Empirical evidence for the neurocognitive effect of nitrous oxide as an adjunctive therapy in patients with treatment resistant depression: A randomized controlled study.
Jin Liu, Xiaotian Zhao, Xiyu Wei, Danfeng Yan, Wenwen Ou, Mei Liao, Shanling Ji, Yan Peng, Shibin Wu, Mi Wang, Yumeng Ju, Li Zhang, Zexuan Li, Bangshan Liu, Lingjiang Li, Yan Zhang
Psychiatry Research August 1, 2023 DOI: 10.1016/j.psychres.2023.115326 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized controlled trial Placebo-controlled Double-blind Peer reviewed |
|---|---|
| Sample size | 44 |
| Population | Patients with treatment-resistant depression |
| Intervention | Nitrous oxide |
| Dose | 50% N2O/50% oxygen for one hour |
| Duration | 1-week and 2-week follow-up |
| Measures | subjective cognitive function, processing speed, attention, executive function |
| Topics | Depression |
| Keywords | Cognitive deficits Executive function Nitrous oxide Randomized controlled trial |
| Key findings | Nitrous oxide improved executive function at 1 week post-treatment compared with placebo, independent of changes in depressive symptoms. |
Abstract
Nitrous oxide (N2O) has demonstrated an antidepressant effect for treatment-resistant depression (TRD), but no studies investigated the effects of N2O on different cognition domains. This study aimed to test whether N2O would display pro-cognitive effects. We conducted a double-blinded, placebo-controlled, randomized controlled trial, 44 patients with TRD were randomized to N2O group (one-hour inhalation of 50% N2O/50% oxygen) or placebo group (50% air/50% oxygen). Thirty-four patients completed cognitive tests at the pre-treatment phase, 1-week, and 2 weeks post-treatment including subjective cognitive function, processing speed, attention, and executive function. Although the antidepressant effect of N2O was not significant at 1 week, patients still showed better performance of executive function at 1 week after receiving N2O compared with the placebo. Moreover, this significant improvement still existed at 1 week after controlling for the change in depressive symptoms over-time. Additionally, no significant difference was observed in subjective cognitive function, processing speed, and attention between these two groups across the 2-week follow-up period. As the first study investigating the treatment effects of N2O on improving cognitive function in TRD patients, the current study indicated that N2O has a potential pro-cognitive effect on executive function and this effect might be independent from improvements in depressive symptoms.