A study suggests that in the right context, the rewards are there.
“She appears to have a hyperkinetic behaviour disorder,” he said to Chris as he wrote.
“A what?”
“A disorder of the nerves … She shows all the symptoms: the hyperactivity, the temper, her performance in math.”
This exchange is from William Peter Blatty’s 1971 novel The Exorcist, and the patient thus diagnosed with an ADHD-type disorder is young Regan, whose mother will soon wish it was only her maths marks that were diabolical.
The Back Page imagines there are mothers of children with ADHD who have been tempted at one time or another to call in the priests.
But with the increasing diagnosis rates, recognition and visibility of this form of neurodivergence, it’s fair to ask: could it at some time have offered an evolutionary advantage?
A team from the University of Pennsylvania has explored that question in a study published in Proceedings of the Royal Society B, starting with the fact that some nomadic hunter-gatherer populations, such as the Ariaal people of Kenya, have genetic mutations in dopamine receptors that are implicated in ADHD.
The team hypothesised that in an experimental foraging situation, people with ADHD would be more likely to strike out for unknown patches than stay in known but depleting ones.
They tested this with 457 subjects, who scored themselves on a validated ADHD diagnostic tool (the Optimal RiskSLIM DSM-5 ASRS Screening Scale) and completed a virtual berry-picking game.
The Back Page would have preferred to see them compete in an Alone-style reality TV game to introduce some real stakes. Maybe the funding wasn’t there, or the ethics board had questions. Oh, also it was during covid.
Optimal foraging theory models – which can be applied not only to food-seeking but also to quests for sexual encounters or information on the internet – dictate that “individuals should leave a depleting resource patch when local intake rates fall below the average for the environment”.
The team predicted that “stronger self-reported ADHD symptoms would be associated with shorter patch residence times, less optimal behaviour and lower cumulative rewards in our online foraging task”.
To their surprise, they found while the first part of the hypothesis was confirmed, the subjects who scored above a pass mark for ADHD also achieved higher reward rates.
Their behaviour also accorded better with optimal model predictions than those with “normal” scores.
“These findings are consistent with systematic amplification of activity within neural circuits involved in exploration, such as the default mode network, and changes in levels of the neuromodulator norepinephrine broadcast from the locus coeruleus, both implicated in individuals with ADHD,” the authors say.
They note that a huge 45% of their subjects had elevated ADHD-type symptoms – about 10 times the actual adult rate of ADHD – and that this does not equate to a diagnosis in the absence of clinical examination.
Beyond day-to-day foraging, the Back Page often wonders what kind of people led the various waves of human migration across the planet.
It isn’t a stretch to imagine that it took a special subset of people each time to leave whatever comfort and familiarity they had to strike out into unknown territory, accepting new hazards for the rewards of new hunting grounds.
Now may just be the stay-at-home scaredy cat’s time to shine.
Send tales of derring-do or demonic possession to penny@medicalrepublic.com.au.
