The biochemistry of generational trauma

After her presentation this month at a conference in Boston, Rachel Yehuda unofficially earned the title of the “Robin Williams of biochemistry.” She deserves it. It is refreshing to hear an academic of her considerable bandwidth bring wit, charm and humor to her topic. But the presenter who gave her that title also joked that he had decided, on hearing her, to abandon a longstanding and distinguished career as a psychotherapist to become a biochemist, so powerful was Yehuda’s work in explaining the challenge to those of us who deal with trauma, biochemist or not. At the center of this lies cortisol.

Cortisol is the marker of stress, a chemical our bodies make when we are under fire, in fight and flight. High cortisol indicates trouble, or so the conventional thinking went, but then this story is full of conventional thinking that needed to be turned on its head. As with many stories in psychiatry, this one is rooted in rats, and the research was aimed at passing on wellbeing, not trauma, from one generation of rats to another. To do this, researchers handled and cuddled mother rats each day to see if they would pass on affection to their young. Sure enough, fondled mothers did indeed spend more time fawning over and licking the pups, and pups did show lower levels of cortisol. So far so good? Not really.

First, understand the complicated role of cortisol. It is indeed present in people under stress in higher levels, but it is there for a reason. Cortisol helps us shut down fight and flight, that is, returns the body clenched by stress to a normal state, and this is precisely what people suffering from PTSD or developmental trauma cannot do. Further, we now understand that these people can’t do this, at least in part, because their bodies do not produce cortisol. Taking them to their trauma trigger does not produce increased cortisol, the chemical tracer of PTSD. High cortisol levels do indeed indicate stress in most people, but low cortisol levels in those under stress announces PTSD.

So what’s up with the rats? The experiment was based on a couple of assumptions: One was that handling mothers pleases them, but if you think about this, only people in white lab coats could consider a rat a warm cuddly. How would you like to be tossed around by something a couple of orders of magnitude larger than you are? Handling stresses them. The second assumption was that the licking and fawning was nurturing the pups. It wasn’t. The mother was responding to her stress by being overprotective, which was exactly the source of stress Yehuda discovered in second-generation holocaust survivors. Traumatized mothers were frightened mothers, behavior that in turn traumatized their children. One can trace this across generations with low cortisol, as researchers did indeed do with the rats.

But this is where the story takes us well beyond rats to a more sobering look at inter-generational trauma. “Generation” and “gene” have the same root word for a reason, and cortisol is, like everything else that makes our bodies work, a gene product. Can trauma be passed on not by licking, but by genes? It does, after all, run in families. It turns out that it can’t, and Yehuda cites some family patterns to show this. (This is also why this malady, developmental trauma, is a very different beast from, say, anxiety or depression, no matter what the powers of the American Psychiatric Association might say. (A cheap shot, and I will elaborate on this in subsequent postings.)) Both of the latter disorders run in families, and children are just as likely to have them, no matter which parent suffered. But with PTSD, children are far more likely to have it if their mothers did. Because a child’s genes are as likely to come from father as mother, the patterns with anxiety and depression suggest a genetic route; the pattern of PTSD rules it out.

But now we can turn this story on its head one more time. If a PTSD sufferer’s cortisol level is low and genes make cortisol, what’s wrong with the genes? It is something called “methylation” Genes are geometry and make cortisol by transcribing RNA that is a perfect mirror image of the chemical. But it turns out that when the transcription process unzips to recruit the elements of cortisol, it can also recruit methyl compounds that are geometric matches to the allele for making cortisol. The methyl compounds lock on and prevent the manufacture of cortisol. This methylation process endures and becomes a part of a PTSD sufferer’s body chemistry, at least until some successful intervention reverses it.

Now for the interesting and sobering part for those of us who battle inter-generational trauma. This faulty biochemistry can be inherited by infants in utero. The inheritance is not genetic. It is epigenetic, but physical, hard-wired inheritance, nonetheless. Immediately, this reshapes our story and offers some pretty firm marching orders in regards to how we treat infants of mothers with PTSD.

But beyond, it gives us some elegant and sophisticated physical evidence about PTSD. And further beyond, the whole story wonderfully deconstructs the nature/nurture and body/mind dichotomies, just as does PTSD. It is neither. It is both. It is also nicely subversive to received biological wisdom in that it makes way for a neo-Lamarckian view of evolution. All in all, not a bad day’s work.

(Yehuda’s paper on this has been provisionally accepted for publication by the Journal of Traumatic Stress, and if one of you spots it before I do, I’d appreciate a heads up so we can share it with all. She presented at the 20^th Annual International Trauma Conference in Boston, and I’ll post more reports from the conference during the coming weeks.)

Dick Manning