Why are some people hooked on adrenaline?

We received this question from Ben who was actually at a theme park. Chris Smith asked addiction expert Bianca Jupp to provide an answer.

Bianca - Yeah. It’s a very good question. And I definitely have to put my hand up and say I’m a bit of an adrenaline junkie. I love snowboarding. So this is actually a personality trait that some of us have and it’s because, basically, we find doing risky things rewarding. Essentially, what happens when you do something risky is you get a release of this neurochemical known as adrenaline so again, adrenaline junkies. The body creates this because basically it’s priming us for this ‘flight or fight’ response, so making us ready if we need to run away in case of danger, or if we want to stand and fight.

Now for some people, for these sensation seekers, adrenaline is particularly rewarding, and so we have another neurochemical in the brain known as dopamine. And anytime we do something that's rewarding we get an increase in the level of this neurochemical dopamine. So people who are adrenaline junkies, we think what happens is basically anytime they do something that releases adrenaline it increases the level of this neurotransmitter dopamine and it feels good.

Chris - Is that learned or is that something they were born with?

Bianca - No, it’s something they were born with. Yeah, actually to be fair, it’s roughly 50 percent heritable this behavioural trait.

Chris - So you get a family of  thrill seekers?

Bianca - Most definitely.

Chris - And how do you know it’s definitely genetic and it’s not that if you’ve got parents who are really really - they’re out there go getting, doing exciting things that they just immerse you from a young age, you’ve got no choice and you get hooked on adrenaline because of your family environment?

Bianca - Yes, certainly. But we do actually see this in animals.

Chris - Really, thrill seeking animals?

Bianca - Thrill seeking animals, yeah. I actually work on rats and we look for this behavioural trait because it is really interesting, because being a sensation seeker actually increases your risk for addiction. We’re not quite sure why. Is it something about your underlying biology, or is it because you’re more likely to take drugs because you’re looking for that kind of novel, exciting experience associated with taking drugs or booze?

And, yeah, we actually see in our rats some of them prefer novel environments. So if you put them in a maze and they have exposure to one side, if you open up the other side of the maze and they can then go and explore it, some rats will bolt straight into the other side and spend more time exploring it than others. And we see this is heritable amongst our rats.

Chris - Wonderful! There was a story that was published in an Indian science journal not so long ago and these two men were described - two cases - and they had been professional, I suppose you could describe them as, professional drug abusers for decades. And they go to the stage where nothing was really working any more. So they had been written up because they were persuading snake charmers to get King Cobras to bit them in the tongue.

Bianca - My goodness!

Chris - Because they found this elicited a state of near nirvana for these people for a couple of hours and they would wake up all woozy and say well, that was wonderful, can you do it again. But the medical profession are fascinated because they want to know how these people can survive mega lethal doses of cobra venom envenomated into their tongue and actually they’re fine. So there’s clearly something about the addiction that’s happened in these people and they’ve obviously changed the way their brain chemistry works because of drug addiction which has then led them to be less vulnerable to one of the most potent venoms we know. A fascinating case!

Jacob?

Jacob - No. I was just thinking of this from kind of the other end of the evolutionary spectrum if you like because you can study behaviour from the very kind of proximate end, and you can study behaviour from the ultimate end thinking of why these sorts of things evolve? It’s really important to understand exactly what the mechanisms are as well but I find it interesting to ask why these things evolve?

And thinking of human behaviour in that sense, why people go out of their way to jump off a cliff with a parachute on their back or whatever it might be? Part of the explanation might also be because it somehow enhances your reproductive success. You’re showing off, you look cool, you look sexy, and you’re more likely to…

Chris - Only if it works!

Jacob - Only if it works - exactly!

Chris - It can be very counterproductive and you can look very unsexy if you really fall flat on your backside. Is that really the case though, Bianca?

Bianca - Maybe not so much for reproductive health. But it’s actually an exceptionally important behavioural trait that exists within us and we wouldn’t have evolved with it otherwise. It’s basically so we can take risks. It’s really really important that I decided to jump on a plane from Australia seven years ago and come to Cambridge.

Chris - Is that a risk? I don’t know, is it?

Bianca - Some people would say the weather’s not very nice here.

Chris - Jess?

Jess - So it you start out with it and it’s inherited from your parents, does it not change over the course of your life? So you’re quite into taking risks when you’re a teenager and up to your 30s maybe, and then you just don’t want to take any risks anymore?

Bianca - That’s very true. It definitely changes over the lifespan. And you’re right, during your adolescence it’s at its highest and this is when, yeah, people are very happy to go and do these crazy things.