects neurometabolism may help to understand adaptive stress responses, and distinguish maladaptation in neuropsychiatric disorders. In this study, neurometabolic responses to fasting stress in healthy women were investigated. Fifteen healthy females were examined for mood and cognition and using whole-brain MR spectroscopic imaging before and immediately after a 72-h fasting. Results were compared to 15 age-matched healthy females who did not taken part in fasting (non-fasting). Maps of the distributions in the brain of N-acetylaspartate (NAA), total choline (tCho), total creatine (tCr), glutamine/glutamate (Glx), and myo-Inositol (mI) were derived. Metabolite concentrations of each brain lobe and cerebellum measured before fasting were compared to those of post-fasting and non-fasting by repeated-measures ANOVA. After fasting, mood scores significantly increased. Glx decreased in all nine brain regions, tCho in eight, NAA in four and tCr in one, with Glx having the greatest change and the frontal lobes being the most affected brain region. In conclusion, fasting directly influences neurometabolism, and the adaptive brain response to maintain energy homeostasis under food deprivation in healthy women is associated with metabolite-selective and region-dependent changes of metabolite contents.

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.

Magnetization Transfer Imaging of Treatment-resistant Depression

Purpose To detect biophysical abnormalities in patients with postmedication treatment-resistant depression (TRD) with magnetization transfer imaging. Materials and Methods This study was approved by the local ethics committee, and written informed consent was obtained from all participants. Participants included 69 patients with major depressive disorder (MDD) (30 with TRD; 39 with non-TRD) and 41 healthy control subjects. Age and sex were examined with one-way analysis of variance and χ² tests and were well matched among the three groups. Whole-brain voxel-based analysis was used to compare the magnetization transfer ratio (MTR) between the three groups. Regional MTR values were used to analyze the correlations with symptom severity and illness duration. Results MTR differences were identified in the bilateral precentral gyrus, left cerebellum posterior lobe, left middle occipital lobe, left precuneus, and left temporal lobe among the three groups. Relative to patients with non-TRD, those with TRD had significantly lower MTR in the task-positive network regions, including the bilateral precentral gyrus and left middle occipital lobe, and had lower MTR in the default mode network regions, including the left precuneus and left temporal lobe. Regional MTRs were not associated with symptom severity or illness duration. Conclusion These results suggest that treatment resistance in patients with MDD may be mediated by macromolecular abnormalities in the task-positive and default mode functional networks. ^© RSNA, 2017 Online supplemental material is available for this article. An earlier incorrect version of this article appeared online. This article was corrected on March 29, 2017.

Transcranial Direct Current Stimulation: Considerations for Research in Adolescent Depression

Adolescent depression is a prevalent disorder with substantial morbidity and mortality. Current treatment interventions do not target relevant pathophysiology and are frequently ineffective, thereby leading to a substantial burden for individuals, families, and society. During adolescence, the prefrontal cortex undergoes extensive structural and functional changes. Recent work suggests that frontolimbic development in depressed adolescents is delayed or aberrant. The judicious application of non-invasive brain stimulation techniques to the prefrontal cortex may present a promising opportunity for durable interventions in adolescent depression. Transcranial direct current stimulation (tDCS) applies a low-intensity, continuous current that alters cortical excitability. While this modality does not elicit action potentials, it is thought to manipulate neuronal activity and neuroplasticity. Specifically, tDCS may modulate N-methyl-d-aspartate receptors and L-type voltage-gated calcium channels and effect changes through long-term potentiation or long-term depression-like mechanisms. This mini-review considers the neurobiological rationale for developing tDCS protocols in adolescent depression, reviews existing work in adult mood disorders, surveys the existing tDCS literature in adolescent populations, reviews safety studies, and discusses distinct ethical considerations in work with adolescents.