Cannabis, Psychosis and Video games: Video Lay Summary

Can cannabis users playing video games help us learn about psychosis?

We need to learn more about psychosis, but it’s hard to study. Scientists at King’s Collage London, Yale and Oxford might have found a new way to study it. By working with cannabis users playing video games.

Psychosis is what happens to someone when their brain can’t tell what’s real. You might see, feel, smell or taste things that other people can’t. You might see other people or animals or demons that aren’t really there. You might hear voices or sounds no one else can hear. Or you might believe things that aren’t true. These might be things that other people find strange. This mix-up about what’s real and what’s not is often very frightening and upsetting. It can make looking after yourself and holding down a job really difficult.

About 1 in every 100 people will experience psychosis in their lifetime. You can take medicine to help you manage psychosis. But sadly, the medicine doesn’t work for everyone. We need to learn more about what’s happening in your brain when you have psychosis. Scientists have been looking into this. If they learn more, perhaps they can help.

So, what do scientists think is happening?

In life things around us are constantly changing. Our brains sort these changes into things that are useful and things that aren’t. Then our brains use this information to update what we believe about stuff. This helps us make sense of change.

Lots of the change that happens is change is that doesn’t surprise us. We expect it. And so, we don’t have to update what we believe much. But sometimes life can surprise us. When these surprising changes happen, we have to update our beliefs more.

Here’s an example: imagine playing a game you know well. You know you’ll win sometimes and lose sometimes – you expect this. But suddenly you start losing every time. You’re surprised. You stop, think ‘why?’, and try to work out what’s happening. Then you adjust how you play. That’s you updating your beliefs.

Scientists think that when we have psychosis, our belief updating isn’t working as it should. When changes happen we expect our brain is updating our beliefs too much. And when surprising changes happen it isn’t updating our beliefs properly. But is this really what’s happening? Scientists need to answer this question so they can better help people with psychosis. But doing research with people who have psychosis is difficult. People often take medicine that helps with the psychosis. But this medicine changes the symptoms scientists need to study. People with psychosis who aren’t taking the medicine are often very upset. So it isn’t right to do research with them.

Scientists had an idea to solve this problem. Researching people who don’t have psychosis, but are at higher risk of getting it. They decided to look at people who use cannabis. They’re 3 times more likely to get psychosis than people who don’t use cannabis. In fact, they may already be having some of the symptoms.

Two scientists called Xinyi Liang and Maria-Mihaela Avram led a group looking at cannabis users. They looked at how cannabis users updated their beliefs when surprising changes happen. They compared them to people who don’t use cannabis.

So this is what they did.

They compared two groups of British 18–40-year-olds. Group 1 was 49 people who use cannabis 3 times a week or more. Group 2 was 52 people who’d never used cannabis before. They all played a video game called The Space Game.

What’s the Space Game?

You’re in charge of a rover on the ground. There’s a space ship in the sky above you that you can’t see. Space junk falls from the space ship. You need to catch the junk using the beam on your rover. You need to guess where the junk is going to land. Then, get your rover and beam into position to catch it. You can change the width of your beam if you want. The more junk you catch the more points you get. If you can catch the junk with a narrower beam, you get extra points.

But….
The pattern of how the junk falls changes. Sometimes it lands spread across a certain area. But then the area it lands in suddenly changes. This is the surprising change we talked about earlier.

Whilst people played the game the scientists measured 4 things. One, your score. If you missed the junk you got zero, if you caught it you could score between 1 and 10 points, with more points for using a narrower beam. Two your performance error. How far away your guess was from the junk, with smaller being better. Three your confidence. How sure you were based on the width of the beam. A wide beam means you’re not very sure, a narrow beam means you’re pretty sure. Four your learning rate. How much you moved your next guess after failing to catch the junk.

Your scores show how good you are at updating your beliefs when change happens. So were the cannabis users worse at the game?
Scientists found no difference between people who used cannabis and those that didn’t. Both updated their beliefs quickly when surprising changes happened in the Space Game.

Scientists then looked closely at just the people that used cannabis. And they found something new. Within cannabis users, daily cannabis users got the worst scores. Why was this? Daily cannabis users seemed to make fewer updates in their beliefs. This is also what scientists think is happening in psychosis.

This research was all carried out online. This meant scientists had to trust people to be honest about using cannabis and how often they used it. They also had to trust them to follow the instructions. They took out people who looked like they weren’t playing properly. But they may not have spotted everyone. But doing the research online made it easier to find people who use cannabis.

The results of this research suggest 3 things. 1. Like other scientists have found before, it seems the more often you use cannabis, the higher your risk is of getting psychosis. So when we talk about the risks of cannabis use, we should focus more on the risks of using it every day. 2. people who use cannabis every day might help us learn more about psychosis. 3. the Space Game might help us test people for early signs of psychosis.

So, what’s next?

This research didn’t have many people in it who used cannabis daily. This means scientists need to do the research again. But this time with more people who are using cannabis every day. This would mean that the scientists could be more certain about the results. It would also be good to do the research in person. This means they can be sure people are playing the game correctly. And by doing the research again with a new group of people the scientists can be more confident the space game measures how people update their beliefs.

If scientist do the research again, they could explore the connections more. The connections between heavy cannabis use, how people update their beliefs and psychosis.

Thank you for watching. This video was created using a scientific paper by Xinyi Liang and Maria-Mihaela Avram at King’s College London, and colleagues Toni Gibbs-Dean, Edward Chesney, Dominic Oliver, Simiao Wang, Stiliyana Obreshkova, Tom Spencer, Amir Englund and Kelly Diederen. Adam Wallis programmed the Space Game. The full paper can be found using this link. Visuals and font for this video were produced by Ailsa Baldwin. Financial support for the research was given by the Springboard Award of the Academy of Medical Sciences.