Uncovering the truth about ADHD through empirical tests

Table of Contents

1. Introduction
2. What is ADHD?
3. The Challenge to Natural Selection
4. Evolutionary Hypotheses
   • 4.1 The Hunter-Farmer Theory
   • 4.2 The Waiter and Fighter Theory
   • 4.3 The Response Readiness Theory
5. The Traits of ADHD in Ancestral and Modern Environments
6. The Need for Empirical Evidence
7. Conducting a Systematic Review
8. Findings of the Review
   • 8.1 Studies Included in the Review
   • 8.2 Limitations of the Studies
9. Implications and Potential Benefits
10. Conclusion

Empirical Tests of Natural Selection-Based Evolutionary Accounts of ADHD

Attention Deficit Hyperactivity Disorder (ADHD) is a childhood onset neurodevelopmental disorder characterized by inattention, impulsivity, and hyperactivity. It poses a significant burden on those affected, their families, and society as a whole. The high prevalence and heritability of ADHD present a challenge to natural selection-Based accounts of human evolution. One would expect a disabling and impairing mental disorder like ADHD to reduce an individual's reproductive fitness and result in the selection of genetic variants responsible for it.

Several evolutionary hypotheses have been proposed to resolve this apparent paradox. The Hunter-Farmer theory suggests that individuals with ADHD traits were hunters, while those without ADHD traits possessed the virtues of farmers. The Waiter and Fighter theory proposed other possible interpretations, and the Response Readiness theory claimed that ADHD traits may be beneficial in environments characterized by rapid changes, external threats, and scarce food resources.

In an unsafe and depleted ancestral environment, inattention could have been advantageous as vigilance and the ability to scan for dangers. Impulsivity could have facilitated the ability to attack or flee, while hyperactivity and exploratory behavior were useful for identifying new food sources and migrating towards better habitats. These traits would have contributed to the survival and reproductive fitness of individuals carrying ADHD traits in the ancestral environment.

However, in our modern safe and resource-rich environment, the defining traits of ADHD do not fit the adaptive functions they once served. This is why ADHD is considered a mental disorder in the present Context. These evolutionary hypotheses remain speculative until supported by empirical evidence.

To investigate the extent to which natural selection-based accounts of ADHD have been investigated in empirical studies, we conducted a systematic review of the literature following PRISMA guidelines. We screened the PubMed, Embase, and PsycINFO databases and identified 790 records. After excluding irrelevant articles, we assessed 15 full-text articles for eligibility, resulting in the inclusion of three studies in our review.

The included studies focused on the genetic evolution of the ADHD-associated dopamine receptor gene and The Simulation study of the effect of suggested ADHD traits on group survival. While the authors interpreted their findings as supporting the Notion of ADHD traits being associated with increased fitness during human evolution, we argue that none of these studies truly tap into the Core symptoms of ADHD. Therefore, their conclusions lack validity for the disorder.

Although the natural selection-based accounts of ADHD have not been subjected to empirical tests, exploring ADHD symptoms within the context of adaptive functions holds promise for understanding gene-environment and brain-behavior interactions. Furthermore, adopting a natural selection perspective may inform the design of new behavioral interventions to improve the educational and vocational outcomes of children with ADHD.

In conclusion, there is a need for future studies to address the gap in knowledge by subjecting natural selection-based accounts of ADHD to empirical tests. Only then can we gain a more comprehensive understanding of the disorder and its evolutionary implications.