Stressed dads can affect offspring's brain development

Dads-to-be, please note! Stress felt by the father - whether as a preadolescent or adult - leaves a lasting impression on his sperm that can affect his offspring's brain development, a new study has found.
The findings by researchers at the University of Pennsylvania, point to a never-before-seen epigenetic link to stress-related diseases such as anxiety and depression passed from father to child.
While environmental challenges, like diet, drug abuse, and chronic stress, felt by mothers during pregnancy have been shown to affect offspring neurodevelopment and increase the risk for certain diseases, dad's influence on his children are less well understood.

The team of researchers led by Tracy L Bale, associate professor of neuroscience in the Perelman School of Medicine Department of Psychiatry and the School of Veterinary Medicine Department of Animal Biology have shown that stress on preadolescent and adult male mice induced an epigenetic mark in their sperm that reprogrammed their offspring's hypothalamic-pituitary-adrenal (HPA) axis, a region of the brain that governs responses to stress.
Surprisingly, both male and female offspring had abnormally low reactivity to stress.
This stress pathway dysregulation - when reactivity is either heightened or reduced - is a sign that an organism doesn't have the ability to respond appropriately to a changing environment.

And as a result, their stress response becomes irregular, which can lead to stress-related disorders.

"It didn't matter if dads were going through puberty or in adulthood when stressed before they mated. We've shown here for the first time that stress can produce long-term changes to sperm that reprogramme the offspring HPA stress axis regulation," said Bale.
"These findings suggest one way in which paternal-stress exposure may be linked to such neuropsychiatric diseases," Bale said.
In the study, male mice were exposed to six weeks of chronic stress, before breeding, either throughout puberty or only in adulthood.
Researchers found that offspring from paternal stress groups displayed significantly blunted levels of the stress hormone corticosterone - in humans, it is cortisol - in response to stress.

The authors pointed out that a reduced physiological stress response may reflect some adaptive evolutionary benefit passed on to offspring to ensure survival in what is expected to be a more stressful environment.
The findings were published in the Journal of Neuroscience.