medRxiv : the preprint server for health sciences
August 17, 2024
Charles R Conway, Ben Julian A Palanca, Thomas Zeffiro et al.
preprint
Nitrous oxide (N2O) reduces functional connectivity in mood-related brain networks in people with treatment-resistant major depression (TRD) but increases connectivity in healthy controls. In a crossover trial, 14 TRD patients and 16 healthy controls received one-hour inhalations of 50% N2O or placebo. Resting-state fMRI scans before, 2 hours, and 24 hours after inhalation showed that N2O progressively decreased connectivity in TRD patients across five brain networks (salience, default mode, reward, cingulo-opercular, and the dorsal nexus), while increasing connectivity in controls. The findings suggest N2O's antidepressant effects involve specific alterations in depressed brains.
Biological psychiatry global open science
October 1, 2023
Ben Julian A Palanca, Charles R Conway, Thomas Zeffiro et al.
In healthy volunteers, a single 1-hour inhalation of 50% nitrous oxide produced changes in brain connectivity that lasted at least 24 hours. Using resting-state functional MRI, the study found increased global connectivity in the occipital cortex at 2 and 24 hours after inhalation, particularly between the visual network and the dorsal attention network. Weaker connectivity changes were observed between the visual cortex and frontoparietal and default mode networks. No significant connectivity changes followed inhalation of air/oxygen. These persistent cortical effects suggest nitrous oxide induces neurophysiological changes beyond its acute psychotropic effects.
Science translational medicine
June 9, 2021
Peter Nagele, Ben J Palanca, Britt Gott et al.
A single 1-hour inhalation of 25% nitrous oxide improves depressive symptoms in patients with severe treatment-resistant major depression as effectively as 50% nitrous oxide, but with substantially fewer adverse effects. In a phase 2 crossover trial with 24 patients, both concentrations significantly reduced depression scores on the Hamilton Depression Rating Scale compared to placebo over two weeks. The 25% dose showed significant improvements at week 1 and week 2, while the 50% dose showed significant improvement at week 2. Adverse events declined substantially with the lower dose.