Traits commonly associated with attention deficit hyperactivity disorder (ADHD) could have provided an evolutionary advantage for humanity's early ancestors by improving their food foraging tactics, researchers say.
ADHD is a neurodevelopmental disorder and those diagnosed with it often exhibit impulsiveness, disorganisation and difficulty focusing.
However, the distractibility and impulsivity often associated with ADHD could also have proved advantageous, according to new research from David Barack from the University of Pennsylvania, who was the lead author of the study.
Dr Barack said the study offered a possible explanation for why ADHD was more prevalent than expected from random genetic mutations alone and, more broadly, why traits like distractibility or impulsivity were common.
"If [those traits] were truly negative, then you would think that over evolutionary time, they would be selected against."
The findings are far from definitive but they do provide a good direction for future research, Dr Barack said.
"Our findings are an initial data point, suggestive of advantages in certain choice contexts."
The study was published in the scientific journal Proceedings of the Royal Society B: Biological Sciences.
Dr Barack and his colleagues collected data from 457 adults who completed an online foraging game where they had to collect as many berries as possible within eight minutes.
The number of berries obtained from each bush decreased the more times it was foraged.
Participants could either continue to collect berries from the bushes in their original location or move to a new patch, which would cost them time.
The participants were also screened for ADHD-like symptoms, 206 of whom returned positive results - though the team stressed this did not constitute a diagnosis.
Participants who scored higher on the ADHD scale spent shorter periods of time in each patch of bushes and were thus more likely to gain more points in the game than participants with lower scores on the ADHD scale.
The researchers said the results aligned with other work that suggested populations with nomadic lifestyles that benefitted from exploration also tended to have genes associated with ADHD.
They made clear their study did have limitations, a key factor being the ADHD-like symptoms were based on the participants' self-reporting.
In future, Dr Barack wants to carry out real world experiments involving people diagnosed with ADHD and foraging tasks, but this will require more effort.
Michael J Reiss, a professor not involved in the work, has argued ADHD can help in situations where physical activity and rapid decision-making were highly valued.
"It is great to see experimental evidence from David Barack and colleagues that participants who score highly for ADHD are more likely to switch their foraging activities in ways that can indeed be characterised as impulsive.
"In our evolutionary past such behaviour may sometimes have been highly advantageous,” he said.
