Altered Brain pH Linked to Cognitive Disorders

Summary: A global study involving 131 researchers from 105 labs across seven countries has found altered brain pH and lactate levels across various animal models of neuropsychiatric and neurodegenerative disorders. This large-scale research reveals a common endophenotype involving energy metabolism dysfunction as a hallmark in disorders such as schizophrenia, autism, and Alzheimer’s.

The study demonstrates that about 30% of the examined animal models showed significant alterations in brain pH and lactate levels, linking these metabolic changes to impaired working memory and suggesting intrinsic disease characteristics rather than effects of medication. These findings open new avenues for understanding the transdiagnostic characteristics of cognitive impairments and developing targeted treatment strategies.

Key Facts:

  1. Widespread Phenomenon: Significant changes in brain pH and lactate levels were observed in 30% of the animal models studied, indicating a common energy metabolism dysfunction across various neuropsychiatric conditions.
  2. Link to Cognitive Impairment: Elevated lactate levels were predominantly associated with impaired working memory, highlighting a direct impact on cognitive function.
  3. Potential for New Treatments: The identification of altered brain energy metabolism as a transdiagnostic endophenotype paves the way for innovative treatment approaches targeting shared metabolic dysfunctions.

Source: Fujita Health University

A global collaborative research group comprising 131 researchers from 105 laboratories across seven countries announces a groundbreaking research paper submitted to Life.

Titled “Large-scale Animal Model Study Uncovers Altered Brain pH and Lactate Levels as a Transdiagnostic Endophenotype of Neuropsychiatric Disorders Involving Cognitive Impairment,” the study identifies brain energy metabolism dysfunction leading to altered pH and lactate levels as common hallmarks in numerous animal models of neuropsychiatric and neurodegenerative disorders, such as intellectual disability, autism spectrum disorders, schizophrenia, bipolar disorder, depressive disorders, and Alzheimer’s disease.

This shows a brain scan.
Additionally, the relationship between alterations in brain pH and lactate levels and specific behavioral abnormalities had not been clearly established. Credit: Neuroscience News

At the forefront of neuroscience research, the research group sheds light on altered energy metabolism as a key factor in various neuropsychiatric and neurodegenerative disorders. While considered controversial, an elevated lactate level and the resulting decrease in pH is now also proposed as a potential primary component of these diseases.

Unlike previous assumptions associating these changes with external factors like medication, the research group’s previous findings suggest that they may be intrinsic to the disorders.

This conclusion was drawn from five animal models of schizophrenia/developmental disorders, bipolar disorder, and autism, which are exempt from such confounding factors.

However, research on brain pH and lactate levels in animal models of other neuropsychiatric and neurological disorders has been limited. Until now, it was unclear whether such changes in the brain were a common phenomenon.

Additionally, the relationship between alterations in brain pH and lactate levels and specific behavioral abnormalities had not been clearly established.

This study, encompassing 109 strains/conditions of mice, rats, and chicks, including animal models related to neuropsychiatric conditions, reveals that changes in brain pH and lactate levels are a common feature in a diverse range of animal models of disorders, including schizophrenia/developmental disorders, bipolar disorder, autism, as well as models of depression, epilepsy, and Alzheimer’s disease. This study’s significant insights include:

I. Common Phenomenon Across Disorders: About 30% of the 109 types of animal models exhibited significant changes in brain pH and lactate levels, emphasizing the widespread occurrence of energy metabolism changes in the brain across various neuropsychiatric conditions.

II. Environmental Factors as a Cause: Models simulating depression through psychological stress, and those induced to develop diabetes or colitis, which have a high comorbidity risk for depression, showed decreased brain pH and increased lactate levels. Various acquired environmental factors could contribute to these changes.

III. Cognitive Impairment Link: A comprehensive analysis integrating behavioral test data revealed a predominant association between increased brain lactate levels and impaired working memory, illuminating an aspect of cognitive dysfunction.

IV. Confirmation in Independent Cohort: These associations, particularly between higher brain lactate levels and poor working memory performance, were validated in an independent cohort of animal models, reinforcing the initial findings.

V. Autism Spectrum Complexity: Variable responses were noted in autism models, with some showing increased pH and decreased lactate levels, suggesting subpopulations within the autism spectrum with diverse metabolic patterns.

“This is the first and largest systematic study evaluating brain pH and lactate levels across a range of animal models for neuropsychiatric and neurodegenerative disorders.

“Our findings may lay the groundwork for new approaches to develop the transdiagnostic characterization of different disorders involving cognitive impairment,” states Dr. Hideo Hagihara, the study’s lead author.

Professor Tsuyoshi Miyakawa, the corresponding author, explains, “This research could be a stepping stone towards identifying shared therapeutic targets in various neuropsychiatric disorders.

“Future studies will center on uncovering treatment strategies that are effective across diverse animal models with brain pH changes. This could significantly contribute to developing tailored treatments for patient subgroups characterized by specific alterations in brain energy metabolism.”

In this paper, the mechanistic insights into the reduction in pH and the increase in lactate levels remain elusive. However, it is known that lactate production increases in response to neural hyperactivity to meet the energy demand, and the authors seem to think this might be the underlying reason.

About this neuroscience and neurology research news

Author: Hisatsugu Koshimizu
Source: Fujita Health University
Contact: Hisatsugu Koshimizu – Fujita Health University
Image: The image is credited to Neuroscience News

Original Research: Open access.
Large-scale animal model study uncovers altered brain pH and lactate levels as a transdiagnostic endophenotype of neuropsychiatric disorders involving cognitive impairment” by Hideo Hagihara et al. eLife


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

Increased levels of lactate, an end-product of glycolysis, have been proposed as a potential surrogate marker for metabolic changes during neuronal excitation. These changes in lactate levels can result in decreased brain pH, which has been implicated in patients with various neuropsychiatric disorders.

We previously demonstrated that such alterations are commonly observed in five mouse models of schizophrenia, bipolar disorder, and autism, suggesting a shared endophenotype among these disorders rather than mere artifacts due to medications or agonal state.

However, there is still limited research on this phenomenon in animal models, leaving its generality across other disease animal models uncertain. Moreover, the association between changes in brain lactate levels and specific behavioral abnormalities remains unclear.

To address these gaps, the International Brain pH Project Consortium investigated brain pH and lactate levels in 109 strains/conditions of 2294 animals with genetic and other experimental manipulations relevant to neuropsychiatric disorders.

Systematic analysis revealed that decreased brain pH and increased lactate levels were common features observed in multiple models of depression, epilepsy, Alzheimer’s disease, and some additional schizophrenia models.

While certain autism models also exhibited decreased pH and increased lactate levels, others showed the opposite pattern, potentially reflecting subpopulations within the autism spectrum.

Furthermore, utilizing large-scale behavioral test battery, a multivariate cross-validated prediction analysis demonstrated that poor working memory performance was predominantly associated with increased brain lactate levels. Importantly, this association was confirmed in an independent cohort of animal models.

Collectively, these findings suggest that altered brain pH and lactate levels, which could be attributed to dysregulated excitation/inhibition balance, may serve as transdiagnostic endophenotypes of debilitating neuropsychiatric disorders characterized by cognitive impairment, irrespective of their beneficial or detrimental nature.

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