First three years decide a child’s future

Early years of a child are critical. Aside from shaping up health, childhood decides happiness, growth, learning skills, and also somebody’s life in family and society. Because, in the first three years, the brain grows great deal establishing important pathways for future development. As a result, early life experiences influence DNA in the adult brain, says a study. In more clear terms, childhood environments affect brain development.

This could provide insights into neuropsychiatric disorders such as depression and schizophrenia. A research on mice proves this. When mice pups were neglected by their mother, it triggered 'jumping' genes in mice brain cells. Human DNA is believed to be stable and unchanging. But in reality, it is much more dynamic, says Rusty Gage, a professor in Salk's Laboratory of Genetics, California. There are genes in your cells that are capable of copying themselves and moving around, which means your DNA does change.

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). They move from one spot in the genome to another. In 2005, the Gage lab discovered that a jumping gene called L1, which can copy and paste itself into new places in the genome, could jump in developing neuronal brain cells.

Such changes, according to scientists, could create potentially helpful diversity among brain cells, fine-tuning function; these changes might also contribute to neuropsychiatric conditions such as autism spectrum disorder.

In order to know this, scientists observed natural variations in maternal care between mice and their offspring. They then looked at DNA from the offspring's hippocampus, which manages emotion, memory and some involuntary functions.The researchers observed how mothers raised their offspring over a period of two weeks. They were then divided into groups based on how the mothers cared for their brood, how they licked and nursed them.

There is a clear relationship between maternal care and L1 copy number. The worse the care, the more times the gene copied itself and relocated. Mice with attentive mothers had fewer copies of the jumping gene L1, and those with neglectful mothers had more L1 copies.

Offspring whose mothers were neglectful were more stressed. Somehow this made genes to copy and move around more frequently. Interestingly, there was no similar correlation between maternal care and the numbers of other known jumping genes, which suggested a unique role for L1.

The team also looked at methylation—the pattern of chemical marks on DNA—that signals whether genes should or should not be copied and that can be influenced by environmental factors.

Mice with neglectful mothers had noticeably fewer methylated L1 genes than those with attentive mothers, suggesting that methylation is the mechanism responsible for the mobility of the L1 gene.

Exactly what this means for humans is a matter for future studies. But it's a sign that our childhood experiences could have effect right down to the level of our genes.