The amount of close and comforting contact that babies young infants receive doesn’t just keep them warm, snug, and loved. A 2017 study says it can actually affect babies at the molecular level, and the effects can last for years. Based on the study, babies who get less physical contact and are more distressed at a young age, end up with changes in molecular processes that affect gene expression.
The team from the University of British Columbia in Canada emphasizes that it’s still very early days for this research, and it’s not clear exactly what’s causing the change. But it could give scientists some useful insights into how touching affects the epigenome – the biochemical changes that influence gene expression in the body.
During the study, parents of 94 babies were asked to keep diaries of their touching and cuddling habits from five weeks after birth, as well as logging the behaviour of the infants – sleeping, crying, and so on. Four-and-a-half years later, DNA swabs were taken of the kids to analyse a biochemical modification called DNA methylation. It’s an epigenetic mechanism in which some parts of the chromosome are tagged with small carbon and hydrogen molecules, often changing how genes function and affecting their expression.
The researchers found DNA methylation differences between “high-contact” children and “low-contact” children at five specific DNA sites, two of which were within genes: one related to the immune system, and one to the metabolic system. DNA methylation also acts as a marker for normal biological development and the processes that go along with it, and it can be influenced by external, environmental factors as well.
Then there was the epigenetic age, the biological ageing of blood and tissue. This marker was lower than expected in the kids who hadn’t had much contact as babies, and had experienced more distress in their early years, compared with their actual age. “In children, we think slower epigenetic aging could reflect less favorable developmental progress,” said one of the team, Michael Kobor.