October 1st, 2014

Study: xenon gas could reduce or omit painful memories

There may be a new treatment for those dealing with posttraumatic stress disorder, according to a study by researchers at McLean Hospital in Belmont, Mass.

The study, published Aug. 27 in PLOS ONE, suggests that xenon gas – used as an anesthetic and for diagnostic imaging – could reduce or erase the memories of traumatic events.

Researchers studied the use of xenon gas in rats who had been conditioned to fear certain environmental stimuli by foot shocks. “We were able to block this learning and memory phenomenon called reconsolidation,” says Edward G. Meloni, Ph.D., assistant psychologist at McLean Hospital and an assistant professor of psychiatry at Harvard Medical School. “It’s a type of updating process that’s evolutionarily conserved. The animal studies with xenon indicated that breathing the gas right after you reactivate the memory in this reconsolidation window was effective in reducing the memory. We tested up to two weeks and it appeared the rats were no longer afraid of this stimuli that they should have been afraid of.”

Meloni says translating that effect to humans, xenon gas could theoretically inhibit the traumatic memory from being reincorporated during the reconsolidation process alleviating the painful memories that plague those with PTSD.
But isn’t that like erasing a memory?

“If you take what we think is going on in the brain at face value and that is that the biological processes that hold the memory are now interfered with, it is a lot like erasing a memory. The memory is no longer stored in the brain,” Meloni says. “So we need to go to humans to really figure out what components are still there. Will they still remember the facts of that trauma or are we erasing the emotional part? The rats don’t really tell us that.”

Meloni and Marc J. Kaufman, Ph.D., director of the McLean Hospital Translational Imaging Laboratory and associate professor of psychiatry at Harvard Medical School are trying to raise support for studies in humans.

Xenon is known for its excellent safety and side effect profile, says Kaufman. It is used in Europe as an anesthetic and as an imaging agent. It is not often used in the U.S. because it is expensive to produce, he says.

“We take very seriously the idea that having memory is very important, but we also believe that xenon has to be administered in a such a way that it is therapeutic and helps people that have troublesome memories, rather than wiping memories that we don’t mean to erase,” says Kaufman.

The researchers say that use of xenon during a psychotherapy session would be most effective. To read the study, visit http://dx.plos.org/10.1371/journal.pone.0106189.

By Rivkela Brodsky

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