Characterizing Synaptic Density in Treatment Resistant Depression
Key facts
- Where
- Toronto, CanadaSee the site
Could this be for you?
Answer for yourself. This is not a decision: only the study team can say whether you can take part.
- Are you between 25 and 65 years old?
Source: NCT03537794, who can take part
Where in Canada
- Unity Health TorontoToronto, CanadaTaking people
Questions to ask the study team
- How often do I need to come in, and for how long each time?
- Are travel costs paid?
- Can I keep my own doctor?
- What happens if I want to stop?
Trial details
- Who runs it
- Unity Health Toronto
- Trial code
- NCT03537794
- Record updated
- 15 September 2026
- Original description
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.Read full original descriptionShow less
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.
Inclusion: 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.).
Exclusion: Lifetime history of receiving an antidepressant; 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; Pregnancy/lactation; Use of any psychotropic use within 5 half-lives before the PET scanning, with the exception of SSRIs and SNRIs; Pregnancy/lactation.