The Prevalence Inflation Hypothesis and Autism Overdiagnosis

Over the past decade, mental health awareness campaigns have expanded significantly across the Western world. These efforts, ranging from school-based interventions to high-profile celebrity disclosures, have reduced stigma, improved mental health literacy, and encouraged help-seeking (Sampogna et al. 2017; Schomerus et al. 2012; Henderson et al. 2017). At the same time, however, reported rates of mental health conditions—including anxiety, depression, eating disorders, and self-harm—have risen sharply (Collishaw 2015; McManus et al. 2019; Santomauro et al. 2021).

Discussions about autism have also become much more visible in public life. Charities, schools, workplaces, radio, and television frequently run campaigns highlighting autistic experiences, and social media is filled with posts aiming to educate and destigmatise ASD. These efforts have had real benefits: they have improved recognition of autistic traits, reduced stigma, and made it easier for individuals to seek assessment and support. At the same time, however, the number of people identified as autistic has risen dramatically.

Foulkes and Andrews (2023) propose what they call the prevalence inflation hypothesis, which may help explain this paradox. They suggest that mental health awareness campaigns and rising prevalence rates form a feedback loop. Greater awareness leads to higher reported rates of mental health problems, which, in turn, generate further awareness campaigns, reinforcing the cycle. This hypothesis is especially relevant in debates about possible autism overdiagnosis.

The hypothesis is based on two mechanisms: improved recognition and overinterpretation.

Improved recognition refers to how awareness efforts may be leading to better recognition and more accurate reporting of mental health problems. As stigma decreases and knowledge improves, individuals are better able to identify and report difficulties that were always present but previously overlooked. Accurate recognition can provide access to services, accommodations, and communities that improve quality of life.

Overinterpretation refers to how awareness efforts have led some individuals to overpathologise common psychological experiences. Foulkes and Andrews (2023) argue that awareness efforts sometimes encourage individuals to interpret milder or transient difficulties as symptoms of a mental disorder that require labelling, reporting, and treating—i.e., problems of living that were not previously considered mental health problems (and still should not be)—and to perceive themselves as being vulnerable to psychological harm. In the context of autism, this could mean that behaviours such as social discomfort (Chetcuti et al. 2025), preference for routines, or strong personal interests are pathologised when they may, in fact, reflect normative personality variation.

This process has been described as the “psychiatrisation” of everyday experiences (Brinkmann 2014). Importantly, it does not always remain a matter of language or self-concept. Labelling theory (Schef 1974) and Ian Hacking’s notion of “looping effects” (1996; 2007) suggest that once people adopt a diagnostic identity—whether given by professionals or self-applied—the label can shape behaviour in ways that reinforce the diagnosis. In this way, overinterpretation can create a self-fulfilling prophecy.

Autism as a case study

These dynamics are visible across mental health domains, but autism provides a particularly salient example of how prevalence inflation may operate. Reported rates of autism have increased significantly over the past two decades. While much of this rise can be explained by improved recognition and broadened diagnostic criteria, some scholars argue that part of it may also stem from overinterpretation (Foulkes & Andrews 2023).

Public campaigns often encourage people to “check for the signs” of autism, which can be empowering but also risks encouraging self-pathologisation (and self-diagnosis). Everyday traits such as being introverted, preferring solitude, struggling with eye contact, disliking noisy environments, or finding small talk uncomfortable are increasingly interpreted through a diagnostic lens.

These patterns are amplified by online platforms and the broader neurodiversity movement, where awareness and identity politics intersect. On social media platforms like TikTok and Instagram, short videos presenting lists of “hidden signs of autism” attract millions of views, often blurring the line between clinically significant difficulties and subclinical traits, normative variations in behaviour or ordinary quirks. These dynamics intersect with self-diagnosis and the neurodiversity movement, both of which have been shaped by awareness campaigns and online discourse. While such developments can provide community and validation, they also complicate prevalence inflation dynamics by influencing how individuals conceptualise their own experiences and identities.

This phenomenon does not diminish the validity of genuine autistic experiences. Rather, it highlights how awareness can sometimes shift too far, contributing to what some clinicians perceive as diagnostic “stretching.” For example, people who might once have been considered shy, eccentric, or highly focused are now more likely to frame these traits as autistic symptoms. While this can provide community and validation, it may also inflate prevalence rates in ways that complicate research, resource allocation, and public understanding.

Evidence of overinterpretation in other mental health problems

While autism illustrates this process vividly, evidence from other areas of mental health further supports the prevalence inflation hypothesis. There is evidence that awareness can inadvertently increase symptom reporting. For instance, school-based programmes designed to teach psychological skills or cognitive-behavioural therapy techniques have, in some cases, increased rather than reduced distress among adolescents (Andrews et al. 2022; Montero-Marin et al. 2022). Similarly, exposure to psychiatric terminology, symptom checklists, or instructions to monitor negative thoughts has been shown to heighten distress in otherwise healthy young people (Garmy et al. 2015; Lindholm & Zetterqvist Nelson 2015). Experimental studies also demonstrate that when individuals are led to believe they have health-related symptoms, they are more likely to subsequently report and even experience them, regardless of their initial state (Baumann et al. 1989; Merckelbach et al. 2011).

Taken together, these findings suggest that awareness does not simply reflect underlying problems but can actively shape how they are experienced and reported—fuelling a self-reinforcing cycle.

A bidirectional, escalating cycle

The prevalence inflation hypothesis emphasises the cyclical nature of these processes. Foulkes and Andrews (2023) argue that greater awareness leads to higher reported rates of mental health problems, which in turn prompt further awareness efforts—reinforcing the cycle. In the context of autism, rising prevalence understandably motivates organisations and schools to increase awareness campaigns. Yet these very efforts may also contribute to further rises in reported cases, creating an escalating feedback loop.

This does not mean awareness is harmful by default. On the contrary, reducing stigma and promoting understanding are vital. But it does suggest we need to reflect critically on how awareness is framed. Messages that blur the boundaries between everyday experiences and clinically significant traits may unintentionally lead to overdiagnosis.

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The challenge, then, is not whether to pursue awareness—since its benefits are undeniable—but how to frame it responsibly to minimise overinterpretation. Ultimately, the prevalence inflation hypothesis offers a useful frame for understanding the autism overdiagnosis debate. It reminds us that rising prevalence is not solely a matter of biology or better detection, but also of culture, language, and identity. Striking the right balance—between empowering recognition and avoiding overinterpretation—will be crucial as awareness of autism continues to grow.