Depressive behaviour in children diagnosed with a mitochondrial disorder

Psychosocial experiences are associated with human brain mitochondrial biology

Psychosocial experiences affect brain health and aging trajectories, but the molecular pathways underlying these associations remain unclear. Normal brain function relies on energy transformation by mitochondria oxidative phosphorylation (OxPhos). Two main lines of evidence position mitochondria both as targets and drivers of psychosocial experiences. On the one hand, chronic stress exposure and mood states may alter multiple aspects of mitochondrial biology; on the other hand, functional variations in mitochondrial OxPhos capacity may alter social behavior, stress reactivity, and mood. But are psychosocial exposures and subjective experiences linked to mitochondrial biology in the human brain? By combining longitudinal antemortem assessments of psychosocial factors with postmortem brain (dorsolateral prefrontal cortex) proteomics in older adults, we find that higher well-being is linked to greater abundance of the mitochondrial OxPhos machinery, whereas higher negative mood is linked to lower OxPhos protein content. Combined, positive and negative psychosocial factors explained 18 to 25% of the variance in the abundance of OxPhos complex I, the primary biochemical entry point that energizes brain mitochondria. Moreover, interrogating mitochondrial psychobiological associations in specific neuronal and nonneuronal brain cells with single-nucleus RNA sequencing (RNA-seq) revealed strong cell-type-specific associations for positive psychosocial experiences and mitochondria in glia but opposite associations in neurons. As a result, these "mind-mitochondria" associations were masked in bulk RNA-seq, highlighting the likely underestimation of true psychobiological effect sizes in bulk brain tissues. Thus, self-reported psychosocial experiences are linked to human brain mitochondrial phenotypes.

Heat stroke-induced cerebral cortex nerve injury by mitochondrial dysfunction: A comprehensive multi-omics profiling analysis

In recent years, global warming has led to frequent instances of extremely high temperatures during summer, arousing significant concern about the adverse effects of high temperature. Among these, heat stroke is the most serious, which has detrimental effects on the all organs of human body, especially on brain. However, the comprehensive pathogenesis leading to brain damage remains unclear. In this study, we constructed a mouse model of heat stroke and conducted multi-omics profiling to identify relevant pathogenesis induced by heat stroke. The mice were placed in a constant temperature chamber at 42 °C with a humidity of 50 %, and the criteria for success in modeling were that the rectal temperature reached 42 °C and that the mice were trembling. Then the mice were immediately taken out for further experiments. Firstly, we conducted cFos protein localization and identified the cerebral cortex, especially the anterior cingulate cortex as the region exhibiting the most pronounced damage. Secondly, we performed metabolomics, transcriptomics, and proteomics analysis on cerebral cortex. This multi-omics investigation unveiled noteworthy alterations in proteins and metabolites within pathways associated with neurotransmitter systems, heatstroke-induced mitochondrial dysfunction, encompassing histidine and pentose phosphate metabolic pathways, as well as oxidative stress. In addition, the cerebral cortex exhibited pronounced Reactive Oxygen Species (ROS) production, alongside significant downregulation of the mitochondrial outer membrane protein Tomm40 and mitochondrial permeability transition pore, implicating cerebral cortex mitochondrial dysfunction as the primary instigator of neural impairment. This study marks a significant milestone as the first to employ multi-omics analysis in exploring the molecular mechanisms underlying heat stroke-induced damage in cerebral cortex neurons. It comprehensively identifies all potentially impacted pathways by heat stroke, laying a solid foundation for ensuing research endeavors. Consequently, this study introduces a fresh angle to clinical approaches in heatstroke prevention and treatment, as well as establishes an innovative groundwork for shaping future-forward environmental policies.

Mitochondrial and Cellular Function in Fibroblasts, Induced Neurons, and Astrocytes Derived from Case Study Patients: Insights into Major Depression as a Mitochondria-Associated Disease

The link between mitochondria and major depressive disorder (MDD) is increasingly evident, underscored both by mitochondria's involvement in many mechanisms identified in depression and the high prevalence of MDD in individuals with mitochondrial disorders. Mitochondrial functions and energy metabolism are increasingly considered to be involved in MDD's pathogenesis. This study focused on cellular and mitochondrial (dys)function in two atypical cases: an antidepressant non-responding MDD patient ("Non-R") and another with an unexplained mitochondrial disorder ("Mito"). Skin biopsies from these patients and controls were used to generate various cell types, including astrocytes and neurons, and cellular and mitochondrial functions were analyzed. Similarities were observed between the Mito patient and a broader MDD cohort, including decreased respiration and mitochondrial function. Conversely, the Non-R patient exhibited increased respiratory rates, mitochondrial calcium, and resting membrane potential. In conclusion, the Non-R patient's data offered a new perspective on MDD, suggesting a detrimental imbalance in mitochondrial and cellular processes, rather than simply reduced functions. Meanwhile, the Mito patient's data revealed the extensive effects of mitochondrial dysfunctions on cellular functions, potentially highlighting new MDD-associated impairments. Together, these case studies enhance our comprehension of MDD.

Ndufs4 KO mice: A model to study comorbid mood disorders associated with mitochondrial dysfunction

The Ndufs4 knockout (KO) mouse is a validated and robust preclinical model of mitochondrial diseases (specifically Leigh syndrome), that displays a narrow window of relative phenotypical normality, despite its inherent mitochondrial complex I dysfunction and severe phenotype. Preclinical observations related to psychiatric comorbidities that arise in patients with mitochondrial diseases and indeed in Leigh syndrome are, however, yet to be investigated in this model. Strengthening this narrative is the fact that major depression and bipolar disorder are known to present with deficits in mitochondrial function. We therefore screened the behavioural profile of male and female Ndufs4 KO mice (relative to heterozygous; HET and wildtype; WT mice) between postnatal days 28 and 35 for locomotor, depressive- and anxiety-like alterations and linked it with selected brain biomarkers, viz. serotonin, kynurenine, and redox status in brain areas relevant to psychiatric pathologies (i.e., prefrontal cortex, hippocampus, and striatum). The Ndufs4 KO mice initially displayed depressive-like behaviour in the tail suspension test on PND31 but not on PND35 in the forced swim test. In the mirror box test, increased risk resilience was observed. Serotonin levels of KO mice, compared to HET controls, were increased on PND36, together with increased tryptophan to serotonin and kynurenine turnover. Kynurenine to kynurenic acid turnover was however decreased, while reduced versus oxidized glutathione ratio (GSH/GSSG) was increased. When considering the comorbid psychiatric traits of patients with mitochondrial disorders, this work elaborates on the neuropsychiatric profile of the Ndufs KO mouse. Secondly, despite locomotor differences, Ndufs4 KO mice present with a behavioural profile not unlike rodent models of bipolar disorder, namely variable mood states and risk-taking behaviour. The model may elucidate the bio-energetic mechanisms underlying mood disorders, especially in the presence of mitochondrial disease. Studies are however required to further validate the model's translational relevance.

Mitochondrial fission drives neuronal metabolic burden to promote stress susceptibility in male mice

Neurons are particularly susceptible to energy fluctuations in response to stress. Mitochondrial fission is highly regulated to generate ATP via oxidative phosphorylation; however, the role of a regulator of mitochondrial fission in neuronal energy metabolism and synaptic efficacy under chronic stress remains elusive. Here, we show that chronic stress promotes mitochondrial fission in the medial prefrontal cortex via activating dynamin-related protein 1 (Drp1), resulting in mitochondrial dysfunction in male mice. Both pharmacological inhibition and genetic reduction of Drp1 ameliorates the deficit of excitatory synaptic transmission and stress-related depressive-like behavior. In addition, enhancing Drp1 fission promotes stress susceptibility, which is alleviated by coenzyme Q10, which potentiates mitochondrial ATP production. Together, our findings unmask the role of Drp1-dependent mitochondrial fission in the deficits of neuronal metabolic burden and depressive-like behavior and provides medication basis for metabolism-related emotional disorders.

Targeting the ferroptosis crosstalk: novel alternative strategies for the treatment of major depressive disorder

Depression is a major contributor to poor global health and disability, with a recently increasing incidence. Although drug therapy is commonly used to treat depression, conventional antidepressant drugs have several disadvantages, including slow onset, low response rates and severe adverse effects. Therefore, developing effective therapies for depression remains challenging. Although various aetiological theories of depression exist, the underlying mechanisms of depression are complex, and further research is crucial. Moreover, oxidative stress (OS)-induced lipid peroxidation has been demonstrated to trigger ferroptosis. Both OS and ferroptosis are pivotal mechanisms implicated in the pathogenesis of neurological disorders, and investigation of the mediators involved in these processes has emerged as a prominent and active research direction. One previous study revealed that regulatory proteins involved in ferroptosis are implicated in the pathogenesis of depression, and antidepressant drugs could reverse depressive symptoms by inhibiting ferroptosis in vivo, suggesting an important role of ferroptosis in the pathogenesis of depression. Hence, our current comprehensive review offers an up-to-date perspective on the intricate mechanisms involved, specifically concerning ferroptosis and OS in the context of depression, along with promising prospects for using molecular mediators to target ferroptosis. We delineate the key targets of molecular mediators involved in OS and ferroptosis implicated in depression, most notably reactive oxygen species and iron overload. Considering the pivotal role of OS-induced ferroptosis in the pathogenesis of neurological disorders, delving deeper into the underlying subsequent mechanisms will contribute significantly to the identification of novel therapeutic targets for depression.

Targeting mitophagy for depression amelioration: a novel therapeutic strategy

Major depressive disorder is a global psychiatric condition characterized by persistent low mood and anhedonia, which seriously jeopardizes the physical and mental well-being of affected individuals. While various hypotheses have been proposed to explicate the etiology of depression, the precise pathogenesis and effective treatment of this disorder remain elusive. Mitochondria, as the primary organelles responsible for cellular energy production, possess the ability to meet the essential energy demands of the brain. Research indicated that the accumulation of damaged mitochondria is associated with the onset of depression. Mitophagy, a type of cellular autophagy, specifically targets and removes excess or damaged mitochondria. Emerging evidence demonstrated that mitophagy dysfunction was involved in the progression of depression, and several pharmacological interventions that stimulating mitophagy exerted excellent antidepressant actions. We provided an overview of updated advancements on the regulatory mechanism of mitophagy and the mitophagy abnormality in depressed patients and animals, as well as in cell models of depression. Meanwhile, various therapeutic strategies to restore mitophagy for depression alleviation were also discussed in this review.

Psychiatric manifestations of inborn errors of metabolism: A systematic review

Inborn errors of metabolism (IEMs) are characterized by deficits in metabolic enzymes as a result of an inherited disease, leading to the accumulation or decreased excretion of proteins, carbohydrates and lipids. Although IEMs are often diagnosed during childhood, adolescent and adult onset variants may be accompanied by less somatic and more psychiatric manifestations, which often hampers recognition by psychiatrists of the distinction between a primary and secondary psychiatric disorder. To help clinicians in the diagnostic process, we aimed to provide an overview of psychiatric manifestations in IEMs. Our literature search yielded 4380 records in total, of which 88 studies were included in the qualitative synthesis. Reported psychiatric disorders in adolescent and adult IEMs included depression, anxiety disorder, psychosis, attention deficit hyperactivity disorder, autism spectrum disorder, bipolar disorder and obsessive-compulsive disorder as assessed by semi-structured diagnostic interviews and validated questionnaires. A diagnostic screener and multidisciplinary IEM clinics are proposed to help clinicians during the diagnostic process, to prevent diagnostic delay and to raise awareness of the psychiatric manifestations among IEMs.

Agomelatine, Ketamine and Vortioxetine Attenuate Energy Cell Metabolism-In Vitro Study

This determination of the mitochondrial effect of pharmacologically different antidepressants (agomelatine, ketamine and vortioxetine) was evaluated and quantified in vitro in pig brain-isolated mitochondria. We measured the activity of mitochondrial complexes, citrate synthase, malate dehydrogenase and monoamine oxidase, and the mitochondrial respiratory rate. Total hydrogen peroxide production and ATP production were assayed. The most potent inhibitor of all mitochondrial complexes and complex I-linked respiration was vortioxetine. Agomelatine and ketamine inhibited only complex IV activity. None of the drugs affected complex II-linked respiration, citrate synthase or malate dehydrogenase activity. Hydrogen peroxide production was mildly increased by agomelatine, which might contribute to increased oxidative damage and adverse effects at high drug concentrations. Vortioxetine significantly reduced hydrogen peroxide concentrations, which might suggest antioxidant mechanism activation. All tested antidepressants were partial MAO-A inhibitors, which might contribute to their antidepressant effect. We observed vortioxetine-induced MAO-B inhibition, which might be linked to decreased hydrogen peroxide formation and contribute to its procognitive and neuroprotective effects. Mitochondrial dysfunction could be linked to the adverse effects of vortioxetine, as vortioxetine is the most potent inhibitor of mitochondrial complexes and complex I-linked respiration. Clarifying the molecular interaction between drugs and mitochondria is important to fully understand their mechanism of action and the connection between their mechanisms and their therapeutic and/or adverse effects.

Cognitive functioning and mental health in children with a primary mitochondrial disease

Background

Studies regarding cognitive and mental health functioning in children with mitochondrial disease (MD) are scarce, while both are important issues given their impact on QoL. Knowledge on these aspects of functioning and its relationship with disease parameters is essential to gather more insight in working mechanisms and provide recommendations for future research and patientcare. The aim of this study was to map the cognitive functioning and mental health in children with MD in relation to disease specific factors.

Methods

Pediatric patients (< 18 year) with a genetically confirmed MD were included. Demographic and disease specific factors (International Paediatric Mitochondrial Disease Scale) were assessed, as well as cognitive functioning (intelligence, attention, working memory (WM)), and mental health (psychological functioning and quality of life). Individual patient data was described.

Results

Thirty-three children with MD were included. Intellectual functioning ranged from a clinically low IQ (36% of the patients, N = 12/33) to an average or above average IQ (39%, N = 13/33). A higher verbal versus performance IQ was observed (36% N = 5/14), a lower processing speed (43%, N = 6/14), attentional problems (50%, N = 7/14), and verbal WM problems (11%, N = 2/18). Regarding mental health, general behavioral problems were reported (45%, N = 10/22), and on subscale level, attention problems (45%, N = 10), withdrawn/depressed (36%, N = 8/22) and anxious/depressed behavior (14%, N = 3/22). Furthermore, QoL impairments were reported (42%, N = 5/12). The specific intelligence profiles, cognitive impairments, behavioral problems and QoL impairments occurred in every intelligence subgroup. Children with an average or above general intellectual functioning had a generally lower and less variability in IPMDS scores, less frequently epilepsy, vision and hearing problems, and a relatively later age of onset, as compared to patients with a clinically low intellectual functioning.

Conclusions

Despite considerable heterogeneity, overall results showed a high rate of impairments in both cognitive and mental health functioning. Also in children with an average or above level of intellectual functioning, specific cognitive impairments were observed. Children with a clinically low intellectual functioning more often had disease related impairments compared to children with a higher intellectual functioning. The importance of structural assessment of cognitive functioning and mental health is warranted, also in children with mild disease related symptoms.

Mitochondrial dysfunction in psychiatric disorders

Psychiatric disorders are a heterogeneous group of mental disorders with abnormal mental or behavioral patterns, which severely distress or disable affected individuals and can have a grave socioeconomic burden. Growing evidence indicates that mitochondrial function plays an important role in developing psychiatric disorders. This review discusses the neuropsychiatric consequences of mitochondrial abnormalities in both animal models and patients. We also discuss recent studies associated with compromised mitochondrial function in various psychiatric disorders, such as schizophrenia (SCZ), major depressive disorder (MD), and bipolar disorders (BD). These studies employ various approaches including postmortem studies, imaging studies, genetic studies, and induced pluripotent stem cells (iPSCs) studies. We also summarize the evidence from animal models and clinical trials to support mitochondrial function as a potential therapeutic target to treat various psychiatric disorders. This review will contribute to furthering our understanding of the metabolic etiology of various psychiatric disorders, and help guide the development of optimal therapies.

Recent Advances in Mitochondrial Diseases: from Molecular Insights to Therapeutic Perspectives

Mitochondria are double-membraned cytoplasmic organelles that are responsible for the production of energy in eukaryotic cells. The process is completed through oxidative phosphorylation (OXPHOS) by the respiratory chain (RC) in mitochondria. Thousands of mitochondria may be present in each cell, depending on the function of that cell. Primary mitochondria disorder (PMD) is a clinically heterogeneous disease associated with germline mutations in mitochondrial DNA (mtDNA) and/or nuclear DNA (nDNA) genes, and impairs mitochondrial structure and function. Mitochondrial dysfunction can be detected in early childhood and may be severe, progressive and often multi-systemic, involving a wide range of organs. Understanding epigenetic factors and pathways mutations can help pave the way for developing an effective cure. However, the lack of information about the disease (including age of onset, symptoms, clinical phenotype, morbidity and mortality), the limits of current preclinical models and the wide range of phenotypic presentations hamper the development of effective medicines. Although new therapeutic approaches have been introduced with encouraging preclinical and clinical outcomes, there is no definitive cure for PMD. This review highlights recent advances, particularly in children, in terms of etiology, pathophysiology, clinical diagnosis, molecular pathways and epigenetic alterations. Current therapeutic approaches, future advances and proposed new therapeutic plans will also be discussed.

Neuropsychological Features of Children and Adolescents With Mitochondrial Disorders: A Descriptive Case Series

BACKGROUND

Mitochondrial disorders (MD) are metabolic diseases related to genetic mutations in mitochondrial DNA and nuclear DNA that cause dysfunction of the mitochondrial respiratory chain. Cognitive impairment and psychiatric symptoms are frequently associated with MD in the adult population. The aim of this study is to describe the neuropsychological profile in children and adolescents with MD.

METHODS

We prospectively recruited a sample of 12 children and adolescents between February 2019 and February 2020 in the Reference Center for Mitochondrial Disorders of Angers (France). Participants and their parents completed an anamnestic form describing socio-demographic data and completed the WISC-V (Wechsler Intelligence Scale for Children, 5th edition) and the Parent and Teacher forms of the BRIEF (Behavior Rating Inventory of Executive Function).

RESULTS

In our sample, the mean IQ (Intellectual Quotient) score was 87.3 ± 25.3. The score ranged from 52 to 120. Concerning executive functions, a significant global clinical complaint was found for parents (six times more than normal) and to a lesser extent, for teachers (among 3 to 4 times more). Levels of intelligence and executive functioning were globally linked in our cohort but dissociation remains a possibility.

CONCLUSION

The results of this study show that MD can be associated to neuropsychological disorders in children and adolescents, especially regarding the intelligence quotient and the executive function. Our study also highlights the need for regular neuropsychological assessments in individuals with MD and developing brains, such as children and adolescents.

Psychiatric Symptoms of Children and Adolescents With Mitochondrial Disorders: A Descriptive Case Series

Background: Mitochondrial disorders (MD) are a group of clinically heterogeneous genetic disorders resulting from dysfunction of the mitochondrial respiratory chain. Cognitive impairment is a common feature in adults with MD and psychiatric symptoms are associated with MD in up to 70% of the adult population. The aim of this study is to describe the psychiatric profile in children and adolescents with MD by focusing on the description of psychiatric symptoms. Methods: A cohort of 12 children and adolescents was prospectively recruited between February 2019 and February 2020 in the Reference Center for Mitochondrial Disorders of Angers (France). Participants and their parents completed an anamnestic form to provide socio-demographic data and completed the Global Assessment of Functioning scale, the Brief Psychiatric Rating Scale, the Child Depression Inventory, the Revised Children's Manifest Anxiety Scale, and the Conner's Rating Scale to evaluate the inattention/hyperactivity symptoms as well as the Quality of Life scale. Results: Four children (33.3%) were diagnosed with depressive symptoms. With regarding to anxiety, 6 children (50%) reported anxiety issues during the psychiatric interview and 3 children (25%) were suffering from anxiety according to the RCMAS scale. Compared to other children with chronic illnesses, the individuals in our cohort reported a lower overall quality of life score and lower scores in physical and social subscales. Conclusion: Our study shows that MD can lead to psychiatric disorders in children and adolescents, in particular anxiety and depression, as well as poor quality of life. This highlights the need for regular psychiatric assessments in individuals with developing brains, such as children and adolescents. We do not, however, have data regarding the neuropsychological profile of this population.

Stress and circulating cell-free mitochondrial DNA: A systematic review of human studies, physiological considerations, and technical recommendations

Cell-free mitochondrial DNA (cf-mtDNA) is a marker of inflammatory disease and a predictor of mortality, but little is known about cf-mtDNA in relation to psychobiology. A systematic review of the literature reveals that blood cf-mtDNA varies in response to common real-world stressors including psychopathology, acute psychological stress, and exercise. Moreover, cf-mtDNA is inducible within minutes and exhibits high intra-individual day-to-day variation, highlighting the dynamic regulation of cf-mtDNA levels. We discuss current knowledge on the mechanisms of cf-mtDNA release, its forms of transport ("cell-free" does not mean "membrane-free"), potential physiological functions, putative cellular and neuroendocrine triggers, and factors that may contribute to cf-mtDNA removal from the circulation. A review of in vitro, pre-clinical, and clinical studies shows conflicting results around the dogma that physiological forms of cf-mtDNA are pro-inflammatory, opening the possibility of other physiological functions, including the cell-to-cell transfer of whole mitochondria. Finally, to enhance the reproducibility and biological interpretation of human cf-mtDNA research, we propose guidelines for blood collection, cf-mtDNA isolation, quantification, and reporting standards, which can promote concerted advances by the community. Defining the mechanistic basis for cf-mtDNA signaling is an opportunity to elucidate the role of mitochondria in brain-body interactions and psychopathology.

Early-adolescent antibiotic exposure results in mitochondrial and behavioral deficits in adult male mice

Exposure to antibiotic treatment has been associated with increased vulnerability to various psychiatric disorders. However, a research gap exists in understanding how adolescent antibiotic therapy affects behavior and cognition. Many antibiotics that target bacterial translation may also affect mitochondrial translation resulting in impaired mitochondrial function. The brain is one of the most metabolically active organs, and hence is the most vulnerable to impaired mitochondrial function. We hypothesized that exposure to antibiotics during early adolescence would directly affect brain mitochondrial function, and result in altered behavior and cognition. We administered amoxicillin, chloramphenicol, or gentamicin in the drinking water to young adolescent male wild-type mice. Next, we assayed mitochondrial oxidative phosphorylation complex activities in the cerebral cortex, performed behavioral screening and targeted mass spectrometry-based acylcarnitine profiling in the cerebral cortex. We found that mice exposed to chloramphenicol showed increased repetitive and compulsive-like behavior in the marble burying test, an accurate and sensitive assay of anxiety, concomitant with decreased mitochondrial complex IV activity. Our results suggest that only adolescent chloramphenicol exposure leads to impaired brain mitochondrial complex IV function, and could therefore be a candidate driver event for increased anxiety-like and repetitive, compulsive-like behaviors.

Effect of neuropsychiatric medications on mitochondrial function: For better or for worse

Individuals with mitochondrial disease often present with psychopathological comorbidity, and mitochondrial dysfunction has been proposed as the underlying pathobiology in various psychiatric disorders. Several studies have suggested that medications used to treat neuropsychiatric disorders could directly influence mitochondrial function. This review provides a comprehensive overview of the effect of these medications on mitochondrial function. We collected preclinical information on six major groups of antidepressants and other neuropsychiatric medications and found that the majority of these medications either positively influenced mitochondrial function or showed mixed effects. Only amitriptyline, escitalopram, and haloperidol were identified as having exclusively adverse effects on mitochondrial function. In the absence of formal clinical trials, and until such trials are completed, the data from preclinical studies reported and discussed here could inform medication prescribing practices for individuals with psychopathology and impaired mitochondrial function in the underlying pathology.

Mitochondrial dysfunction as a critical event in the pathophysiology of bipolar disorder

The understanding of the pathophysiology of bipolar disorder (BD) remains modest, despite recent advances in neurobiological research. The mitochondrial dysfunction hypothesis of bipolar disorder has been corroborated by several studies involving postmortem brain analysis, neuroimaging, and specific biomarkers in both rodent models and humans. Evidence suggests that BD might be related to abnormal mitochondrial morphology and dynamics, neuroimmune dysfunction, and atypical mitochondrial metabolism and oxidative stress pathways. Mitochondrial dysfunction in mood disorders is also associated with abnormal Ca2+ levels, glutamate excitotoxicity, an imbalance between pro- and antiapoptotic proteins towards apoptosis, abnormal gene expression of electron transport chain complexes, and decreased ATP synthesis. This paper aims to review and discuss the implications of mitochondrial dysfunction in BD etiology and to explore mitochondria as a potential target for novel therapeutic agents.

Cognitive functioning and mental health in mitochondrial disease: A systematic scoping review

Mitochondrial diseases (MDs) are rare, heterogeneous, hereditary and progressive in nature. In addition to the serious somatic symptoms, patients with MD also experience problems regarding their cognitive functioning and mental health. We provide an overview of all published studies reporting on any aspect of cognitive functioning and/or mental health in patients with MD and their relatives. A total of 58 research articles and 45 case studies were included and critically reviewed. Cognitive impairments in multiple domains were reported. Mental disorders were frequently reported, especially depression and anxiety. Furthermore, most studies showed impairments in self-reported psychological functioning and high prevalence of mental health problems in (matrilineal) relatives. The included studies showed heterogeneity regarding patient samples, measurement instruments and reference groups, making comparisons cautious. Results highlight a high prevalence of cognitive impairments and mental disorders in patients with MD. Recommendations for further research as well as tailored patientcare with standardized follow-up are provided. Key gaps in the literature are identified, of which studies on natural history are of highest importance.

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.

Chronic fluoxetine or ketamine treatment differentially affects brain energy homeostasis which is not exacerbated in mice with trait suboptimal mitochondrial function

Antidepressants have been shown to influence mitochondrial function directly, and suboptimal mitochondrial function (SMF) has been implicated in complex psychiatric disorders. In the current study, we used a mouse model for trait SMF to test the hypothesis that chronic fluoxetine treatment in mice subjected to chronic stress would negatively impact brain bioenergetics, a response that would be more pronounced in mice with trait SMF. In contrast, we hypothesized that chronic ketamine treatment would positively impact mitochondrial function in both WT and mice with SMF. We used an animal model for trait SMF, the Ndufs4^GT/GT mice, which exhibit 25% lower mitochondrial complex I activity. In addition to antidepressant treatment, mice were subjected to chronic unpredictable stress (CUS). This paradigm is widely used to model complex behaviours expressed in various psychiatric disorders. We assayed several physiological indices as proxies for the impact of chronic stress and antidepressant treatment. Furthermore, we measured brain mitochondrial complex activities using clinically validated assays as well as established metabolic signatures using targeted metabolomics. As hypothesized, we found evidence that chronic fluoxetine treatment negatively impacted brain bioenergetics. This phenotype was, however, not further exacerbated in mice with trait SMF. Ketamine did not have a significant influence on brain mitochondrial function in either genotype. Here we report that trait SMF could be a moderator for an individual's response to antidepressant treatment. Based on these results, we propose that in individuals with SMF and comorbid psychopathology, fluoxetine should be avoided, whereas ketamine could be a safer choice of treatment.

Impaired mitochondrial complex I function as a candidate driver in the biological stress response and a concomitant stress-induced brain metabolic reprogramming in male mice

Mitochondria play a critical role in bioenergetics, enabling stress adaptation, and therefore, are central in biological stress responses and stress-related complex psychopathologies. To investigate the effect of mitochondrial dysfunction on the stress response and the impact on various biological domains linked to the pathobiology of depression, a novel mouse model was created. These mice harbor a gene trap in the first intron of the Ndufs4 gene (Ndufs4GT/GT mice), encoding the NDUFS4 protein, a structural component of complex I (CI), the first enzyme of the mitochondrial electron transport chain. We performed a comprehensive behavioral screening with a broad range of behavioral, physiological, and endocrine markers, high-resolution ex vivo brain imaging, brain immunohistochemistry, and multi-platform targeted mass spectrometry-based metabolomics. Ndufs4GT/GT mice presented with a 25% reduction of CI activity in the hippocampus, resulting in a relatively mild phenotype of reduced body weight, increased physical activity, decreased neurogenesis and neuroinflammation compared to WT littermates. Brain metabolite profiling revealed characteristic biosignatures discriminating Ndufs4GT/GT from WT mice. Specifically, we observed a reversed TCA cycle flux and rewiring of amino acid metabolism in the prefrontal cortex. Next, exposing mice to chronic variable stress (a model for depression-like behavior), we found that Ndufs4GT/GT mice showed altered stress response and coping strategies with a robust stress-associated reprogramming of amino acid metabolism. Our data suggest that impaired mitochondrial CI function is a candidate driver for altered stress reactivity and stress-induced brain metabolic reprogramming. These changes result in unique phenomic and metabolomic signatures distinguishing groups based on their mitochondrial genotype.

Depression-like behaviors are accompanied by disrupted mitochondrial energy metabolism in chronic corticosterone-induced mice

Stress exerts its negative effects by interference with mitochondrial energy production in rodents, and is able to impair mitochondrial bioenergetics. However, the underlying mechanism that stress hormone impacts depression-like behaviors and mitochondrial energy metabolism is still not well understood. Here, we investigated the changes of depression-like behaviors and mitochondrial energy metabolism induced by chronic corticosterone (CORT). The results showed that after treatment with CORT for 6 weeks, mice displayed depression-like behaviors, which were identified by tail suspension test, forced swimming test and open field test. Then, the livers were isolated and tested by RNA sequencing and metabolome analysis. RNA sequencing showed 354 up-regulated genes and 284 down-regulated genes, and metabolome analysis revealed 280 metabolites with increased abundances and 193 metabolites with reduced abundances in the liver of mice after CORT, which were closely associated with lipid metabolism and oxidative phosphorylation in mitochondria. Based on these findings, the changes of mitochondrial energy metabolism were investigated, and we revealed that CORT condition inhibited glycolysis and fatty acid degradation pathway, and activated synthesis of triacylglycerol, leading to the reduced levels of acetyl-CoA and attenuated TCA cycle. Also, the pathways of NAD⁺ synthesis were inhibited, resulting in the reduced activity of sirtuin 3 (SIRT3). Thus, all of these observations disrupted the function of mitochondria, and led to the decrease of ATP production. Our findings uncover a novel mechanism of stress on depression-like behaviors and mitochondrial energy metabolism in rodents.

Psychological functioning in children suspected for mitochondrial disease: the need for care

Background

Mitochondrial diseases (MD) are generally serious and progressive, inherited metabolic diseases. There is a high comorbidity of anxiety and depression and limitations in daily functioning. The complexity and duration of the diagnostic process and lack of knowledge about prognosis leads to uncertainty. In this study, we investigated the psychological well-being of children who are suspected for MD and their parents.

Methods

In total 122 children suspected for MD and their parents, received questionnaires as part of standard clinical investigation.

Results

Parent proxy report revealed a lower quality of life (QoL) compared to norms and even more physical problems compared to chronically ill patients. They also reported more behavioral problems in general and more internalizing problems compared to the norms. Most frequent reported somatic complaints were tiredness and pain. Parents did not report enhanced levels of stress regarding parenting and experienced sufficient social support. At the end of the diagnostic process, 5.7% of the children received the genetically confirmed diagnosis of MD, 26% showed non-conclusive abnormalities in the muscle biopsy, 54% did not receive any diagnosis, and the remaining received other diagnoses. Strikingly, children without a diagnosis showed equally QoL and behavioral problems as children with a diagnosis, and even more internalizing problems.

Conclusions

This study highlights the psychological concerns of children with a suspicion of MD. It is important to realize that as well as children with a confirmed diagnosis, children without a diagnosis are vulnerable since explanation for their complaints is still lacking.

Nicotinamide mononucleotide ameliorates the depression-like behaviors and is associated with attenuating the disruption of mitochondrial bioenergetics in depressed mice

BACKGROUND

Nicotinamide mononucleotide (NMN) has been shown to stimulate oxidative phosphorylation in mitochondria and to improve various pathologies in patients and mouse disease models. However, whether NMN mediates mitochondrial energy production and its mechanism of action in depressed animals remain unclear.

METHODS

Mice were subcutaneously injected with corticosterone (CORT; 20 mg/kg) each day for 6 weeks, while another group was given an additional dose of NMN (300 mg/kg) by oral gavage in the last 2 weeks. Then, transcriptome analyses, metabolome analyses and transient gene knockdown in primary mouse cells were performed.

RESULTS

NMN administration alleviated depression-like behavior and the liver weight to body weight ratio in a mouse model of CORT-induced depression. Transcriptome and metabolome analyses revealed that in depressed mice, NMN reduced the mRNA expression of genes involved in fatty acid synthesis, stimulation of β-oxidation and glycolysis, and increased production of acetyl-coenzyme A for the tricarboxylic acid cycle. Importantly, NMN supplementation increased NAD⁺ levels to enhance sirtuin (SIRT)3 activity, thereby improving mitochondrial energy metabolism in the hippocampus and liver of CORT-treated mice. Sirt3knockdown in primary mouse astrocytes reversed the effect of NMN by inhibiting energy production, although it did not affect NAD⁺ synthesis LIMITATIONS: Group sample sizes were small, and only one type of primary mouse cell was used CONCLUSION: These results provide evidence for the beneficial role of NMN in energy production and suggest that therapeutic strategies that increase the level of NMN can be an effective treatment for depression.

Neuropsychological and Psychiatric Features of Children and Adolescents Affected With Mitochondrial Diseases: A Systematic Review

Mitochondrial diseases (MDs) are a group of clinically heterogeneous genetic disorders that arise as the result of dysfunctional mitochondria. Only few medical articles deal with neuropsychological or psychiatric aspects of MDs.

AIM

The present article aims to provide a systematic review of neuropsychological and psychiatric aspects of MDs.

METHODS

In order to identify all studies dealing with psychiatric and neuropsychological aspects of MDs in children and adolescents, we performed a search in the medical literature between April 2009 and April 2019 using PubMed, Cochrane, and Web of Science and we defined inclusion and exclusion criteria.

RESULTS

We found only seven studies that satisfy the inclusion requirements and criteria. The main psychiatric aspects reported in MDs were depressive and behavioral disorders. With regard to the neuropsychological aspects of MDs, developmental analyses showed an overall deterioration and developmental delay.

INTERPRETATION

Children and adolescents with MDs may present psychiatric symptoms and neuropsychological impairment. A more systematic investigation of psychiatric and neuropsychological features of MDs is needed to foster a better understanding of the phenotype of these diseases and their links with the genotype, which may have significant implications for the developmental trajectories of patients.

Proteomic profiling of the neurons in mice with depressive-like behavior induced by corticosterone and the regulation of berberine: pivotal sites of oxidative phosphorylation

Chronic corticosterone (CORT) stress is an anxiety and depression inducing factor that involves the dysfunction of glucocorticoid receptor (GR), brain-derived neurotrophic factor (BDNF), and neuronal plasticity. However, the regulation of proteomic profiles in neurons suffering CORT stress is remaining elusive. Thus, the proteomic profiles of mouse neuronal C17.2 stem cells were comprehensively investigated by TMT (tandem mass tag)-labeling quantitative proteomics. The quantitative proteomics conjugated gene ontology analysis revealed the inhibitory effect of CORT on the expression of mitochondrial oxidative phosphorylation-related proteins, which can be antagonized by berberine (BBR) treatment. In addition, animal studies showed that changes in mitochondria by CORT can affect neuropsychiatric activities and disturb the physiological functions of neurons via disordering mitochondrial oxidative phosphorylation. Thus, the mitochondrial energy metabolism can be considered as one of the major mechanism underlying CORT-mediated depression. Since CORT is important for depression after traumatic stress disorder, our study will shed light on the prevention and treatment of depression as well as posttraumatic stress disorder (PTSD).

Identification of diagnostic markers for major depressive disorder by cross-validation of data from whole blood samples

Background

Major depressive disorder (MDD) is a severe disease characterized by multiple pathological changes. However, there are no reliable diagnostic biomarkers for MDD. The aim of the current study was to investigate the gene network and biomarkers underlying the pathophysiology of MDD.

Methods

In this study, we conducted a comprehensive analysis of the mRNA expression profile of MDD using data from Gene Expression Omnibus (GEO). The MDD dataset (GSE98793) with 128 MDD and 64 control whole blood samples was divided randomly into two non-overlapping groups for cross-validated differential gene expression analysis. The gene ontology (GO) enrichment and gene set enrichment analysis (GSEA) were performed for annotation, visualization, and integrated discovery. Protein–protein interaction (PPI) network was constructed by STRING database and hub genes were identified by the CytoHubba plugin. The gene expression difference and the functional similarity of hub genes were investigated for further gene expression and function exploration. Moreover, the receiver operating characteristic curve was performed to verify the diagnostic value of the hub genes.

Results

We identified 761 differentially expressed genes closely related to MDD. The Venn diagram and GO analyses indicated that changes in MDD are mainly enriched in ribonucleoprotein complex biogenesis, antigen receptor-mediated signaling pathway, catalytic activity (acting on RNA), structural constituent of ribosome, mitochondrial matrix, and mitochondrial protein complex. The GSEA suggested that tumor necrosis factor signaling pathway, Toll-like receptor signaling pathway, apoptosis pathway, and NF-kappa B signaling pathway are all crucial in the development of MDD. A total of 20 hub genes were selected via the PPI network. Additionally, the identified hub genes were downregulated and show high functional similarity and diagnostic value in MDD.

Conclusions

Our findings may provide novel insight into the functional characteristics of MDD through integrative analysis of GEO data, and suggest potential biomarkers and therapeutic targets for MDD.

Link between depression and cardiovascular diseases due to epigenomics and proteomics: Focus on energy metabolism

Major depression is the most common mental disorder and a leading cause of years lived with disability. In addition to the burden attributed to depressive symptoms and reduced daily life functioning, people with major depression are at increased risk of premature mortality, particularly due to cardiovascular diseases. Several studies point to a bi-directional relation between major depression and cardiovascular diseases, thereby indicating that both diseases may share common pathophysiological pathways. These include lifestyle factors (e.g. physical activity, smoking behavior), dysfunctions of endocrine systems (e.g. hypothalamus-pituitary adrenal axis), and a dysbalance of pro- and anti-inflammatory factors. Furthermore, recent research point to the role of epigenomic and proteomic factors, that are reviewed here with a particular focus on the mitochondrial energy metabolism.

Biomarkers for major depressive and bipolar disorders using metabolomics: A systematic review

Major depressive disorder (MDD) and bipolar disorder (BD) lack robust biomarkers useful for screening purposes in a clinical setting. A systematic review of the literature was conducted on metabolomic studies of patients with MDD or BD through the use of analytical platforms such as in vivo brain imaging, mass spectrometry, and nuclear magnetic resonance. Our search identified a total of 7,590 articles, of which 266 articles remained for full-text revision. Overall, 249 metabolites were found to be dysregulated with 122 of these metabolites being reported in two or more of the studies included. A list of biomarkers for MDD and BD established from metabolites found to be abnormal, along with the number of studies supporting each metabolite and a comparison of which biological fluids they were reported in, is provided. Metabolic pathways that may be important in the pathophysiology of MDD and BD were identified and predominantly center on glutamatergic metabolism, energy metabolism, and neurotransmission. Using online drug registries, we also illustrate how metabolomics can facilitate the discovery of novel candidate drug targets.

Neurobiology and consequences of social isolation stress in animal model-A comprehensive review

The brain is a vital organ, susceptible to alterations under genetic influences and environmental experiences. Social isolation (SI) acts as a stressor which results in alterations in reactivity to stress, social behavior, function of neurochemical and neuroendocrine system, physiological, anatomical and behavioral changes in both animal and humans. During early stages of life, acute or chronic SIS has been proposed to show signs and symptoms of psychiatric and neurological disorders such as anxiety, depression, schizophrenia, epilepsy and memory loss. Exposure to social isolation stress induces a variety of endocrinological changes including the activation of hypothalamic-pituitary-adrenal (HPA) axis, culminating in the release of glucocorticoids (GCs), release of catecholamines, activation of the sympatho-adrenomedullary system, release of Oxytocin and vasopressin. In several regions of the central nervous system (CNS), SIS alters the level of neurotransmitter such as dopamine, serotonin, gamma aminobutyric acid (GABA), glutamate, nitrergic system and adrenaline as well as leads to alteration in receptor sensitivity of N-methyl-D-aspartate (NMDA) and opioid system. A change in the function of oxidative and nitrosative stress (O&NS) mediated mitochondrial dysfunction, inflammatory factors, neurotrophins and neurotrophicfactors (NTFs), early growth response transcription factor genes (Egr) and C-Fos expression are also involved as a pathophysiological consequences of SIS which induce neurological and psychiatric disorders.

Mitochondria and Mood: Mitochondrial Dysfunction as a Key Player in the Manifestation of Depression

Human and animal studies suggest an intriguing link between mitochondrial diseases and depression. Although depression has historically been linked to alterations in monoaminergic pharmacology and adult hippocampal neurogenesis, new data increasingly implicate broader forms of dampened plasticity, including plasticity within the cell. Mitochondria are the cellular powerhouse of eukaryotic cells, and they also regulate brain function through oxidative stress and apoptosis. In this paper, we make the case that mitochondrial dysfunction could play an important role in the pathophysiology of depression. Alterations in mitochondrial functions such as oxidative phosphorylation (OXPHOS) and membrane polarity, which increase oxidative stress and apoptosis, may precede the development of depressive symptoms. However, the data in relation to antidepressant drug effects are contradictory: some studies reveal they have no effect on mitochondrial function or even potentiate dysfunction, whereas other studies show more beneficial effects. Overall, the data suggest an intriguing link between mitochondrial function and depression that warrants further investigation. Mitochondria could be targeted in the development of novel antidepressant drugs, and specific forms of mitochondrial dysfunction could be identified as biomarkers to personalize treatment and aid in early diagnosis by differentiating between disorders with overlapping symptoms.

An investigation into closed-loop treatment of neurological disorders based on sensing mitochondrial dysfunction

Dynamic feedback based closed-loop medical devices offer a number of advantages for treatment of heterogeneous neurological conditions. Closed-loop devices integrate a level of neurobiological feedback, which allows for real-time adjustments to be made with the overarching aim of improving treatment efficacy and minimizing risks for adverse events. One target which has not been extensively explored as a potential feedback component in closed-loop therapies is mitochondrial function. Several neurodegenerative and psychiatric disorders including Parkinson's disease, Major Depressive disorder and Bipolar disorder have been linked to perturbations in the mitochondrial respiratory chain. This paper investigates the potential to monitor this mitochondrial function as a method of feedback for closed-loop neuromodulation treatments. A generic model of the closed-loop treatment is developed to describe the high-level functions of any system designed to control neural function based on mitochondrial response to stimulation, simplifying comparison and future meta-analysis. This model has four key functional components including: a sensor, signal manipulator, controller and effector. Each of these components are described and several potential technologies for each are investigated. While some of these candidate technologies are quite mature, there are still technological gaps remaining. The field of closed-loop medical devices is rapidly evolving, and whilst there is a lot of interest in this area, widespread adoption has not yet been achieved due to several remaining technological hurdles. However, the significant therapeutic benefits offered by this technology mean that this will be an active area for research for years to come.

Methylene blue and its analogues as antidepressant compounds

Methylene Blue (MB) is considered to have diverse medical applications and is a well-described treatment for methemoglobinemias and ifosfamide-induced encephalopathy. In recent years the focus has shifted to MB as an antimalarial agent and as a potential treatment for neurodegenerative disorders such as Alzheimer's disease. Of interest are reports that MB possesses antidepressant and anxiolytic activity in pre-clinical models and has shown promise in clinical trials for schizophrenia and bipolar disorder. MB is a noteworthy inhibitor of monoamine oxidase A (MAO-A), which is a well-established target for antidepressant action. MB is also recognized as a non-selective inhibitor of nitric oxide synthase (NOS) and guanylate cyclase. Dysfunction of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) cascade is strongly linked to the neurobiology of mood, anxiety and psychosis, while the inhibition of NOS and/or guanylate cyclase has been associated with an antidepressant response. This action of MB may contribute significantly to its psychotropic activity. However, these disorders are also characterised by mitochondrial dysfunction and redox imbalance. By acting as an alternative electron acceptor/donor MB restores mitochondrial function, improves neuronal energy production and inhibits the formation of superoxide, effects that also may contribute to its therapeutic activity. Using MB in depression co-morbid with neurodegenerative disorders, like Alzheimer's and Parkinson's disease, also represents a particularly relevant strategy. By considering their physicochemical and pharmacokinetic properties, analogues of MB may provide therapeutic potential as novel multi-target strategies in the treatment of depression. In addition, low MAO-A active analogues may provide equal or improved response with a lower risk of adverse effects.

The Energy Metabolism Dysfunction in Psychiatric Disorders Postmortem Brains: Focus on Proteomic Evidence

Psychiatric disorders represent a great medical and social challenge and people suffering from these conditions face many impairments regarding personal and professional life. In addition, a mental disorder will manifest itself in approximately one quarter of the world's population at some period of their life. Dysfunction in energy metabolism is one of the most consistent scientific findings associated with these disorders. With this is mind, this review compiled data on disturbances in energy metabolism found by proteomic analyses of postmortem brains collected from patients affected by the most prevalent psychiatric disorders: schizophrenia (SCZ), bipolar disorder (BPD), and major depressive disorder (MDD). We searched in the PubMed database to gather the studies and compiled all the differentially expressed proteins reported in each work. SCZ studies revealed 92 differentially expressed proteins related to energy metabolism, while 95 proteins were discovered in BPD, and 41 proteins in MDD. With the compiled data, it was possible to determine which proteins related to energy metabolism were found to be altered in all the disorders as well as which ones were altered exclusively in one of them. In conclusion, the information gathered in this work could contribute to a better understanding of the impaired metabolic mechanisms and hopefully bring insights into the underlying neuropathology of psychiatric disorders.

Molecular Mechanisms Underlying the Anti-depressant Effects of Resveratrol: a Review

Major depression is a public health problem, affecting 121 million people worldwide. Patients suffering from depression present high rates of morbidity, causing profound economic and social impacts. Furthermore, patients with depression present cognitive impairments, which could influence on treatment adherence and long-term outcomes. The pathophysiology of major depression is not completely understood yet but involves reduced levels of monoamine neurotransmitters, bioenergetics, and redox disturbances, as well as inflammation and neuronal loss. Treatment with anti-depressants provides a complete remission of symptoms in approximately 50% of patients with major depression. However, these drugs may cause side effects, as sedation and weight gain. In this context, there is increasing interest in studies focusing on the anti-depressant effects of natural compounds found in the diet. Resveratrol is a polyphenolic phytoalexin (3,4',5-trihydroxystilbene; C₁₄H₁₂O₃; MW 228.247 g/mol) and has been found in peanuts, berries, grapes, and wine and induces anti-oxidant, anti-inflammatory, and anti-apoptotic effects in several mammalian cell types. Resveratrol also elicits anti-depressant effects, as observed in experimental models using animals. Therefore, resveratrol may be viewed as a potential anti-depressant agent, as well as may serve as a model of molecule to be modified aiming to ameliorate depressive symptoms in humans. In the present review, we describe and discuss the anti-depressant effects of resveratrol focusing on the mechanism of action of this phytoalexin in different experimental models.

Mitochondrial Dysfunction in Depression

Abstract: Background

Depression is the most debilitating neuropsychiatric disorder with significant impact on socio-occupational and well being of individual. The exact pathophysiology of depression is still enigmatic though various theories have been put forwarded. There are evidences showing that mitochondrial dysfunction in various brain regions is associated with depression. Recent findings have sparked renewed appreciation for the role of mitochondria in many intracellular processes coupled to synaptic plasticity and cellular resilience. New insights in depression pathophysiology are revolving around the impairment of neuroplasticity. Mitochondria have potential role in ATP production, intracellular Ca²⁺ signalling to establish membrane stability, reactive oxygen species (ROS) balance and to execute the complex processes of neurotransmission and plasticity. So understanding the various concepts of mitochondrial dysfunction in pathogenesis of depression indubitably helps to generate novel and more targeted therapeutic approaches for depression treatment.

Objective

The review was aimed to give a comprehensive insight on role of mitochondrial dysfunction in depression.

Result

Targeting mitochondrial dysfunction and enhancing the mitochondrial functions might act as potential target for the treatment of depression.

Conclusion

Literature cited in this review highly supports the role of mitochondrial dysfunction in depression. As impairment in the mitochondrial functions lead to the generation of various insults that exaggerate the pathogenesis of depression. So, it is useful to study mitochondrial dysfunction in relation to mood disorders, synaptic plasticity, neurogenesis and enhancing the functions of mitochondria might show promiscuous effects in the treatment of depressed patients.

Neuropsychiatric Features in Primary Mitochondrial Disease

Mitochondrial diseases are a clinically heterogeneous group of disorders that ultimately result from dysfunction of the mitochondrial respiratory chain. There is some evidence to suggest that mitochondrial dysfunction plays a role in neuropsychiatric illness; however, the data are inconclusive. This article summarizes the available literature published in the area of neuropsychiatric manifestations in both children and adults with primary mitochondrial disease, with a focus on autism spectrum disorder in children and mood disorders and schizophrenia in adults.

Combined Metabolomics and Proteomics Analysis of Major Depression in an Animal Model: Perturbed Energy Metabolism in the Chronic Mild Stressed Rat Cerebellum

Major depressive disorder (MDD) is a highly prevalent, debilitating mental illness of importance for global health. However, its molecular pathophysiology remains poorly understood. Combined proteomics and metabolomics approaches should provide a comprehensive understanding of MDD's etiology. The present study reports novel "-omics" insights from a rodent model of MDD. Cerebellar samples from chronic mild stressed (CMS)-treated depressed rats and controls were compared with a focus on the differentially expressed proteins and metabolites using isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomics and gas chromotography/mass spectrometry (GC-MS) metabolomics techniques, respectively. The combined analyses found significant alterations associated with cerebellar energy metabolism, as indicated by (1) abnormal amino acid metabolism accompanied by corresponding metabolic enzymatic alterations and disturbed protein turnover, (2) increased glycolytic and tricarboxylic acid (TCA) cycle enzyme levels paralleled by changes in the concentrations of associated metabolites, and (3) perturbation of ATP biosynthesis through adenosine accompanied by perturbation of the mitochondrial respiratory chain. To the best of our knowledge, this study is the first to integrate proteomics and metabolomics analyses to examine the pathophysiological mechanism(s) underlying MDD in a CMS rodent model of depression. These results can offer important insights into the pathogenesis of MDD.

Mitochondrial function in the brain links anxiety with social subordination

Dominance hierarchies are integral aspects of social groups, yet whether personality traits may predispose individuals to a particular rank remains unclear. Here we show that trait anxiety directly influences social dominance in male outbred rats and identify an important mediating role for mitochondrial function in the nucleus accumbens. High-anxious animals that are prone to become subordinate during a social encounter with a low-anxious rat exhibit reduced mitochondrial complex I and II proteins and respiratory capacity as well as decreased ATP and increased ROS production in the nucleus accumbens. A causal link for these findings is indicated by pharmacological approaches. In a dyadic contest between anxiety-matched animals, microinfusion of specific mitochondrial complex I or II inhibitors into the nucleus accumbens reduced social rank, mimicking the low probability to become dominant observed in high-anxious animals. Conversely, intraaccumbal infusion of nicotinamide, an amide form of vitamin B3 known to enhance brain energy metabolism, prevented the development of a subordinate status in high-anxious individuals. We conclude that mitochondrial function in the nucleus accumbens is crucial for social hierarchy establishment and is critically involved in the low social competitiveness associated with high anxiety. Our findings highlight a key role for brain energy metabolism in social behavior and point to mitochondrial function in the nucleus accumbens as a potential marker and avenue of treatment for anxiety-related social disorders.

Causes of Death in Adults with Mitochondrial Disease

INTRODUCTION

Mitochondrial diseases are a clinically, biochemically and genetically heterogeneous group of disorders with a variable age of onset and rate of disease progression. It might therefore be expected that this variation be reflected in the age and cause of death. However, to date, little has been reported regarding the 'end-of-life' period and causes of death in mitochondrial disease patients. For some specific syndromes, the associated clinical problems might predict the cause of death, but for many patients, it remains difficult to provide an accurate prognosis.

AIMS

To describe a retrospective cohort of adult mitochondrial disease patients who had attended the NHS Highly Specialised Services for Rare Mitochondrial Diseases in Newcastle upon Tyne (UK), evaluate life expectancy and causes of death and assess the consequences for daily patient care.

METHODS

All deceased adult patients cared for at this centre over a period of 10 years were included in the study. Patient history, data on laboratory findings, biochemical investigations and genetic studies were analysed retrospectively.

RESULTS

A total of 30 adult mitochondrial patients died within the time period of the study. The main mitochondrial disease-related causes of death in this patient cohort were respiratory failure, cardiac failure and acute cerebral incidents such as seizures and strokes. In almost half of the patients, the cause of death remained unknown. Based on our study, we present recommendations regarding the care of patients with mitochondrial disease.

Risk factors for suicide in bipolar disorder: a systematic review

BACKGROUND

Bipolar disorder confers the highest risk of suicide among major psychological disorders. The risk factors associated with bipolar disorder and suicide exist and are relevant to clinicians and researchers.

OBJECTIVE

The aim of the present study was to conduct a systematic review of articles regarding the suicide risk factors in bipolar disorder.

METHODS

A systematic review of articles on suicide risk factors in bipolar disorder, published from January 1, 2010 to April 05, 2014, on SCOPUS and PUBMED databases was carried out. Search terms were "Suicide" (medical subject headings [MeSH]), "Risk factors" (MeSH), and "Bipolar" (keyword). Of the 220 retrieved studies, 42 met the eligibility criteria.

RESULTS

Bipolar disorder is associated with an increased rate death by suicide which contributes to overall mortality rates. Studies covered a wide range of aspects regarding suicide risk factors in bipolar disorder, such as risk factors associated to Sociodemographic conditions, Biological characteristics, Drugs Relationships, Psychological Factors, Genetic Compound, Religious and Spirituals conditions. Recent scientific literature regarding the suicide risk factors in bipolar disorder converge to, directly or indirectly, highlight the negative impacts of risk factors to the affected population quality of life.

CONCLUSION

This review demonstrated that Bipolar disorders commonly leads to other psychiatric disorders and co-morbidities involving risk of suicide. Thus the risk factors are relevant to have a better diagnosis and prognosis of BD cases involving risk of suicide.

A mitochondrial bioenergetic basis of depression

Major depressive disorder (MDD) is an important public health problem affecting 350 million people worldwide. After decades of study, the pathophysiology of MDD remains elusive, resulting in treatments that are only 30-60% effective. This review summarizes the emerging evidence that implicates impaired mitochondrial bioenergetics as a basis for MDD. It is suggested that impaired mitochondrial bioenergetic function contributes to the pathophysiology of MDD via several potential pathways including: genetics/genomics, inflammation, oxidative stress, and alterations in neuroplasticity. A discussion of mitochondrial bioenergetic pathways that lead to MDD is provided. Evidence is reviewed regarding the mito-toxic or mito-protective impact of various antidepressant medications currently in use. Opportunities for further research on novel therapeutic approaches, including mitochondrial modulators, as stand-alone or adjunct therapy for reducing depression are suggested. In conclusion, while there is substantial evidence linking mitochondrial bioenergetics and MDD, there are currently no clear mitochondrial phenotypes or biomarkers to use as guides in targeting therapies beyond individuals with MDD and known mitochondrial disorders toward the general population of individuals with MDD. Further study is needed to develop these phenotypes and biomarkers, to identify therapeutic targets, and to test therapies aimed at improving mitochondrial function in individuals whose MDD is to some extent symptomatic of impaired mitochondrial bioenergetics.