NCT05528718

SMILE Trial - Imaging Sub-Study

Sustained Mood Improvement With Laughing Gas Exposure: A Randomized Controlled Pilot Trial - Sub-Study Protocol to Include Neuroimaging

• Status: Completed
• Phase: —
• Study type: Observational
• Enrollment: 11 (actual)
• Sponsor: Unity Health Toronto · Academic / Other
• Sex: All
• Age: 18 Years – 65 Years
• Healthy volunteers: Not accepted

Summary

This is a pilot sub-study of an ongoing trial comparing N2O to midazolam in MDD and will examine neuroimaging correlates of treatment response.

Detailed description

Magnetic resonance imaging (MRI) scans of MDD-affected brains have revealed changes in structural and functional connectivity compared to healthy subjects. This pilot sub-study examines structural and functional connectivity associated with MDD-affected patient participants' responsiveness to N2O compared to the midazolam placebo, which induces similar sedative effects. The investigators intend to address the changes in brain functional activity and connectivity between baseline and after a four-week intervention course involving weekly nitrous oxide inhalations measured by MRI.

Conditions

• Major Depressive Disorder

Interventions

Type	Name	Description
DRUG	Nitrous oxide gas for inhalation	This sub-study does not have an intervention and based on the main study the participants who have received N2O will be compared with the midazolam placebo group.
DRUG	Midazolam injection	This sub-study does not have an intervention and based on the main study the participants who have received N2O will be compared with the midazolam placebo group.

Timeline

• Start date: 2023-03-07
• Primary completion: 2024-03-30
• Completion: 2024-06-14
• First posted: 2022-09-06
• Last updated: 2026-03-27

Locations

1 site across 1 country: Canada