RecruitingOBSERVATIONAL

Characterizing Dopamine Receptor Binding in Treatment Resistant Depression

This research is trying to understand why about 3 in 10 people with depression don't respond to standard treatments, a condition called 'treatment-resistant depression'. We know these individuals often have other health issues, a lower quality of life, and a higher risk of suicidal thoughts, yet there's not much known about how their brains are different. Using special brain scans, called PET scans, this study will investigate how a brain chemical called dopamine works in people with treatment-resistant depression compared to those who respond well to treatment and healthy individuals. By understanding these differences, we hope to discover new ways to develop more effective treatments and better understand this type of depression.

At a glance

Status

Recruiting

Sponsor

Unity Health Toronto

Enrolment target

Start

22 Aug 2025

Estimated completion

01 Dec 2028

Treatment Resistant Depression

What is this study about?

Imagine your brain is a complex city with tiny roads and messengers. This study is like sending out explorers to understand how one specific messenger, called dopamine, behaves in different areas of the brain. We're especially interested in people whose depression hasn't improved with typical treatments, which doctors call 'treatment-resistant depression'.

Around one in three people with depression find that common medications don't help them feel better. This can be really frustrating and lead to other health problems, make daily life harder, and increase feelings of hopelessness. Currently, we don't fully understand why some people's depression is so persistent. This study aims to fill that gap by looking closely at how dopamine, a brain chemical linked to mood and motivation, might be working differently in these individuals.

By comparing brain scans of people with treatment-resistant depression, people whose depression responds to treatment, and healthy volunteers, the researchers hope to find specific differences in how dopamine is used. This knowledge could be a big step towards developing new, more targeted treatments and better ways to identify who might benefit most from them.

Key takeaways

Exploring why some depression doesn't respond to usual treatments.
Using special brain scans (PET scans) to look at brain chemistry (dopamine).
Aims to find new ways to help people with hard-to-treat depression.
Involves 3 visits to a hospital over a few weeks.
Participation helps future patients, with minimal direct benefit to you.

Who may be eligible?

To join this study, you would generally need to be between 25 and 55 years old.

If you have depression, your symptoms would need to be moderate to severe. For those with depression that hasn't responded well to treatment, the study is looking for participants who have tried and not improved with at least two different antidepressant treatments for your current episode of depression. If your depression has responded well to treatment in the past, you might also be eligible.

There are some reasons you couldn't take part, such as being pregnant or breastfeeding, having certain serious medical conditions, or a history of drug abuse in the last six months. If you've ever had certain serious mental health conditions like psychosis, you wouldn't be able to join either. You also can't be taking any mental health medications within certain timeframes before the brain scans.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you between 25 and 55 years old?
Have you been diagnosed with depression?
If you have depression, are your symptoms moderate to severe right now?
Are you able to stop any mental health medications temporarily for the scans?
Are you able to have an MRI scan (e.g., no metal implants in your body)?
Are you not currently pregnant or breastfeeding?

Answer every question to see your result.

What does participation involve?

If you decide to take part, there would be three visits to a hospital. First, you'd have a screening visit where doctors would check if the study is right for you. They'd ask about your health, medical history, and current medications, and you'd have an interview to confirm your diagnosis. You'd also need to sign a consent form, making sure you understand everything involved.

Within two weeks of this first visit, you would have an MRI scan, which is a type of brain scan that gives detailed pictures. Soon after, you'd have a PET scan, which is another special brain scan that looks at how chemicals like dopamine are working. For this scan, you would need to stop taking any psychiatric medications for a specific period before the scan. The order of these scans might vary between participants. Each scan takes some time, but typically you'd be in and out within a day for each visit. The total duration of your involvement would likely be over a few weeks, encompassing these three separate visits.

Potential risks and benefits

Participating in this study might not directly benefit your health immediately, but the information gained could greatly help others with treatment-resistant depression in the future by leading to better treatments. The main procedures, MRI and PET scans, involve some minor risks. MRI scans use strong magnetic fields, so you can't have certain metal implants. PET scans involve a very small amount of a radioactive tracer, but this is generally considered safe and quickly leaves your body. You might experience some discomfort lying still during scans. You are free to withdraw from the study at any time, for any reason, without affecting your medical care.

Locations (1)

Unity Health Toronto
Verified postcode
Toronto, Canada· Recruiting

Common questions

What is 'treatment-resistant depression'?

It's when your depression hasn't improved after trying at least two different antidepressant treatments.

What is dopamine and why is it important?

Dopamine is a brain chemical that plays a role in mood, motivation, and pleasure. We're studying how it works differently in people with depression.

What is a PET scan?

A PET scan is a special type of brain scan that shows how chemicals are working inside your brain by using a tiny amount of a safe, temporary tracer.

Will I have to stop my depression medication?

Yes, if you're taking mental health medications, you would need to temporarily stop them for a certain time before the PET scan.

Will I get results from my scans?

The scans are for research, not for personal diagnosis. The researchers won't be giving individual results, but the overall study findings will be shared.

How to find out more

Sakina J Rizvi, PhD

rizvis@smh.ca 416-864-6060 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.