Harsh parenting leads to depression later in life

Strict parenting can influence how the body reads the children’s DNA. These modifications can become “hard-wired” into the DNA of kids who consider their parents to be harsh, enhancing their biological risk for depression in adolescence and later life.

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The study was presented at the ECNP Congress in Vienna.

We discovered that perceived harsh parenting, with physical punishment and psychological manipulation, can introduce an additional set of instructions on how a gene is read to become hard-wired into DNA. We have some indications that these changes themselves can predispose the growing child to depression. This does not happen to the same extent if the children have had a supportive upbringing.”

Dr Evelien Van Assche, University of Münster

The investigators, from the University of Leuven in Belgium, chose 21 adolescents who claimed good parenting (such as the parents’ support and allowance of the kids’ autonomy), and they compared them to 23 adolescents who reported severe parenting (for instance, physical punishment, manipulative behavior, and excessive strictness).

All of the adolescents were between the ages of 12 and 16, with a mean age of 14 for both groups. Both groups had 11 adolescents who were boys, indicating that the two groups were equal in terms of age and gender distribution. Many of those who had been subjected to harsh parenting displayed early, subclinical indicators 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 that 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.  Increased variation in methylation is known to be associated with depression.

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 Evelien Van Assche, University of Münster

Dr Van Assche adds, “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.”

Dr Evelien Van Assche, University of Münster

Dr Van Assche states, “In this study we investigated the role of harsh parenting, but 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.”

“This is extremely important work to understand the mechanisms how adverse experiences during childhood have life-long consequences for both mental health and physical health. There is a lot to gain if we can understand who is at risk, but also why there are differing effects of strict parenting,” added commenting, Professor Christiaan Vinkers, Department of Psychiatry, Amsterdam University Medical Centre.

Professor Vinkers was not involved in this study.