All together now, ahhh (Image: Max Dereta/Getty)

Do you have an annoying friend who loves bungee jumping or hang-gliding, and is always blathering on about how it never scares them? Rather than being a macho front, their bravado may have a biological basis.

Research from Stony Brook University in New York shows that not all risk-takers are cut from the same cloth. Some actually seem to feel no fear – or at least their bodies and brains don’t respond to danger in the usual way. The study is the first to attempt to tease apart the differences in the risk-taking population.

In order to ensure every participant was a card-carrying risk-taker, the team led by Lilianne Mujica-Parodi, recruited 30 first-time skydivers. “Most studies on sensation-seeking compare people who take risks and people who don’t. We were interested in something more subtle – those who take risks adaptively and those who do so maladaptively.” In other words, do all risk-takers process potential danger in the same way or do some ignore the risks more than others?


To find out, the researchers got their participants to complete several personality questionnaires, including one that asked them to rank how well statements such as, “The greater the risk the more fun the activity,” described them.

Off-kilter circuit

Next, the team used fMRI imaging to observe whether the participants’ corticolimbic brain circuit – which is involved in risk assessment – was well-regulated. A well-regulated circuit is one that reacts to a threat and then returns to a normal state afterwards.

To test this, a loud, unpleasant noise was made as the skydivers lay in the scanner. They were also shown a series of faces – some aggressive, some less so – to test their threat perception. And on the day of the jump, the team measured a stress hormone called cortisol in spit samples collected before and after.

They found that people with better regulation were better at recognising threat in angry faces. They also showed larger increases in stress hormones. Conversely, poor regulation was linked with poorer threat recognition and smaller hormone rises. “The less people regulated their corticolimbic system, the more muted a stress response they showed,” says co-author Jiook Cha.

While the study didn’t look at fear itself, an emotion that is difficult to measure objectively, the dampened stress hormones and lesser response to threat of some skydivers suggest that they were less affected by it.

No fear

“It really has to do with the reckless and the brave,” says Bruce McEwen at Rockefeller University, New York, who wasn’t involved with the work. The brave feel fear but are able to overcome it, whereas the reckless seem to have a brain that doesn’t react as it should to alert them to danger, he says.

Being able to tell the brave and the reckless apart is important in fields like the military, says Mujica-Parodi. A healthy amount of fear is necessary; those who have none may put their own lives at risk as well as the lives of others around them.

Some types of military recruitment involve personality tests but Mujica-Parodi’s results show that brain scans are a better test. “The brain is much more predictive of how people will respond to genuine risk than just asking them,” she says. In certain high-stakes scenarios, therefore, it might be worth complementing psychological screening with neurobiological screening, to help to distinguish the brave from the reckless.

Journal reference: NeuroImage, DOI: 10.1016/j.neuroimage.2014.08.038