McLean Hospital 115 Mill Street Belmont, MA 02478
With new discoveries by McLean Hospital researchers, a fast and effective treatment for PTSD, anxiety, and addiction disorders could be close at hand. Literally.
Right now, work is underway to develop a handheld inhaler containing xenon gas that could be used to block traumatic memories as soon as they are experienced. Whether used in a clinical setting or self-administered in the real world, the treatment could “help PTSD patients and others be better able to cope with the emotional toll of re-experiencing their trauma memories,” according to Edward G. Meloni, PhD, an investigator in the Behavioral Genetics Laboratory at McLean Hospital and an assistant professor of psychiatry at Harvard Medical School.
Meloni and his colleague Marc J. Kaufman, PhD, director of the Translational Imaging Laboratory at McLean Hospital and an associate professor of psychiatry at Harvard Medical School, were recently issued a patent allowance for their invention covering the use of xenon to treat psychiatric illnesses such as PTSD. Now the researchers are working with the biotech firm Nobilis Therapeutics on the development and testing of a portable administration device as well as devising other uses for the invention to help individuals with a range of neurological and psychiatric disorders. Also, Meloni and Kaufman are preparing to move beyond the initial animal testing that led to their invention and study the effects of xenon gas on human patients.
The invention, Kaufman explained, grew out of research “to see if xenon could protect against some of the natural processes in the brain that cause Parkinson’s disease.” A series of setbacks slowed their investigations into Parkinson’s, but triggered a new line of inquiry—the potential impact of xenon gas on PTSD and anxiety disorders.
The researchers hypothesized that xenon, which can affect multiple brain systems involved in memory formation, had potential for targeting parts of the brain that store and process aversive memories. To test their hypothesis, Kaufman and Meloni began to investigate the impact of xenon through a series of experiments on rats. In a controlled environment, rats were exposed to an aversive event—a brief footshock—after hearing a loud tone. In this way, the rats were conditioned to fear the tone much in the same way a person may acquire fear to stimuli associated with a traumatic experience. Then, the researchers conducted experiments in which xenon gas was introduced into the rats’ environment after hearing the tone. They found that xenon greatly reduced the fearful responses in the subjects who were re-exposed to the tone.
Based on their findings, the researchers came to believe that xenon had potential for treating people with PTSD and related conditions. Just as xenon helped the rats forget the traumatic memory triggered by the tone, Meloni said “xenon gas could modulate the memories of an individual after experiencing a troubling flashback or nightmare.”
“Applying xenon gas right after someone experiences a traumatic memory could help inhibit a natural process called ‘reconsolidation’ or the process in which memories are re-remembered or restored,” he explained.
Because xenon gas may be able to modulate fear-related memories, the researchers believe their invention could augment commonly used treatments for PTSD, which focus on medication and cognitive behavioral therapy in a clinician’s office. Unfortunately, the use of standard antidepressants alone “does not get at the core pathology of what’s sustaining PTSD” and are only effective in roughly half of people with the condition. For the other half, Meloni stated, “the brain just recalls the trauma, reconsolidates it, and doesn’t extinguish it.” By using xenon gas as a supplement to the standard of care, an individual could “inhale xenon at the end of a therapy session, and it would help prevent the reconsolidation process, maybe even facilitate the extinction process,” he said.
For flashbacks and nightmares that occur outside of the therapist’s office, the gas could be self-administered with an inhaler. “Using xenon with a handheld device by the bedside could be the perfect thing to help someone who wakes up with a disturbing memory,” Kaufman explained. The gas, he said, “works and dissipates quickly.”
“We want to prove that it is effective and can be part of regular therapy for people who are really struggling with this disorder.”– Edward G. Meloni, PhD
Clinical trials on individuals with PTSD are now being organized. In upcoming studies to be funded by Nobilis, police officers, firefighters, active members of the military, first responders, and others who come to McLean Hospital for PTSD treatment in the LEADER program can enroll in a study that will use xenon in conjunction with trauma memory reactivation sessions.
“We’ll have them talk about their trauma, and we’ll tape the sessions,” Meloni said. The tapes will then be played back to the patient to reactivate the memory. Emotional and physical responses will be recorded, and xenon will then be introduced using a handheld device “to see if we can interfere with the brain’s ability to reconsolidate these painful memories and potentially begin a natural mental healing process,” he explained. The individuals will be brought back a week later and asked if they are still experiencing nightmares, thoughts of suicide, or continuing traumatic memories. In all, study participants will take part in six rounds of therapy and xenon exposure and followed for up to six months to document recovery.
“This study is our proof of concept, our way of seeing if xenon makes people with PTSD feel better,” Meloni said. “Already, existing data shows that the treatment is very safe. Now we want to prove that it is effective and can be part of regular therapy for people who are struggling with this disorder.”