ADHD helped our ancestors survive
Research suggests attention deficit hyperactivity disorder (ADHD) may have had an evolutionary advantage.
Traits common to attention deficit hyperactivity disorder (ADHD), such as distractibility or impulsivity, may have been an evolutionary advantage for our ancestors, improving their foraging tactics, say researchers.
As The Guardian explains, ADHD – is a neurodevelopmental disorder whose symptoms include impulsivity, disorganization, and difficulty concentrating. Although estimates of its prevalence have varied, diagnoses of the syndrome are increasing in many countries, including the UK.
Now the researchers say that while some of these traits are typically viewed negatively, they may have helped humans seek out new areas to forage for.
Dr. David Barak of the University of Pennsylvania, who was the study's first author, said That the study offers a potential explanation for why ADHD was more common than expected due to random genetic mutations alone, and – more broadly – why traits such as distractibility or impulsivity were common.
“If these traits were truly negative, you would think that over evolutionary time they would be selected against,” he said. “Our results provide initial evidence of benefits in certain choice contexts.”.
In a paper published in the journal Proceedings of the Royal Society B: Biological Sciences, David Barak and his colleagues reported how they analyzed data from 457 adults who completed an online foraging game in which they had to collect as many berries as possible in for eight minutes.
The number of berries obtained from each bush decreased depending on how many times it was collected. During the task, participants could either continue picking berries from the bushes in their original location, or move to a new area – although the latter cost them time.
The team also screened participants for ADHD-like symptoms – although they stress this is not a diagnosis – finding that 206 participants had positive results.
The researchers found that participants with higher ADHD scores spent shorter periods of time in each bush patch than those with lower scores. In other words, they were more likely to leave their current site and look for a new one. Importantly, the team found that these participants also scored higher in the game than those who scored lower on ADHD scales.
The researchers said their results are consistent with other work that suggests that the nomadic populations that benefited from the study tended to have genes associated with ADHD.
However, the scientists added that the study had limitations, including that ADHD-like symptoms , were based on self-report.
Dr Barak notes that experiments need to be conducted with people diagnosed with ADHD and real-world foraging tasks, not least because the latter would require much more effort to move between patches than in an online game.
Michael Jay Reiss, a professor of science education at University College London who was not involved in the work, said that while ADHD appears to be associated with serious negative consequences, he and his colleagues argued that it could help in situations where physical activity and quick decision making are highly valued.
“It is encouraging to see experimental evidence from David Barak and colleagues that participants who scored high on ADHD were more likely to switch their activities to searching for food in ways that can truly be described as impulsive. In our evolutionary past, such behavior could sometimes be quite advantageous, he said. – ADHD can be a serious problem, but it is largely a problem due to modern conditions”.
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