Child Abuse Causes Lifelong Changes to DNA
Study Analyzed Post Mortem Brain Samples of Childhood Abuse Victims
Sep 30, 2009
A study led by researchers from the Douglas Mental Health University Institute and McGill University in Montreal, Quebec entitled “Epigenetic regulation of the glucocorticoid receptor in human brain associates with childhood abuse,"analyzed post mortem brain samples of suicide victims with a history of being abused in childhood.
Researchers discovered changes in DNA expression that were not present in suicide victims with no childhood abuse history or in people who died of other causes. The affected DNA was in a gene that regulates the way the brain controls the stress response.
In this study the researchers looked at samples of the hippocampus from human suicide victims with a history of childhood abuse. The hippocampus is a region of the brain that plays a key role in regulating the stress response.
They found changes in expression of the NC3R1 gene that were not present in suicide victims with no history of being abused in childhood. The changes weren't present in people who had died of other causes either.
For the study the researchers used samples from 36 brains: 12 came from suicide victims who had been abused as children, 12 came from suicide victims who had no such history, and 12 came from people who had died of other causes (the controls).
The researchers found that the child abuse victims had different "epigenetic" markings in a part of the brain that influences the hypothalamic-pituitary-adrenal (HPA) function, a stress-response that increases suicide risk.
The interaction between environment and DNA plays a key role in our ability to resist and deal with stress and this affects the risk of suicide, said the researchers. Epigenetic marks are the product of DNA and environment.
Researchers found that different types of care from the mothers changed the hypothalamic-pituitary-adrenal (HPA) function in rats by altering the receptors in the brain. In earlier studies they showed that simple behaviours such as when mothers licked their baby rats in early life had a significant effect on epigentic markings on specific genes that affected behaviour throughout the offsprings' lives.
They also found that these epigenetic marks can be changed in adulthood with treatments that change the DNA coating: the treatment is called DNA methylation and it reverses the change to the stress response.
The brain samples in this latest study came from the Quebec Suicide Brain Bank and the Canadian Institutes for Health Research and the National Institute of Child Health and Development in the US paid for the research.
If children are abused early, they are flooded with stress-related hormones such as cortisol and adrenaline. This directly impacts on how the brain develops and the stress regulation mechanism. It becomes highly stressed so it's like setting the thermostat on high, setting up a system which regulates stress less efficiently.
Also it impacts on the area which controls feelings, so they're more likely to be highly stressed, have difficulties with anger and emotions, and be prone to self-harm, anxiety, suicide and depression." It's not clear why some people overcome their past while others succumb to it.
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