SMILE Trial - Imaging Sub-Study

Unity Health Toronto

Status: Completed

Conditions: Major Depressive Disorder

Treatments: Drug: Nitrous oxide gas for inhalation; Drug: Midazolam injection

Study type: Observational

Funder types: Other

Identifiers

NCT05528718

22-139

Details and patient eligibility

About

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

Full 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.

Enrollment: 11 patients

Sex: All

Ages: 18 to 65 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Eligible for main nitrous oxide (SMILE) study

Exclusion criteria

• Contraindication for undergoing MRI scans (e.g., hip circumference < 180 cm or metal in the body)

Trial design

11 participants in 2 patient groups

Experimental group

Description:

Participants assigned to this intervention arm in the main study will have been administered nitrous oxide at an inspiratory concentration of 50% with concurrent intravenous saline (100mL) for one hour.

Treatment:

Drug: Nitrous oxide gas for inhalation

Placebo group

Description:

Participants assigned to this intervention arm in the main study will have been administered 50% oxygen with intravenous midazolam (0.02mg/kg in 100mL) for one hour.

Treatment:

Drug: Midazolam injection