ADHD: Origins and Outcomes

ADHD is unique amongst mental health disorders for a variety of reasons. Firstly, it is one of the most ‘heritable’ psychological conditions that we currently know of. This leads us to the common-sense conclusion that ADHD is likely genetic, meaning there may be a specific gene, or combination of genes, that can be identified that predisposes an individual to ADHD. The other area in which ADHD is unique is that it confers several advantages. In my clinical experience, I have met many ADHD patients who advise that even if given the choice, they would not give up ADHD; they would rather manage and live with the challenges and keep the strengths it provides than erase it entirely. The same is rarely said about other disorders such as depression or bi-polar. 

These two unique features are linked and I will explain why here. When a trait is highly heritable, it indicates that it may also be ‘evolutionary’ in that it must have offered our ancient, hunter-gatherer ancestors distinct advantages; otherwise, it likely would have been wiped out of the gene pool. Not every trait that is passed on is advantageous, though when a trait is more likely to be passed on than other traits, there is a strong indication that this is the case. A fascinating study was done on this very idea to try and determine if ADHD would have been advantageous to our ancestors.

In 2008, a famous anthropological study led by researcher Dan Eisenberg examined the Ariaal people of northern Kenya. This group was specially selected as most members were still living as nomadic herdsmen, almost entirely shut off from modern civilisation. Over time, some individuals from this tribe had moved to settled communities more closely resembling modern society. The researcher tested tribe members from both groups for the DRD4 gene (specifically the 7R allele), which regulates dopamine in the brain. In modern, industrial societies, this genetic variant is heavily linked to impulsivity, novelty-seeking, food cravings, and diagnoses of ADHD. He then tested their BMI (Body Mass Index) and height, using it as an indication of their overall nutritional fitness (high BMI is usually preferred where food is scarce).

The results showed that those with the DRD4 gene variant (most associated with ADHD) had higher nutritional fitness in the nomadic herdsmen group and lower nutritional fitness in the settled communities. In the nomadic herdsmen groups, these likely ‘ADHD’ individuals were viewed as capable, proactive defenders and providers. In the settled communities, they were viewed as distracted, impulsive, and unreliable. The advantages that were conveyed by the ADHD traits to the herdsmen were observed as impulsivity, hyper-vigilance, and rapid switching of attention to help a person effectively defend livestock from raiders, track unpredictable wildlife, and quickly locate shifting water or food sources. In the settled setting, these exact same behavioural traits clashed with pursuits that require prolonged, stationary focus, such as sitting in a classroom, standard agriculture, or managing a market stall.

ADHD does not impact intelligence positively or negatively, and ‘high functioning’ or high-IQ ADHD is often associated with success in the business world; many famous CEOs such as Richard Branson identify with the disorder. Likewise, low-functioning ADHD is associated with less than ideal outcomes such as incarceration, where estimates suggest up to 40% of the prison population could qualify for a diagnosis. Having high energy and impulsivity can be an excellent trait if you have the capacity for problem-solving and critical thinking, though equally it can work against you if you lack these skills and do not consider consequences.

All of the above points to a trait that was likely handed down to us by evolution to help us thrive and survive in the natural world. Most of what evolution provides comes at a cost; for example, our large brains as humans require an enormous amount of energy (in the form of calories) and a long period of dependency in infancy. Similarly, ADHD offers us the ability to act quickly, sometimes fearlessly, and notice small changes, though with this comes distractibility and a perceived lack of self-control. Learning to harness the positive traits of ADHD and manage the difficult ones is a highly individualised process that factors in your environment, relationships, and personal and career goals. We cannot change our genes, though we can learn to harness our unique gifts, and luckily great inroads have been made into our understanding of ADHD and its presentation in modern humans.