Strict parenting may 'hard-wire' depression risk — but brain changes are possible

Strict parenting can alter the way the body reads the DNA of children, according to research presented at last month’s European College of Neuropsychopharmacology Congress in Vienna. These changes can effectively become ‘hard-wired’ to the DNA of those children who perceive their parents as harsh, increasing their biological risk for depression in adolescence and later life.

Researchers from KU Leuven selected 21 adolescents who reported good parenting (eg, the parents being supportive and giving the children autonomy) and compared them with 23 adolescents who reported harsh parenting (eg, manipulative behaviour, physical punishment, excessive strictness). 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. Increased variation in methylation is known to be associated with depression.

“We based our approach on prior research with identical twins,” said team member Dr Evelien Van Assche, now working at the University of Munster. “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.

“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.”

Van Assche said it was likely that any significant stress — not just harsh parenting — could 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 good news is that while scientists previously believed that the structure of the adult brain is generally rigid and incapable of rapid changes, researchers from the University of Muenster have now shown that this is not true. Their research presented at the Congress showed that in-patient treatment for depression can lead to an increase in brain connectivity, and those patients who respond well to this treatment show a greater increase in connectivity than those who don’t.

The researchers studied 109 patients with serious depression and compared them with 55 healthy controls. Their brains were scanned using an MRI scanner that had been set up to identify which parts of the brain were communicating with other parts, determining the level of connections within the brain. The patients were then treated for depression — some with electroconvulsive therapy (ECT), some with psychological therapy or medication, and some with a combination of all therapies. After treatment they were then rescanned and the number of connections recounted. They were also retested for symptoms of depression.

“We found that treatment for depression changed the infrastructure of the brain, which goes against previous expectations,” said team member Professor Jonathan Repple, now at the University of Frankfurt. “Treated patients showed a greater number of connections than they had shown before treatment. Moreover, those who showed the most response to treatment had developed a greater number of new connections than those who showed little response.

Representative map of the affected connections in the brain. The number of these connections increased after treatment. Image credit: Jonathan Repple.

“A second scan showing that there are no time effects in healthy controls supports our findings that we see something that is related to the disease and more importantly, the treatment of this disease. We found these changes took place over a period of only around six weeks; we were surprised at the speed of response. We don’t have an explanation as to how these changes take place or why they should happen with such different forms of treatment.

“This means that the brain structure of patients with serious clinical depression is not as fixed as we thought, and we can improve brain structure within a short time frame … We found that if this treatment leads to an increase in brain connectivity, it is also effective in tackling depression symptoms. This gives hope to patients who believe nothing can change and they have to live with a disease forever, because it is ‘set in stone’ in their brain.”

Top image credit: iStock.com/dragana991

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