PTSD: Genetically Inheritable?

PTSD has been shown to be one of the most debilitating conditions to live with, considering the constant re-experiencing of the trauma and the inability to cope with future stress.  There are now studies to show that PTSD may in fact be genetically passed on to the children of PTSD sufferers.

It is generally believed that there were 3 main factors that contributed to a person’s likelihood of developing PSTD.  A person’s predisposition to develop psychiatric illnesses, a person’s life experiences and traumas, and a person’s temperament are all contributing factors. 

With this new research comes a new debate: is the condition really passed down through the genes, is a predisposition passed down, or is the condition “taught”?

Rachel Yehuda did the first research with survivors of the Holocaust.  It was believed that those who survived would present with symptoms of PTSD, although there was not yet a diagnosis as such. The research was conducted on the children of these survivors to see whether they exhibited any symptoms, compared to the control group of people their age from non-PTSD parents. The studies showed that there were higher levels of Cortisol, the stress hormone, in the children of the PTSD parents. The children of the PSTD parents were shown to have trouble coping with stress, but didn’t show any significant differences in self-esteem or psychopathology. The research further showed that the more severe the PTSD in the parent was, the more severely the Cortisol levels in the children were affected. 

In further support of the heritability of PTSD an experiment was conducted where a generation of male mice were taken away from their parents at continuous but unpredictable intervals, until the age of 14 days.  Thereafter, their mother raised them normally.  This separation was seen as an early trauma and for the purpose of the experiment, these mice were then considered to be the equivalent of the 1^st generation Holocaust survivors.  These mice then had litters of their own which were raised without the trauma their male parent experienced. These mice were considered to be the equivalent of the children and grandchildren of the Holocaust survivors.  These mice, however, showed the same symptoms as their traumatized parents; isolation, jumpiness, skittishness and hyper vigilance. Examination of the father and offspring mice showed that all the genes that deal with stress were either over-active or under- active.  These genetic changes had been transferred to the offspring of the original trauma-affected male mice.  This study showed that traumatic stress may alter the regulation of genes in the germ line cells in males, meaning that the stress effects may be passed across generations. 

More recently, there has been the discovery of a specific gene, which could be responsible for PSTD.  The D2A1 allele genetic anomaly has been shown to determine the effectiveness of the D2 receptor (dealing with Dopamine), which can predict the onset of PSTD.

The idea of epigenetics was then introduced.  This is the change in the expression of DNA due to environmental factors, not an actual change in the DNA.  Blood samples taken from PTSD patients had 6 to 7 times the number of abnormalities in the function of genes in comparison to those not suffering from PTSD. In the offspring of PTSD sufferers, the epigenetic changes lead to reduced sensitivity.   They showed constant hyper vigilance, as if their bodies had been programmed into thinking that the world was simply too dangerous a place to ever relax.

On the opposite side of the scale, there are those who believe that the PTSD is passed on to the next generation by “teaching”.  It is very likely that parents who are suffering from PTSD are hyper vigilant, jumpy, neurotic, isolated and have a negative world-view.  If a child is raised in this environment, it can be expected that the child will learn some of these habits and also begin to exhibit the symptoms of a PTSD sufferer.

It would seem though, that a combination of the above theories makes the most sense.  One study divided the children of PTSD sufferers into two groups, the post-trauma children, children born after their parent/s had experienced a severe trauma, and the pre-trauma children, who were conceived before their parent/s had experienced a severe trauma. It was decided that the post-trauma children that displayed the symptoms of PSTD had both inherited the genetic abnormalities as well as learnt the symptoms from their parents.  The pre-trauma children that displayed PTSD symptoms could only have learnt them from their PTSD parent/s. Both groups did display symptoms of PTSD and so a combination of the two theories seems to be reasonable.

It is frightening to think that one could suffer from the symptoms of PTSD without having experienced a severe trauma, but ultimately that’s all it is; the symptoms.  One cannot be diagnosed as suffering from PTSD without the presence of a serious traumatic event.  This is according to the DSM-IV. So it would be fair to conclude that one can inherit genetic abnormalities from PTSD parents, inherit a predisposition to PTSD with a PTSD prone personality as well as learn the symptoms from a parent. However, it is not possible to actually inherit the PTSD, by its current definition.