ADHD and Overdiagnosis: What the Data Says

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Last Update: May 19th, 2025 | Estimated Read Time: 5 min    

The question of whether Attention-Deficit/Hyperactivity Disorder (ADHD) is overdiagnosed has generated substantial public and academic debate. With diagnostic rates increasing in recent decades, some critics argue that ADHD is becoming a catch-all label for normative behavioural challenges. Others contend that, despite growing awareness, many individuals, particularly women, adults, and those from underserved communities, remain undiagnosed or misdiagnosed.

This article synthesizes peer-reviewed evidence to explore the data behind ADHD diagnoses and the complex factors influencing perceptions of overdiagnosis.

Rising Diagnosis Rates: Interpreting the Data

According to national surveys in Canada and the United States, the prevalence of ADHD diagnoses has risen steadily over the past two decades. In the U.S., parent-reported ADHD diagnoses among children aged 4-17 increased from 6.1% in the late 1990s to over 10% by 2016 (Danielson et al., 2018). Canadian studies have noted similar trends, particularly in the school-aged population.

While these figures suggest growing diagnostic momentum, it is critical to contextualize this rise. Historically, ADHD has been significantly underdiagnosed, particularly among girls, adults, and individuals from minority or rural backgrounds. Research has shown that women are often diagnosed later in life, after years of coping with unrecognized symptoms that may have been misattributed to anxiety, depression, or personality traits (Ginsberg et al., 2014). Consequently, some portion of the increase likely reflects greater awareness, improved screening tools, and broader access to mental health services, not diagnostic excess.

What Constitutes Overdiagnosis?

Overdiagnosis refers to the identification of a disorder in individuals who would not have experienced significant functional impairment if left undiagnosed and untreated. It differs from misdiagnosis, which implies that an incorrect condition has been assigned. In the context of ADHD, overdiagnosis would entail the application of the label to individuals whose symptoms do not cause sustained impairment across multiple domains of life, or whose difficulties are better explained by other developmental, psychiatric, or contextual factors.

A study by Bruchmüller, Margraf, and Schneider (2012) found that clinicians were more likely to diagnose ADHD when presented with vignettes describing male children exhibiting disruptive behaviour, even when diagnostic criteria were only partially met. This suggests that gender stereotypes and observable hyperactivity may influence diagnostic decisions, raising concerns about superficial assessments. However, these findings should not be taken as evidence that ADHD is broadly overdiagnosed. Rather, they underscore the importance of adhering to structured diagnostic protocols to ensure accuracy and objectivity.

The Coexistence of Overdiagnosis and Underdiagnosis

Importantly, overdiagnosis in some populations does not preclude underdiagnosis in others. Substantial evidence indicates that ADHD remains under-recognized among girls, racialized individuals, and adults, particularly those whose symptoms present in inattentive or internalized forms rather than overt hyperactivity.

In a large-scale epidemiological study, Ramtekkar et al. (2010) found that sex and age significantly influenced ADHD symptom presentation and referral patterns. Girls were notably less likely to be referred for clinical assessment, despite exhibiting comparable functional impairment. Similarly, adults with undiagnosed ADHD often report chronic academic, occupational, and interpersonal difficulties prior to diagnosis, highlighting a gap in early detection and support (Ginsberg et al., 2014).

Thus, rather than a uniform trend of overdiagnosis, the literature suggests a more complex pattern of diagnostic disparity: overrepresentation of some groups and persistent under-recognition of others.

Improving Diagnostic Accuracy

Accurate ADHD diagnosis relies on comprehensive assessment procedures, including structured clinical interviews, validated behavioural rating scales, and information gathered across multiple settings (e.g., home, school, workplace). These tools help differentiate ADHD from other conditions with overlapping symptoms, such as anxiety disorders, learning disabilities, or trauma-related responses.

Standardized protocols, when followed, reduce the likelihood of diagnostic error. However, studies indicate that time constraints, lack of training, and limited access to multidisciplinary teams can hinder the diagnostic process. Ensuring that evaluations are thorough, culturally informed, and evidence-based is critical to minimizing both over- and underdiagnosis.

Final Reflections: Moving Beyond the Myth

The notion that ADHD is categorically overdiagnosed does not withstand close empirical scrutiny. While certain trends, such as higher diagnosis rates among young boys, may reflect bias or inconsistent application of diagnostic criteria, the broader evidence points to a more nuanced reality. Diagnostic rates have increased, but so has recognition of the disorder in historically neglected populations. At the same time, many individuals remain undiagnosed due to subtle symptom profiles, societal stigma, or systemic barriers to care.

Ultimately, accurate ADHD diagnosis requires rigour, reflection, and a commitment to holistic assessment. Public discourse should shift away from unsubstantiated claims of diagnostic inflation and toward ensuring equitable access to high-quality mental health evaluation and support.  

Finding Focus Care Team

We are a group of nurse practitioners, continuous care specialists, creators, and writers, all committed to excellence in patient care and expertise in ADHD. We share content that illuminates aspects of ADHD and broader health care topics. Each article is medically verified and approved by the Finding Focus Care Team. You can contact us at Finding Focus Support if you have any questions!  

References

Bruchmüller, K., Margraf, J., & Schneider, S. (2012). Is ADHD diagnosed in accord with diagnostic criteria? Overdiagnosis and influence of client gender on diagnosis. Journal of Consulting and Clinical Psychology, 80(1), 128–138. Link

Danielson, M. L., Bitsko, R. H., Ghandour, R. M., Holbrook, J. R., Kogan, M. D., & Blumberg, S. J. (2018). Prevalence of parent-reported ADHD diagnosis and associated treatment among U.S. children and adolescents, 2016. Journal of Clinical Child & Adolescent Psychology, 47(2), 199–212. Link  

Ginsberg, Y., Quintero, J., Anand, E., Casillas, M., & Upadhyaya, H. (2014). Underdiagnosis of Attention-Deficit/Hyperactivity Disorder in adult patients: A review of the literature. The Primary Care Companion for CNS Disorders, 16(3). Link

Ramtekkar, U. P., Reiersen, A. M., Todorov, A. A., & Todd, R. D. (2010). Sex and age differences in ADHD symptoms and diagnoses: Implications for DSM-V and ICD-11. Journal of the American Academy of Child and Adolescent Psychiatry, 49(3), 217–228. Link