Role of magnetic resonance spectroscopy in cerebral glutathione quantification for youth mental health: A systematic review

Glutathione Therapy in Diseases: Challenges and Potential Solutions for Therapeutic Advancement

An endogenous antioxidant, reduced glutathione (GSH), is found at high concentrations in nearly all typical cells. GSH synthesis is a controlled process, and any disruption in the process of GSH synthesis could result in GSH depletion. Cellular oxidative damage results from GSH depletion. Various pathological conditions such as aging, cardiovascular disease (CVD), psychiatric disorders, neurological disorders, liver disorders, and diabetes mellitus are more affected by this stress. There are various reasons for GSH reduction, but replenishing it can help to improve this condition. However, there are challenges in this field. Low bioavailability and poor stability of GSH limit its delivery to tissues, mainly brain tissue. Today, new approaches are used for the optimal amount and efficiency of drugs and alternative substances such as GSH. The use of nano-materials and liposomes are effective methods for improving the treatment effects of GSH. The difficulties of GSH decrease and its connection to the most important associated disorders are reviewed for the first time in this essay. The other major concerns are the molecular mechanisms involved in them; the impact of treatment with replacement GSH; the signaling pathways impacted; and the issues with alternative therapies. The utilization of nano-materials and liposomes as potential new approaches to solving these issues is being considered.

Sex hormones as correlates of oxidative stress in the adult brain

Oxidative stress, an imbalance between the production of reactive oxygen species and available antioxidant capacity, is implicated in multiple psychiatric disorders and neurodegenerative conditions. Peripheral and preclinical studies suggest oxidative stress differs by biological sex and covaries with estrogens. However, limited knowledge exists on the effect of circulating sex hormones on oxidative stress in the brain in humans in vivo. We aimed to examine the relationship of circulating estrogen with regional concentrations of brain glutathione (GSH) as a marker of oxidative stress. GSH was measured using magnetic resonance spectroscopy (MRS) at 7 Tesla in the dorsal anterior cingulate cortex (ACC), ventromedial prefrontal cortex (VMPFC), and left dorsolateral prefrontal cortex (DLPFC) in 34 individuals (18 females and 16 males). We observed an inverse correlation of estradiol with DLPFC GSH, as well as a trend inverse correlation of estrone with DLPFC GSH, in the combined sample of males and females and in females only. No significant sex differences were observed for GSH levels in the brain. Our study provides evidence of diminished DLPFC GSH in females with higher estradiol, suggesting circulating sex hormones may be important factors to consider in future studies examining brain GSH levels related to psychiatric and other disorders.

Is There a Glutathione Centered Redox Dysregulation Subtype of Schizophrenia?

Schizophrenia continues to be an illness with poor outcome. Most mechanistic changes occur many years before the first episode of schizophrenia; these are not reversible after the illness onset. A developmental mechanism that is still modifiable in adult life may center on intracortical glutathione (GSH). A large body of pre-clinical data has suggested the possibility of notable GSH-deficit in a subgroup of patients with schizophrenia. Nevertheless, studies of intracortical GSH are not conclusive in this regard. In this review, we highlight the recent ultra-high field magnetic resonance spectroscopic studies linking GSH to critical outcome measures across various stages of schizophrenia. We discuss the methodological steps required to conclusively establish or refute the persistence of GSH-deficit subtype and clarify the role of the central antioxidant system in disrupting the brain structure and connectivity in the early stages of schizophrenia. We propose in-vivo GSH quantification for patient selection in forthcoming antioxidant trials in psychosis. This review offers directions for a promising non-dopaminergic early intervention approach in schizophrenia.

In Vivo Brain GSH: MRS Methods and Clinical Applications

Glutathione (GSH) is an important antioxidant implicated in several physiological functions, including the oxidation−reduction reaction balance and brain antioxidant defense against endogenous and exogenous toxic agents. Altered brain GSH levels may reflect inflammatory processes associated with several neurologic disorders. An accurate and reliable estimation of cerebral GSH concentrations could give a clear and thorough understanding of its metabolism within the brain, thus providing a valuable benchmark for clinical applications. In this context, we aimed to provide an overview of the different magnetic resonance spectroscopy (MRS) technologies introduced for in vivo human brain GSH quantification both in healthy control (HC) volunteers and in subjects affected by different neurological disorders (e.g., brain tumors, and psychiatric and degenerative disorders). Additionally, we aimed to provide an exhaustive list of normal GSH concentrations within different brain areas. The definition of standard reference values for different brain areas could lead to a better interpretation of the altered GSH levels recorded in subjects with neurological disorders, with insights into the possible role of GSH as a biomarker and therapeutic target.

Oxidative Stress and the Pathophysiology and Symptom Profile of Schizophrenia Spectrum Disorders

Schizophrenia is associated with increased levels of oxidative stress, as reflected by an increase in the concentrations of damaging reactive species and a reduction in anti-oxidant defences to combat them. Evidence has suggested that whilst not the likely primary cause of schizophrenia, increased oxidative stress may contribute to declining course and poor outcomes associated with schizophrenia. Here we discuss how oxidative stress may be implicated in the aetiology of schizophrenia and examine how current understanding relates associations with symptoms, potentially via lipid peroxidation induced neuronal damage. We argue that oxidative stress may be a good target for future pharmacotherapy in schizophrenia and suggest a multi-step model of illness progression with oxidative stress involved at each stage.

Exercise as a protective mechanism against the negative effects of oxidative stress in first-episode psychosis: a biomarker-led study

First-episode psychosis (FEP) is a psychiatric disorder, characterised by positive and negative symptoms, usually emerging during adolescence and early adulthood. FEP represents an early intervention opportunity for intervention in psychosis. Redox disturbance and subsequent oxidative stress have been linked to the pathophysiology of FEP. Exercise training can perturb oxidative stress and rebalance the antioxidant system and thus represents an intervention with the potential to interact with a mechanism of disease. The aim of this study was to assess the effect of exercise on markers of redox status in FEP. Twenty-two young men were recruited from Birmingham Early Intervention services and randomised to either a 12-week exercise programme or treatment as usual (control). Measures of blood and brain glutathione (GSH), markers of oxidative damage, inflammation, neuronal health, symptomology and habitual physical activity were assessed. Exercise training was protective against changes related to continued psychosis. Symptomatically, those in the exercise group showed reductions in positive and general psychopathology, and stable negative symptoms (compared to increased negative symptoms in the control group). Peripheral GSH was increased by 5.6% in the exercise group, compared to a significant decrease (24.4%) (p = 0.04) in the control group. Exercise attenuated negative changes in markers of neuronal function (brain-derived neurotrophic factor), lipid damage (thiobarbituric acid-reactive substances) and total antioxidant capacity. C-reactive protein and tumour necrosis factor-α also decreased in the exercise group, although protein and DNA oxidation were unchanged. Moderate-intensity exercise training has the ability to elicit changes in markers of oxidative stress and antioxidant concentration, with subsequent improvements in symptoms of psychosis.

Role of magnetic resonance spectroscopy in cerebral glutathione quantification for youth mental health: A systematic review

AIM

Oxidative stress is strongly implicated in many psychiatric disorders, which has resulted in the development of new interventions to attempt to perturb this pathology. A great deal of attention has been paid to glutathione, which is the brain's dominant antioxidant and plays a fundamental role in removing free radicals and other reactive oxygen species. Measurement of glutathione concentration in the brain in vivo can provide information on redox status and potential for oxidative stress to develop. Glutathione might also represent a marker to assess treatment response.

METHODS

This paper systematically reviews studies that assess glutathione concentration (measured using magnetic resonance spectroscopy) in various mental health conditions.

RESULTS

There is limited evidence showing altered brain glutathione concentration in mental disorders; the best evidence suggests glutathione is decreased in depression, but is not altered in bipolar disorder. The review then outlines the various methodological options for acquiring glutathione data using spectroscopy.

CONCLUSIONS

Analysis of the minimum effect size measurable in existing studies indicates that increased number of participants is required to measure subtle but possibly important differences and move the field forward.