Sleep sounds reencode traumatic memories for PTSD patients

Post traumatic stress disorder, PTSD, is a psychiatric condition where, upon suffering a traumatic event (a car accident, for example) a portion of people form traumatic memories which continually resurface. They may get intrusions during the day, or in nightmares, where they re-experience the same event with similar levels of fear and arousal as when it actually happened. 

Hein van Marle is a psychiatrist and neuroscientist at the University Hospital in Amsterdam. He uses psychotherapy to treat PTSD patients, helping them reencode their traumatic memories so they’re less troublesome. He’s working on an innovative new method to improve treatment using the neuroscience of sleep and its role in memory storage.

One of the methods of treating PTSD involves using auditory clicks to help patients reprogramme traumatic memories. It’s called eye movement desensitisation and reprocessing (EMDR.) By playing targeted clicks to patients while they sleep, at times when the parts of the brain associated with memory formation are most active, it’s thought they could make the therapy sessions more impactful.

James Tytko started by asking Hein how the current gold standard treatment - EMDR - works…

Hein - It's a form of exposure based psychotherapy where the first step is that you reactivate the traumatic memory. The patient revisits their traumatic event and then different things can happen, but with EMDR, technically, we tax the working memory of the patient by giving them all kinds of sensory stimulations.; they have to follow a light that goes from left to right, or they listen to clicks, audio clicks, or they have to do maths. The effect of that is that the normal fear and arousal that they experience when they have a flashback, or even a nightmare, that doesn't get any room to happen because their brain is very much occupied with all the things that you let them do. That results in the fact that the memory gets re-encoded again in the brain in a more neutral form, in a form that is associated with less fear and arousal.

James - I guess it must be pretty draining for the patients to go through this therapy and to live through the source of this trauma over and again if they're having repeat sessions.

Hein - Yes, that's definitely true. On the one hand, you can say that psychotherapy in PTSD is to a certain level quite effective. On the other hand, it's also very demanding for the patient because basically every cell in their body says, 'I don't want to go back to that specific moment,' and then they have to. Our research is focused on ways to augment the trauma treatment and for this we use the time window of sleep. Sleep has a very important function in the long term storage of memories. What we do with this experiment is that we try to use a new technique from neuroscience that is called targeted memory reactivation. It works that if people form a new memory during the day, they learn something, then you pair that learning experience with a sensory stimulus like a sound or a smell maybe. Then, when people are asleep, then you again present that same sensory stimulus, the smell or the sound, and that biases the brain to process that associated memory in a prioritised way. This therapy called EMDR that we just explained, we use an auditory click that is already part of the normal standard therapeutic procedures, but for us the click can also be used at nighttime to present again and to use as a cue in order to strengthen the consolidation of the treatment memory.

James - Did you have concerns, with the limits that exist in our understanding of memory, the brain and sleep, that, by inducing the re-encoding of these memories while the patients were sleeping, you might see unintended consequences?

Hein - On the neuroscience side, people were very hesitant to use this in real patients with real traumatic memories. Nobody knew what was going to happen. Are you going to trigger nightmares? Are patients going to get more symptoms? But I think we had a very strong team of both hardcore sleep scientists and psychiatrists. We felt safe enough to do this. Then we saw that it was actually a safe procedure. We didn't induce any extra nightmares, we didn't induce any extra symptoms. Also it was technically feasible to do.

James - That's obviously a very positive step, the fact that this innovative treatment is safe and feasible. What about the findings, though, more concerned with what you were looking for, which is the brain activity involved with memory formation while the patients were sleeping conjured up by the triggers, the noises, that you'd worked on with them in previous therapy sessions?

Hein - We had two groups. All the patients got the EMDR session at nighttime, then they all went to sleep in the sleep lab. Half of the patients got the TMR cue during the night and the other half patients did not get any cue during the night. Then, when we looked at the brain activity, because we measured their EEG during sleep, we saw that the TMR cue induced an enhancement in the brainwave activity that is mostly related with this process of memory consolidation. These physiological sleep phenomena are very much linked to the process of memory consolidation. We saw that by giving the TMR cue during sleep we evoked the sleep phenomena in a more profound way than in the control group. Then we saw, within the TMR group itself, a correlation with these induced sleep phenomena and the reduction in PTSD symptom level. But we didn't see, however, that is important to mention, a clear difference between the TMR group and the control group. So the TMR by itself didn't result in less PTSD symptoms than the only EMDR group.

James - How do you assess that final finding? Is this a case of you need to go back and tweak the experiments to time the targeted therapy differently or to do more of it to see a greater benefit?

Hein - This effect that we saw the TMR induce, the sleep physiology changes that are related to consolidation, is basically a sign for us that we're on the right track. We're doing something that does something in the memory processing up to a level that it reduces the PTSD symptoms. Our next step will be that we're going to basically have a repeated application of the TMR and we are hoping that by this repeated application that we get a cumulative effect and that we'll be able to really create a difference and a benefit of TMR as opposed to the control group.