Researchers have confirmed that exposure to adverse events in childhood can lead to alterations in DNA and affect brain development too, contributing to neuropsychiatric conditions such as depression and schizophrenia.

Experiencing an adverse environment in childhood may lead to alterations in the DNA and influence brain development in children when they grow up, finds a study on mice. "We are taught that our DNA is something stable and unchanging which makes us who we are, but in reality it's much more dynamic," said Rusty Gage, Professor at the Salk University in La Jolla, US.

"It turns out there are genes in your cells that are capable of copying themselves and moving around, which means that, in some ways, your DNA does change," Gage added. Previous studies had shown that most cells in the mammalian brain undergo changes to their DNA that make each neuron, for example, slightly different from its neighbour.

Some of these changes are caused by "jumping" genes -- officially known as long interspersed nuclear elements (LINEs) -- that move from one spot in the genome to another. One of the jumping genes, called L1, which was already known to copy and paste itself into new places in the genome, could jump in developing neuronal brain cells, researchers had found. The team had then hypothesised that such changes create potentially helpful diversity among brain cells, fine-tuning function, but might also contribute to neuropsychiatric conditions such as depression and schizophrenia.

For the new study, published in the journal Science, the researchers observed natural variations in maternal care between mice and their offspring. They then looked at DNA from the offspring's hippocampus, which is involved in emotion, memory and some involuntary functions. Results noted a correlation between maternal care and L1 copy number: Mice with attentive mothers had fewer copies of the jumping gene L1, and those with neglectful mothers had more L1 copies, and thus more genetic diversity in their brains. "This finding agrees with studies of childhood neglect that also show altered patterns of DNA methylation for other genes," Gage said. "That's a hopeful thing, because once you understand a mechanism, you can begin to develop strategies for intervention," he noted.