Pregnancy: Violence leaves epigenetic traces

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Expectant mothers must take care to avoid real or perceived harm; serious stress can lead to changes in the child-to-be’s genome. Source: Harry Hautmann/pixelio.de

14.09.2011  - 

Pregnancy is a highly sensitive time for both mother and child. It has been known for a long time that any considerable strain experienced by expectant mothers can have an effect on the unborn child. Researchers at the Genomics Center (GeCKo) at the University of Konstanz have now demonstrated that stressful experiences during pregnancy can even influence the genetics of the child-to-be. A working group led by psychology professor Thomas Elbert and Axel Meyer, Professor of Behavioural Biology at the University of Konstanz, have shown that children of mothers exposed to domestic violence during pregnancy have a higher genetic predisposition to behavioural problems and mental disorders. The GeCKo is funded within federal and state excellence initiatives. The results have been published in the scientific journal Translational Psychiatry (2011, online edition).

The process specifically concerns the glucocorticoid receptor gene, a hereditary predisposition that scientists have linked to behavioural problems and stress resistance. The team of scientists headed by Elbert and Meyer have demonstrated that ongoing threat situations and the related stress in the expectant mother triggers an epigenetic change in the methylation patterns of the gene. The methylation patterns influence the expression of the predisposition without changing the DNA itself. This is not a matter of a mutation in the child's genes. Instead, aided by specific enzymes, individual genes are switched on or off. There is similar evidence in cancer research, where it has been proven that regularly drinking green tea lowers the genetically inherited risk of cancer – a substance in the drink alters the corresponding gene expression. If an expecting mother is faced with a constant threat, the genetic predisposition for stress resistance will chemically affect the child.

“The cycle of violence is transported epigenetically,” says Elbert. The Professor of Clinical Psychology works with traumatised patients who have experienced domestic violence; many come from war and crisis regions. Elbert analysed the effects of violence on groups of children and youths aged ten to 19. “The stress axis is more prone in children of women who report a variety of stressors during pregnancy,” he explains. The body of the mother prepares the children for life in a threatening situation: Later, the children are more anxious and less curious. “Our investigations show that the mother prepares the unborn child for later life via the epigenetic code,” summarises the Professor of Psychology. Similar correlations have also been demonstrated in children of women who experienced the ‘Winter of Hunger’ after the Second World War. “Many of the children of mothers who had not eaten enough during pregnancy tended to be overweight”, says Elbert.

Such changes were previously only known in the immune system – children of stressed mothers are more vulnerable to diseases; related research into neural memory is also underway. Studies on rhesus monkeys have shown that the readability of genes is significantly altered as a result of stress. “If the children are separated from monkey mothers at a young age, one-fifth of the genes are differently methylated; the young are not as resistant to stress,” says Elbert. For his young patients, this knowledge can be used to make predictions about possible predispositions to behavioural problems.

An absolute causal relationship has not been proven, emphasise the researchers. The scientists are still at the beginning of their research into epigenetic changes. In the meantime, these abnormalities can also be detected with blood tests.  “It is new to be able to read the epigenetic code from the blood,” says Elbert. “We still know very little in humans.” For this reason, the working groups in Constance want to expand their investigations into the cortisol receptor gene to the full human genome, and characterise its exact effects. With this knowledge of biological mechanisms, we could one day possibly see predictions about predisposition to disease from blood tests, or even manipulate these dispositions accordingly. “These are questions that extend to the foundations of a society,” says Elbert. In this case, the simplest remedy is prevention: “Of course, the best approach is to protect pregnant women from violence.”

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