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RECRUITING

NCT03537794

Characterizing Synaptic Density in Treatment Resistant Depression

Sponsor: Unity Health Toronto

View on ClinicalTrials.gov

Summary

The purpose of this study is to better understand how certain brain systems work in people with depression, especially in those whose symptoms have not improved with antidepressant treatments. The investigators are particularly interested in synaptic density, which helps to understand how different parts of the brain communicate with one another. Synaptic density levels have implications on overall brain function and cognition. By comparing brain function in people with treatment-resistant depression, people with treatment-responsive depression, and healthy controls, investigators hope to better understand why some individuals do not respond to antidepressants. This research may help guide the development of more effective treatments in the future.

Key Details

Gender

All

Age Range

25 Years - 65 Years

Study Type

OBSERVATIONAL

Enrollment

Start Date

2025-08-22

Completion Date

2029-12

Last Updated

2026-09-15

Healthy Volunteers

Yes

Conditions

Treatment Resistant Depression Depression - Major Depressive Disorder

Interventions

DIAGNOSTIC_TEST

PET scans

PET scans and PHNO scans

Inclusion Criteria: * Key inclusion criteria for the MDD patients: * DSM-5 criteria for a Major Depressive Episode (MDE) within a MDD, confirmed through MINI diagnosis (Sheehan et al, 2015) * Age between 25 and 65 years * Hamilton Depression Rating Scale - 17 item (HRSD-17; Hamilton, 1960) \> 14 (moderate to severe symptoms) * Free of psychotropic medications (with the exception of SSRIs or SNRIs) for at least 5 half-lives before PET scanning per investigator discretion, after which an insignificant amount of drug is circulating through the body and accessing the brain. This determination will be based on self-report from the participant of when their last dose was. Use of benzodiazepines (except for diazepam) or sedative hypnotics (e.g. zopiclone) is allowable, but the last dose must be at least 72 hours prior to scanning. * Ability to undergo MRI scanning (absence of metal, pacemakers, etc.) * For non-resistant patients: Previous history of response to an antidepressant, in order to increase signal to noise between resistant and non-resistant patients Key inclusion criteria for the Healthy Controls: * Ages between 25 and 65 years * Ability to undergo MRI scanning (absence of metal, pacemakers, etc.) Exclusion Criteria: Key exclusion criteria for the MDD patients: * Pregnancy/lactation * Medical condition requiring immediate investigation or treatment * Recent (\< 6 months)/current history of drug abuse/dependence * Lifetime history of psychosis, other Axis I comorbidities are allowable * Use of any psychotropic use within 5 half-lives before the PET scanning, with the exception of SSRIs and SNRIs * For non-resistant patients: Failure of \> 2 antidepressant treatments of adequate dose and duration for current MDE. Key exclusion criteria for the Healthy Controls: * Pregnancy/lactation * Medical condition requiring immediate investigation or treatment * Lifetime history of any psychiatric disorder * Lifetime history of receiving an antidepressant

Locations (1)

Unity Health Toronto

Toronto, Ontario, Canada