Nitrous oxide speeds the reduction of distressing intrusive memories in an experimental model of psychological trauma
Ravi Das, Amanda J. F. Tamman, Viktoriya L. Nikolova, Tom P. Freeman, James A. Bisby, Antonio Ivan Lazzarino, Sunjeev K. Kamboj
Psychological Medicine March 3, 2016 DOI: 10.1017/s003329171600026x (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized controlled trial Peer reviewed |
|---|---|
| Sample size | 50 |
| Population | Healthy participants who viewed a negatively valenced emotional film clip |
| Interventions | Nitrous oxide Medical air |
| Duration | 1 week follow-up |
| Keywords | Intrusion Recall Dissociative Audiology Memory consolidation Dissociation chemistry Traumatic memories Nitrous oxide Psychological trauma Clinical psychology Anesthesia Cognitive psychology |
| Citations | 48 |
| Key findings | Nitrous oxide speeds the reduction of intrusive memory frequency after analogue trauma, but increases intrusion frequency in highly dissociated individuals. |
Abstract
Background: Post-traumatic stress disorder (PTSD) involves maladaptive long-term memory formation which underlies involuntary intrusive thoughts about the trauma. Preventing the development of such maladaptive memory is a key aim in preventing the development of PTSD. We examined whether the N-methyl d-aspartate receptor (NMDAR) antagonist gas nitrous oxide (N2O) could reduce the frequency of intrusive memories by inhibiting NMDAR-dependent memory consolidation in a laboratory analogue of psychological trauma.
Method: Participants were randomized to inhale N2O (N = 25) or medical air (N = 25) after viewing a negatively valenced emotional film clip ('trauma film'). Participants subsequently completed a daily diary assessing frequency of intrusive thoughts relating to the film clip. A week later, participants completed an explicit memory recall task related to the film.
Results: Post-encoding N2O sped the reduction in intrusive memory frequency, with a significant reduction by the next day in the N2O group compared to 4 days later in the air group. N2O also interacted with post-film dissociation, producing increased intrusion frequency in those who were highly dissociated at baseline. Sleep length and quality the night after viewing the film did not differ between the groups.
Conclusion: N2O speeds the reduction of intrusive analogue trauma memory in a time-dependent manner, consistent with sleep-dependent long-term consolidation disruption. Further research with this drug is warranted to determine its potential to inoculate against enduring effects of psychological trauma; however, caution is also urged in dissociated individuals where N2O may aggravate PTSD-like symptomatology.