Dr. Evelien Van Assche presented her work in Vienna at the ECNP Congress and said that her researchers discovered that when a child experiences physical punishment and psychological manipulation, i.e., strict parenting, it can lead to a change in the DNA that introduces an extra set of instructions on how a gene is read to become more hardwired in the DNA. They have found some indications that the growing child can be predisposed to depression with these changes. If the child has a supportive parent and upbringing, then this does not happen to the same extent.
The researchers, from the University of Leuven in Belgium, chose 21 children who said they had good parenting (ex-parents being supportive and giving freedom to children) and 23 children who experienced bad parenting (ex-excessive strictness, physical punishment, manipulative behaviour) and compared them. All the children in this research were between the ages of 12 and 16 years old, with 14 being the mean for both groups. 11 children from both groups were boys and the rest were girls, which means that both groups were comparable (similar age and similar distribution). It was found that many children showed initial subclinical signs of depression when they reported saying that they had experienced strict parenting.
When they measured it, researchers found that there was a significant increase in methylation in more than 450,000 places in the DNA. Methylation is a common process that takes place when a tiny chemical molecule is added to the DNA, altering how the instructions contained in your DNA are read. For instance, methylation could make a gene produce more or less of a certain enzyme than it otherwise would.
Depression has been linked to increased methylation variation. Evelien Van Assche said that they based their strategy on earlier work with identical twins. Two different research teams discovered that the twin with significant depression also had a wider range of DNA methylation than the healthy twin for most of these hundreds of thousands of data points.
The DNA is unchanged, but the new chemical groups have an impact on how the DNA instructions are read, according to Dr Van Assche (who is currently employed at the University of Münster in Germany). We hypothesised that the inclination towards depression was baked into the DNA of those who experienced harsher parenting through greater methylation variation.
They are currently attempting to close the loop by connecting it to a later diagnosis of depression. If they are successful, they may be able to utilise this enhanced methylation variation as a marker to identify those who may be more susceptible to developing depression as a result of their upbringing.
The influence of strict parenting was examined in this study, but it’s probable that any severe stress may cause similar changes in DNA methylation. As a result, stress experienced as a kid may affect how your DNA is read in later life, increasing your risk of developing depression. However, bigger sample size is required to corroborate these findings.
Without taking part in the study, Professor Christiaan Vinkers of the Department of Psychiatry at Amsterdam University Medical Centre said that this is an extremely important study to understand the mechanisms by which adverse childhood experiences have life-long effects on both mental health and physical health. If we can figure out who is at risk and why different types of harsh parenting have different results, we will benefit greatly.