Is ADHD a prehistoric gift?

There’s no question that ADHD presents challenges to millions of people suffering from the disorder. But recent research seems to suggest that ADHD conveyed advantages to early humans that aided in their survival.

Different Genes

ADHD is associated with novelty-seeking behavior, and there seems to be a higher genetic threshold for which ADHD individuals find an experience rewarding . From the New York Times:

“Dr. Nora D. Volkow, a scientist who directs the National Institute on Drug Abuse, has studied the dopamine reward pathway in people with A.D.H.D. Using a PET scan, she and her colleagues compared the number of dopamine receptors in this brain region in a group of unmedicated adults with A.D.H.D. with a group of healthy controls. What she found was striking. The adults with A.D.H.D. had significantly fewer D2 and D3 receptors (two specific subtypes of dopamine receptors) in their reward circuits than did healthy controls. Furthermore, the lower the level of dopamine receptors was, the greater the subjects’ symptoms of inattention. Studies in children showed similar changes in dopamine function as well.

These findings suggest that people with A.D.H.D are walking around with reward circuits that are less sensitive at baseline than those of the rest of us. Having a sluggish reward circuit makes normally interesting activities seem dull and would explain, in part, why people with A.D.H.D. find repetitive and routine tasks unrewarding and even painfully boring.”

This doesn’t really sound like a gift to me, but if you think about early humans living in hunter-gatherer communities it begins to make sense:

As hunters, we had to adapt to an ever-changing environment where the dangers were as unpredictable as our next meal. In such a context, having a rapidly shifting but intense attention span and a taste for novelty would have proved highly advantageous in locating and securing rewards — like a mate and a nice chunk of mastodon. In short, having the profile of what we now call A.D.H.D. would have made you a Paleolithic success story.

Taking it a step further

While this explanation sounds reasonable enough, it still involves a great deal of speculation – and doesn’t quite amount to scientific evidence supporting ADHD as an evolutionary advantage. So researchers took things a step further and looked at modern-day hunter-gatherer societies. Specifically, they examined the nomadic Ariaal people of Kenya, a sub-group of which only recently settled and begun practicing agriculture. The results were astounding:

Dan T. A. Eisenberg, an anthropologist at the University of Washington, examined the frequency of a genetic variant of the dopamine type-four receptor called DRD4 7R in the nomadic and settler groups of the Ariaal. This genetic variant makes the dopamine receptor less responsive than normal and is specifically linked with A.D.H.D. Dr. Eisenberg discovered that the nomadic men who had the DRD4 7R variant were better nourished than the nomadic men who lacked it. Strikingly, the reverse was true for the Ariaal who had settled: Those with this genetic variant were significantly more underweight than those without it.

So if you are nomadic, having a gene that promotes A.D.H.D.-like behavior is clearly advantageous (you are better nourished), but the same trait is a disadvantage if you live in a settled context. It’s not hard to see why. Nomadic Ariaal, with short attention spans and novelty-seeking tendencies, are probably going to have an easier time making the most of a dynamic environment, including getting more to eat. But this same brief attention span would not be very useful among the settled, who have to focus on activities that call for sustained focus, like going to school, growing crops and selling goods.

As fascinating as this research is, it’s obviously not very comforting to those dealing with ADHD in a modern world with grocery stores and 9-5 desk jobs.

However, this research does help us to reconsider ADHD as not necessarily a disease so much as a set of cognitive traits that are advantageous in certain situations. With this mindset we can focus on controlling ADHD in the scenarios that require it (taking a test or completing an assignment), while embracing the gifts it can offer in others (creative problem solving).