Early Experiences Have Lasting Effects on DNA
It is well established that certain early experiences can affect a person’s risk of developing a mental illness. Adversity in childhood, including abuse or the loss of a parent, is a risk factor not only for diagnosis of a mood disorder, but also for a more difficult course of illness. This may occur through epigenetic means. Epigenetics refers to a process by which environmental factors can change the way that DNA is transcribed, for example through the addition of methyl groups to strands of DNA. This tends to inhibit DNA from being transcribed and producing protein growth factors and other neurochemicals that are important for development.
A study by Kieran J. O’Donnell and colleagues presented at the 2015 meeting of the Society of Biological Psychiatry investigated whether epigenetics play a role in the success of a parenting intervention called the Nurse Family Partnership. Participants were 27-year-olds born to women who had received the intervention or a control intervention. Genome-wide DNA methylation was measured in the 188 participants’ blood.
Analysis of the blood revealed that the Nurse Family Partnership intervention was associated with DNA methylation at 1015 sites across 593 genes. Some of these sites were enriched for certain neurodevelopmental processes. Maltreatment in childhood was also associated with methylation at 1552 sites across 878 genes.
Editor’s Note: The take-home message of this landmark study is that maltreatment in childhood exerts lasting effects on the genome via epigenetic mechanisms, but early positive intervention also exerts lasting epigenetic effects, which likely have a normalizing impact.
Harsh Physical Punishment is Associated with Mood and Other Disorders
Physical punishment of children has long been a controversial subject. A 2012 article by Afifi et al. in the journal Pediatrics suggests that having experienced harsh physical punishment during childhood is associated with mood disorders, anxiety disorders, substance abuse and dependence, and personality disorders in adulthood.
In this study harsh physical punishment included pushing, grabbing, shoving, slapping, or hitting. Participants who had experienced more severe maltreatment in childhood (including physical abuse, sexual abuse, emotional abuse, physical neglect, emotional neglect, and exposure to violence between intimate partners) were excluded from the study, and the results were adjusted for sociodemographic variables and family history of dysfunction, suggesting that physical punishment was the mediator of these effects.
Parental Nurturing Linked to Greater Hippocampal Volume in Young Children
An article published by Medscape reports that in a recent study by Dr. Joan Luby of Washington University School of Medicine in St. Louis, non-depressed preschool children whose parents showed more nurturing behaviors during a mildly stressful task were found to have hippocampal volume almost 10% greater than their peers whose parents showed fewer nurturing behaviors. The hippocampus affects cognitive functioning and emotion regulation.
Unfortunately, parental nurturing did not effect the hippocampal volume of children with early-onset depression.
Dr. Luby and colleagues think their findings could have “profound public health implications and suggest that greater public health emphasis on early parenting could be a very fruitful social investment.”
“The finding that early parenting support, a modifiable psychosocial factor, is directly related to healthy development of a key brain region known to impact cognitive functioning and emotion regulation opens an exciting opportunity to impact the development of children in a powerful and positive fashion”.
