NCT03537794Recruiting
Characterizing Synaptic Density in Treatment Resistant Depression
Source: ClinicalTrials.gov · Last updated 15 Sept 2026
Brief summary (registry, in English)
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.
- Status (registry)
- Recruiting
- Study type
- Observational
- Enrollment
- 45 (estimated)
- First submitted
- 15 May 2018
- Start date
- 22 Aug 2025
- Primary completion date
- Dec 2028
- Lead sponsor
- Unity Health Toronto
- Diseases
- Depression
- NCT number
- NCT03537794
What you commit to
- Study type: Observational
- Planned participants: 45
- From 22 Aug 2025 to the primary completion date, Dec 2028
- 1 site in 1 country
- Visits and tests: ask the trial team, the registry does not list them
Built from the registry fields of ClinicalTrials.gov. It describes the study design.
Who cannot take part
Copied verbatim from ClinicalTrials.gov and grouped by topic. Only the trial team decides who can take part.
Prior treatment
- Lifetime history of receiving an antidepressant
Other illness
- 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
- For non-resistant patients: Failure of > 2 antidepressant treatments of adequate dose and duration for current MDE.
- Medical condition requiring immediate investigation or treatment
- Lifetime history of any psychiatric disorder
Other
- Pregnancy/lactation
- Use of any psychotropic use within 5 half-lives before the PET scanning, with the exception of SSRIs and SNRIs
- Pregnancy/lactation
Who the study is looking for
- 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
- Ages between 25 and 65 years
- Ability to undergo MRI scanning (absence of metal, pacemakers, etc.)
Age in the registry: 25 years to 65 years · Sex: All · Accepts healthy volunteers
Sites (1)
Sites in registry order. Save your city in your profile to sort them by distance.
| Site | City | Country | Site status |
|---|---|---|---|
| Unity Health Toronto Coordinator of this site? Confirm its status | Toronto | Canada | Recruiting |
This page is information, not medical advice. Discuss any trial with your doctor.