Basal ganglia choline levels in depression and response to fluoxetine treatment: an in vivo proton magnetic resonance spectroscopy study

Proton magnetic resonance spectroscopy of N-acetyl aspartate in first depressive episode and chronic major depressive disorder: A systematic review and meta-analysis

N-acetyl aspartate (NAA) is a marker of neuronal integrity and metabolism. Deficiency in neuronal plasticity and hypometabolism are implicated in Major Depressive Disorder (MDD) pathophysiology. To test if cerebral NAA concentrations decrease progressively over the MDD course, we conducted a pre-registered meta-analysis of Proton Magnetic Resonance Spectroscopy (1H-MRS) studies comparing NAA concentrations in chronic MDD (n = 1308) and first episode of depression (n = 242) patients to healthy controls (HC, n = 1242). Sixty-two studies were meta-analyzed using a random-effect model for each brain region. NAA concentrations were significantly reduced in chronic MDD compared to HC within the frontal lobe (Hedges' g = -0.330; p = 0.018), the occipital lobe (Hedges' g = -0.677; p = 0.007), thalamus (Hedges' g = -0.673; p = 0.016), and frontal (Hedges' g = -0.471; p = 0.034) and periventricular white matter (Hedges' g = -0.478; p = 0.047). We highlighted a gap of knowledge regarding NAA levels in first episode of depression patients. Sensitivity analyses indicated that antidepressant treatment may reverse NAA alterations in the frontal lobe. We highlighted field strength and correction for voxel grey matter as moderators of NAA levels detection. Future studies should assess NAA alterations in the early stages of the illness and their longitudinal progression.

Functional and structural neuroimaging in premenstrual dysphoric disorder: A systematic review

This systematic review aimed to summarize the most recent data on changes in brain structure and function in premenstrual dysphoric disorder (PMDD) as well as elucidate the possible correlations between these findings and symptom severity. Articles published in PubMed, EMBASE, ScienceDirect, PsycInfo, Web of Science, and Scopus from inception until April 2023 were systematically reviewed according to the PICO framework: population (women with PMDD), intervention (neuroimaging study), control (healthy subjects), and outcome (neuroimaging changes). In total, 1026 individuals were included from controlled (n = 22) and non-controlled (n = 2) trials. Among them, 608 had PMDD, and 418 were healthy controls. Different neuroimaging methods were addressed, such as task-based functional magnetic resonance imaging (MRI), resting-state functional MRI, proton magnetic resonance spectroscopy, diffusion tensor imaging, proton emission tomography, and structural MRI. Despite the absence of consensual results, several brain structures have been implicated in PMDD, including the prefrontal cortex, amygdala, hippocampus, insula, basal ganglia, and cerebellum. In addition, some brain changes are related to the intensity of symptoms and phases of the menstrual cycle, such as the correlation between depressive symptoms and increased serotonin transporter binding potential in the midbrain during the luteal phase.

Gut Biofactory-Neurocompetent Metabolites within the Gastrointestinal Tract. A Scoping Review

The gut microbiota have gained much scientific attention recently. Apart from unravelling the taxonomic data, we should understand how the altered microbiota structure corresponds to functions of this complex ecosystem. The metabolites of intestinal microorganisms, especially bacteria, exert pleiotropic effects on the human organism and contribute to the host systemic balance. These molecules play key roles in regulating immune and metabolic processes. A subset of them affect the gut brain axis signaling and balance the mental wellbeing. Neurotransmitters, short chain fatty acids, tryptophan catabolites, bile acids and phosphatidylcholine, choline, serotonin, and L-carnitine metabolites possess high neuroactive potential. A scoping literature search in PubMed/Embase was conducted up until 20 June 2020, using three major search terms "microbiota metabolites" AND "gut brain axis" AND "mental health". This review aimed to enhance our knowledge regarding the gut microbiota functional capacity, and support current and future attempts to create new compounds for future clinical interventions.

Altered neurometabolism in major depressive disorder: A whole brain 1H-magnetic resonance spectroscopic imaging study at 3T

INTRODUCTION

Major depressive disorder (MDD) is a severe mental disorder with a neurobiological basis that is poorly understood. Several studies demonstrated widespread, functional and neurometabolic alterations in MDD. However, little is known about whole brain neurometabolic alterations in MDD.

METHOD

Thirty-two patients with MDD and 32 paired on a one-to-one basis healthy controls (CTRL) underwent ¹H-whole brain spectroscopic (¹H-WBS) imaging. Lobar and cerebellar metabolite concentrations of brain N-acetylaspartate (NAA), total choline (tCho), total creatine (tCr), glutamine (Gln), glutamate (Glu), and myo-Inositol (mI) were assessed in patients and controls.

RESULTS

Decreased NAA, tCho, and tCr were found in the right frontal and right parietal lobe in MDD compared to CTRL, and to a lesser extent in the left frontal lobe. Furthermore, in MDD increased glutamine was observed in the right frontal lobe and bitemporal lobes, and increased glutamate in the cerebellum.

CONCLUSION

Altered global neurometabolism examined using ¹H-WBS imaging in MDD may be interpreted as signs of neuronal dysfunction, altered energy metabolism, and oligodendrocyte dysfunction. In particular, the parallel decrease in NAA, tCr and tCho in the same brain regions may be indicative of neuronal dysfunction that may be counterbalanced by an increase of the neuroprotective metabolite glutamine. Future prospective investigations are warranted to study the functional importance of these findings.

Gut microbial metabolites in depression: understanding the biochemical mechanisms

Gastrointestinal and central function are intrinsically connected by the gut microbiota, an ecosystem that has co-evolved with the host to expand its biotransformational capabilities and interact with host physiological processes by means of its metabolic products. Abnormalities in this microbiota-gut-brain axis have emerged as a key component in the pathophysiology of depression, leading to more research attempting to understand the neuroactive potential of the products of gut microbial metabolism. This review explores the potential for the gut microbiota to contribute to depression and focuses on the role that microbially-derived molecules – neurotransmitters, short-chain fatty acids, indoles, bile acids, choline metabolites, lactate and vitamins – play in the context of emotional behavior. The future of gut-brain axis research lies is moving away from association, towards the mechanisms underlying the relationship between the gut bacteria and depressive behavior. We propose that direct and indirect mechanisms exist through which gut microbial metabolites affect depressive behavior: these include (i) direct stimulation of central receptors, (ii) peripheral stimulation of neural, endocrine, and immune mediators, and (iii) epigenetic regulation of histone acetylation and DNA methylation. Elucidating these mechanisms is essential to expand our understanding of the etiology of depression, and to develop new strategies to harness the beneficial psychotropic effects of these molecules. Overall, the review highlights the potential for dietary interventions to represent such novel therapeutic strategies for major depressive disorder.

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.

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.

Applications of Magnetic Resonance Spectroscopy to Psychiatry

The inaccessibility of the human brain to biochemical studies has historically challenged the ability of in vestigators to elucidate the pathophysiology of psychiatric syndromes. Magnetic resonance spectroscopy (MRS) now provides a noninvasive means of assessing neurochemistry in vivo. Since the first application of the technique to the study of the human brain, many new advances have been made. This new technology broadens the applications of the MRS. The major principles of the technique and compounds currently available for study are discussed in this article. A brief review of current and future applications of the technology to the field of psychiatry are discussed. NEUROSCIENTIST 5:192-196, 1999

Imaging changes in neural circuits in patients with depression using (1)H-magnetic resonance spectroscopy and diffusion tensor imaging

(1)H-magnetic resonance spectroscopy imaging and diffusion tensor imaging were performed in 19 patients with mild depression and in 13 controls. The mean age of the patients was 31 years. The mean Hamilton depression score of the patients was 22.5 ± 13.2. N-acetylaspartate, choline and creatine concentrations and the average diffusion coefficient and fractional anisotropy values were measured in the bilateral hippocampus, striatum, thalamus and prefrontal deep white matter. Compared with the control group, the mild depressed patients had: (1) a higher choline/creatine ratio and a negative correlation between the choline/creatine ratio and the average diffusion coefficient in the hippocampus; (2) a lower choline/creatine ratio and a higher fractional anisotropy in the striatum; (3) a lower fractional anisotropy and a positive correlation between the fractional anisotropy and the choline/creatine ratio in the prefrontal deep white matter; and (4) a higher average diffusion coefficient and a positive correlation between the choline/creatine ratio and the N-acetylaspartate/creatine ratio in the thalamus, as well as positive correlation between the choline/creatine ratio and Hamilton depression scores. These data suggest evidence of abnormal connectivity in neurofibrotic microstructures and abnormal metabolic alterations in the limbic-cortical-striatal-pallidal-thalamic neural circuit in patients with mild depression.

Chronic repetitive transcranial magnetic stimulation enhances GABAergic and cholinergic metabolism in chronic unpredictable mild stress rat model: ¹H-NMR spectroscopy study at 11.7T

Gamma-animobutyric acid (GABA) systems are emerging as targets for development of medications for mood disorders. Deficits in GABA-containing neurons are consistently reported in psychiatric disease, particularly in the prefrontal cortex and hippocampus. Repetitive transcranial magnetic stimulation (rTMS) that use magnetic field to stimulate focal cortical regions with electrical current have a potential therapeutic effects with non-invasive and painless method. In this study, we used chronic unpredictable mild stress (CUMS) rat model of depression to investigate the behavioral and neurochemical alterations. Furthermore, chronic rTMS treatment effect on neurochemical profile in prefrontal cortex and hippocampus of rats were assessed. The CUMS induced significant reductions in absolute sucrose intake and sucrose preference. In addition, high-resolution (1)H-NMR spectra from brain extracts revealed significantly reduced prefrontal and hippocampal GABA levels in CUMS rats compared to control. The behavioral and neurochemical changes were reversed by chronic rTMS treatment. Furthermore, chronic rTMS treatments results in differential effects on different brain regions. Our results suggest specific and regionally different metabolic response to chronic rTMS treatment in animal model of depression.

Surrogate markers of treatment outcome in major depressive disorder

Major depressive disorder (MDD) is a common medical illness affecting millions worldwide. Despite their widespread use since the 1950s and 1960s, the 'downstream' mechanism by which antidepressants ultimately exert their therapeutic effects remains elusive. In addition, except for a few exceptions such as episode severity and the presence of comorbid Axis-I or Axis-III disorders, biological or clinical characteristics which can accurately quantify the risk of poor treatment outcome are lacking, as are factors which could help patients and clinicians select treatment options that would result in superior outcome. The identification of such markers, termed 'surrogate' markers, could help shed further insights into what constitutes illness and recovery, help identify molecular targets for the development of future antidepressants, and lead the way to the design and refinement of a personalized medicine treatment model for MDD. In the following text, several major areas ('leads') where evidence exists regarding the presence of surrogate markers of efficacy outcome in MDD will be briefly reviewed. Leads include evidence from the role of demographic and clinical factors as surrogate markers, to the role of various biological markers including genotype, brain functional imaging, electroencephalography, dichotic listening, and molecular biology and immunology. The purpose of this work is to focus selectively on areas where there have been findings, as opposed to conducting an exhaustive literature review of studies which have failed to yield any significant breakthrough in our knowledge.

Hippocampal neurometabolite changes in depression treatment: a (1)H magnetic resonance spectroscopy study

Previous studies using magnetic resonance spectroscopy have related abnormalities in hippocampal metabolism to depression. Current evidence is consistent with the conclusion that the hippocampal formation plays an important role in the presentation of depressive symptoms. Eighteen adult patients with major depressive disorder, aged 20 to 60 years, underwent magnetic resonance spectroscopy of the hippocampus during a period of depressive symptomatology and after 7-11 weeks of antidepressant medication with at least 50% reduction in the Montgomery-Åsberg Depression Rating Scale ()MADRS score. During therapy, we found a significantly decreased Lac/Cr ratio in the left hippocampus. The Ins/Cr ratio showed a significant negative correlation with the severity of depression as assessed by the MADRS at baseline. Moreover, we found a negative association of NAA/Cho with age and a positive association of Cho/Cr with age, both on the left and right sides at baseline. In light of our findings and previous studies results we hypothesize that mitochondrial dysfunction leading to predominantly anaerobic glycolysis in connection with the intracellular signaling pathways disturbances and decreased astrocytic function/number might subsequently lead to decreased brain neuroplasticity in depression. These mechanisms could be positively influenced by antidepressant treatment with selective serotonin or norepineprine reuptake inhibitors, with potential effects on untimely neuronal aging in depression.

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.

Review: magnetic resonance spectroscopy studies of pediatric major depressive disorder

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

Prefrontal brain metabolites in short-term weight-recovered adolescent anorexia nervosa patients

Various neuroimaging techniques have revealed morphological and functional alterations in anorexia nervosa (AN), although few spectroscopic magnetic resonance studies have examined short-term weight-recovered AN patients. Subjects were 32 female adolescent patients (between 13 and 18 years old) seen consecutively in our department and who met DSM-IV diagnostic criteria for AN. All of them had received a minimum of six months of treatment and were short-term weight-recovered (for one to three months) with a body mass index ranging from 18 to 23. A group of 20 healthy female volunteer controls of similar age were also included. All subjects were assessed with psychopathological scales and magnetic resonance spectroscopy. Total choline (Cho) (p=0.007) and creatine (Cr) (p=0.008) levels were significantly higher in AN patients than in controls. AN patients receiving psychopharmacological treatment with SSRIs (N=9) had metabolite levels similar to control subjects, but patients without this treatment did not. The present study shows abnormalities in brain neurometabolites related to Cho compounds and Cr in the prefrontal cortex in short-term weight-recovered adolescent AN patients, principally in patients not undergoing psychopharmacological treatment. More studies with larger samples are necessary to test the generalizability of the present results.

The kynurenine pathway in adolescent depression: preliminary findings from a proton MR spectroscopy study

BACKGROUND

Cytokine induction of the enzyme indoleamine 2,3-dioxygenase (IDO) has been implicated in the development of major depressive disorder (MDD). IDO metabolizes tryptophan (TRP) into kynurenine (KYN), thereby decreasing TRP availability to the brain. KYN is further metabolized into several neurotoxins. The aims of this pilot were to examine possible relationships between plasma TRP, KYN, and 3-hydroxyanthranilic acid (3-HAA, neurotoxic metabolite) and striatal total choline (tCho, cell membrane turnover biomarker) in adolescents with MDD. We hypothesized that MDD adolescents would exhibit: i) positive correlations between KYN and 3-HAA and striatal tCho and a negative correlation between TRP and striatal tCho; and, ii) the anticipated correlations would be more pronounced in the melancholic subtype group.

METHODS

Fourteen adolescents with MDD (seven with melancholic features) and six healthy controls were enrolled. Minimums of 6 weeks MDD duration and a severity score of 40 on the Children's Depression Rating Scale-Revised were required. All were scanned at 3T with MRI, multi-voxel 3-dimensional, high, 0.75 cm(3), spatial resolution proton magnetic resonance spectroscopic imaging. Striatal tCho concentrations were assessed using phantom replacement. Spearman correlation coefficients were Bonferroni-corrected.

RESULTS

Positive correlations were found only in the melancholic group, between KYN and 3-HAA and tCho in the right caudate (r=0.93, p=0.03) and the left putamen (r=0.96, p=.006), respectively.

CONCLUSIONS

These preliminary findings suggest a possible role of the KYN pathway in adolescent melancholic MDD. Larger studies should follow.

Choline in anxiety and depression: the Hordaland Health Study

BACKGROUND

Despite its importance in the central nervous system as a precursor for acetylcholine and membrane phosphatidylcholine, the role of choline in mental illness has been little studied.

OBJECTIVE

We examined the cross-sectional association between plasma choline concentrations and scores of anxiety and depression symptoms in a general population sample.

DESIGN

We studied a subsample (n = 5918) of the Hordaland Health Study, including both sexes and 2 age groups of 46-49 and 70-74 y who had valid information on plasma choline concentrations and symptoms of anxiety and depression measured by the Hospital Anxiety and Depression Scale--the latter 2 as continuous measures and dichotomized at a score > or =8 for both subscales.

RESULTS

The lowest choline quintile was significantly associated with high anxiety levels (odds ratio: 1.33; 95% CI: 1.06, 1.69) in the fully adjusted (age group, sex, time since last meal, educational level, and smoking habits) logistic regression model. Also, the trend test in the anxiety model was significant (P = 0.007). In the equivalent fully adjusted linear regression model, a significant inverse association was found between choline quintiles and anxiety levels (standardized regression coefficient = -0.027, P = 0.045). We found no significant associations in the corresponding analyses of the relation between plasma choline and depression symptoms.

CONCLUSION

In this large population-based study, choline concentrations were negatively associated with anxiety symptoms but not with depression symptoms.

Lithium and valproate protect against dextro-amphetamine induced brain choline concentration changes in bipolar disorder patients

BACKGROUND

Lithium may affect brain choline concentrations, and this effect has been proposed to potentially explain its clinical efficacy. Since dextro-amphetamine is a useful human model of mania, we were interested in determining firstly whether dextro-amphetamine would alter brain choline concentrations, and secondly to determine if lithium would protect against any such changes in bipolar patients. In addition, we wanted to determine if valproate would also have any effects upon choline levels.

METHODS

Healthy controls (n=18) were compared with euthymic Bipolar Disorder patients (Type I and Type II) who were taking lithium (n=14) or valproate (n=11). We utilized (1)H-magnetic resonance spectroscopy ((1)H-MRS) in a 3.0T scanner to examine brain choline/phosphocholine+creatine (Cho/Cr) ratios. Changes in this ratio were measured to determine any changes in choline concentrations in the temporal lobe.

RESULTS

The results showed that administration of dextro-amphetamine decreased the Cho/Cr ratios. In contrast, in both the lithium-treated and valproate-treated patients this decrease was not seen; this attenuation in the change in Cho/Cr ratio changes was statistically significant. It should be noted that Cho/Cr ratios were significantly higher at baseline in the controls compared to both groups of patients, which may have influenced the results.

CONCLUSIONS

These findings are the first to examine the effects of dextro-amphetamine on brain choline concentrations. They show that while in controls dextro-amphetamine decreases choline concentrations, lithium and valproate both appear to protect against this effect in bipolar patients. However, as brain ratios were measured rather than the absolute concentration of choline, and these ratios were lowered in patients at baseline, these results must be regarded as preliminary and require replication in future studies.

Research applications of magnetic resonance spectroscopy to investigate psychiatric disorders

Advances in magnetic resonance spectroscopy (MRS) methodology and related analytic strategies allow sophisticated testing of neurobiological models of disease pathology in psychiatric disorders. An overview of principles underlying MRS, methodological considerations, and investigative approaches is presented. A review of recent research is presented that highlights innovative approaches applying MRS, in particular, hydrogen MRS, to systematically investigate specific psychiatric disorders, including autism spectrum disorders, schizophrenia, panic disorder, major depression, and bipolar disorder.

Biochemical abnormalities of the medial temporal lobe and medial prefrontal cortex in late-life depression

We utilized single-voxel (1)H magnetic resonance spectroscopy (MRS) to investigate biochemical abnormalities related to late-life depression in the medial prefrontal cortex and medial temporal lobe. Fourteen elderly subjects whose depression responded to treatment and 12 nondepressed subjects were enrolled. Subjects were scanned using a GE 3.0 Tesla whole body MR scanner. Metabolite concentrations were quantified using the LC Model software and adjusted for CSF and ratio of gray to white matter. ANCOVA models tested for group differences while controlling for age and sex. Older previously depressed individuals showed significantly reduced concentrations of total N-acetyl aspartate (NAA), choline, and creatine in the prefrontal cortex and significantly elevated left medial temporal lobe concentrations of NAA and myo-inositol. There were no significant group differences in right temporal metabolite concentrations. The prefrontal cortex observations suggest that reduced neuronal, phospolipid, and energy metabolism is present even in clinically improved depression. In contrast, elevated NAA and myo-inositol concentrations in the left medial temporal lobe could be associated with neuronal and glial cell changes in the amygdala.

Genetic risk factors and markers for Alzheimer's disease and/or depression in the VITA study

OBJECTIVES

In ageing population, both Alzheimer's disease (AD) and depression are common. Significant depressive symptoms are often co-morbid with cognitive impairment and dementia. In this study, we attempted to find various factors and markers for both AD and depression in a longitudinal cohort, the Vienna-Transdanube-Aging (VITA)-study.

METHODS

The VITA-Study consisted of 305 healthy subjects, 174 subjects with depression only, 55 subjects diagnosed with AD only and 72 subjects with depression as well as AD. Associations between AD and/or depression to gene polymorphisms APO E (epsilon4), choline acetyltransferase (ChAT) 4G to A, serotonin-transporter gene promoter-length, dopamine-D4-receptor, ciliary-neurotrophic-factor-null mutation and brain-derived neurotrophic factor (C270T) and to various known factors were analyzed.

RESULTS

AD and depression were significant associated. Significant risk factors found for AD were low education, low folic acid and depressive-symptoms, while for depression were low education and higher nonsteroidal anti-inflammatory drugs (NSAID) consume. Moreover, the ChAT polymorphism associated significant to depression. Gender, education, and ChAT significantly associated with the combination AD and/or depression.

CONCLUSION

Such studies must be conducted cautiously, as co-morbidities and gene-environmental-social influences may sway the results dramatically. We found in the VITA-study significant association between depression and AD and between ChAT polymorphism and depression.

Impact of fluoxetine on the human brain in multiple sclerosis as quantified by proton magnetic resonance spectroscopy and diffusion tensor imaging

The antidepressant fluoxetine stimulates astrocytic glycogenolysis, which serves as an energy source for axons. In multiple sclerosis patients fluoxetine administration may improve energy supply in neuron cells and thus inhibit axonal degeneration. In a preliminary pilot study, 15 patients with multiple sclerosis (MS) were examined by diffusion tensor imaging (DTI) and (1)H magnetic resonance spectroscopy (MRS) in order to quantify the brain tissue diffusion properties (fractional anisotropy, apparent diffusion coefficient) and metabolite levels (choline, creatine and N-acetylaspartate) in cortical gray matter brain tissue, in normal appearing white matter and in white matter lesions. After oral administration of fluoxetine (20 mg/day) for 1 week, the DTI and MRS measurements were repeated and after treatment with a higher dose (40 mg/day) during the next week, a third series of DTI/MRS examinations was performed in order to assess any changes in diffusion properties and metabolism. One trend was observed in gray matter tissue, a decrease of choline measured at weeks 1 and 2 (significant in a subgroup of 11 relapsing remitting/secondary progressive MS patients). In white matter lesions, the apparent diffusion coefficient was increased at week 1 and N-acetylaspartate was increased at week 2 (both significant). These preliminary results provide evidence of a neuroprotective effect of fluoxetine in MS by the observed partial normalization of the structure-related MRS parameter N-acetylaspartate in white matter lesions.

In vivo proton magnetic resonance spectroscopy in patients with mood disorders: a technically oriented review

Proton MR spectroscopy (1HMRS) has been extensively used among mood disorders patients. A review of the published literature in 1HMRS studies of mood disorders was carried out for the period 1991 to July 2006. Of 71 1HMRS studies, 77.5% were done at 1.5T and 66.2% used single voxel sequences (SVS), implying limitations of spectral resolution and anatomic coverage, respectively. In all, 47.9% of studies relied on creatine (Cr) as internal signal standard, although Cr changes were reported in major depression (MD). Most reported metabolic alterations related to mood state affected the left frontal lobe. Depressed adult and pediatric MD patients had reduced glutamate (Glu) in frontal lobe regions, which reversed with successful treatment. A consistent reduction of N-acetyl-aspartate (NAA) was reported in the hippocampal formation among bipolar disorder (BD) patients, along with an increment in frontal Glu. The differences in results of 1HMRS studies in mood disorders reflect heterogeneity of technical factors and subject selection. Future studies should benefit from higher spectral resolution and more extensive anatomic coverage as well as standardized data-processing protocols and subject selection criteria.

Making sense of neuroimaging in psychiatry

OBJECTIVE

Neuroimaging of psychiatric disorders has increased exponentially in the last decade; however, much of the uptake thus far has been in the realm of research. We anticipate that clinical use of neuroimaging modalities in psychiatry will increase dramatically in the near future and suggest that clinicians need to be aware of the potential applications.

METHOD

The authors conducted an extensive MEDLINE, EMBASE, PubMED and PsychInfo search of the published literature (1965-2007) using a variety of search terms to find relevant articles. Bibliographies of retrieved papers were further scrutinised for publications of interest, as were indices of books. Articles that reported clinically significant findings and research reports conducted using pertinent neuroimaging modalities were reviewed in detail.

RESULTS

The review suggests that exciting neuroimaging advances are being made that have relevance to psychiatry. Novel neuroimaging applications with potential clinical utility are rapidly emerging and the accessibility and use of these technologies will increase in coming years. Clinically meaningful findings have begun to emerge in mood disorders, post-traumatic stress disorder, schizophrenia and dementia. Coupling multimodal imaging with genetics and pharmacotherapeutic studies will further assist in understanding the pathophysiology of neuropsychiatric disorders.

CONCLUSION

It is important that clinicians understand the benefits and limitations of modern neuroimaging techniques and are also suitably equipped to appraise future developments. The use of neuroimaging in evaluating psychopathology is likely to impact upon the future nosology of psychiatric disorders, and assist in diagnosis and clinical management. The integrated use of neuroimaging in conjunction with clinical assessments promises to improve clinical care and markedly alter psychiatric practice.

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

OBJECTIVE

Proton magnetic resonance spectroscopy ((1)H-MRS) has been increasingly used to examine striatal neurochemistry in adult major depressive disorder. This study extends the use of this modality to pediatric major depression to test the hypothesis that adolescents with major depression have elevated concentrations of striatal choline and creatine and lower concentrations of N-acetylaspartate.

METHOD

Fourteen adolescents (ages 12-19 years, eight female) who had major depressive disorder for at least 8 weeks and a severity score of 40 or higher on the Children's Depression Rating Scale-Revised and 10 healthy comparison adolescents (six female) group-matched for gender, age, and handedness were enrolled. All underwent three-dimensional 3-T (1)H-MRS at high spatial resolution (0.75-cm(3) voxels). Relative levels of choline, creatine, and N-acetylaspartate in the left and right caudate, putamen, and thalamus were scaled into concentrations using phantom replacement, and levels were compared for the two cohorts.

RESULTS

Relative to comparison subjects, adolescents with major depressive disorder had significantly elevated concentrations of choline (2.11 mM versus 1.56 mM) and creatine (6.65 mM versus 5.26 mM) in the left caudate. No other neurochemical differences were observed between the groups.

CONCLUSIONS

These findings most likely reflect accelerated membrane turnover and impaired metabolism in the left caudate. The results are consistent with prior imaging reports of focal and lateralized abnormalities in the caudate in adult major depression.

Metabolic alterations in the dorsolateral prefrontal cortex after treatment with high-frequency repetitive transcranial magnetic stimulation in patients with unipolar major depression

Neuroimaging studies suggest a specific role of anterior cingulate cortex (ACC) and left dorsolateral prefrontal cortex (DLPFC) in major depression. Stimulation of the latter by means of repetitive transcranial magnetic stimulation (rTMS) as an antidepressant intervention has increasingly been investigated in the past. The objective of the present study was to examine in vivo neurochemical alterations in both brain regions in 17 patients with unipolar major depression before and after 10 days of high-frequency (20Hz) rTMS of the left DLPFC using 3-tesla proton magnetic resonance spectroscopy. Six out of seventeen patients were treatment responders, defined as a 50% reduction of the Hamilton depression rating scale. No neurochemical alterations in the ACC were detected after rTMS. As compared to the non-responders, responders had lower baseline concentrations of DLPFC glutamate which increased after successful rTMS. Correspondingly, besides a correlation between clinical improvement and an increase in glutamate concentration, an interaction between glutamate concentration changes and stimulation intensity was observed. Our results indicate that metabolic, state-dependent changes within the left DLPFC in major depressive disorder involve the glutamate system and can be reversed in a dose-dependent manner by rTMS.

Variation of the choline signal intensity in the dorsolateral prefrontal cortex of rats exposed to the forced swimming test as detected by in vivo 1H MR spectroscopy

BACKGROUND

(1)H magnetic resonance spectroscopy (MRS) has documented an increased Cho/Cr ratio in the dorsolateral prefrontal cortex (DLPFC) in major depressive disorder (MDD). The aim of this study was to investigate neurochemical alterations in the left DLPFC, considered a main area of pathogenesis in depression, using rats exposed to the forced swimming test (FST).

MATERIALS AND METHODS

Twenty-four male rats were used for the MRI and in vivo(1)H MRS studies. Rats exposed to the FST to induce a depressed mental status. Using in vivo(1)H MRS, the metabolite ratios of the rats with a depressed mental status and the controls, were measured and the values of the two groups were compared.

RESULTS

The Cho/Cr and Cho/NAA ratios in the DLPFC of the rats with a depressed mental status were significantly higher than that in the controls.

CONCLUSIONS

The present study demonstrates a significantly increased Cho/Cr ratio in the DLPFC of rats with depression compared with controls. This result may suggest an accelerated turnover of membrane without neuronal loss is occurring in the DLPFC of the rats with depression.

Mania, glutamate/glutamine and risperidone in pediatric bipolar disorder: a proton magnetic resonance spectroscopy study of the anterior cingulate cortex

BACKGROUND

The purpose of this study was to investigate the anterior cingulate cortex (ACC) glutamate/glutamine (Glx) to creatine ratio (Glx/Cr) in two groups of children with Bipolar Disorder (BPD): those exhibiting manic symptoms requiring treatment and those being stably treated with the atypical antipsychotic risperidone. Atypical antipsychotics have been shown to increase serum glutamate levels and ACC Glx/Cr in subjects with schizophrenia. In this study, we hypothesized that the children with BPD in need of treatment would have lower Glx/Cr compared with the children with BPD being stably treated with risperidone.

METHODS

Proton MR spectra were acquired, at 1.5 T, from the ACC of eighteen subjects with a DSM-IV diagnosis of BPD: ten (11.10+/-3.48 years; five female) were manic and not medicated with any antipsychotic and eight (10.88+/-2.99 years; one female) were medicated with the atypical antipsychotic risperidone.

RESULTS

Children with BPD exhibiting manic symptoms requiring treatment had lower Glx/Cr than children with BPD being stably treated with the atypical antipsychotic risperidone. The children treated with risperidone also had significantly lower YMRS and CGI-Mania scores than the children not treated with risperidone. Both YMRS and CGI-Mania scores correlated negatively with ACC Glx/Cr levels.

LIMITATIONS

The cross-sectional design, small sample size, the use of Glx rather than glutamate or glutamine and the use of Cr ratios rather than absolute concentrations are limitations of this study.

CONCLUSIONS

Children with mania have lower Glx/Cr levels than children with BPD being stably treated with the atypical antipsychotic risperidone. Mania may be associated with reduced glutamate/glutamine levels in the ACC: other imaging studies have shown mania associated with hypometabolism in the ACC. These reductions in glutamate/glutamine may be increased following successful treatment with glutamatergic agents.

Subcortical and medial temporal MR-detectable metabolite abnormalities in unipolar major depression

The purpose of the present study was to determine whether MR-detectable alterations of choline-containing compounds in two key neural systems involved in major depression disorder namely the hippocampus and the basal ganglia can be detected. Multislice proton magnetic resonance spectroscopic imaging was applied in 11 patients with major depressive disorder (MDD) and ten matched healthy subjects. Voxels were selected from the left and right side of the hippocampus and the putamen. Significantly lower choline-containing compounds in the hippocampus and significantly higher choline-containing compounds in the putamen of patients with MDD compared to healthy subjects were found. No significant differences were found for the other metabolites in the two regions evaluated. Abnormal levels of choline-containing compounds most likely reflect altered membrane phospholipid metabolism. A reduced level in the hippocampus and an increased level in the putamen suggest regionally opponent membrane abnormalities.

Human choline transporter gene variation is associated with corticolimbic reactivity and autonomic-cholinergic function

BACKGROUND

Our previous work has shown genetic variation in the human choline transporter gene (CHT1) to be associated with depressive symptoms and autonomic cardiac (cholinergic) dysregulation. Here, functional magnetic resonance imaging (fMRI) was used to examine the relation between a single nucleotide polymorphism (SNP) in CHT1 on regional brain reactivity relevant to autonomic (cholinergic) function.

METHODS

Thirty-two participants of European ancestry (18 men, 14 women; age: 33-54 years) completed an fMRI protocol using corticolimbic reactivity and prefrontal inhibitory control paradigms. Resting cholinergic function, as measured by heart rate variability (HRV), was quantified from electrocardiogram. Subjects were genotyped for a CHT1 G/T SNP.

RESULTS

GG homozygotes had greater right (R) dorsal amygdala (p < .008), bilateral anterior cingulate (p < .009), and R caudate reactivity (p < .015) than T-allele carriers. Heart rate variability was related to R frontal cortex (Brodmann Areas 6, 9, and 46), R hippocampal formation, bilateral caudate, and bilateral anterior cingulate reactivity (p's < .007).

CONCLUSIONS

CHT1 variation is related to differences in a distributed corticolimbic circuitry mediating behavioral and physiologic arousal. These relations may contribute to a biological mechanism by which genetic variation in cholinergic neurotransmission affects cognition, mood, and autonomic cardiac function.

Review of 1H magnetic resonance spectroscopy findings in major depressive disorder: a meta-analysis

In a review of the current literature, we identified (1)H MRS studies of major depressive disorder (MDD) that examined the metabolites N-acetylaspartate (NAA), choline (Cho), myo-inositol (mI), glutamate/glutamine/gamma-aminobutyric acid-GABA (Glx), and creatine (Cr). Separate meta-analyses comparing adult and pediatric MDD patients with healthy controls were performed. For adults, 14 studies with 227 patients/246 controls for NAA, 15 studies with 240 patients/261 controls for Cho, seven studies with 96 patients/104 controls for mI, six studies with 86 patients/109 controls for Glx, and nine studies with 146 patients/173 controls for Cr were identified. There were six studies containing a total of 79 pediatric depressed patients. We performed 15 separate meta-analyses to combine results from studies with similar characteristics. Adult MDD patients had higher Cho/Cr values than controls in the basal ganglia. In contrast, three studies on Glx levels indicated significantly lower Glx levels in the frontal lobe of MDD patients. The review indicated increased Cho/Cr in the basal ganglia in MDD and no alteration of NAA, suggesting an increased membrane turnover in MDD without a neurodegenerative outcome. Lower Glx levels in depressed patients in contrast to a likely hyperglutamatergic state in bipolar disorder may implicate a different pathophysiological ground in MDD.

The biochemistry of dysfunctional emotions: proton MR spectroscopic findings in major depressive disorder

Key neural systems involved in the processing and communication of emotions are impaired in patients with major depressive disorder (MDD). Emotional and behavioral symptoms are thought to be caused by damage or dysfunction in specific areas of the brain that are responsible for directing attention, motivating behavior, and learning the significance of environmental stimuli. Functional brain studies with positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) give support for functional abnormalities in MDD that are predominantly located in areas known to play an important role in the communication and processing of emotions. Disturbances in emotional processing as they are observed in MDD, if any, have very subtle morphometrical brain correlates. With proton magnetic resonance spectroscopy (1H MRS), brain metabolites can be measured noninvasively in vivo, thus furthering the understanding of the effects of changes in neurotransmitters within the brain. The current literature on 1H MRS studies in MDD is small with a large diversity of MRS methods applied, brain regions studied, and metabolite changes found. Nevertheless, there is strong evidence that changes in neurometabolite concentrations in MDD occur within brain regions, which are involved in the processing and communication of emotions that can be monitored by 1H MRS. This review summarizes the literature about biochemical changes quantified via 1H MRS in MDD patients in brain regions that play an important role for the communication and processing of emotions.

Normal prefrontal gamma-aminobutyric acid levels in remitted depressed subjects determined by proton magnetic resonance spectroscopy

BACKGROUND

There is growing evidence that the brain gamma-aminobutyric acid (GABA) system is involved in depression. Lowered plasma GABA levels were identified as a traitlike abnormality found in patients with remitted unipolar depression and in healthy first-degree relatives of patients with unipolar depression. Major depressive disorder has been associated with neuroimaging and neuropathological abnormalities in the prefrontal cortex by various types of evidence. As a result, the current study investigates whether GABA levels in the prefrontal cortex differ between unmedicated subjects with remitted major depressive disorder (rMDD) and healthy control subjects.

METHODS

Sixteen rMDD subjects and 15 healthy control subjects underwent magnetic resonance spectroscopy. We used a 3 Tesla GE whole body scanner with a homogeneous resonator coil providing a homogenous radiofrequency field and capability of obtaining measurement from the prefrontal cortex. Gamma-aminobutyric acid levels were measured in the ventromedial prefrontal cortex and dorsolateral/anterior medial prefrontal cortex.

RESULTS

There was no difference in GABA concentrations between rMDD subjects and healthy control subjects in the ventromedial prefrontal cortex and dorsolateral/anterior medial prefrontal cortex. Secondary analyses provided preliminary evidence for a negative relationship between the glutamate/glutamine (Glx)/GABA ratio and age of onset of major depression in the ventromedial prefrontal cortex.

CONCLUSIONS

This result suggests that GABA levels in the prefrontal cortex, if found to be reduced in symptomatic depression, do not represent a persistent characteristic of major depression. Further research is needed to determine brain GABA levels in different brain regions, in different stages of depressive illness, and in different depressive subtypes.

Proton spectroscopy study of the left dorsolateral prefrontal cortex in pediatric depressed patients

The dorsolateral prefrontal cortex (DLPFC) plays an essential role in mood regulation and integration of cognitive functions that are abnormal in major depressive disorder (MDD). Few neuroimaging studies have evaluated the still maturing DLPFC in depressed children and adolescents. We conducted single voxel proton magnetic resonance spectroscopy ((1)H MRS) of the left DLPFC in 14 depressed children and adolescents (13.3 +/- 2.3 years old, 10 males) and 22 matched healthy controls (13.6 +/- 2.8 years old, 13 males). Depressed subjects had significantly lower levels of glycerophosphocholine plus phosphocholine (GPC + PC; or choline-containing compounds) and higher myo-inositol levels in the left DLPFC compared to healthy controls. In the depressed subjects, we found significant inverse correlations between glutamate levels and both duration of illness and number of episodes. In healthy controls there was a significant direct correlation between age and glutamine levels, which was not present in the patient group. Lower GPC + PC levels in pediatric MDD may reflect lower cell membrane content per volume in the DLPFC. Increased myo-inositol levels in MDD may represent a disturbed secondary messenger system. GPC + PC and myo-inositol abnormalities further demonstrate the involvement of DLPFC in pediatric MDD.

Examining SLV-323, a novel NK1 receptor antagonist, in a chronic psychosocial stress model for depression

RATIONALE

Substance P antagonists have been proposed as candidates for a new class of antidepressant compounds.

OBJECTIVES

We examined the effects of SLV-323, a novel neurokinin 1 receptor (NK1R) antagonist, in the chronic psychosocial stress paradigm of adult male tree shrews.

METHODS

Animals were subjected to a 7 day period of psychosocial stress before being treated daily with SLV-323 (20 mg kg(-1) day(-1)). The psychosocial stress continued throughout the treatment period of 28 days. Brain metabolite concentrations were determined in vivo by proton magnetic resonance spectroscopy. Norepinephrine excretion was monitored from daily urine samples, and serum testosterone concentrations were measured at the end of the experiment. All animals were videotaped daily to analyze scent-marking behavior and locomotor activity. Cell proliferation in the dentate gyrus and hippocampal volume were measured postmortem.

RESULTS

Stress significantly decreased cerebral concentrations of N-acetyl-aspartate, total creatine, and choline-containing compounds in vivo and resulted in an increase of urinary norepinephrine and decrease of serum testosterone concentrations. Moreover, stressed animals displayed decreased scent-marking behavior and locomotor activity. The proliferation rate of the granule precursor cells in the dentate gyrus was reduced, and hippocampal volume was mildly decreased. The stress-induced alterations in the central nervous system were partially prevented by concomitant administration of SLV-323, while drug treatment had only a minor effect on the stress-induced behavioral changes.

CONCLUSIONS

The novel NK1R antagonist SLV-323 has certain antidepressant-like effects in a valid animal model of depression.

The functional neuroanatomy of bipolar disorder: a review of neuroimaging findings

The authors review existing structural and functional neuroimaging studies of patients with bipolar disorder and discuss how these investigations enhance our understanding of the neurophysiology of this illness. Findings from structural magnetic resonance imaging (MRI) studies suggest that some abnormalities, such as those in prefrontal cortical areas (SGPFC), striatum and amygdala exist early in the course of illness and, therefore, potentially, predate illness onset. In contrast, other abnormalities, such as those found in the cerebellar vermis, lateral ventricles and other prefrontal regions (eg, left inferior), appear to develop with repeated affective episodes, and may represent the effects of illness progression and associated factors. Magnetic resonance spectroscopy investigations have revealed abnormalities of membrane and second messenger metabolism, as well as bioenergetics, in striatum and prefrontal cortex. Functional imaging studies report activation differences between bipolar and healthy controls in these same anterior limibic regions. Together, these studies support a model of bipolar disorder that involves dysfunction within subcortical (striatal-thalamic)-prefrontal networks and the associated limbic modulating regions (amygdala, midline cerebellum). These studies suggest that, in bipolar disorder, there may be diminished prefrontal modulation of subcortical and medial temporal structures within the anterior limbic network (eg, amygdala, anterior striatum and thalamus) that results in dysregulation of mood. Future prospective and longitudinal studies focusing on these specific relationships are necessary to clarify the functional neuroanatomy of bipolar disorder.

Brain metabolites and cognitive function among older depressed and healthy individuals using 2D MR spectroscopy

Brain metabolites of choline (Ch) and myo-Inisotol (mI) have been reported as elevated among geriatric depressed patients. Two-dimensional (2D) magnetic resonance spectroscopy (MRS) provides estimates of Ch, mI, and creatine (Cr) similar to one-dimensional MRS, and it also estimates the resonances of the Ch-containing compounds of phosphoethanolamine (Pe) and phosphocholine (PCh). In this cross-sectional geriatric study, 14 depressed patients and 14 healthy volunteers who were comparable in age, gender, education, comorbid medical burden, and Mini-Mental State Examination (MMSE) scores completed 2D MRS and a neurocognitive battery. A voxel in the left dorsolateral cortex, which was comprised of approximately 60% white matter, was used to estimate the CR ratios of Ch, PCh, Pe, and mI. Composite scores for cognitive function were developed for verbal learning, recall, recognition, executive function, hypothesis generation, and processing speed. Among nondepressed subjects, cognition was positively correlated with Ch/Cr and mI/Cr and negatively correlated with PCh/Cr in four domains of verbal learning, recognition, recall, and hypothesis generation. In contrast, depressed patients did not have consistent relationships between Ch/Cr, mI/Cr, and PCh/Cr and cognition. There was a significant difference in the overall pattern of associations between the four metabolites and verbal learning and processing speed in depressed patients compared to healthy controls. The attenuated relationship between metabolites and specific cognitive domains in patients with late-life MDD suggests that the level of cognitive performance observed during depressive episodes may be associated with changes in biochemistry within the frontostriatal neuronal circuitry.

Ethanolamine and phosphoethanolamine inhibit mitochondrial function in vitro: implications for mitochondrial dysfunction hypothesis in depression and bipolar disorder

BACKGROUND

A growing body of experimental evidence suggests that mitochondrial dysfunction, including alterations in phospholipid metabolism, might be involved in the pathophysiology of affective illnesses, such as depression and bipolar disorder. The purpose of this study was to determine whether the phosphomonoester phosphoethanolamine (PE) and the lipid metabolite choline (Cho), which are known to be altered in depression and bipolar disorder, and/or their precursors/metabolites, might directly affect mitochondrial bioenergetic function in vitro.

METHODS

To this end, rates of oxygen consumption in freshly isolated, intact mitochondria were determined polarographically in the presence and absence of PE, Cho, ethanolamine (Etn), glycerophosphoethanolamine (GPE), and glycerophosphocholine (GPC).

RESULTS

The data demonstrate that PE and Etn inhibit mitochondrial respiratory activity in a dose-dependent manner, whereas Cho, GPC, and GPE have no measurable effect on bioenergetic function.

CONCLUSIONS

This reflects a specific inhibition by Etn and PE on mitochondrial function rather than a more generalized phenomenon induced by similarities in structure between the lipid metabolites. These results also suggest a possible relationship between mitochondrial dysfunction and altered phospholipid metabolism in the brains of patients with depression and bipolar disorder.

Increased medial thalamic choline found in pediatric patients with obsessive-compulsive disorder versus major depression or healthy control subjects: a magnetic resonance spectroscopy study

BACKGROUND

Neurobiologic abnormalities in medial thalamus have been implicated in the pathogenesis of obsessive-compulsive disorder (OCD). We previously used multislice proton magnetic resonance spectroscopic imaging (1-H MRSI) to identify localized functional neurochemical marker alterations in choline (Cho) in medial but not lateral thalamus in treatment-naïve pediatric patients with OCD compared with matched control subjects. Altered brain Cho levels have also been implicated in the pathogenesis of mood disorders.

METHODS

We used 1-H MRSI to study absolute Cho concentrations in 18 psychotropic-naïve pediatric patients with major depressive disorder (MDD) not suffering from OCD, 9-17 years of age, 18 case-matched healthy control subjects, and 27 nondepressed, psychotropic-naïve pediatric patients with OCD, 7-16 years of age.

RESULTS

Significantly increased left and right medial thalamic Cho concentrations were observed in OCD patients compared with both healthy control subjects and patients with MDD. Medial thalamic Cho concentrations did not differ significantly between patients with MDD and control subjects.

CONCLUSIONS

These results suggest that localized functional neurochemical marker alterations in medial thalamic Cho differentiate patients with OCD from healthy control subjects and patients with MDD. Although these results must be considered preliminary, further study of the diagnostic specificity of Cho as a relevant biomarker in OCD is clearly warranted.

Anatomical MRI study of basal ganglia in major depressive disorder

The basal ganglia form a part of the brain neuroanatomic circuits that may be involved in mood regulation. Decreases in basal ganglia volumes have been previously reported in major depressive disorder patients in comparison to healthy controls. In this study, we measured caudate, putamen, and globus pallidus volumes in 25 patients with major depressive disorder (4 M; age+/-S.D.=41+/-11 years) and 48 healthy controls (29 M; age+/-S.D.=35+/-10 years), using high-resolution magnetic resonance imaging (MRI), in an attempt to replicate prior findings. Unlike most previous studies, we did not find significant differences between patient and control groups in basal ganglia volumetric measures. Nonetheless, there was a significant interaction between diagnosis and cerebral hemisphere, with MDD patients showing decreased asymmetry in globus pallidus volumes in comparison with healthy controls. Furthermore, in the patient group, left putamen volumes correlated inversely with length of illness, and left globus pallidus volume correlated directly with number of prior depressive episodes. These findings suggest that abnormalities in lateralization and possibly neurodegenerative changes in basal ganglia structures participate in the pathophysiology of major depressive disorder.

Focal and lateralized subcortical abnormalities in unipolar major depressive disorder: an automated multivoxel proton magnetic resonance spectroscopy study

BACKGROUND

The results of prior proton magnetic resonance spectroscopy ((1)H-MRS) studies in unipolar major depressive disorder (MDD) evaluating choline (Cho)/creatine (Cr) and N-acetyl-L-aspartate (NAA)/Cr ratios are mixed. These single-voxel or one-dimensional chemical-shift imaging (CSI) nonautomated (1)H-MRS studies has been unable to evaluate global or lateralized abnormalities in neuronal or membrane function. Using automated multivoxel two-dimensional CSI (1)H-MRS techniques, we tested the hypothesis that patients with MDD have focal neuronal and membrane abnormalities localized in the subcortical region.

METHODS

Whole brain and subcortical measures of Cho, NAA, Cr, and myo-inositol (mI) were obtained in 18 patients with MDD and 20 control subjects using automated two-dimensional CSI (1)H-MRS.

RESULTS

Compared with control subjects, MDD patients had a significantly lower mean NAA/Cr amplitude in the caudate and a significantly higher mean Cho/Cr amplitude in the putamen, particularly on the right side. No differences were observed for global whole brain measurements.

CONCLUSIONS

The findings support reduced neuronal viability or function in the caudate and altered membrane phospholipid metabolism in the putamen for patients with MDD. Our results are consistent with prior magnetic resonance imaging, positron emission tomography, and postmortem reports of focal and lateralized abnormalities of the basal ganglia in MDD.

Selective deficit of hippocampal N-acetylaspartate in antipsychotic-naive patients with schizophrenia

BACKGROUND

Studies using proton magnetic resonance spectroscopy in schizophrenia have demonstrated abnormality of N-acetylaspartate but are confounded by the effects of phase of illness and medication. There is mounting evidence that antipsychotic medication influences N-acetylaspartate.

METHODS

A group of first-episode patients who had received no, or minimal, antipsychotic medication was examined at baseline and after 3 months treatment. Normal comparison subjects were examined at the same interval. Ratios of N-acetylaspartate, creatine plus phosphocreatine, and choline-containing compounds in the left prefrontal cortex, hippocampus, and basal ganglia were measured.

RESULTS

The mean duration of symptoms for all patients was 31.6 (SD 26.1) weeks. A significant reduction of hippocampal N-acetylaspartate/creatine plus phosphocreatine was found in the antipsychotic-naive group relative to those previously treated and to controls at baseline (F = 7.3, p <.002). No group differences were found at follow-up.

CONCLUSIONS

Hippocampal N-acetylaspartate/creatine plus phosphocreatine appears to be selectively affected early in the course of illness. The finding of neurochemical differences between treatment naive and previously treated patients confirms the relevance of medication status in proton magnetic resonance spectroscopy studies. Further investigation of the influence of medication at this stage of illness is warranted.

Selective serotonin reuptake inhibitor discontinuation syndrome is associated with a rostral anterior cingulate choline metabolite decrease: a proton magnetic resonance spectroscopic imaging study

The selective serotonin reuptake inhibitor (SSRI) discontinuation syndrome (DS) is an important potential complication of treatment for major depression. We hypothesized that SSRI treatment discontinuation, resulting in change in clinical state, would be associated with reduced rostral anterior cingulate choline (Cho) metabolite ratios. Individuals with a DSM-III-R diagnosis of unipolar major depression who had been stabilized on paroxetine (n = 13) or fluoxetine (n = 13) were study subjects. They were monitored for change in clinical state (mood ratings, discontinuation symptoms) and underwent proton magnetic resonance spectroscopic imaging of the rostral anterior cingulate 3 days after medication substitution with active SSRI and placebo.Placebo-day Cho/Cre (choline/total creatine) metabolite ratios were decreased in four paroxetine and two fluoxetine subjects meeting DS criteria, as compared with asymptomatic subjects (Mann-Whitney z = -2.31, p =.021). Discontinuation syndrome is associated with a rostral anterior cingulate Cho/Cre metabolite ratio decrease that may reflect dynamics of rostral anterior cingulate function.

Oral choline decreases brain purine levels in lithium-treated subjects with rapid-cycling bipolar disorder: a double-blind trial using proton and lithium magnetic resonance spectroscopy

OBJECTIVES

Oral choline administration has been reported to increase brain phosphatidylcholine levels. As phospholipid synthesis for maintaining membrane integrity in mammalian brain cells consumes approximately 10-15% of the total adenosine triphosphate (ATP) pool, an increased availability of brain choline may lead to an increase in ATP consumption. Given reports of genetic studies, which suggest mitochondrial dysfunction, and phosphorus (31P) magnetic resonance spectroscopy (MRS) studies, which report dysfunction in high-energy phosphate metabolism in patients with bipolar disorder, the current study is designed to evaluate the role of oral choline supplementation in modifying high-energy phosphate metabolism in subjects with bipolar disorder.

METHODS

Eight lithium-treated patients with DSM-IV bipolar disorder, rapid cycling type were randomly assigned to 50 mg/kg/day of choline bitartrate or placebo for 12 weeks. Brain purine, choline and lithium levels were assessed using 1H- and 7Li-MRS. Patients received four to six MRS scans, at baseline and weeks 2, 3, 5, 8, 10 and 12 of treatment (n = 40 scans). Patients were assessed using the Clinical Global Impression Scale (CGIS), the Young Mania Rating Scale (YRMS) and the Hamilton Depression Rating Scale (HDRS) at each MRS scan.

RESULTS

There were no significant differences in change-from-baseline measures of CGIS, YMRS, and HDRS, brain choline/creatine ratios, and brain lithium levels over a 12-week assessment period between the choline and placebo groups or within each group. However, the choline treatment group showed a significant decrease in purine metabolite ratios from baseline (purine/n-acetyl aspartate: coef = -0.08, z = -2.17, df = 22, p = 0.030; purine/choline: coef = -0.12, z = -1.97, df = 22, p = 0.049) compared to the placebo group, controlling for brain lithium level changes. Brain lithium level change was not a significant predictor of purine ratios.

CONCLUSIONS

The current study reports that oral choline supplementation resulted in a significant decrease in brain purine levels over a 12-week treatment period in lithium-treated patients with DSM-IV bipolar disorder, rapid-cycling type, which may be related to the anti-manic effects of adjuvant choline. This result is consistent with mitochondrial dysfunction in bipolar disorder inadequately meeting the demand for increased ATP production as exogenous oral choline administration increases membrane phospholipid synthesis.

Biological predictors of treatment response in affective illness

Attempts to identify biological response predictors generally have met with limited success, particularly where the goal is to develop clinically useful indices. This article reviews the biological approaches to predicting treatment response, beginning with neuroendocrine studies and electroencephalogram analysis and concluding with structural and functional neuroimaging. The article describes the designs of typical studies to aid in interpreting their results and concludes by addressing some of the problems and limitations associated with these approaches and suggesting future directions for this research.

Neuronal pathology in the hippocampal area of patients with bipolar disorder: a study with proton magnetic resonance spectroscopic imaging

BACKGROUND

The brain regions involved in the pathophysiology of bipolar disorder have not been definitively determined. Previous studies have suggested possible involvement of the hippocampus and of prefrontal regions. Proton magnetic resonance spectroscopic imaging ((1)H-MRSI) allows measurement of N-acetylaspartate (NAA, marker of neuronal integrity), choline-containing compounds (CHO), and creatine+phosphocreatine (CRE) in multiple brain regions. The objective of this study was to assess possible NAA reductions in hippocampus and prefrontal regions in patients with bipolar disorder.

METHODS

We studied 17 patients with bipolar disorder and 17 age- and gender-matched healthy subjects on a 1.5-T nuclear magnetic resonance (NMR) machine. With (1)H-MRSI we measured ratios of areas under the metabolite peaks of the proton spectra (i.e., NAA/CRE, NAA/CHO, CHO/CRE) for multiple cortical and subcortical regions.

RESULTS

Patients showed significant reductions of NAA/CRE bilaterally in the hippocampus. There were no significant changes in CHO/CRE or in NAA ratios in any other area sampled.

CONCLUSIONS

This study shows that patients with bipolar disorder have a regional reduction of NAA relative signals, suggesting neuronal damage or malfunction of the hippocampus. As suggested by other studies, neuronal pathology in the hippocampus may be involved in the pathophysiology of bipolar disorder and in susceptibility to psychosis.

Substance P receptor antagonist and clomipramine prevent stress-induced alterations in cerebral metabolites, cytogenesis in the dentate gyrus and hippocampal volume

The neuropeptide substance P and its receptor, the neurokinin 1 receptor (NK(1)R) have been proposed as possible targets for new antidepressant therapies. The present study investigated the effect of the NK(1)R antagonist L-760,735 and the tricyclic antidepressant clomipramine in the chronic psychosocial stress paradigm of adult male tree shrews. Animals were subjected to a 7-day period of psychosocial stress before the onset of daily oral administration of L-760,735 (10 mg kg(-1) day(-1)) or clomipramine (50 mg kg(-1) day(-1)). The psychosocial stress continued throughout the treatment period of 28 days. Brain metabolite concentrations were determined in vivo by proton magnetic resonance spectroscopy. Cell proliferation in the dentate gyrus and hippocampal volume were measured post mortem. Stress significantly decreased in vivo concentrations of N-acetyl-aspartate (-14%), creatine and phosphocreatine (-15%) and choline-containing compounds (-15%). The proliferation rate of the granule precursor cells in the dentate gyrus was reduced (-45%), and hippocampal volume was decreased (-14%). The stress-induced changes of brain metabolites, hippocampal volume and dentate cytogenesis rate were prevented by concomitant drug administration. Elevated myo-inositol concentrations after both treatments hint to an astrocytic enhancement. These results suggest that-despite a different pharmacological profile-the NK(1)R antagonist L-760,735, a member of a novel class of antidepressant drugs, has comparable neurobiological efficacy to tricyclic antidepressants such as clomipramine.

The neurobiology of depression: perspectives from animal and human sleep studies

This article reviews human and animal studies in the neurobiology of depression. The etiology of the illness, associated neurotransmitter dysregulation, sex steroids, the role of stress, and sleep regulation are discussed. It is suggested that the genesis of depression is related to homeostatic maladaptation that is sexually dimorphic. The authors propose that depressed females are hyperresponsive to stress, whereas depressed males are hyporesponsive to stress. This divergence reflects the exaggeration of naturally occurring differences between males and females, which are most obvious under challenge conditions. The authors conclude that future work in this area should fully evaluate sexual dimorphism, neural plasticity, critical periods, and individual differences in vulnerability.