It turns out that the ancestors of attention deficit hyperactivity disorder (ADHD) patients received an evolutionary gift. Even if it doesn’t necessarily translate into today’s society.
Scientists from Pennsylvania University and the Indian Institutes of Technology collaborated on a research project that shows traits tied to ADHD – distractibility and excessive movement – might have helped early humans when foraging for resources.
“If [these traits] were truly negative, then you would think that over evolutionary time, they would be selected against,” lead author and Penn researcher David Barack, PhD, told The Guardian. “Our findings are an initial data point, suggestive of advantages in certain choice contexts.”
ADHD and Its Ripple Effects
Estimates vary, but according to the American Psychiatric Association, 8.4 percent of children and 2.5 percent of adults have ADHD.
However, more recent research suggests that up to 3.1 percent of adults live with the disorder. And the historical data has reinforced the conventional wisdom that ADHD can spill over into everyday life, whether it’s “elevated rates of depression, anxiety, substance abuse, and self-harm,” as Psychiatrist.com has reported before.
Clinicians have also linked lifelong – and often undiagnosed – ADHD with “poor social outcomes, impacting emotional support and leading to higher rates of unemployment or disengagement from education, a phenomenon known as NEET (Not in Education, Employment, or Training).”
Looking Past a Genetic Anamoly
To test their theory that there might be more to ADHD than just random genetic mutations, Barack and his team assembled 457 adults and had them complete an online assessment that had them conduct foraging tasks. The drill had participants attempt to collect as many berries as they could within a set time.
Additionally, the computer foragers could either linger at a single foraging site in a bid to dig up more berries, or they could move on to other potential sites.
After the exercise, the scientists tested each of the participants for ADHD.
Consistent Results
Nearly half of the participants screened positive for ADHD on a short self-assessment, a statistically higher share than one would normally expect for a random sampling.
The researchers discovered that the subjects who scored higher on the ADHD self-assessment spent less time with each berry patch than others. They were willing to leave a berry patch after the yield dwindled and search for a new one. And maybe most importantly, those participants consistently posted higher scores in the game.
“In competitive environments where foragers must keep track of other foragers, impulsively leaving patches could yield a competitive advantage by enabling learning about competitors and capturing newly renewed resources first,” the authors in the study, published in the Proceedings of the Royal Society B: Biological Sciences. “The increased foraging proficiency of participants with ADHD-like behavior observed here suggests the prevalence and persistence of ADHD in human populations may serve an adaptive function in some environments.”
