Severe Childhood Abuse May Alter Myelin Sheaths in the Brain

New research links severe child abuse with less myelination in the human brain.

Posted May 15, 2018

Victims of abuse during childhood are statistically more vulnerable to stress-related psychiatric conditions across their lifespan. This uptick in mental health problems among children who are abused may be linked to molecular and cellular changes in how the brain is structured and wired. 

Geoff B. Hall/Wikipedia Commons
Anterior cingulate cortex (ACC) in yellow.
Source: Geoff B. Hall/Wikipedia Commons

Researchers at McGill University in Canada have identified that severe child abuse may trigger a chain reaction that alters the architecture and functional connectivity of the anterior cingulate cortex (ACC). This brain region is associated with mood and emotion regulation. In May 2018, a neuroimaging study from China reported that the ACC also plays a pivotal role in the brain mechanics of gratitude and an intermediary role in converting gratitude into altruistic reciprocity.

Child Abuse May Alter Myelination in the Anterior Cingulate Cortex

For the latest McGill study, researchers in Canada used advanced microscopy techniques to measure the thickness of myelin sheaths surrounding ACC neurons in various cohorts. By comparing the brains of depressed suicides (both with or without a history of severe child abuse) to the brains of healthy controls, the researchers unearthed noticeable myelination differences in the ACC.

Notably, the brains of healthy controls, who had not been abused as children, contained a much thicker layer of myelin in the ACC. Thicker myelin sheaths optimize the ability of white matter tracts to communicate efficiently within and between brain regions.

This state-of-the-art research on child abuse and myelin in the ACC was conducted by Naguib Mechawar and Gustavo Turecki of the McGill Group for Suicide Studies (MGSS). Mechawar shared these findings in a lecture, “The Impact of Child Abuse on Oligodendrocytes and Myelination in the Human Brain,” as part of a symposium, “Novel insights on the neurobiology of depression,” on May 14 at the 12th Annual Canadian Neuroscience Meeting in Vancouver. 

"Our results demonstrate that gene expression is strongly altered in a class of cells called oligodendrocytes in the ACC. This class of cells is responsible for producing myelin, which is an insulating compound that can be likened to the coating on electrical wires. Myelin-coated axons transmit nerve impulses efficiently, while a loss of myelin is generally associated with loss of transmission efficiency,” Mechawar said in a statement. "Our data clearly shows how severe child abuse modifies the architecture of the ACC by affecting the formation of the myelin sheath around neurons. This modification in a region that is key for mood regulation may underlie the increased vulnerability of abused individuals to mood disorders, such as depression.”

In 2009, Turecki along with colleagues Michael Meaney and Moshe Szyf published a landmark paper, "Epigenetic Regulation of the Glucocorticoid Receptor in Human Brain Associates with Childhood Abuse," in Nature Neuroscience. This study identified how severe child abuse may trigger epigenetic changes in the human brain. The latest findings by Turecki & Mechawa presented at the 2018 CAN-ACN annual conference add valuable insights into specific ways severe childhood abuse may have lasting impact on oligodendrocytes and myelination in the human brain. 

References

"The Impact of Child Abuse on Oligodendrocytes and Myelination in the Human Brain" by Naguib Mechawar and Gustavo Turecki. Presented at a symposium: "Novel Insights in the Neurobiology of Depression." Chaired by Naguib Mechawar of Douglas Institute/McGill University at the 12th Annual CAN-ACN Meeting in Vancouver (May 13-16, 2018). 

Patrick O McGowan, Aya Sasaki, Ana C D'Alessio, Sergiy Dymov, Benoit Labonté, Moshe Szyf, Gustavo Turecki, and Michael J Meaney. "Epigenetic Regulation of the Glucocorticoid Receptor in Human Brain Associates with Childhood Abuse." Nature Neuroscience (2009) DOI: 10.1038/nn.2270

Hongbo Yu, Xiaoxue Gao, Yuanyuan Zhou and Xiaolin Zhou. “Decomposing Gratitude: Representation and Integration of Cognitive Antecedents of Gratitude in the Brain.” The Journal of Neuroscience (Published: May 7, 2018) DOI: 10.1523/JNEUROSCI.2944-17.2018

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