A viral infection during pregnancy not only affects a woman’s subsequent ability to provide maternal care, a new study has found, but it can also trigger depression in her offspring, which can then even extend into the next generation as a result of changes to genetic mechanisms in the brain.

In a transgenerational study conducted at MedUni Vienna, researchers were able to demonstrate several effects in a mouse model.

First, stimulation of the immune system, comparable with a viral infection in the pregnant mother, results in diminished maternal behavior towards her offspring after birth. This results in the tendency for offspring to develop depression. Daughters in their turn are less maternal towards their own offspring, even if they suffer no infection, so that the next generation is also more likely to develop depression.

Transgenerational Epigenetic Changes

Daniela Pollak, of the Division of Neurophysiology and Neuropharmacology, explains:

“We were therefore able to show that there is a transgenerational effect and that epigenetic changes occur in the brain."

Pollak, together with her team, is concerned with identifying the neurobiological bases of psychiatric illnesses, particularly depression and anxiety disorders.

Although epigenetic changes do not involve any change in the actual DNA sequence of the individual in question, changes due to external influences, such as the lack of maternal care in this case, take the form of changes in DNA methylation (modulation of the basic building blocks of the genetic material of a cell) or histone acetylation (modulation of the histone proteins).

Says Pollak:

“This brings about a change in the regulatory mechanisms, how the genes are read."

This in turn can lead to a permanent behavioral change or development of a mental illness. Additional studies are now required to clarify the causality.

For example, does infection of the mother in itself affect the baby’s brain, and cause the development of depression? Also, what exactly happens in the mother’s brain during infection. Further studies will even look at the father’s behavior.

It has previously been proven that an premature start in life – approximately one in ten children in the world is born prematurely before the 32nd week of gestation – is often associated with impaired cognitive and emotional development.

Marianne Ronovsky et al. Maternal immune activation transgenerationally modulates maternal care and offspring depression-like behavior Brain, Behavior, and Immunity (2016). DOI: 10.1016/j.bbi.2016.10.016

Image: Medical University of Vienna

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