Researchers alleviate PTSD in mice while they sleep
October 19, 2012
Though often associated with exposure to war, Post-Traumatic Stress Disorder (PTSD), is a severe anxiety disorder which can arise following exposure to any event which has caused psychological trauma. Those who suffer from PTSD are often subjected to re-living the source of their despair through nightmares and flashbacks, and current treatment results in only occasional success. However, researchers at Stanford University appear to have alleviated PTSD in mice while the rodents slept, by using a new technique which may prove applicable for humans in the future.
At present, treatment for PTSD often involves the patient being required to repeatedly detail the experience which caused the trauma while under the care of a psychiatrist. With frequent exposure to the memory in a safe environment, some patients are thus able to limit the anguish that it causes, and reduce the power of loud noises and other triggers to cause flashbacks and panic attacks. This process can be distressing for a patient with PTSD, and sometimes does not translate well to the world outside the psychiatrists office, where relapses may occur.
As an alternative, Asya Rolls and her team, which includes Megha Makam, Professor Luis de Lecea, and Professor Craig Heller, propose that it may be possible to manipulate memories, and therefore, PTSD, while a patient sleeps. In the study, the scientists trained mice to fear a particular smell by repeatedly exposing the rodents to puffs of the chemical amyl acetate, alongside weak electric shocks, which were delivered to the feet of the mice. The mice involved in the study exhibited classic fear responses when smelling the chemical alone.
A selection of the mice were subsequently given conventional exposure therapy. This involved subjecting the rodents to the odor puffs without the electric shocks, over and over again. Following this, the mice seemed to recover for a time, but subsequently relapsed when placed in a new cage which was not associated with the therapy.
A second group of mice were then administered a drug to block protein production in the basolateral amygdala, which is an area of the brain associated with storing fearful memories. This was done just before the animals went to sleep. While they slept, the team then exposed the rodents to repeated odor puffs alone, and upon waking, the animals showed reduced fear responses to amyl acetate that carried over even into a new cage.
“The idea that you can actually erase memories during sleep, that you can manipulate them,” said Rolls. “It’s exciting.”
Despite the apparent success of the research thus far, it's important to note that the protein-blocking drug used on the mice would not be safe for use on humans. However, Rolls believes that existing anti-anxiety medications may produce similar effects. Either way, the work is an intriguing avenue of inquiry which joins recent research conducted at Uppsala University, in offering to increase our understanding of PTSD and related conditions.