Strict discipline of children can alter the way the body reads DNA, scientists find

Physical punishments and psychological manipulation can alter the way that the body reads the DNA, new research has found, and these changes can become hard wired to the DNA of children who perceive adults who care for them as “harsh”, increasing their risk of depression in adolescence and beyond.

The work of the researchers, from the University of Leuven in Belgium, was presented at the ECNP Congress in Vienna recently by Dr Evelien Van Assche.

To reach their findings, the researchers chose 21 adolescents who reported good parenting (for example, the parents being supportive and giving the children autonomy), and compared them with 23 adolescents who reported harsh parenting (for example, manipulative behaviour, physical punishment, excessive strictness).

All adolescents were between 12 and 16 years old, with a mean of 14 years for both groups. For both groups 11 adolescents were boys meaning that the two groups were comparable, with a similar age and a similar, boy-girl distribution. Many of those who had experienced harsh parenting showed initial, subclinical signs of depression.

The researchers then measured the range of methylation at more than 450,000 places in the DNA of each subject and found that this was significantly increased in those who reported a harsh upbringing. Methylation is a normal process which occurs when a small chemical molecule is added to the DNA, changing the way that the instructions written in your DNA are read: for example, methylation may increase or decrease the amount of an enzyme produced by a gene.

“We based our approach on prior research with identical twins. Two independent groups found that the twin diagnosed with major depression also had a higher range of DNA methylation for the majority of these hundreds of thousands of data points, as compared to the healthy twin,” Dr Van Assche said.

“The DNA remains the same, but these additional chemical groups affect how the instructions from the DNA are read. Those who reported harsher parenting showed a tendency towards depression, and we believe that this tendency has been baked into their DNA through increased variation in methylation.”

“We are now seeing if we can close the loop by linking it to a later diagnosis of depression and perhaps use this increased methylation variation as a marker, to give advance warning of who might be at greater risk of developing depression as a result of their upbringing”.

While the study focused on harsh discipline, she continued “it’s likely that any significant stress will lead to such changes in DNA methylation; so in general, stresses in childhood may lead to a general tendency to depression in later life by altering the way your DNA is read. However these results need to be confirmed in a larger sample”.

The work adds to a growing body of research which suggests that adverse experiences during childhood have life-long consequences for both mental health and physical health.

Having just been presented at the Congress, the findings have not yet been made available. To access Dr Van Assche’s presentation, please visit the dedicated Congress website, here.