epigenetic signatures

Violence at home can leave scars on your children’s – and grandchildren’s – DNA

Domestic violence can cause disruptions in how genes regulate mental and physical health in future generations.

Dr Nayreen Daruwalla has observed the direct effects of domestic violence on children in Mumbai’s slums. “Some drop out of schools, others start walking awkwardly, and some become perpetrators of violence themselves,” said Daruwalla, who is the programme director for prevention of violence against women and children at the non-profit organisation SNEHA.

Child rights workers and child psychologists have long observed how domestic violence leads to psychological impairments in children who have been victims or witnesses. However, research into how external environments affect a person’s DNA now tells us that the impact of violence-related stress on a woman may even be transmitted genetically to her children and grandchildren.

Fernanda Serpeloni, a psychology researcher at the University of Konstanz in Germany, has been studying how a person’s experiences change genetic expression – the way that genes are translated into the manufacture of proteins that regulate biological processes in the body. This area of research is called epigenetics, which Serpeloni describes as the study of “biological mechanisms that translate the quality of the social environment to the genome and can potentially affect child development even in future generations”.

In a recent paper published in the Nature group journal Translational Psychiatry, Serpeloni and her colleagues have described how domestic violence on a pregnant woman can affect the expression of her child’s genes in such a way that the child’s health might be affected. The fallout of violence does not stop there – the gene expression changes and health effects may also be passed down to the woman’s grandchildren.

Every person inherits a set of characteristics from his or her ancestors, which is determined by his or her DNA and articulated by his or her genes. Mutations in the DNA itself can change these characteristics and the changes can be passed down generations. But hereditary changes may also be brought about by molecules that attach to DNA that influence how genes are expressed. This is what epigenetic (epi being the Greek-origin prefix for over) researchers look at.

Among the the common molecules responsible for gene expression are methyl groups that attach to DNA and suppress gene expression. The methyl group binding can occur as a response to environmental changes like a shift in diet or exposure to chemicals. Epigenetic researchers have found that DNA methylation, where methyl groups attach to receptors on certain genes, also occurs in response to certain behaviours and stressors.

Scientists have also found that epigenetic changes can occur throughout the life of an individual– from the time period around conception right through to adulthood.

Serpeloni and her colleagues analysed DNA profiles of 121 children. They observed differences in DNA methylation of children whose grandmothers had reported experiencing intimate partner violence. Specifically, this DNA had methyl groups attached to genes that were associated with circulatory system processes and foetal development. Poor regulation of these genes could lead to heart failure, hypertension and congenital abnormalities.

“We observed that grand-maternal experiences of violence during pregnancy left epigenetic marks in different genes of grandchildren,” said Serpeloni. “We think about it as epigenetic memories of our ancestral experiences. That means violence impacts not only the person directly exposed but also future generations.”

Epigenetic changes can impact more than physical qualities like cardiovascular health and congenital development. In 2008, a study by pioneering epigenetic researcher Michael Meaney showed that the brains of suicide victims who had been abused as children had low levels of a glucocorticoid receptor that helps respond to stress. Since then, epigenetic links have been established between childhood exposure to trauma and incidence of depression, aggression, criminal behaviour and even repetition of abusive behaviour.

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Neurobiologist Michael Meaney explains why genetic variation and environment are interdependent factors in influencing a person's development. (Credit: McGill University/YouTube)

Nature and nurture

British psychoanalyst John Bowlby’s pioneering “attachment theory” explained how children have an innate need to attach to a person, usually their mothers. Bowlby studied how children in a hospital experienced traumatic disruptions every time there was a change in nurses on shift.

This showed that having a constant caregiver can help the child grow better compared to being in an environment where such an attachment figure is absent. Psychiatrist Dayal Mirchandani pointed out that, in Indian joint-families, children are sometimes close to other family members.

Psychologists have often found explanations of behavioral and mental health problems in children as a result of disruptive relationships with their caregivers, particularly parents.

“Children of alcoholic parents are more likely to have psychological problems,” said Mirchandani. “We don’t know whether it’s genetic or not.”

Epigenetics researchers, meanwhile, are testing the effect of parenting, or the lack of it, on growth of offspring. Scientists at the Indian Institute of Science Education and Research at conducted a study in which they separated newborn mice every day for three hours from their mothers, thus simulating a form of parental neglect. They found that mice that were separated showed some advantage in early adult life compared to mice that were not separated from their mothers.

“When we gave these mice some tasks, they fared better, which could be because of the element of street smartness which we see in humans too,” said Sanjeev Galande, team leader at the institute’s Center of Excellence in Epigenetics. But these mice that were exposed to parental separation lost their advantage of street smartness later in life. When the same tasks were given to them as adults, they performed poorly compared to mice that did not suffer separation.

“We saw a significant change in the hippocampus region of the brain,” said Galande. The hippocampus region of the brain is responsible for processing long-term memories and emotional responses and the changes may be transmitted epigenetically.

Experiences in early childhood in human beings have been seen to impact adults. “We know that children of women who have suffered from post-partum depression are more likely to develop anxiety and depression later in life, ” observed Mirchandani. This, he said, could be a result of a combination psychological, social and hereditary factors.

Cycle of violence

Epigenetic research also offers a different approach to understanding why victims of violence often turn into perpetrators of violence.

“In families where the father abuses the mother, we sometimes see that the male child also is abusive towards women, both at home and outside,” said Minu Gandhi, programme manager at Apnalaya, a non-profit working in the Govandi slum area in Mumbai. “Right now, we think that children who witness and face violence repeat the behaviour they experience in childhood.

Apnalay conducts a workshop on domestic violence with women from Govandi in Mumbai. (Photo: Apnalaya)
Apnalay conducts a workshop on domestic violence with women from Govandi in Mumbai. (Photo: Apnalaya)

Gandhi’s colleague Shweta Sinha, who has worked with children of sex workers, recalled a case of a 4-year-old boy with violent behaviour. “His mother was beaten during pregnancy and we were relating his behaviour to the violence at home. But, later he was diagnosed as a case of attention deficit hyperactive disorder. Now, it is difficult to point to one single reason for his behaviour,” she said.

But, epigenetics may hold answers to some of these questions. “Some children develop resilience, others don’t,” Sinha pointed out. “Is it that some children have changes in genes that help them adapt better?”

Public health impact

Epigenetic findings about the impact of domestic abuse has significant implications for public health in India.

According to the National Family Health Survey-4, 3% of married women suffer violence during pregnancy, The National Family Health Survey-4 is a representative study on various social and health indicators. Researchers have already found that nearly one in ten infant deaths in India can be attributed to domestic violence against the mother during the marriage. This is largely due to psychological stress on the mother leading to pre-term or low birth weight babies who are at higher risk of death. Given that physical and psychological risks may be transmitted epigenetically to children and grandchildren, the impact of domestic violence on morbidity and mortality may be much higher.

Daruwalla reiterated that children who are victims or witnesses of domestic violence are more likely to develop behavioural disorders later in life than children who grow up in non-abusive environments. “But, it is a combination of several factors, and we can’t really identify one cause,” she said.

In brain development, both genetics and environment play an important role, agreed Serpeloni. “Our brain has the capacity to adapt to stressful situations,” she said. “However, chronic and repetitive stress, such as domestic violence, might lead to maladaptive responses and negatively influence brain development.”

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