Mitochondrial dysfunction in bipolar disorder: evidence from magnetic resonance spectroscopy research

Gender-related alterations of serum trace elements and neurometabolism in the anterior cingulate cortex of patients with major depressive disorder

BACKGROUND

It is widely known that sex differences have a significant impact on patients with major depressive disorder (MDD). This study aims to evaluate the sex-related connection between serum trace elements and changes in neurometabolism in the anterior cingulate cortex (ACC) of MDD patients.

METHODS

109 untreated MDD patients and 59 healthy controls underwent proton magnetic resonance spectroscopy (1H-MRS) under resting conditions. We measured metabolic ratios in the ACC from both sides. Additionally, venous blood samples were taken from all participants to detect calcium (Ca), phosphorus, magnesium (Mg), copper (Cu), ceruloplasmin (CER), zinc (Zn), and iron (Fe) levels. We performed association and interaction analyses to explore the connections between the disease and gender.

RESULTS

In individuals with MDD, the Cu/Zn ratio increased, while the levels of Mg, CER, Zn and Fe decreased. Male MDD patients had lower Cu levels, while female patients had an increased Cu/Zn ratio. We observed significant gender differences in Cu, CER and the Cu/Zn ratio in MDD. Male patients showed a reduced N-acetyl aspartate (NAA)/phosphocreatine + creatine (PCr + Cr) ratio in the left ACC. The NAA/PCr + Cr ratio decreased in the right ACC in patients with MDD. In the left ACC of male MDD patients, the Cu/Zn ratio was inversely related to the NAA/PCr + Cr ratio, and Fe levels were negatively associated with the GPC + PC/PCr + Cr ratio.

CONCLUSIONS

Our findings highlight gender-specific changes in Cu homeostasis among male MDD patients. The Cu/Zn ratio and Fe levels in male MDD patients were significantly linked to neurometabolic alterations in the ACC.

Large-scale animal model study uncovers altered brain pH and lactate levels as a transdiagnostic endophenotype of neuropsychiatric disorders involving cognitive impairment

Increased levels of lactate, an end-product of glycolysis, have been proposed as a potential surrogate marker for metabolic changes during neuronal excitation. These changes in lactate levels can result in decreased brain pH, which has been implicated in patients with various neuropsychiatric disorders. We previously demonstrated that such alterations are commonly observed in five mouse models of schizophrenia, bipolar disorder, and autism, suggesting a shared endophenotype among these disorders rather than mere artifacts due to medications or agonal state. However, there is still limited research on this phenomenon in animal models, leaving its generality across other disease animal models uncertain. Moreover, the association between changes in brain lactate levels and specific behavioral abnormalities remains unclear. To address these gaps, the International Brain pH Project Consortium investigated brain pH and lactate levels in 109 strains/conditions of 2294 animals with genetic and other experimental manipulations relevant to neuropsychiatric disorders. Systematic analysis revealed that decreased brain pH and increased lactate levels were common features observed in multiple models of depression, epilepsy, Alzheimer's disease, and some additional schizophrenia models. While certain autism models also exhibited decreased pH and increased lactate levels, others showed the opposite pattern, potentially reflecting subpopulations within the autism spectrum. Furthermore, utilizing large-scale behavioral test battery, a multivariate cross-validated prediction analysis demonstrated that poor working memory performance was predominantly associated with increased brain lactate levels. Importantly, this association was confirmed in an independent cohort of animal models. Collectively, these findings suggest that altered brain pH and lactate levels, which could be attributed to dysregulated excitation/inhibition balance, may serve as transdiagnostic endophenotypes of debilitating neuropsychiatric disorders characterized by cognitive impairment, irrespective of their beneficial or detrimental nature.

Tremendous Fidelity of Vitamin D3 in Age-related Neurological Disorders

Vitamin D3 (VD) is a secosteroid hormone and shows a pleiotropic effect in brain-related disorders where it regulates redox imbalance, inflammation, apoptosis, energy production, and growth factor synthesis. Vitamin D3's active metabolic form, 1,25-dihydroxy Vitamin D3 (1,25(OH)2D3 or calcitriol), is a known regulator of several genes involved in neuroplasticity, neuroprotection, neurotropism, and neuroinflammation. Multiple studies suggest that VD deficiency can be proposed as a risk factor for the development of several age-related neurological disorders. The evidence for low serum levels of 25-hydroxy Vitamin D3 (25(OH)D3 or calcidiol), the major circulating form of VD, is associated with an increased risk of Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), dementia, and cognitive impairment. Despite decades of evidence on low VD association with neurological disorders, the precise molecular mechanism behind its beneficial effect remains controversial. Here, we will be delving into the neurobiological importance of VD and discuss its benefits in different neuropsychiatric disorders. The focus will be on AD, PD, and HD as they share some common clinical, pathological, and epidemiological features. The central focus will be on the different attributes of VD in the aspect of its anti-oxidative, anti-inflammatory, anti-apoptotic, anti-cholinesterase activity, and psychotropic effect in different neurodegenerative diseases.

Integrating mitoepigenetics into research in mood disorders: a state-of-the-art review

Mood disorders, including major depressive disorder and bipolar disorder, are highly prevalent and stand among the leading causes of disability. Despite the largely elusive nature of the molecular mechanisms underpinning these disorders, two pivotal contributors-mitochondrial dysfunctions and epigenetic alterations-have emerged as significant players in their pathogenesis. This state-of-the-art review aims to present existing data on epigenetic alterations in the mitochondrial genome in mood disorders, laying the groundwork for future research into their pathogenesis. Associations between abnormalities in mitochondrial function and mood disorders have been observed, with evidence pointing to notable changes in mitochondrial DNA (mtDNA). These changes encompass variations in copy number and oxidative damage. However, information on additional epigenetic alterations in the mitochondrial genome remains limited. Recent studies have delved into alterations in mtDNA and regulations in the mitochondrial genome, giving rise to the burgeoning field of mitochondrial epigenetics. Mitochondrial epigenetics encompasses three main categories of modifications: mtDNA methylation/hydroxymethylation, modifications of mitochondrial nucleoids, and mitochondrial RNA alterations. The epigenetic modulation of mitochondrial nucleoids, lacking histones, may impact mtDNA function. Additionally, mitochondrial RNAs, including non-coding RNAs, present a complex landscape influencing interactions between the mitochondria and the nucleus. The exploration of mitochondrial epigenetics offers valuable perspectives on how these alterations impact neurodegenerative diseases, presenting an intriguing avenue for research on mood disorders. Investigations into post-translational modifications and the role of mitochondrial non-coding RNAs hold promise to unravel the dynamics of mitoepigenetics in mood disorders, providing crucial insights for future therapeutic interventions.

The metabolic overdrive hypothesis: hyperglycolysis and glutaminolysis in bipolar mania

Evidence from diverse areas of research including chronobiology, metabolomics and magnetic resonance spectroscopy indicate that energy dysregulation is a central feature of bipolar disorder pathophysiology. In this paper, we propose that mania represents a condition of heightened cerebral energy metabolism facilitated by hyperglycolysis and glutaminolysis. When oxidative glucose metabolism becomes impaired in the brain, neurons can utilize glutamate as an alternative substrate to generate energy through oxidative phosphorylation. Glycolysis in astrocytes fuels the formation of denovo glutamate, which can be used as a mitochondrial fuel source in neurons via transamination to alpha-ketoglutarate and subsequent reductive carboxylation to replenish tricarboxylic acid cycle intermediates. Upregulation of glycolysis and glutaminolysis in this manner causes the brain to enter a state of heightened metabolism and excitatory activity which we propose to underlie the subjective experience of mania. Under normal conditions, this mechanism serves an adaptive function to transiently upregulate brain metabolism in response to acute energy demand. However, when recruited in the long term to counteract impaired oxidative metabolism it may become a pathological process. In this article, we develop these ideas in detail, present supporting evidence and propose this as a novel avenue of investigation to understand the biological basis for mania.

Impaired neural stress resistance and loss of REST in bipolar disorder

Neurodevelopmental changes and impaired stress resistance have been implicated in the pathogenesis of bipolar disorder (BD), but the underlying regulatory mechanisms are unresolved. Here we describe a human cerebral organoid model of BD that exhibits altered neural development, elevated neural network activity, and a major shift in the transcriptome. These phenotypic changes were reproduced in cerebral organoids generated from iPS cell lines derived in different laboratories. The BD cerebral organoid transcriptome showed highly significant enrichment for gene targets of the transcriptional repressor REST. This was associated with reduced nuclear REST and REST binding to target gene recognition sites. Reducing the oxygen concentration in organoid cultures to a physiological range ameliorated the developmental phenotype and restored REST expression. These effects were mimicked by treatment with lithium. Reduced nuclear REST and derepression of REST targets genes were also observed in the prefrontal cortex of BD patients. Thus, an impaired cellular stress response in BD cerebral organoids leads to altered neural development and transcriptional dysregulation associated with downregulation of REST. These findings provide a new model and conceptual framework for exploring the molecular basis of BD.

Prefrontal photobiomodulation produces beneficial mitochondrial and oxygenation effects in older adults with bipolar disorder

There is growing evidence of mitochondrial dysfunction and prefrontal cortex (PFC) hypometabolism in bipolar disorder (BD). Older adults with BD exhibit greater decline in PFC-related neurocognitive functions than is expected for age-matched controls, and clinical interventions intended for mood stabilization are not targeted to prevent or ameliorate mitochondrial deficits and neurocognitive decline in this population. Transcranial infrared laser stimulation (TILS) is a non-invasive form of photobiomodulation, in which photons delivered to the PFC photo-oxidize the mitochondrial respiratory enzyme, cytochrome-c-oxidase (CCO), a major intracellular photon acceptor in photobiomodulation. TILS at 1064-nm can significantly upregulate oxidized CCO concentrations to promote differential levels of oxygenated vs. deoxygenated hemoglobin (HbD), an index of cerebral oxygenation. The objective of this controlled study was to use non-invasive broadband near-infrared spectroscopy to assess if TILS to bilateral PFC (Brodmann area 10) produces beneficial effects on mitochondrial oxidative energy metabolism (oxidized CCO) and cerebral oxygenation (HbD) in older (≥50 years old) euthymic adults with BD (N = 15). As compared to sham, TILS to the PFC in adults with BD increased oxidized CCO both during and after TILS, and increased HbD concentrations after TILS. By significantly increasing oxidized CCO and HbD concentrations above sham levels, TILS has the potential ability to stabilize mitochondrial oxidative energy production and prevent oxidative damage in the PFC of adults with BD. In conclusion, TILS was both safe and effective in enhancing metabolic function and subsequent hemodynamic responses in the PFC, which might help alleviate the accelerated neurocognitive decline and dysfunctional mitochondria present in BD.

Diagnosis and Treatment of X-Linked Creatine Transporter Deficiency: Case Report and Literature Review

(1) Background: X-linked creatine transporter deficiency (CTD) (OMIM 300036) is a rare group of inherited metabolic disorders characterized by global developmental delay/intellectual disability (GDD/ID), seizures, autistic behavior, and movement disorders. Pathogenic variants in the SLC6A8 gene, located at Xq28, are causative of the disease, leading to impaired creatine transport into the brain. Supplementation with creatine and its precursors, glycine and arginine, has been attempted, yet the treatment efficacy remains controversial. (2) Methods: Here we report a de novo SLC6A8 variant in a boy aged 3 years 9 months presenting with GDD, autistic behavior, and epilepsy. Elevated urinary creatine/creatinine ratio and diminished creatine peak on brain MR spectroscopy suggested the diagnosis of CTD. Genetic sequencing revealed a de novo hemizygous frameshift variant (NM_005629: c.1136_1137del, p. Glu379ValfsTer85). Creatine supplementation therapy was initiated after definitive diagnosis. Electroencephalography and MR spectroscopy were monitored during follow-up in concurrence with neuropsychological evaluations. The clinical phenotype and treatment response of CTD were summarized by systematic view of the literature. (3) Results: In silico analysis showed this variant to be deleterious, probably interfering with substrate binding and conformational changes during creatine transport. Creatine supplementation therapy led to seizure cessation and modest cognitive improvement after half-year's treatment. (4) Conclusions: This case highlights the importance of MR spectroscopy and metabolic screening in males with GDD/ID, allowing for early diagnosis and therapeutic intervention. Mechanistic understanding and case-per-se analysis are required to enable precision treatment for the patients.

Differentiation between bipolar disorder and major depressive disorder in adolescents: from clinical to biological biomarkers

Background

Mood disorders are very common among adolescents and include mainly bipolar disorder (BD) and major depressive disorder (MDD), with overlapping depressive symptoms that pose a significant challenge to realizing a rapid and accurate differential diagnosis in clinical practice. Misdiagnosis of BD as MDD can lead to inappropriate treatment and detrimental outcomes, including a poorer ultimate clinical and functional prognosis and even an increased risk of suicide. Therefore, it is of great significance for clinical management to identify clinical symptoms or features and biological markers that can accurately distinguish BD from MDD. With the aid of bibliometric analysis, we explore, visualize, and conclude the important directions of differential diagnostic studies of BD and MDD in adolescents.

Materials and methods

A literature search was performed for studies on differential diagnostic studies of BD and MDD among adolescents in the Web of Science Core Collection database. All studies considered for this article were published between 2004 and 2023. Bibliometric analysis and visualization were performed using the VOSviewer and CiteSpace software.

Results

In total, 148 publications were retrieved. The number of publications on differential diagnostic studies of BD and MDD among adolescents has been generally increasing since 2012, with the United States being an emerging hub with a growing influence in the field. Boris Birmaher is the top author in terms of the number of publications, and the Journal of Affective Disorders is the most published journal in the field. Co-occurrence analysis of keywords showed that clinical characteristics, genetic factors, and neuroimaging are current research hotspots. Ultimately, we comprehensively sorted out the current state of research in this area and proposed possible research directions in future.

Conclusion

This is the first-ever study of bibliometric and visual analyses of differential diagnostic studies of BD and MDD in adolescents to reveal the current research status and important directions in the field. Our research and analysis results might provide some practical sources for academic scholars and clinical practice.

Mitochondrial DNA Copy Number and Heteroplasmy in Monozygotic Twins Discordant for Schizophrenia

Schizophrenia (SZ) is a severe, complex, and common mental disorder with high heritability (80%), an adult age of onset, and high discordance (∼50%) in monozygotic twins (MZ). Extensive studies on familial and non-familial cases have implicated a number of segregating mutations and de novo changes in SZ that may include changes to the mitochondrial genome. Yet, no single universally causal variant has been identified, highlighting its extensive genetic heterogeneity. This report specifically focuses on the assessment of changes in the mitochondrial genome in a unique set of monozygotic twins discordant (MZD) for SZ using blood. Genomic DNA from six pairs of MZD twins and two sets of parents (N = 16) was hybridized to the Affymetrix Human SNP Array 6.0 to assess mitochondrial DNA copy number (mtDNA-CN). Whole genome sequencing (WGS) and quantitative polymerase chain reaction (qPCR) was performed for a subset of MZD pairs and their parents and was also used to derive mtDNA-CN estimates. The WGS data were further analyzed to generate heteroplasmy (HP) estimates. Our results show that mtDNA-CN estimates for within-pair and mother-child differences were smaller than comparisons involving unrelated individuals, as expected. MZD twins showed discordance in mtDNA-CN estimates and displayed concordance in directionality of differences for mtDNA-CN across all technologies. Further, qPCR performed better than Affymetrix in estimating mtDNA-CN based on relatedness. No reliable differences in HP were detected between MZD twins. The within-MZD differences in mtDNA-CN observed represent postzygotic somatic changes that may contribute to discordance of MZ twins for diseases, including SZ.

Lactate: A Theranostic Biomarker for Metabolic Psychiatry?

Alterations in neurometabolism and mitochondria are implicated in the pathophysiology of psychiatric conditions such as mood disorders and schizophrenia. Thus, developing objective biomarkers related to brain mitochondrial function is crucial for the development of interventions, such as central nervous system penetrating agents that target brain health. Lactate, a major circulatory fuel source that can be produced and utilized by the brain and body, is presented as a theranostic biomarker for neurometabolic dysfunction in psychiatric conditions. This concept is based on three key properties of lactate that make it an intriguing metabolic intermediate with implications for this field: Firstly, the lactate response to various stimuli, including physiological or psychological stress, represents a quantifiable and dynamic marker that reflects metabolic and mitochondrial health. Second, lactate concentration in the brain is tightly regulated according to the sleep-wake cycle, the dysregulation of which is implicated in both metabolic and mood disorders. Third, lactate universally integrates arousal behaviours, pH, cellular metabolism, redox states, oxidative stress, and inflammation, and can signal and encode this information via intra- and extracellular pathways in the brain. In this review, we expand on the above properties of lactate and discuss the methodological developments and rationale for the use of functional magnetic resonance spectroscopy for in vivo monitoring of brain lactate. We conclude that accurate and dynamic assessment of brain lactate responses might contribute to the development of novel and personalized therapies that improve mitochondrial health in psychiatric disorders and other conditions associated with neurometabolic dysfunction.

Optimization of differential filtration-based mitochondrial isolation for mitochondrial transplant to cerebral organoids

BACKGROUND

Mitochondrial dysfunction is involved in several diseases ranging from genetic mitochondrial disorders to chronic metabolic diseases. An emerging approach to potentially treat mitochondrial dysfunction is the transplantation of autologous live mitochondria to promote cell regeneration. We tested the differential filtration-based mitochondrial isolation protocol established by the McCully laboratory for use in cellular models but found whole cell contaminants in the mitochondrial isolate.

METHODS

Therefore, we explored alternative types of 5-μm filters (filters A and B) for isolation of mitochondria from multiple cell lines including HEK293 cells and induced pluripotent stem cells (iPSCs). MitoTracker™ staining combined with flow cytometry was used to quantify the concentration of viable mitochondria. A proof-of-principle mitochondrial transplant was performed using mitoDsRed2-tagged mitochondria into a H9-derived cerebral organoid.

RESULTS

We found that filter B provided the highest quality mitochondria as compared to the 5-μm filter used in the original protocol. Using this method, mitochondria were also successfully isolated from induced pluripotent stem cells. To test for viability, mitoDsRed2-tagged mitochondria were isolated and transplanted into H9-derived cerebral organoids and observed that mitochondria were engulfed as indicated by immunofluorescent co-localization of TOMM20 and MAP2.

CONCLUSIONS

Thus, use of filter B in a differential filtration approach is ideal for isolating pure and viable mitochondria from cells, allowing us to begin evaluating long-term integration and safety of mitochondrial transplant using cellular sources.

Age-Dependent Alterations in Platelet Mitochondrial Respiration

Mitochondrial dysfunction is an important cellular hallmark of aging and neurodegeneration. Platelets are a useful model to study the systemic manifestations of mitochondrial dysfunction. To evaluate the age dependence of mitochondrial parameters, citrate synthase activity, respiratory chain complex activity, and oxygen consumption kinetics were assessed. The effect of cognitive impairment was examined by comparing the age dependence of mitochondrial parameters in healthy individuals and those with neuropsychiatric disease. The study found a significant negative slope of age-dependence for both the activity of individual mitochondrial enzymes (citrate synthase and complex II) and parameters of mitochondrial respiration in intact platelets (routine respiration, maximum capacity of electron transport system, and respiratory rate after complex I inhibition). However, there was no significant difference in the age-related changes of mitochondrial parameters between individuals with and without cognitive impairment. These findings highlight the potential of measuring mitochondrial respiration in intact platelets as a means to assess age-related mitochondrial dysfunction. The results indicate that drugs and interventions targeting mitochondrial respiration may have the potential to slow down or eliminate certain aging and neurodegenerative processes. Mitochondrial respiration in platelets holds promise as a biomarker of aging, irrespective of the degree of cognitive impairment.

Effects of serotonergic psychedelics on mitochondria: Transdiagnostic implications for mitochondria-related pathologies

The use of serotonergic psychedelics has gained increasing attention in research, clinical practice and society. Growing evidence suggests fast-acting, transdiagnostic health benefits of these 5-hydroxytryptamine 2A receptor agonists. Here, we provide a brief overview of their benefits for psychological, cardiovascular, metabolic, neurodegenerative, and immunological pathologies. We then review their effect on mitochondria including mitochondrial biogenesis, functioning and transport. Mitochondrial dysregulation is a transdiagnostic mechanism that contributes to the aforementioned pathologies. Hence, we postulate that psychedelic-induced effects on mitochondria partially underlie their transdiagnostic benefits. Based on this assumption, we propose new treatment indications for psychedelics and that the health benefits induced by psychedelics depend on patient-specific mitochondrial dysregulation.

Antidepressants that increase mitochondrial energetics may elevate risk of treatment-emergent mania

Preclinical evidence suggests that antidepressants (ADs) may differentially influence mitochondrial energetics. This study was conducted to investigate the relationship between mitochondrial function and illness vulnerability in bipolar disorder (BD), specifically risk of treatment-emergent mania (TEM). Participants with BD already clinically phenotyped as TEM+ (n = 176) or TEM- (n = 516) were further classified whether the TEM associated AD, based on preclinical studies, increased (Mito+, n = 600) or decreased (Mito-, n = 289) mitochondrial electron transport chain (ETC) activity. Comparison of TEM+ rates between Mito+ and Mito- ADs was performed using generalized estimating equations to account for participants exposed to multiple ADs while adjusting for sex, age at time of enrollment into the biobank and BD type (BD-I/schizoaffective vs. BD-II). A total of 692 subjects (62.7% female, 91.4% White, mean age 43.0 ± 14.0 years) including 176 cases (25.3%) of TEM+ and 516 cases (74.7%) of TEM- with previous exposure to Mito+ and/or Mito- antidepressants were identified. Adjusting for age, sex and BD subtype, TEM+ was more frequent with antidepressants that increased (24.7%), versus decreased (13.5%) mitochondrial energetics (OR = 2.21; p = 0.000009). Our preliminary retrospective data suggests there may be merit in reconceptualizing AD classification, not solely based on monoaminergic conventional drug mechanism of action, but additionally based on mitochondrial energetics. Future prospective clinical studies on specific antidepressants and mitochondrial activity are encouraged. Recognizing pharmacogenomic investigation of drug response may extend or overlap to genomics of disease risk, future studies should investigate potential interactions between mitochondrial mechanisms of disease risk and drug response.

BDNF rs6265 differentially influences neurometabolites in the anterior cingulate of healthy and bipolar disorder subjects

Brain-derived neurotrophic factor (BDNF) is the most abundant brain neurotrophin and plays a critical role in neuronal growth, survival and plasticity, implicated in the pathophysiology of Bipolar Disorders (BD). The single-nucleotide polymorphism in the BDNF gene (BDNF rs6265) has been associated with decreased hippocampal BDNF secretion and volume in met carriers in different populations, although the val allele has been reported to be more frequent in BD patients. The anterior cingulate cortex (ACC) is a key center integrating cognitive and affective neuronal connections, where consistent alterations in brain metabolites such as Glx (Glutamate + Glutamine) and N-acetylaspartate (NAA) have been consistently reported in BD. However, little is known about the influence of BDNF rs6265 on neurochemical profile in the ACC of Healthy Controls (HC) and BD subjects. The aim of this study was to assess the influence of BDNF rs6265 on ACC neurometabolites (Glx, NAA and total creatine- Cr) in 124 euthymic BD type I patients and 76 HC, who were genotyped for BDNF rs6265 and underwent a 3-Tesla proton magnetic resonance imaging and spectroscopy scan (¹ H-MRS) using a PRESS ACC single-voxel (8cm³) sequence. BDNF rs6265 polymorphism showed a significant two-way interaction (diagnosis × genotype) in relation to NAA/Cr and total Cr. While met carriers presented increased NAA/Cr in HC, BD-I subjects with the val allele revealed higher total Cr, denoting an enhanced ACC metabolism likely associated with increased glutamatergic metabolites observed in BD-I val carriers. However, these results were replicated only in men. Therefore, our results support evidences that the BDNF rs6265 polymorphism exerts a complex pleiotropic effect on ACC metabolites influenced by the diagnosis and sex.

The gene expression patterns as surrogate indices of pH in the brain

Hydrogen ion (H⁺) is one of the most potent intrinsic neuromodulators in the brain in terms of concentration. Changes in H⁺ concentration, expressed as pH, are thought to be associated with various biological processes, such as gene expression, in the brain. Accumulating evidence suggests that decreased brain pH is a common feature of several neuropsychiatric disorders, including schizophrenia, bipolar disorder, autism spectrum disorder, and Alzheimer's disease. However, it remains unclear whether gene expression patterns can be used as surrogates for pH changes in the brain. In this study, we performed meta-analyses using publicly available gene expression datasets to profile the expression patterns of pH-associated genes, whose expression levels were correlated with brain pH, in human patients and mouse models of major central nervous system (CNS) diseases, as well as in mouse cell-type datasets. Comprehensive analysis of 281 human datasets from 11 CNS disorders revealed that gene expression associated with decreased pH was over-represented in disorders including schizophrenia, bipolar disorder, autism spectrum disorders, Alzheimer's disease, Huntington's disease, Parkinson's disease, and brain tumors. Expression patterns of pH-associated genes in mouse models of neurodegenerative disease showed a common time course trend toward lower pH over time. Furthermore, cell type analysis identified astrocytes as the cell type with the most acidity-related gene expression, consistent with previous experimental measurements showing a lower intracellular pH in astrocytes than in neurons. These results suggest that the expression pattern of pH-associated genes may be a surrogate for the state- and trait-related changes in pH in brain cells. Altered expression of pH-associated genes may serve as a novel molecular mechanism for a more complete understanding of the transdiagnostic pathophysiology of neuropsychiatric and neurodegenerative disorders.

Ultrastructural evidence for glutamatergic dysregulation in schizophrenia

The aim of this paper is to summarize ultrastructural evidence for glutamatergic dysregulation in several linked regions in postmortem schizophrenia brain. Following a brief summary of glutamate circuitry and how synapses are identified at the electron microscopic (EM) level, we will review EM pathology in the cortex and basal ganglia. We will include the effects of antipsychotic drugs and the relation of treatment response. We will discuss how these findings support or confirm other postmortem findings as well as imaging results. Briefly, synaptic and mitochondrial density in anterior cingulate cortex was decreased in schizophrenia, versus normal controls (NCs), in a selective layer specific pattern. In dorsal striatum, increases in excitatory synaptic density were detected in caudate matrix, a compartment associated with cognitive and motor function, and in the putamen patches, a region associated with limbic function and in the core of the nucleus accumbens. Patients who were treatment resistant or untreated had significantly elevated numbers of excitatory synapses in limbic striatal areas in comparison to NCs and responders. Protein levels of vGLUT2, found in subcortical glutamatergic neurons, were increased in the nucleus accumbens in schizophrenia. At the EM level, schizophrenia subjects had an increase in density of excitatory synapses in several areas of the basal ganglia. In the substantia nigra, the protein levels of vGLUT2 were elevated in untreated patients compared to NCs. The density of inhibitory synapses was decreased in schizophrenia versus NCs. In schizophrenia, glutamatergic synapses are differentially affected depending on the brain region, treatment status, and treatment response.

Emerging roles of brain metabolism in cognitive impairment and neuropsychiatric disorders

Here we discuss the role of diverse environmental manipulations affecting cognition with special regard to psychiatric conditions. We present evidence supporting a direct causal correlation between the valence of the environmental stimulation and some psychopathological traits and how the environment influences brain structure and function with special regard to oxidative stress and mitochondrial activity. Increasing experimental evidence supports a role for mitochondrial dysfunctions in neuropsychiatric disorders. Brain mitochondria are considered crucial mediators of allostasis, that is the capability to adapt to stress via a complex interaction between the autonomic, metabolic, and immune systems to maintain cellular homeostasis. In this process, mitochondria act as highly dynamic integrators by sensing and transducing stressors into adaptation mechanisms via metabolic stress mediators, such as glucocorticoids and catecholamines. Alterations in cellular homeostasis induced by chronic stress are thought to predispose to disease by triggering the so-called "mitochondrial allostatic load". This process is characterized by functional and structural changes of the mitochondria, ultimately leading to oxidative stress, inflammation, mitochondrial DNA damage and apoptosis. In this review we discuss the role of diverse environmental manipulations to affect cognition with special regard to psychiatric conditions. How the environment influences brain structure and function, and the interactions between rearing conditions, oxidative stress and mitochondrial activity are fundamental questions that are still poorly understood. As will be discussed, increasing experimental evidence supports a role for mitochondrial dysfunctions in neuropsychiatric disorders. Brain mitochondria are considered crucial mediators of allostasis, that is the capability to adapt to stress via a complex interaction between the autonomic, metabolic, and immune systems to maintain cellular homeostasis. In this process, mitochondria act as highly dynamic integrators by sensing and transducing stressors into adaptation mechanisms via metabolic stress mediators, such as glucocorticoids and catecholamines. Alterations in cellular homeostasis induced by chronic stress are thought to predispose to disease by triggering the so-called "mitochondrial allostatic load". This process is characterized by functional and structural changes of the mitochondria, ultimately leading to oxidative stress, inflammation, mitochondrial DNA damage and apoptosis. The brain requires considerable mitochondrial reserve not only to sustain basal neuronal needs but a also to provide increasing energy demands during stress. Consistently with these high energetic requirements, it is reasonable to hypothesise that the brain is particularly vulnerable to mitochondrial defects. Thus, even subtle metabolic alterations might have a substantial impact on cognitive functions. Over the last decade, several experimental evidence supported the hypothesis that a suboptimal mitochondrial function, which could be of genetic origin or acquired following adverse life events, is a key vulnerability factor for stress-related psychopathologies. Chronic psychological stress is a major promoter of anxiety as well as of oxidative damage, as shown in several studies. Recent evidence from mouse models harbouring mutations in mitochondrial genes demonstrated the role of mitochondria in modulating the response to acute psychological stress. However, it has yet to be determined whether mitochondrial dysfunctions are the cause or the consequence of anxiety. In this review, we discuss how adverse psychosocial environments can impact mitochondrial bioenergetics at the molecular level and we gather evidence from several studies linking energy metabolism and stress resilience/vulnerability. Moreover, we review recent findings supporting that metabolic dysfunction can underlie deficits in complex social behaviours. As will be discussed, aberrations in mitochondrial functionality have been found in the nucleus accumbens of highly anxious mice and mediate low social competitiveness. In addition, alterations in sociability can be reversed by enhancing mitochondrial functions. Recent evidence also demonstrated that a specific mutation in mitochondrial DNA, previously linked to autism spectrum disorder, produces autistic endophenotypes in mice by altering respiration chain and reactive oxygen species (ROS) production. Finally, we discuss a "Negative Enrichment" model that can explain some of the psychopathological conditions relevant to humans. Evidence of a direct causal correlation of valence of environmental stimulation and psychopathological traits will be presented, and possible molecular mechanisms that focus on oxidative stress. Collectively, the findings described here have been achieved with a wide set of behavioural and cognitive tasks with translational validity. Thus, they will be useful for future work aimed to elucidate the fine metabolic alterations in psychopathologies and devise novel approaches targeting mitochondria to alleviate these conditions.

Changes in regulators of lipid metabolism in the brain: a study of animal models of depression and hypothyroidism

Metabolic disturbances in the brain are assumed to be early changes involved in the pathogenesis of depression, and these alterations may be intensified by a deficiency of thyroid hormones. In contrast to glucose metabolism, the link between altered brain lipids and the pathogenesis of depression is poorly understood, therefore in the present study, we determine transcription factors and enzymes regulating cholesterol and fatty acid biosynthesis in the brain structures in an animal model of depression, hypothyroidism and the coexistence of these diseases.

In used model of depression, a decrease in the active form of the transcription factor SREBP-2 in the hippocampus was demonstrated, thus suggesting a reduction in cholesterol biosynthesis. In turn, in the hypothyroidism model, the reduction of cholesterol biosynthesis in the frontal cortex was demonstrated by both the reduction of mature SREBP-2 and the concentration of enzymes involved in cholesterol biosynthesis. The lower expression of LDL receptors in the frontal cortex indicates the restriction of cholesterol uptake into the cells in the model of coexistence of depression and hypothyroidism. Moreover, the identified changes in the levels of SNAP-25, GLP-1R and GLP-2R pointed to disturbances in synaptic plasticity and neuroprotection mechanisms in the examined brain structures.

In conclusion, a reduction in cholesterol synthesis in the hippocampus in the model of depression may be the reason for the reduction of synaptic plasticity, whereas a lower level of LDL-R occurring in the frontal cortex in rats from the model of depression and hypothyroidism coexistence could be the reason of anxiogenic and depression-like behaviors.

Peripheral biomarkers to predict the diagnosis of bipolar disorder from major depressive disorder in adolescents

The onset of bipolar disorder (BD) occurs in childhood or adolescence in half of the patients. Early stages of BD usually present depressive episodes, which makes it difficult to be distinguished from major depressive disorder (MDD). Objective biomarkers for discriminating BD from MDD in adolescent patients are limited. We collected basic demographic data and the information of the first blood examination performed after the admission to psychiatry unit of BD and MDD inpatients during 2009-2018. We recruited 261 adolescents (aged from 10 to 18), including 160 MDD and 101 BD. Forward-Stepwise Selection of binary logistic regression was used to construct predictive models for the total sample and subgroups by gender. Independent external validation was made by 255 matched patients from another hospital in China. Regression models of total adolescents, male and female subgroups showed accuracy of 73.3%, 70.6% and 75.2%, with area under curves (AUC) as 0.785, 0.816 and 0.793, respectively. Age, direct bilirubin (DBIL), lactic dehydrogenase (LDH), free triiodothyronine (FT3) and C-reactive protein (CRP) were final factors included into the models. The discrimination was well at external validation (AUC = 0.714). This study offers the evidence that accessible information of common clinical laboratory examination might be valuable in distinguishing BD form MDD in adolescents. With good diagnostic accuracies and external validation, the total regression equation might potentially be applied to individualized clinical inferences on adolescent BD patients.

Distinct proteomic profiles in prefrontal subareas of elderly major depressive disorder and bipolar disorder patients

We investigated for the first time the proteomic profiles both in the dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC) of major depressive disorder (MDD) and bipolar disorder (BD) patients. Cryostat sections of DLPFC and ACC of MDD and BD patients with their respective well-matched controls were used for study. Proteins were quantified by tandem mass tag and high-performance liquid chromatography-mass spectrometry system. Gene Ontology terms and functional cluster alteration were analyzed through bioinformatic analysis. Over 3000 proteins were accurately quantified, with more than 100 protein expressions identified as significantly changed in these two brain areas of MDD and BD patients as compared to their respective controls. These include OGDH, SDHA and COX5B in the DLPFC in MDD patients; PFN1, HSP90AA1 and PDCD6IP in the ACC of MDD patients; DBN1, DBNL and MYH9 in the DLPFC in BD patients. Impressively, depending on brain area and distinct diseases, the most notable change we found in the DLPFC of MDD was 'suppressed energy metabolism'; in the ACC of MDD it was 'suppressed tissue remodeling and suppressed immune response'; and in the DLPFC of BD it was differentiated 'suppressed tissue remodeling and suppressed neuronal projection'. In summary, there are distinct proteomic changes in different brain areas of the same mood disorder, and in the same brain area between MDD and BD patients, which strengthens the distinct pathogeneses and thus treatment targets.

Brain proton magnetic resonance spectroscopy and neurodevelopment after preterm birth: a systematic review

BACKGROUND

Preterm infants are at risk of neurodevelopmental impairments. At present, proton magnetic resonance spectroscopy (¹H-MRS) is used to evaluate brain metabolites in asphyxiated term infants. The aim of this review is to assess associations between cerebral ¹H-MRS and neurodevelopment after preterm birth.

METHODS

PubMed and Embase were searched to identify studies using ¹H-MRS and preterm birth. Eligible studies for this review included ¹H-MRS of the brain, gestational age ≤32 weeks, and neurodevelopment assessed at a corrected age (CA) of at least 12 months up to the age of 18 years.

RESULTS

Twenty papers evaluated ¹H-MRS in preterm infants at an age between near-term and 18 years and neurodevelopment. ¹H-MRS was performed in both white (WM) and gray matter (GM) in 12 of 20 studies. The main regions were frontal and parietal lobe for WM and basal ganglia for GM. N-acetylaspartate/choline (NAA/Cho) measured in WM and/or GM is the most common metabolite ratio associated with motor, language, and cognitive outcome at 18-24 months CA.

CONCLUSIONS

NAA/Cho in WM assessed at term-equivalent age was associated with motor, cognitive, and language outcome, and NAA/Cho in deep GM was associated with language outcome at 18-24 months CA.

IMPACT

In preterm born infants, brain metabolism assessed using ¹H-MRS at term-equivalent age is associated with motor, cognitive, and language outcomes at 18-24 months. ¹H-MRS at term-equivalent age in preterm born infants may be used as an early indication of brain development. Specific findings relating to NAA were most predictive of outcome.

Neurochemical Alterations in Social Anxiety Disorder (SAD): A Systematic Review of Proton Magnetic Resonance Spectroscopic Studies

(1) Objective: Considering that current knowledge of mechanisms involved in the molecular pathogenesis of Social Anxiety Disorder (SAD) is limited, we conducted a systematic review to evaluate cumulative data obtained by Proton Magnetic Resonance Spectroscopic (¹H MRS) studies. (2) Methods: A computer-based literature search of Medline, EMBASE, PsycInfo, and ProQuest was performed. Only cross-sectional studies using ¹H MRS techniques in participants with SAD and healthy controls (HCs) were selected. (3) Results: The search generated eight studies. The results indicated regional abnormalities in the ‘fear neurocircuitry’ in patients with SAD. The implicated regions included the anterior cingulate cortex (ACC), dorsomedial prefrontal cortex (dmPFC), dorsolateral prefrontal cortex (dlPFC), insula, occipital cortex (OC), as well as the subcortical regions, including the thalamus, caudate, and the putamen. (4) Conclusions: The evidence derived from eight studies suggests that possible pathophysiological mechanisms of SAD include impairments in the integrity and function of neurons and glial cells, including disturbances in energy metabolism, maintenance of phospholipid membranes, dysregulations of second messenger systems, and excitatory/inhibitory neurocircuitry. Conducting more cross-sectional studies with larger sample sizes is warranted given the limited evidence in this area of research.

Distinct patterns of altered quantitative T1ρ and functional BOLD response associated with history of suicide attempts in bipolar disorder

Despite the high risk for suicide, relatively few studies have explored the relationship between suicide and brain imaging measures in bipolar disorder. In addition, fewer studies have explored the possibility that altered brain metabolism may be associated with suicide attempt. To begin to fill in these gaps, we evaluated functional (task based fMRI) and metabolic (quantitative T1ρ) differences associated with suicide attempt in participants with bipolar disorder. Thirty-nine participants with bipolar disorder underwent fMRI during a flashing checkerboard task and 27 also underwent quantitative T1ρ. The relationship between neuroimaging and history of suicide attempt was tested using multiple regression while adjusting for age, sex, and current mood state. Differences between two measures of suicide attempt (binary: yes/no and continuous: number of attempts) were quantified using the corrected Akaike Information Criterion. Participants who had attempted suicide had greater fMRI task-related activation in visual areas and the cerebellum. The number of suicide attempts was associated with a difference in BOLD response in the amygdala, prefrontal cortex, and cerebellum. Increased quantitative T1ρ was associated with number of suicide attempts in limbic, basal ganglia, and prefrontal cortex regions. This study is a secondary analysis with a modest sample size. Differences between measures of suicide history may be due to differences in statistical power. History of suicide was associated with limbic, prefrontal, and cerebellar alterations. Results comparing those with and without suicide attempts differed from results using number of suicide attempts, suggesting that these variables have different neurobiological underpinnings.

Magnetic Resonance Spectroscopy and Bipolar Disorder: How Feasible Is This Pairing?

Bipolar disorder is a psychiatric disorder that affects a significant part of the world's population; however, its diagnosis is difficult, mainly because of the lack of biomarkers and objective tests that aid the clinical evaluation. Proton magnetic resonance spectroscopy (MRS) is a tool that is relatively unused in the medical field. Its application arises from conventional magnetic resonance, and allows non-invasive, in vivo, the study of various metabolites and compounds in the human brain. This method may allow the assessment of neurobiochemical alterations in bipolar patients. One of the main advantages of this study type is the simplicity in its use since it only needs a standard magnetic resonator. All these characteristics make it an attractive diagnostic tool that can be used anywhere, including in low-middle-income countries. In conclusion, MRS has potential as a diagnostic tool for bipolar disorder; nevertheless, using it for this purpose still requires additional steps.

Metabolic abnormalities in the basal ganglia and cerebellum in bipolar disorder: A multi-modal MR study

AIMS

Bipolar type I disorder (BD) is characterized by severe mood swings and occurs in about 1% of the population. The mechanisms underlying the disorder remain unknown. Prior studies have suggested abnormalities in brain metabolism using ¹H and ³¹P magnetic resonance spectroscopy (MRS). Supporting altered metabolism, in previous studies we found T1ρ relaxation times in the cerebellum were elevated in participants with BD. In addition, T1ρ relaxation times in the basal ganglia were lower in participants with BD experiencing depressed mood. Based on these findings, this study sought to probe brain metabolism with a focus of extending these assessments to the cerebellum.

METHODS

This study collected data from 64 participants with Bipolar type I disorder (BD) and 42 controls. Subjects were scanned at both 3T (anatomical, functional, and T1ρ imaging data) and 7T (³¹P and ¹H spectroscopy). Regions of interest defined by the 1H MRS data were used to explore metabolic and functional changes in the cerebellar vermis and putamen.

RESULTS

Elevated concentrations of n-Acetyl-l-aspartate (NAA), glutamate, glutathione, taurine, and creatine were found in the cerebellar vermis along with decreased intra-cellular pH. Similar trends were observed in the right putamen for glutamate, creatine, and pH. We also observed a relationship between T1ρ relaxation times and mood in the putamen. We did not observe a significant effect of medications on these measures.

LIMITATIONS

The study was cross sectional in design and employed a naturalistic approach for assessing the impact of medications on the results.

CONCLUSION

This study supports prior findings of reduced pH in mitochondrial dysfunction in BD while also showing that these differences extend to the cerebellum.

Modifying the maternal microbiota alters the gut-brain metabolome and prevents emotional dysfunction in the adult offspring of obese dams

Maternal obesity disturbs brain-gut-microbiota interactions and induces negative affect in the offspring, but its impact on gut and brain metabolism in the offspring (F1) are unknown. Here, we tested whether perinatal intake of a multispecies probiotic could mitigate the abnormal emotional behavior in the juvenile and adult offspring of obese dams. Untargeted NMR-based metabolomic profiling and gene-expression analysis throughout the gut-brain axis were then used to investigate the biology underpinning behavioral changes in the dams and their offspring. Prolonged high-fat diet feeding reduced maternal gut short-chain fatty acid abundance, increased markers of peripheral inflammation, and decreased the abundance of neuroactive metabolites in maternal milk during nursing. Both juvenile (postnatal day [PND] 21) and adult (PND112) offspring of obese dams exhibited increased anxiety-like behavior, which were prevented by perinatal probiotic exposure. Maternal probiotic treatment increased gut butyrate and brain lactate in the juvenile and adult offspring and increased the expression of prefrontal cortex PFKFB3, a marker of glycolytic metabolism in astrocytes. PFKFB3 expression correlated with the increase in gut butyrate in the juvenile and adult offspring. Maternal obesity reduced synaptophysin expression in the adult offspring, while perinatal probiotic exposure increased expression of brain-derived neurotrophic factor. Finally, we showed that the resilience of juvenile and adult offspring to anxiety-like behavior was most prominently associated with increased brain lactate abundance, independent of maternal group. Taken together, we show that maternal probiotic supplementation exerts a long-lasting effect on offspring neuroplasticity and the offspring gut-liver-brain metabolome, increasing resilience to emotional dysfunction induced by maternal obesity.

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.

Role of Creatine Supplementation in Conditions Involving Mitochondrial Dysfunction: A Narrative Review

Creatine monohydrate (CrM) is one of the most widely used nutritional supplements among active individuals and athletes to improve high-intensity exercise performance and training adaptations. However, research suggests that CrM supplementation may also serve as a therapeutic tool in the management of some chronic and traumatic diseases. Creatine supplementation has been reported to improve high-energy phosphate availability as well as have antioxidative, neuroprotective, anti-lactatic, and calcium-homoeostatic effects. These characteristics may have a direct impact on mitochondrion's survival and health particularly during stressful conditions such as ischemia and injury. This narrative review discusses current scientific evidence for use or supplemental CrM as a therapeutic agent during conditions associated with mitochondrial dysfunction. Based on this analysis, it appears that CrM supplementation may have a role in improving cellular bioenergetics in several mitochondrial dysfunction-related diseases, ischemic conditions, and injury pathology and thereby could provide therapeutic benefit in the management of these conditions. However, larger clinical trials are needed to explore these potential therapeutic applications before definitive conclusions can be drawn.

Pathophysiology and Clinical Features of Neuropsychiatric Manifestations of Thyroid Disease

Thyroid hormones (TH) have a cardinal role in the development of the central nervous system during embryogenesis and early infancy. However, the TH-responsive genes in the developing brain cease to respond to TH in adulthood. Nevertheless, thyroid dysfunction in adults is commonly associated with a host of cognitive and psychiatric problems. Cognitive decline, dysphoria, and depression are common manifestations of overt hypothyroidism while hyperthyroidism can cause agitation, acute psychosis, and apathy, especially in older people. Whereas levothyroxine treatment can reverse dementia in the setting of hypothyroidism, the effect of levothyroxine on depressive symptoms in subjects with subclinical hypothyroidism is controversial. The use of supraphysiologic doses of TH to treat depression refractory to antidepressant remains a viable therapeutic tool with the caveat that excessive doses of thyroid hormone to treat depression may have potentially damaging effects on other organ systems. The present communication describes the pathophysiology of neuropsychiatric manifestations of thyroid disease, including changes in neurotransmission, alterations in neuronal or glial cell gene expression, blood-brain barrier dysfunction, increased risk of cerebrovascular disease, and occasionally cerebral inflammatory disease in the context of autoimmune thyroid disease. Elucidating the molecular mechanisms of TH effect on cerebral tissue will help identify novel therapeutic targets for managing people with neuropsychiatric disorders.

Differences in mitochondrial DNA copy number between patients with bipolar I and II disorders

Mitochondria play a critical role in energy metabolism. Genetic, postmortem brain, and brain imaging studies of bipolar disorder (BD) patients indicated that mitochondrial dysfunction might explain BD pathophysiology. Mitochondrial function can be indirectly evaluated by measuring mitochondrial DNA (mtDNA) copy numbers. We recruited 186 bipolar I disorder (BD1) and 95 bipolar II disorder (BD2) patients, and age- and sex-matched controls. MtDNA copy numbers in peripheral blood cells were measured via quantitative polymerase chain reaction. We explored parameters (including age and clinical features) that might affect mtDNA copy numbers. We found that BD1 patients had a lower mtDNA copy number than controls and that mtDNA copy number was negatively associated with the number of mood episodes. BD2 patients had a higher mtDNA copy number than controls. Thus, changes in mitochondrial function may influence BD pathophysiology. The opposite directions of the association with mtDNA copy number in BD1 and BD2 patients suggests that the difference in pathophysiology may be associated with mitochondrial function.

Proton magnetic resonance spectroscopy (MRS) in individuals with internet gaming

BACKGROUND

Various comorbid psychiatric diagnoses, including attention deficit hyperactivity disorder (ADHD), have been reported in individuals with internet gaming disorder (IGD). Prior research has shown alterations in brain metabolites, including N-acetylaspartate (NAA), and combined glutamate and glutamine in patients with ADHD that were similar to those observed in patients with IGD. We hypothesized that the decreased NAA levels in the IGD group would be associated with a history of ADHD.

METHODS

Forty adults participated in this study. Participants were classified as having a high risk for IGD if they had a total score higher than 21 on the IGD Scale-short form. Proton magnetic resonance spectroscopy (¹H-MRS) and high-resolution structural magnetic resonance imaging (MRI) data were acquired using a 3 Tesla Siemens Prisma scanner system.

RESULTS

Levels of NAA within the right prefrontal cortex were lower in the IGD group than those observed in the control group. In a multiple linear regression analysis, internet addiction test scores and history of ADHD were shown to predict increased game play. In addition, history of ADHD predicted lower levels of NAA within the right prefrontal cortex.

CONCLUSION

The preliminary results of current study suggest a mediating effect of ADHD on the severity of internet game play as well as the levels of NAA within the dorsolateral prefrontal cortex (DLPFC). The inclusion of ADHD in IGD research is important and deserving of further consideration.

Astrocyte Bioenergetics and Major Psychiatric Disorders

Ongoing research continues to add new elements to the emerging picture of involvement of astrocyte energy metabolism in the pathophysiology of major psychiatric disorders, including schizophrenia, mood disorders, and addictions. This review outlines what is known about the energy metabolism in astrocytes, the most numerous cell type in the brain, and summarizes the recent work on how specific perturbations of astrocyte bioenergetics may contribute to the neuropsychiatric conditions. The role of astrocyte energy metabolism in mental health and disease is reviewed on the organism, organ, and cell level. Data arising from genomic, metabolomic, in vitro, and neurobehavioral studies is critically analyzed to suggest future directions in research and possible metabolism-focused therapeutic interventions.

Sex Differences in the Effect of Diabetes on Cerebral Glucose Metabolism

The neuroimaging literature indicates that brain structure and function both deteriorate with diabetes, but information on sexual dimorphism in diabetes-related brain alterations is limited. This study aimed to ascertain whether brain metabolism is influenced by sex in an animal model of diabetes. Eleven rats (male, n = 5; female, n = 6) received a single intraperitoneal injection of 70 mg/kg streptozotocin (STZ) to develop diabetes. Another 11 rats (male, n = 5; female, n = 6) received the same amount of solvent through a single intraperitoneal injection. Longitudinal positron emission tomography scans were used to assess cerebral glucose metabolism before and 4 weeks after STZ or solvent administration. Before STZ or solvent injections, there was no evidence of sexual dimorphism in cerebral metabolism (p > 0.05). Compared with healthy control animals, rats with diabetes had significantly decreased brain metabolism in all brain regions (all p < 0.05). In addition, female diabetic rats exhibited further reduction in cerebral metabolism, relative to male diabetic rats (p < 0.05). The results of this study may provide some biological evidence, supporting the existence of a sexual dimorphism in diabetes-related complications.

Valproate activates the Snf1 kinase in Saccharomyces cerevisiae by decreasing the cytosolic pH

Valproate (VPA) is a widely used mood stabilizer, but its therapeutic mechanism of action is not understood. This knowledge gap hinders the development of more effective drugs with fewer side effects. Using the yeast model to elucidate the effects of VPA on cellular metabolism, we determined that the drug upregulated expression of genes normally repressed during logarithmic growth on glucose medium and increased levels of activated (phosphorylated) Snf1 kinase, the major metabolic regulator of these genes. VPA also decreased the cytosolic pH (pH_c) and reduced glycolytic production of 2/3-phosphoglycerate. ATP levels and mitochondrial membrane potential were increased, and glucose-mediated extracellular acidification decreased in the presence of the drug, as indicated by a smaller glucose-induced shift in pH, suggesting that the major P-type proton pump Pma1 was inhibited. Interestingly, decreasing the pH_c by omeprazole-mediated inhibition of Pma1 led to Snf1 activation. We propose a model whereby VPA lowers the pH_c causing a decrease in glycolytic flux. In response, Pma1 is inhibited and Snf1 is activated, resulting in increased expression of normally repressed metabolic genes. These findings suggest a central role for pH_c in regulating the metabolic program of yeast cells.

Altered neurochemistry in the anterior white matter of bipolar children and adolescents: a multivoxel 1H MRS study

Abnormalities within frontal lobe gray and white matter of bipolar disorder (BD) patients have been consistently reported in adult and pediatric studies, yet little is known about the neurochemistry of the anterior white matter (AWM) in pediatric BD and how medication status may affect it. The present cross-sectional 3T ¹H MRS study is the first to use a multivoxel approach to study the AWM of BD youth. Absolute metabolite levels from four bilateral AWM voxels were collected from 49 subjects between the ages of 8 and 18 (25 healthy controls (HC); 24 BD) and quantified. Our study found BD subjects to have lower levels of N-acetylaspartate (NAA) and glycerophosphocholine plus phosphocholine (GPC + PC), metabolites that are markers of neuronal viability and phospholipid metabolism and have also been implicated in adult BD. Further analysis indicated that the observed patterns were mostly driven by BD subjects who were medicated at the time of scanning and had an ADHD diagnosis. Although limited by possible confounding effects of mood state, medication, and other mood comorbidities, these findings serve as evidence of altered neurochemistry in BD youth that is sensitive to medication status and ADHD comorbidity.

Thyroid Function and Mood Disorders: A Mendelian Randomization Study

Background: Observational studies suggest that even minor variations in thyroid function are associated with the risk of mood disorders, including major depressive disorder (MDD) and bipolar disorder (BD). However, it is unknown whether these associations are causal or not. We used a Mendelian randomization (MR) approach to investigate causal effects of minor variations in thyrotropin (TSH) and free thyroxine (fT4) levels on MDD and BD risk. Materials and Methods: We performed two-sample MR analyses using data from the largest publicly available genome-wide association studies on normal-range TSH (n = 54,288) and fT4 (n = 49,269) levels, MDD (170,756 cases, 329,443 controls) and BD (20,352 cases, 31,358 controls). Secondary MR analyses investigated the effects of TSH and fT4 levels on specific MDD and BD subtypes. Reverse MR was also performed to assess the effects of MDD and BD on TSH and fT4 levels. Results: There were no associations between genetically predicted TSH and fT4 levels and MDD risk, nor MDD subtypes and minor depressive symptoms. A one standard deviation increase in fT4 levels was nominally associated with an 11% decrease in the overall BD risk (odds ratio [OR] = 0.89, 95% confidence interval [CI] = 0.80-0.98, p = 0.022) and a 13% decrease in the BD type 1 risk (OR = 0.87, CI = 0.75-1.00, p = 0.047). In the reverse direction, genetic predisposition to MDD and BD was not associated with TSH nor fT4 levels. Conclusions: Variations in normal-range TSH and fT4 levels have no effects on the risk of MDD and its subtypes, and neither on minor depressive symptoms. This indicates that depressive symptoms should not be attributed to minor variations in thyroid function. Borderline associations with BD and BD type 1 risks suggest that further clinical studies should investigate the effect of thyroid hormone treatment in BD.

Altered brain creatine cycle metabolites in bipolar I disorder with childhood abuse: A 1H magnetic resonance spectroscopy study

BACKGROUND

Childhood abuse (CA) is a risk factor for a number of psychiatric disorders and has been associated with higher risk of developing bipolar disorders (BD). CA in BD has been associated with more severe clinical outcomes, but the neurobiological explanation for this is unknown. Few studies have explored in vivo measurement of brain metabolites using proton magnetic resonance spectroscopy (¹H-MRS) in CA and no studies have investigated the association of CA severity with brain neurometabolites in BD.

OBJECTIVE

To investigate whether CA severity is associated with changes in anterior cingulate cortex (ACC) neurometabolite profile in BD and HC subjects.

METHODS

Fifty-nine BD I euthymic patients and fifty-nine HC subjects were assessed using the Childhood Trauma Questionnaire (CTQ) and underwent a 3-Tesla ¹H-MRS scan. Severity of childhood abuse (physical, sexual and emotional) and its association with levels of brain metabolites was analyzed within each group.

RESULTS

BD patients had higher total scores on the CTQ and higher severity rates of sexual and physical abuse compared to HC subjects. Greater severity of physical and sexual abuse was associated with increased ACC PCr level and lower Cr/PCr ratio in the BD group only.

CONCLUSION

Sexual and physical abuse in BD patients, but not in HC subjects, appeared to be associated with creatine metabolism in the ACC, which can influence neuronal mitochondrial energy production. Further studies should investigate whether this is the mechanism underlying the association between CA and worse clinical outcomes in BD.

Venlafaxine and L-Thyroxine Treatment Combination: Impact on Metabolic and Synaptic Plasticity Changes in an Animal Model of Coexisting Depression and Hypothyroidism

The clinical effectiveness of supportive therapy with thyroid hormones in drug-resistant depression is well-known; however, the mechanisms of action of these hormones in the adult brain have not been fully elucidated to date. We determined the effects of venlafaxine and/or L-thyroxine on metabolic parameters and markers involved in the regulation of synaptic plasticity and cell damage in an animal model of coexisting depression and hypothyroidism, namely, Wistar Kyoto rats treated with propylthiouracil. In this model, in relation to the depression model itself, the glycolysis process in the brain was weakened, and a reduction in pyruvate dehydrogenase in the frontal cortex was normalized only by the combined treatment with L-thyroxine and venlafaxine, whereas changes in pyruvate and lactate levels were affected by all applied therapies. None of the drugs improved the decrease in the expression of mitochondrial respiratory chain enzymes. No intensification of glucocorticoid action was shown, while an unfavorable change caused by the lack of thyroid hormones was an increase in the caspase-1 level, which was not reversed by venlafaxine alone. The results indicated that the combined administration of drugs was more effective in normalizing glycolysis and the transition to the Krebs cycle than the use of venlafaxine or L-thyroxine alone.

Anterior cingulate cortex neurometabolites in bipolar disorder are influenced by mood state and medication: A meta-analysis of 1H-MRS studies

The anterior cingulate cortex (ACC), a brain region that mediates affect and cognition by connecting the frontal cortex to limbic structures, has been consistently implicated in the neurobiology of Bipolar Disorder (BD). Proton magnetic resonance spectroscopy (¹H-MRS) studies have extensively compared in vivo neurometabolite levels of BD patients and healthy controls (HC) in the ACC. However, these studies have not been analyzed in a systematic review or meta-analysis and nor has the influence of mood state and medication on neurometabolites been examined in this cortical region. A systematic review and a meta-analysis of ¹H-MRS studies comparing ACC neurometabolite profiles of adult BD patients and HC subjects was conducted, retrieving 27 articles published between 2000 and 2018. Overall increased ACC levels of Glx [glutamine (Gln) + glutamate)/Creatine], Gln, choline (Cho) and Cho/Creatine were found in BD compared to HC. Bipolar depression was associated with higher Cho levels, while euthymia correlated with higher glutamine (Gln) and Cho. Mood stabilizers appeared to affect ACC Glu and Gln metabolites. Increased ACC Cho observed in euthymia, depression and in medication-free groups could be considered a trait marker in BD and attributed to increased cell membrane phospholipid turnover. Overall increased ACC Glx was associated with elevated Gln levels, particularly influenced by euthymia, but no abnormality in Glu was detected. Further ¹H-MRS studies, on other voxels, should assess more homogeneous (mood state-specific), larger BD samples and account for medication status using more sensitive ¹H-MRS techniques.

Resting-State fMRI Study of ADHD and Internet Gaming Disorder

Objective: We aimed to understand whether Attention Deficit Hyperactivity Disorder (ADHD) and Internet gaming disorder (IGD) share similar brain functional connectivity (FC) between the frontal and subcortices. Method: We compared changes in clinical symptoms and brain activity using functional magnetic resonance imaging (fMRI) in 26 patients with ADHD but without IGD, 29 patients with ADHD and IGD, and 20 patients with IGD but without ADHD. Results: The functional connectivity (FC) from the cortex to subcortex in both groups was decreased relative to that in age-matched healthy participants. One-year treatment for ADHD and IGD symptoms increased the FC between the cortex and subcortex in all ADHD participants and all IGD participants with good prognoses compared with those in all ADHD participants and all IGD participants with poor prognoses. Conclusion: Patients with ADHD and IGD shared similar brain FC at baseline and FC changes in response to treatment.

Do Autophagy Enhancers/ROS Scavengers Alleviate Consequences of Mild Mitochondrial Dysfunction Induced in Neuronal-Derived Cells?

Mitochondrial function is at the nexus of pathways regulating synaptic-plasticity and cellular resilience. The involvement of brain mitochondrial dysfunction along with increased reactive oxygen species (ROS) levels, accumulating mtDNA mutations, and attenuated autophagy is implicated in psychiatric and neurodegenerative diseases. We have previously modeled mild mitochondrial dysfunction assumed to occur in bipolar disorder (BPD) using exposure of human neuronal cells (SH-SY5Y) to rotenone (an inhibitor of mitochondrial-respiration complex-I) for 72 and 96 h, which exhibited up- and down-regulation of mitochondrial respiration, respectively. In this study, we aimed to find out whether autophagy enhancers (lithium, trehalose, rapamycin, and resveratrol) and/or ROS scavengers [resveratrol, N-acetylcysteine (NAC), and Mn-Tbap) can ameliorate neuronal mild mitochondrial dysfunction. Only lithium (added for the last 24/48 h of the exposure to rotenone for 72/96 h, respectively) counteracted the effect of rotenone on most of the mitochondrial respiration parameters (measured as oxygen consumption rate (OCR)). Rapamycin, resveratrol, NAC, and Mn-Tbap counteracted most of rotenone's effects on OCR parameters after 72 h, possibly via different mechanisms, which are not necessarily related to their ROS scavenging and/or autophagy enhancement effects. The effect of lithium reversing rotenone's effect on OCR parameters is compatible with lithium's known positive effects on mitochondrial function and is possibly mediated via its effect on autophagy. By-and-large it may be summarized that some autophagy enhancers/ROS scavengers alleviate some rotenone-induced mild mitochondrial changes in SH-SY5Y cells.

Sirtuins as pharmacological targets in neurodegenerative and neuropsychiatric disorders

Histone deacetylases (HDACs) are enzymes that regulate several processes, such as transcription, cell proliferation, differentiation and development. HDACs are classified as either Zn²⁺ -dependent or NAD⁺ -dependent enzymes. Over the years, experimental and clinical evidence has demonstrated that HDAC modulation is a critical process in neurodegenerative and psychiatric disorders. Nevertheless, most of the studies have focused on the role of Zn²⁺ -dependent HDACs in the development of these diseases, although there is growing evidence showing that the NAD⁺ -dependent HDACs, known as sirtuins, are also very promising targets. This possibility has been strengthened by reports of decreased levels of NAD⁺ in CNS disorders, which can lead to alterations in sirtuin activation and therefore result in increased pathology. In this review, we discuss the role of sirtuins in neurodegenerative and neuropsychiatric disorders as well the possible rationale for them to be considered as pharmacological targets in future therapeutic interventions.

Mitochondria-targeting therapeutic strategies in the treatment of depression

Depression is an affective disease with a complex clinical picture that is characterized by mood and emotional disturbances. It is known that several factors contribute to the risk of developing depression. The concept that mitochondrial dysfunction is one of the causes of depression is supported by a wide range of studies on cell cultures, animal models, and clinical research. An understanding the relationship between mitochondrial processes and central nervous system abnormalities that occur in the course of depression can guide the development of novel mitochondrial targeted therapeutic strategies as well as the usage of currently available antidepressants in a new context. This brief review aims to summarize recent findings on mitochondria dysfunction in depression, provide insight into therapeutic strategies targeting mitochondrial pathways, allude to future promising therapies, and discuss factors that can be used to improve treatment outcomes. The main focus is on new aspects (the effects of nutraceuticals and physical activity on brain metabolism), which can be combined with the available treatment options [monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs) and atypical drugs] to enhance their therapeutic effects.

The Role of Mitonuclear Incompatibility in Bipolar Disorder Susceptibility and Resilience Against Environmental Stressors

It has been postulated that mitochondrial dysfunction has a significant role in the underlying pathophysiology of bipolar disorder (BD). Mitochondrial functioning plays an important role in regulating synaptic transmission, brain function, and cognition. Neuronal activity is energy dependent and neurons are particularly sensitive to changes in bioenergetic fluctuations, suggesting that mitochondria regulate fundamental aspects of brain function. Vigorous evidence supports the role of mitochondrial dysfunction in the etiology of BD, including dysregulated oxidative phosphorylation, general decrease of energy, altered brain bioenergetics, co-morbidity with mitochondrial disorders, and association with genetic variants in mitochondrial DNA (mtDNA) or nuclear-encoded mitochondrial genes. Despite these advances, the underlying etiology of mitochondrial dysfunction in BD is unclear. A plausible evolutionary explanation is that mitochondrial-nuclear (mitonuclear) incompatibility leads to a desynchronization of machinery required for efficient electron transport and cellular energy production. Approximately 1,200 genes, encoded from both nuclear and mitochondrial genomes, are essential for mitochondrial function. Studies suggest that mitochondrial and nuclear genomes co-evolve, and the coordinated expression of these interacting gene products are essential for optimal organism function. Incompatibilities between mtDNA and nuclear-encoded mitochondrial genes results in inefficiency in electron flow down the respiratory chain, differential oxidative phosphorylation efficiency, increased release of free radicals, altered intracellular Ca²⁺ signaling, and reduction of catalytic sites and ATP production. This review explores the role of mitonuclear incompatibility in BD susceptibility and resilience against environmental stressors.

Using mitochondrial respiration inhibitors to design a novel model of bipolar disorder-like phenotype with construct, face and predictive validity

We mimicked mild mitochondrial-distress robustly reported in bipolar-disorder (BD) by chronic exposure to uniquely low doses of inhibitors of mitochondrial-respiration complexes in vitro and in vivo. Exposure of the neuronal-originating SH-SY5Y cells to very low dose (10 pM) rotenone, a mitochondrial-respiration complex (Co)I inhibitor, for 72 or 96 h did not affect cell viability and reactive oxygen species (ROS) levels. Yet, it induced a dual effect on mitochondrial-respiration: overshooting statistically significant several-fold increase of most oxygen-consumption-rate (OCR) parameters vs. significantly decreased all OCR parameters, respectively. Chronic low doses of 3-nitropropionic acid (3-NP) (CoII inhibitor) did not induce long-lasting changes in the cells' mitochondria-related parameters. Intraperitoneal administration of 0.75 mg/kg/day rotenone to male mice for 4 or 8 weeks did not affect spontaneous and motor activity, caused behaviors associated with mania and depression following 4 and 8 weeks, respectively, accompanied by relevant changes in mitochondrial basal OCR and in levels of mitochondrial-respiration proteins. Our model is among the very few BD-like animal models exhibiting construct (mild mitochondrial dysfunction), face (decreased/increased immobility time in the forced-swim test, increased/decreased consumption of sweet solution, increased/decreased time spent in the open arms of the elevated plus maze) and predictive (reversal of rotenone-induced behavioral changes by lithium treatment) validity. Our rotenone regime, employing doses that, to the best of our knowledge, have never been used before, differs from those inducing Parkinson's-like models by not affecting ROS-levels and cell-viability in vitro nor motor activity in vivo.

Inflammation-Related Changes in Mood Disorders and the Immunomodulatory Role of Lithium

Mood disorders are chronic, recurrent diseases characterized by changes in mood and emotions. The most common are major depressive disorder (MDD) and bipolar disorder (BD). Molecular biology studies have indicated an involvement of the immune system in the pathogenesis of mood disorders, and showed their correlation with altered levels of inflammatory markers and energy metabolism. Previous reports, including meta-analyses, also suggested the role of microglia activation in the M1 polarized macrophages, reflecting the pro-inflammatory phenotype. Lithium is an effective mood stabilizer used to treat both manic and depressive episodes in bipolar disorder, and as an augmentation of the antidepressant treatment of depression with a multidimensional mode of action. This review aims to summarize the molecular studies regarding inflammation, microglia activation and energy metabolism changes in mood disorders. We also aimed to outline the impact of lithium on these changes and discuss its immunomodulatory effect in mood disorders.

Effects of psychoactive drugs on cellular bioenergetic pathways

OBJECTIVES

To investigate the actions of lithium, valproate, lamotrigine and quetiapine on bioenergetic pathways in cultured NT2-N neuronal-like cells and C8-B4 microglial cells.

METHODS

NT2-N and C8-B4 cells were cultured and treated with lithium (2.5 mM), valproate (0.5 mM), quetiapine (0.05 mM) or lamotrigine (0.05 mM) for 24 hours. Gene expression and the mitochondrial bioenergetic profile were measured in both cell lines.

RESULTS

In NT2-N cells, valproate increased oxidative phosphorylation (OXPHOS) gene expression, mitochondrial uncoupling and maximal respiratory capacity, while quetiapine decreased OXPHOS gene expression and respiration linked to ATP turnover, as well as decreasing the expression of genes in the citric acid cycle. Lamotrigine decreased OXPHOS gene expression but had no effect on respiration, while lithium reduced the expression of genes in the citric acid cycle. In C8-B4 cells, valproate and lithium increased OXPHOS gene expression, and valproate increased basal respiratory rate and maximal and spare respiratory capacities. In contrast, quetiapine significantly reduced basal respiratory rate and maximal and spare respiratory capacities.

CONCLUSIONS

Overall our data suggest that some drugs used to treat neuropsychiatric and affective disorders have actions on a range of cellular bioenergetic processes, which could impact their effects in patients.