Reply To: Rachel Yehuda – epigenetics and trauma

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Very amazing article, Aleks.
Here are some excerpts:

More recently, a relatively large epigenetic study of the Dutch hunger cohort (422 exposed and 463 sibling controls) identified alterations in DNA methylation specifically associated with in utero exposure to maternal famine152. Among those exposed early in gestation, additional CpG mediators were identified. Interestingly, exposure to famine during pregnancy had biological and behavioral effects on grandchildren, such as on adiposity153. This transgenerational effect has been attributed to the fact that prenatal exposure directly impacts both the fetus and the fetal germ cells, thus directly exposing the third generation. In a recent study, grandmaternal stress during pregnancy was associated with genome‐wide methylation changes in offspring and grandchildren154.

In one study, male mice were fear conditioned with an odorant at two months of age (post‐puberty but not yet adults)175. The odorant acetophenone paired with an electric shock resulted in behavioral sensitivity in the fear conditioned mice, with an accompanying change in DNA methylation in brain and sperm of the M71 receptor, which is involved in sensing acetophenone. An increased size in the M71 specific glomeruli in the olfactory epithelium and bulb was also observed175. The offspring (F1) of odor conditioned F0 males mated with naïve females also showed similar changes in brain and sperm. When the F1 males were themselves mated, changes in brain persisted in the F2 male offspring, demonstrating conservation of the effect through two generations.

These guidelines should be kept in mind as studies on effects of trauma on offspring in the next and subsequent generations are pursued. The concept of intergenerational transmission has resonated among offspring who feel affected by their parents’ experience. The concept has also been embraced by communities that are affected by significant traumatic experiences through several generations. That there may be a biological or molecular representation of an intergenerational effect appears to validate the experience of offspring who may feel that they bear effects of their parents’ hardship, even if the concept may also carry an implication that they are damaged, impaired, or permanently disadvantaged. It is also important to underscore the lack of permanence of effects once environmental conditions are altered.