Glutamate levels across deep brain structures in patients with a psychotic disorder and its relation with cognitive functioning (original) (raw)
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Translational Psychiatry, 2021
Abnormalities in glutamate neurotransmission are linked to psychotic symptoms and cognitive dysfunction in schizophrenia. magnetic resonance spectroscopy (MRS) provides an acceptable means of measuring glutamate in the human brain but findings from patient studies at conventional magnetic field strength show considerable heterogeneity. Ultra-high-field MRS offers greater precision in glutamate measurement, particularly in delineation of glutamate from its precursor and metabolite, glutamine. This study aimed to use high-field (7 T) MRS to measure concentrations of glutamate and glutamine in three brain regions, anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (DLPFC) and putamen (PUT), in young men with early psychosis. MRS was performed in 17 male participants with early psychosis and 18 healthy age-matched controls. Neurometabolite levels were calculated with unsuppressed water signal as the reference and corrected for individual grey matter, white matter and cerebr...
Biological Psychiatry, 2009
Background: The glutamate model of schizophrenia proposes that altered glutamatergic neurotransmission is fundamental to the development of the disorder. In addition, its potential to mediate neurotoxicity raises the possibility that glutamate dysfunction could underlie neuroanatomic changes in schizophrenia. Here we determine whether changes in brain glutamate are present in subjects at ultra high risk of developing psychosis and whether these changes are related to reductions in cortical gray matter volume.
Impact of glutamate levels on neuronal response and cognitive abilities in schizophrenia
NeuroImage. Clinical, 2014
Schizophrenia is characterized by impaired cognitive functioning, and brain regions involved in cognitive control processes show marked glutamatergic abnormalities. However, it is presently unclear whether aberrant neuronal response is directly related to the observed deficits at the metabolite level in schizophrenia. Here, 17 medicated schizophrenia patients and 17 matched healthy participants underwent functional magnetic resonance imaging (fMRI) when performing an auditory cognitive control task, as well as proton magnetic resonance spectroscopy ((1)H-MRS) in order to assess resting-state glutamate in the anterior cingulate cortex. The combined fMRI-(1)H-MRS analysis revealed that glutamate differentially predicted cortical blood-oxygen level-dependent (BOLD) response in patients and controls. While we found a positive correlation between glutamate and BOLD response bilaterally in the inferior parietal lobes in the patients, the corresponding correlation was negative in the healt...
American Journal of Psychiatry, 2003
This in vivo 1 H magnetic resonance spectroscopy study examined levels of glutamate, glutamine, and N-acetylaspartate in medicated patients with chronic schizophrenia. Method: Localized in vivo 1 H spectra were acquired at 4.0 T from the left anterior cingulate and thalamus of 21 patients with schizophrenia and 21 comparable healthy volunteers. Results: Significantly lower levels of glutamine and glutamate were found in the left anterior cingulate cortex of patients with schizophrenia than in the healthy volunteers. For the schizophrenia patients, the glutamine level in the left thalamus was found to be higher than normal, and there was a significant negative correlation between N-acetylaspartate level and duration of positive symptoms. Conclusions: Since previous studies have found higher than normal levels of glutamine in the left anterior cingulate of never-treated patients, decreased levels of these metabolites in chronic patients could be related to neurodegeneration or the effects of chronic medication.
2020
Progressive reduction in glutamatergic transmission has been proposed as an important component of the illness trajectory of schizophrenia. Despite its popularity, to date, this notion has not been convincingly tested in patients in early stages schizophrenia. In a longitudinal 7T magnetic resonance spectroscopy (1H-MRS), we quantified glutamate at the dorsal anterior cingulate cortex in 21 participants with a median lifetime antipsychotic exposure of less than 3 days and followed them up after 6 months of treatment. Healthy controls were also scanned at two time points. While patients had significantly lower overall glutamate levels than healthy controls (F(1,27) = 5.23, p = 0.03), we did not observe a progressive change of glutamate concentration in patients (F(1,18) = 0.47, p = 0.50), and the group by time interaction was not significant (F(1,27) = 0.86, p = 0.36). On average, patients with early psychosis receiving treatment showed a 0.02 mM/year increase, while healthy controls...
Variability and Magnitude of Brain Glutamate Levels in Schizophrenia: A Meta And Mega-Analysis
Glutamatergic dysfunction is implicated in the pathoaetiology of schizophrenia, but this may vary in extent between patients. It is unclear whether inter-individual variability in glutamate is greater in schizophrenia than the general population. We conducted meta-analyses to assess (1) variability of glutamate measures in patients relative to controls, using the log coefficient of variation ratio (CVR); (2) standardised mean differences (SMD) using Hedges g; (3) modal distribution of individual-level glutamate data using Hartigan’s unimodality dip test. MEDLINE and EMBASE databases were searched from inception to October 2021 for proton magnetic resonance spectroscopy (1H-MRS) studies reporting glutamate, glutamine or Glx in schizophrenia patients compared to controls. 116 studies reporting on 7,844 patients and 7,305 controls were included. Compared with controls, patients demonstrated greater variability in glutamatergic metabolites in the medial frontal cortex (MFC, glutamate: C...
Biological Psychiatry, 1994
In the past couple of decades, major efforts were made to increase reliability of metabolic assessments by magnetic resonance methods. Magnetic resonance spectroscopy (MRS) has been valuable for providing in vivo evidence and investigating biomarkers in neuropsychiatric disorders, namely schizophrenia. Alterations of glutamate and glutamine levels in brains of schizophrenia patients relative to healthy subjects are generally interpreted as markers of glutamatergic dysfunction. However, only a small fraction of MRS-detectable glutamate is involved in neurotransmission. Here we review and discuss brain metabolic processes that involve glutamate and that are likely to be implicated in neuropsychiatric disorders.
JAMA psychiatry, 2017
Despite strong theoretical rationale and preclinical evidence, several glutamate-targeted treatments for schizophrenia have failed in recent pivotal trials, prompting questions as to target validity, compound inadequacy, or lack of target engagement. A key limitation for glutamate-based treatment development is the lack of functional target-engagement biomarkers for translation between preclinical and early-stage clinical studies. We evaluated the utility of 3 potential biomarkers-ketamine-evoked changes in the functional magnetic imaging (fMRI) blood oxygen level-dependent response (pharmacoBOLD), glutamate proton magnetic resonance spectroscopy (1H MRS), and task-based fMRI-for detecting ketamine-related alterations in brain glutamate. To identify measures with sufficient effect size and cross-site reliability to serve as glutamatergic target engagement biomarkers within early-phase clinical studies. This randomized clinical trial was conducted at an academic research institution ...