Morphine effects on stress response and social interaction – an exploratory randomized controlled experimental medicine study
Social rejection and physical pain share similar pathways in the human brain. This research study explores whether morphine, a strong painkiller, changes how we react to feeling socially excluded or stressed. Researchers are inviting healthy adult volunteers to take part. During the study, participants will be given either a single dose of morphine or a harmless saltwater drip (placebo) through a vein. They will then play a computer game designed to bring up feelings of being left out, while researchers monitor their brain activity using an MRI scanner. The study team will also measure stress hormone levels in the blood and track how comfortable people feel with personal space. The findings will help scientists understand the brain systems linked to both physical and emotional pain, which could improve treatments for mental health conditions in the future.
At a glance
What is this study about?
Physical pain and emotional distress—such as feeling rejected or left out—activate very similar networks in the human brain. The body naturally produces its own pain-relieving chemicals, called endorphins, which help soothe both physical hurt and emotional upset. Morphine is a well-known medicine that works on these exact same chemical pathways to relieve pain.
In this study, researchers want to see if a small, controlled dose of morphine can also 'dull' the emotional hurt of social exclusion. By understanding this link, scientists hope to learn more about how human social behaviour works and why feelings of loneliness or rejection can feel so physically painful.
To test this, healthy volunteers will take part in an experimental session where they receive either morphine or a simple saltwater solution. They will then carry out social tasks and play an interactive computer game while lying inside an MRI scanner. This machine takes detailed pictures showing blood flow in the brain, revealing which areas light up during social situations.
Researchers will also collect blood samples to check for stress markers, such as cortisol. This research does not aim to treat illness with morphine, but rather to expand our scientific understanding of the mind and body. This knowledge may guide new therapies for mood disorders, anxiety, or addiction in the future.
Key takeaways
- The study explores how morphine affects our brain and stress levels when we feel socially excluded.
- It is looking for healthy adult volunteers aged 18 and older.
- Participants will receive either a single dose of morphine or a dummy saltwater drip.
- The session includes an MRI brain scan, social computer tasks, and blood tests.
- Taking part is voluntary, and you can withdraw at any time.
Who may be eligible?
This trial is designed specifically for healthy adult volunteers aged 18 and older. Both men and women are welcome to apply.
Because this is an early-stage study to observe standard brain responses, participants should be in good general health. This usually means having no major long-term illnesses, no active mental health conditions, and no history of substance misuse or dependency.
Since the study involves an MRI brain scanner, volunteers must also be safe to have an MRI. This means you cannot take part if you have certain metal implants in your body, such as pacemakers, surgical clips, or metal fragments in your eyes.
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 aged 18 or older?
- Are you in good general physical and mental health?
- Are you free from any history of substance or opioid abuse?
- Are you able and safe to undergo an MRI scan (no metal implants or severe claustrophobia)?
- Are you not allergic to morphine or similar painkillers?
What does participation involve?
If you decide to join, you will first attend a screening visit to check your general health and make sure an MRI scan is safe for you. On the main study day, a small plastic tube (cannula) will be placed into a vein in your arm. Through this, you will receive either a single dose of morphine or a plain saltwater drip. Neither you nor the study team will know which one you received until the study is over.
You will then lie down inside an MRI scanner for about an hour. While inside, you will view a screen, answer questions using a hand controller, and play simple interactive tasks that mimic social interactions and being left out of a group. The team will take blood samples before and after the scan to measure natural stress hormones. You will also complete short questionnaires about how you feel. You will be monitored closely until any medicine has completely worn off before you head home. The total time commitment is usually one or two visits.
Potential risks and benefits
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Common questions
Will taking morphine in this study make me addicted?
No. The risk of developing an addiction from a single, low dose given in a safe, controlled medical setting is extremely low.
Will the study cause me real emotional distress?
The computer tasks are designed to create mild, temporary feelings of being left out, similar to everyday social awkwardness. Any mild discomfort fades very quickly.
Can I drive home after the study visit?
No. Morphine can make you drowsy and slow your reactions, so you must arrange for someone else to drive you or take public transport home.
What is an fMRI scan?
An fMRI (functional Magnetic Resonance Imaging) scan uses strong magnetic fields and radio waves to safely take pictures of blood flow in your brain while you do tasks. It does not use any radiation.
Will I be paid for taking part?
Clinical trials with healthy volunteers typically offer reasonable compensation for your time and travel expenses. The study team will provide exact details before you sign up.
How to find out more
Always speak to your GP or specialist before deciding to take part in a study.
Interested in taking part?
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