23 Jun 2024

Dr David Barack: Is ADHD an evolutionary adaptation?

7:27 pm on 23 June 2024
David Barack

Dr David Barack has been researching the benefits of ADHD. Photo: David Barack

Earlier this month, Wellington mayor Tory Whanau revealed she has attention deficit hyperactivity disorder (ADHD) - and she's not alone.

Impulsiveness, disorganisation and problems prioritising and focusing on tasks are just some of the signs of the condition. Last month, RNZ reported that despite a tenfold increase in ADHD prescriptions since 2006, too many New Zealanders are still going without diagnosis or medication.

Dr David Barack, a neuroscientist at the University of Pennsylvania, told Jim Mora on Sunday Morning that, while people with ADHD face real challenges and we shouldn't minimise how detrimental it can be, these individuals can also excel in certain environments.

His team ran an online study where several hundred participants had to play a simple foraging video game.

It showed an image of a berry bush, and when they moved the mouse over it, they would get some berries. Next, they had to decide whether to continue to harvest the berries, or move on to the next bush. The key change was the amount of berries was reset to the full value, so if they chose to keep harvesting, they would get less, until at some point they decided to move on.

The study found that people who identified as being distractible and impulsive performed better, being able to gather more berries in a shorter amount of time.

The researchers wanted to see whether the conditions reflected some natural characteristics of the environment, Barack says.

"So you can imagine aeons and aeons ago, they would constantly be faced with the decision of: should I stick with this depleting resource or should I move on to find a new one? And it might pay to be more willing to move on sooner in that kind of environment."

The findings suggested that such individuals can excel in certain environments. The difference between early humans and their modern descendants, however, was that we are "constantly bombarded with options", he says.

"Think of a busy web page - with all the annoying banners and ads. Having a simpler decision environment, tailoring or engineering [them] so they're more like the kinds of environments our ancestors faced could be a real boon, and could allow us to behave and to even excel at tasks that otherwise we would be distracted away from - especially for these kinds of individuals."

At its heart, the study is a "explore/exploit" challenge. "Should I leave or go? And if I've chosen to go, where should I search next to face the next 'stay or go' decision?"

In his own world, there was room for both types of people, Barack says.

"As a scientist, we're constantly making decisions about which experiment to run next or which question to pursue next, and it helps to have some scientists who are constantly uncovering new ground and new ideas and new experiments. And then other individuals, other labs, can come in and mine those new ideas and experiments and gather the value.

"So here you have a division of labour where individuals with a particular set of personality traits - in this case those who we characterise as distractible or impulsive - are able to turn up new opportunities, and other individuals who are perhaps more focused can then come in and generate the kind of value and wealth that benefits not just themselves, but society at large."

It was "truly unfortunate" that so many people felt forced to conform, he says, "and to be put into this cookie-cutter idea of what it means to be a productive member of society, instead of allowing our differences to flower and bloom and allowing individuals to slot naturally into particular roles".

Distractibility was often portrayed negatively in society and media, but there must have been some evolutionary purpose for being this way, he says. "You get to uncover new fresh ground before others."

It might even be a trait that future humans wanted to turn on and off, Barack says.

"We might be able have a treatment or take a pill where all of a sudden we need to be more impulsive or distractible, or we need to turn that down. Because it's adapted in certain contexts, this paves the way for neurotechnologies and new ways of changing our minds and brains to better suit the challenges that we're facing in those environments.

"There's the basic science finding, but there is a deeper, almost moral message here, which is that it's important to acknowledge the value in this kind of neurodiversity."

Get the RNZ app

for ad-free news and current affairs