By Margarita Nahapetyan
Childhood abuse can permanently alter the way DNA works, leaving victims with lasting effect on their brain, and therefore making them more vulnerable to stressful events throughout their lives, and even suicide-prone, reports a new Canadian study.
According to researchers at Montreal's McGill University and Douglas Institute, abuse and traumas at an early age, as well as bad maternal care, lead to a later development of anxiety and depression. The scientists found clear changes in the brains of people who were abused as children and who committed suicide compared with those who were not abused and died in suicidal accidents.
For the research, Prof. Michael Meaney of McGill University and his colleagues at the Singapore Institute for Clinical Sciences, examined the brain tissue of 36 males in Quebec. The study looked at 12 suicide victims who were abused as children, 12 suicide victims who had no history of such abuse, and 12 other people who had just accidental deaths. The abuse included severe physical abuse, sexual abuse and severe neglect.
The investigators found that there were different epigenetic markings in the brains of the abused victims. In their report they wrote that these markings control a stress-activated biological mechanism known as the hypothalamic-pituitary-adrenal (HPA), a function in the brain which regulates stress responses. It has been known for a certain time that HPA pathway can have harmful effects with its higher activity linked to mood disorders, schizophrenia and an increased risk of suicide.
The glucicorticoid receptor gene affected by abuse at an early age normally acts as a brake on the pathway of HPA. Less activity of the gene leads to an overload in HPA, causing therefore, greater risk for negative emotions. Epigenetics is a process in which gene activity can be permanently altered by influences of the environment. With more and more evidence, scientists are coming to the conclusion that it can have far-reaching influences, even reaching down the generations.
Suicide victims with a history of child abuse had lowered activity of this gene, compared to men who died from a sudden, accidental death and who have not been abused in their childhood. The scientists did not also find any of such differences among suicide victims without a history of childhood abuse.
The researchers are now trying to find out whether other genes and behaviors are being affected by abuse. "Individuals who are abused are also more likely to develop obesity," said Meaney, who plans to determine if that also may be related to genes being turned on or off in response to early traumas or abuse.
Further research on brain tissue can help investigators develop intervention and prevention programs in order to help people, the researchers added. Earlier, negative experience at an early childhood has been shown to cause long-term genetic changes in the stress response pathway in rats, but this is the first evidence to show that the same thing also happens in humans.
The research was funded by the Canadian Institutes for Health Research and the U.S. National Institute of Child Health and Development. A paper on the study is published in the journal Nature Neuroscience.
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