Changes in white matter connections during development associated with the risk of psychosis

Studies with imaging of the brain show structural and functional abnormalities in people with psychosis in the connections between the cortex and thalamus, the main station for incoming sensory information and a critical regulator of cortical activity. A new study shows that these differences are not present during development, but that the integrity of relationships is compromised in young people with symptoms from the psychosis spectrum.

“This paper provides insight into the fundamental changes that occur during the development of white matter connections connecting the thalamus and cortex, and how developmental patterns differ in adolescence with symptoms of the psychotic spectrum at risk of developing a psychotic disorder.” said lead author, Dr. Susan Avery. , Vanderbilt University Medical Center, Nashville, Tennessee, of the study, which appears in Biological psychiatry: cognitive neuroscience and neuroimaging, published by Elsevier.

White matter refers to parts of the brain made up of fatty, myelinated axons that send information to large areas of the brain. Myelin is generated in non-neuronal glial cells that wrap around neuronal axons as isolation to speed signaling. Impaired white matter structure has been observed in the brains of people with psychosis and is thought to play a role in cognitive deficits.

For the current study, Dr. Avery and colleagues examined data from 1,144 participants aged 8 to 22 years; 316 usually developed while the others had symptoms of the psychosis spectrum or some other psychopathology.

Dr Avery said: “Somewhat surprisingly, our findings show that the structural pathways of white matter are relatively stable during typical development and are similar in children at higher risk of psychosis, suggesting that structural deficits that often found in patients with psychosis, may have occurred later, near the onset of the disease, or may be limited to those individuals who will continue to develop a psychotic disorder. “

However, when the authors examined white matter at the microstructural level, she said, “we found that the microstructural integrity of white matter tracts increased significantly during development, especially in the tracts connecting the thalamus to the prefrontal and posterior parietal cortex.” In addition, the structural integrity of these tracts is lower in children exhibiting symptoms of the psychosis spectrum and is related to cognitive function.

“This suggests a critical role for abnormal developmental processes, such as myelination deficiency, for the risk of both cognitive deficits and psychosis,” added Dr. Avery. “This work may have implications for the early detection and treatment of children at risk of developing psychotic illness. New therapeutic approaches should focus on mechanisms that increase myelination, as hypomyelination may increase cognitive deficits and the risk of deterioration. of the symptoms of psychosis. “

This important study complements the authors’ previous work on functional connectivity in thalamocortical tracts in psychosis, outlining the functional brain anatomy of these serious and disturbing symptoms. It also puts them in the context of development and takes us one step closer to understanding the mechanisms underlying serious mental illness and offering new places for prevention and treatment. “

Cameron Carter, MD, editor of Biological psychiatry: cognitive neuroscience and neuroimaging


Reference in the magazine:

Avery, S.N., et al. (2021) Development of thalamocortical structural connectivity in typically developing and young people from the psychotic spectrum. Biological psychiatry Cognitive neuroscience and neuroimaging.

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