February 24, 2009

Early abuse affects stress response

[Posted: Mon 23/02/2009 by Deborah Condon]

Abuse in early childhood alters the way in which people respond to stress and increases the risk of suicide, the results of a new study indicate.

Canadian scientists have found that childhood trauma actually alters DNA and shapes the way genes work in humans. This confirms earlier studies carried out in animals which found that maternal care plays a significant role in influencing the genes that control our stress response.

The scientists studied a sample of 36 brains. Twelve of these came from suicide victims who had been abused, 12 were from suicide victims who had not been abused and the remaining 12 were from people who had not committed suicide and had not been abused.

The researchers discovered different epigenetic markings in the brains of the group who had been abused. (Epigenetics is the study of changes in the function of genes that do not involve changes in the sequences of DNA.) These markings influence the 
hypothalamic-pituitary-adrenal (HPA) function, a stress response which increases the risk of suicide.

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

The researchers discovered that maternal care influences HPA function in rats through epigenetic programming of certain receptors in the brain. In humans, child abuse alters HPA stress responses and increases the risk for suicide.

“We know from clinical experience that a difficult childhood can have an impact on the course of a person’s life. Now we are starting to understand the biological implications of such psychological abuse,” the researchers said.

They added that research carried out on brain tissue is important because it can help develop intervention and prevention programmes to help people suffering mental distress and who are at risk of committing suicide.

Details of these findings are published in the journal, Nature Neuroscience.