Trauma occurs when a threatening experience causes our brains and bodies to "lock into" a state of high alert and stay there, says pioneering psychiatrist and researcher Bessel van der Kolk.
To heal from trauma, we need treatments and practices that instil a sense of physical and psychological safety, he tells Kim Hill.
When a child experiences a disturbing event, they may not have the cognitive capacity to understand they're not to blame themselves, says Van der Kolk, who is best known for his 2014 best-seller The Body Keeps the Score.
"Children by necessity are egocentric. They don't know about other people's feelings. So when something happens to a child their natural reaction is 'this is because of me'.
"Children are the centre of their own world so if bad things are done to them their interpretation of that is 'this is happening to me because I must be a bad person'."
Our brains are programmed not to remember things accurately but to integrate and learn from our experiences, van der Kolk says, and we now know dreaming is part of this process.
"[Dreaming] helps your brain select what was important the day before and to connect it with your past experiences.."
What separates a traumatic memory from a non-traumatic memory is that the former does not get integrated into the narrative but neither does it fade or go away.
"[Trauma results from] a failure of the brain to make [an experience] into a memory belonging in the past."
One way to change the "orientation" of our brains away from trauma is to have new experiences that directly contradict the negative experiences it previously seemed to cling to, van der Kolk says.
He counts himself and his siblings very lucky to find loving partners that have given them an experience of nurturing that their "very traumatised" mother could not provide.
"You can get a later imprint of what it feels like to be loved. And if that works very deeply then the old experience loses some of its relevance in some ways."
Parents transmit their own trauma to their children through attitudes, behaviours and also genetically, he says.
"We inherit the capacity to be compassionate and loving and we also inherit our anger and our rage and our disappointment from our parents."
As a treatment for healing trauma, commonly prescribed antidepressants Prozac and Zoloft can be somewhat helpful but they don't really change anything, van der Kolk says.
Neither was Austrian psychoanalysis pioneer Sigmund Freud correct in his belief that talk therapy was the one true cure.
While validation and compassion are important for healing trauma, revisiting troubling events in conversation doesn't "soften" the memories of them, van der Kolk says.
"Understanding why you're screwed up does not necessarily make you less screwed up."
What has been proven to help people become less screwed up are activities that help the body to calm itself down.
For most people, regular yoga practice is more effective than Prozac in helping to recover a sense of physical safety, he says.
"These movements and the breathing seem to change brain circuits. The brain circuits of fear seem to calm themselves down and people seem to feel safer in their bodies and they seem to be less alert for danger."
Trauma can cause people to live in a very constricted world where the focus is always on "danger and fear and betrayal", van der Kolk says.
To assist them in shifting out of this mode, the therapeutic and "very careful" administration of psychedelic drugs can be very helpful.
"Psychedelics can, under very careful conditions, be exceptionally useful to help people access very painful things about their past and to get context and become aware that [the experience is] over and they were not to blame.
"Something about psychedelics allows people to relax and to actually go to very dark and painful places sometimes without getting too scared of them … and to see what happened and realise it wasn't their fault … It gives people a temporal dimension of 'that was then and this is now'."
When administered safely, psychedelic drugs can enable people to form "a much larger, more compassionate attitude" towards themselves and what happened to them, van der Kolk says.
"My research shows that MDMA and ketamine dramatically change people's capacity for self-compassion, to feel a much greater sense of caring for that creature they are."
Another treatment that's proven highly effective in helping people process and move past traumatic memories is EMDR - Eye Movement, Desensitisation and Processing.
In this "very strange" form of therapy – which van der Kolk learnt to do himself – people describe scenes from their past and talk about how they feel while repeatedly moving their eyes from side to side.
"I, like everybody else, thought 'that's a bizarre treatment' until people I know started coming into his office and they seemed to be very much better. So we decided to study that."
EMDR seems to somehow change the brain circuitry so people are better able to discern that an experience from in the past is no longer a threat in the present, he says.
In addition to yoga, other "synchronous" body activities such as qigong and tai chi can help to reinstate a sense of safety in the body, while martial arts can be healing for people with a sense of physical helplessness.
Closer to home, though, there's also significant healing power in having someone to hug and have a "debrief" with at the end of your day, van der Kolk says.
"Being known, being seen, being respected, being listened to is terribly important… being valued by our community and in synch with our community is the core of human pleasure.
"Cooking together, eating together, singing together, dancing together, doing projects together is our social joy."
Van der Kolk saw this kind of social joy in action while travelling with the late South African bishop and Nobel Prize winner Desmond Tutu.
"He would pray with people, dance with people, single with people, have people tell their stories and share their stories. Bishop Tutu struck me as about the best trauma therapist I'd ever met."
Dr Bessel van der Kolk is a professor of psychiatry at Boston University School of Medicine and president of the Trauma Research Foundation.
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