Stressed fathers ‘raise risk of mental illness in unborn child’

MEN experiencing stress could father children with a greater risk of developing mental illness, research suggests.

Even mild stress can cause damage to a man’s sperm which triggers biological changes in his offspring, the study showed.

In tests on mice, abnormal reactions to stress were seen in the children of stressed fathers. Mild stress was created in the father mice by placing them in a tube – where their levels of stress hormones were measured.

The offspring fathered by the ‘stressed’ mice were later placed in similar stress situations – and found to have lower levels of the stress hormones.

This so-called ‘blunted’ hormonal response has been found in people who develop a variety of mental disorders, including post- traumatic stress disorder and autism.

Scientists believe the stress on the father temporarily affects the DNA in his sperm. Putting the mice in fraught situations caused molecules known as micro-RNA to be released. These micro-RNA switched off the genes in the DNA of the father’s sperm responsible for producing stress hormones.

This led to the baby born from the affected sperm having impaired responses to stress compared to normal.

The offspring were more susceptible to the conditions, such as PTSD, associated with this hormonal shortage.

It has long been known that a mother’s condition during pregnancy can harm her child – with damage caused by factors such as poor diet, stress or infection.

But the latest research highlights how a father’s health at the time of conception can also have an impact.

The findings are important because they show how changes in environment can be passed on to further generations. Speaking at the 2018 AAAS annual meeting in Austin, Texas yesterday, Professor Tracy Bale, from the University of Maryland, said: ‘The findings were fascinating and very surprising.

‘We dealt very mild stress to the dads. I would not equate it to trauma, but mild chronic periods of stress – the type all of us experience in our lives.

‘This effect lasts a very long period. We have not been able to review the animals long enough that the effect is washed out.’

Professor Bale’s research suggests that even mild environmental challenges can have a significant impact. She said: ‘We now know dad’s stress is ultimately reprogramming his offspring’s stress levels.’

Professor Bale said the offspring of a stressed male would have a ‘dampened’ stress reaction, but that too much dampening can be linked to psychological disorders.

She said one application of the research could be to screen the sperm of soldiers returning from war.