Transmethylation Hypothesis of Schizophrenia: Methionine and
Nicotinic Acid

Nestoros, Joannis N.; Ban, Thomas A.; Lehmann, H. E.

doi:10.1159/000468311

Cited by 17 publications

(8 citation statements)

References 68 publications

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“…There are other modern theories of schizophrenia that can provide an explanation to this contradiction. [57][58][59] The specific mechanisms by which L-theanine exerts its neuroprotective action are just beginning to be studied and clarified. L-Theanine acts antagonistically against the stimulatory effects of caffeine on the nervous system.…”

Section: Discussionmentioning

confidence: 99%

L-Theanine Relieves Positive, Activation, and Anxiety Symptoms in Patients With Schizophrenia and Schizoaffective Disorder

Ritsner¹,

Miodownik²,

Ratner³

et al. 2010

J. Clin. Psychiatry

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Section: Discussionmentioning

confidence: 99%

L-Theanine Relieves Positive, Activation, and Anxiety Symptoms in Patients With Schizophrenia and Schizoaffective Disorder

Ritsner¹,

Miodownik²,

Ratner³

et al. 2010

J. Clin. Psychiatry

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“…Certain other investigators have likewise proposed a hypothesis known as the “transmethylation hypothesis of schizophrenia”, which expresses that the regularly occurring biogenic amines like indolamine methylates into the shape of a methylated amine which leaves a daydreaming effector a hallucinating impact in schizophrenic patients. 29-31…”

Section: Schizophreniamentioning

confidence: 99%

5-HIAA as a Potential Biological Marker for Neurological and Psychiatric Disorders

2019

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Neurological and psychiatric disorders occur in about 6 percent of the global population indicating a significant amount of people suffering from neurological disorder on a varying range in day to day life. On an extensive view, there is a critical requirement for the development of an alternative biomarker for these conditions. The thwart found in developing a biomarker is the difficulty in identifying a serum biomarker as these are mostly limited to the central nervous system (CNS). Serotonin being a neurotransmitter synthesized in the raphe nuclei of the brain could serve as an alternative biomarker. Here, the limitation is that it’s quickly metabolized by the mitochondrial enzyme MAO to 5-hydroxy indole acetic acid (5HIAA). This subsequent metabolite can be used for the analysis of serotonin levels in brain by analysing its concentration in the cerebrospinal fluid (CSF). Many theories suggest that the variations in serotonin level could lead to the development of many neurological and psychiatric disorders like Alzheimer’s disease (AD), schizophrenia, depression and so on. A decreased level is noticed in these patients but this could either be due to decreased production or increased reuptake of serotonin from the neuronal synapses. For instance, we know that a patient with depression shows a significant reduction in the levels of 5HIAA, due to the location of the raphe nuclei within regions of memory and cognition. Similarly, it does shows variation in AD and mild cognitive disorder. Evolving of 5HIAA as a biomarker, could be more delicate and enhanced strategy for monitoring these disorders.

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“…Interestingly, it has been reported that the high consumption of methionine could promote brain damage. In the past, the transmethylation theory of schizophrenia was proposed, based on the fact that methyl donors such as methionine can exacerbate psychotic symptoms [ 22 – 25 ]. Additionally, recent clinical studies link high levels of plasma methionine sulfoxide, an intermediate in the methionine cycle, with ageing and Alzheimer’s disease (AD) [ 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

Is L-methionine a trigger factor for Alzheimer’s-like neurodegeneration?: Changes in Aβ oligomers, tau phosphorylation, synaptic proteins, Wnt signaling and behavioral impairment in wild-type mice

Tapia-Rojas

Lindsay

Montecinos-Oliva

et al. 2015

Mol Neurodegeneration

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BackgroundL-methionine, the principal sulfur-containing amino acid in proteins, plays critical roles in cell physiology as an antioxidant and in the breakdown of fats and heavy metals. Previous studies suggesting the use of L-methionine as a treatment for depression and other diseases indicate that it might also improve memory and propose a role in brain function. However, some evidence indicates that an excess of methionine can be harmful and can increase the risk of developing Type-2 diabetes, heart diseases, certain types of cancer, brain alterations such as schizophrenia, and memory impairment.ResultsHere, we report the effects of an L-methionine-enriched diet in wild-type mice and emphasize changes in brain structure and function. The animals in our studypresented 1) higher levels of phosphorylated tau protein, 2) increased levels of amyloid-β (Aβ)-peptides, including the formation of Aβ oligomers, 3) increased levels of inflammatory response,4) increased oxidative stress, 5) decreased level of synaptic proteins, and 6) memory impairment and loss. We also observed dysfunction of the Wnt signaling pathway.ConclusionTaken together, the results of our study indicate that an L-methionine-enriched diet causes neurotoxic effects in vivo and might contribute to the appearance of Alzheimer’s-like neurodegeneration.Electronic supplementary materialThe online version of this article (doi:10.1186/s13024-015-0057-0) contains supplementary material, which is available to authorized users.

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Transmethylation Hypothesis of Schizophrenia: Methionine and Nicotinic Acid

Cited by 17 publications

References 68 publications

L-Theanine Relieves Positive, Activation, and Anxiety Symptoms in Patients With Schizophrenia and Schizoaffective Disorder

L-Theanine Relieves Positive, Activation, and Anxiety Symptoms in Patients With Schizophrenia and Schizoaffective Disorder

5-HIAA as a Potential Biological Marker for Neurological and Psychiatric Disorders

Is L-methionine a trigger factor for Alzheimer’s-like neurodegeneration?: Changes in Aβ oligomers, tau phosphorylation, synaptic proteins, Wnt signaling and behavioral impairment in wild-type mice

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