Child abuse affects genes

Picture 12While adding info to this blog’s resources and research sections today, I found “Abuse affects genes”, an article by Brona McVittie on the Epigenetics? site. The site is put together by The Epigenome Network of Excellence, a European research network that focuses on epigenetics. Epigenetics looks at how our experiences and our environment turn our genes on and off. Yes — it’s an amazing thought, isn’t it. The genes we’re born with don’t set our personalities and behavior in stone. It’s all those experiences — our family life, our school life, our country’s life (war or peace?), our economic life (extreme poverty or jet-setter), our environment.

Epigenome means “above” or “in addition to”  the genome. We all have genes, which have all the code and instructions for how our bodies function. But not all of those genes are functioning all of the time. Our epigenome tells our genes what to do and when to do it. (For more info, go to this blog’s resources section.)

The article describes what researchers at McGill University and the Douglas Institute in Canada found when they compared the brains of 12 suicide victims who’d suffered child abuse, 12 suicide victims who weren’t abused, and 12 normal individuals. They looked at the genes that affect a person’s ability to cope with stress. They found differences between the same genes in the abuse victims and those not abused — the genes weren’t different, but the epigenetic marks on the genes were different. [How this works is shown in a fabulous animation — specifically the second part of the five parts — put together by the folks at NOVA, who have produced an episode about epigenetics:  Ghost in Your Genes. A shorter version is on NOVA’s Science Now.]

What’s important about this? Previous research shows that if these genes don’t function correctly, they can’t keep  stress hormones under control. So, the study suggests this scenario: Children suffer abuse, their nervous systems responds appropriately by producing stress hormones (fight, flight or freeze). But continued abuse without relief produces way too much stress hormone, which sets off something that significantly slows or stifles the genes that sop up those stress hormone. Too much stress keeps a person in a state of anxiety, fear, nervousness, agitation, or rage mixed with depression. One reason people commit suicide is because they feel they can no longer cope with these unrelenting overwhelming feelings over which they feel they have no control.

“The function of our DNA is not as fixed as previously thought,” adds Michael Meaney (Douglas Institute, Quebec). “The interaction between genes and the environment plays a crucial role in determining our resistance to stress and the risk for suicide. Epigenetic marks are the product of this interaction.”

In another article, one of the researchers, Moshe Szyf, a professor of pharmacolog at McGill University, said:

this study is the first that he knew of in which there is a clear link between human social environments and their epigenetic code. “It is dynamic, and it acts through life,” he says. “And it’s not just chemicals that affect these mechanisms, it’s the social, and even political, environment.”

The study was published in the Feb. 22, 2009 issue of Nature Neuroscience.

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