Nurse home visits may leave genetic marks on children
In the 1970s, a pediatrician developed a program in New York with an ambitious goal: to help children of teenage mothers even before they were born.
The Nurse Family Partnership paired nurses with vulnerable, first-time mothers throughout their pregnancy and until the child’s second birthday. These children encountered less abuse and grew up to be more social and commit fewer crimes as adolescents.
Twenty-seven years later, researchers found the program’s effects may also show up on the children’s DNA. The new study led by CIFAR Azrieli Global Scholar Kieran O’Donnell is the first epigenetic analysis of the program. It also offers the first evidence of an intervention program for mothers influencing children’s epigenetic markers.
O’Donnell and a team of researchers including CIFAR Child & Brain Development Senior Fellows Michael Meaney (McGill University) and Michael Kobor (University of British Columbia) published their findings in Translational Psychiatry.
This study was born out of a chance meeting with the founder of the Nurse Family Partnership, David Olds.
“He mentioned that they were collecting blood samples for the first time and my ears perked up. This was really exciting,” says O’Donnell, who is an assistant professor in epigenetics and epidemiology at McGill University.
With blood samples from the grown children, O’Donnell and his colleagues could analyze DNA methylation – marks added to the DNA that affect how genes are expressed. The analysis found an association between children whose mothers were part of the program and variation in their DNA methylation. These preliminary results are the first to suggest that a perinatal intervention would affect variation in DNA methylation.
Conventionally, DNA methylation was thought of as a light switch that turns genes on and off. However, the effects of this epigenetic modification are much more complicated and depend on where in the gene it is laid down.
“So not only is DNA methylation acting somewhat like a dimmer switch, influencing the brightness of the light, but it can also influence the type of message produced from a gene, so in a sense influencing the tone of the light,” O’Donnell explains.
The study also provided more evidence of how childhood adversity shapes DNA methylation. While this relationship has already been established, the study helps show how some of these experiences ‘get under the skin.’ Children who were maltreated had a higher rate of smoking and in turn smoking had a profound effect on DNA methylation.
These findings could help answer a question at the core of CIFAR’s Child & Brain Development program: how does the environment communicate with the genome to influence child development?
“There’s marked individual differences in the effects of child maltreatment. The question is whether or not we can use biology to better understand risk, or conversely, if such biological measures will tell us more about an individual’s likelihood to respond to an intervention that seeks to buffer the effects of early adversity,” says O’Donnell.
Before getting to this clinical stage, researchers will need to demonstrate a causal link between interventions and DNA methylation. The Nurse Family Partnership faced some limitations because samples were collected 27 years later and there are many factors that could have shaped variation in DNA methylation during that time.
O’Donnell is collaborating with a number of cohorts to tackle this issue much earlier in life, beginning before birth. O’Donnell hopes such studies will help determine if there is a causal association between early intervention programs, such as the Nurse Family Partnership, and epigenetic variation in the child.
“DNA methylome variation in a perinatal nurse-visitation program that reduces childmaltreatment: a 27-year follow-up” was publish Jan. 10 in Translational Psychiatry.
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