When Medical Gatekeeping Harms: A Response to "The Age of Diagnosis"
When doctors inadvertently participate in a long tradition of gatekeeping that has historically harmed marginalized communities.
Recently, I came across an interview with Dr. Suzanne O'Sullivan about her new book, "The Age of Diagnosis," in which she challenges the increase in diagnoses of conditions like autism, ADHD, and long COVID. As someone who runs ADHDer.net and works closely with the neurodivergent community, I felt compelled to respond to her assertions with current scientific research and the lived experiences of those she claims are being "over diagnosed."
The Problem with Medical Gatekeeping
When medical professionals like Dr. O'Sullivan argue that we're "not getting sicker" but rather "attributing more to sickness," they inadvertently participate in a long tradition of gatekeeping that has historically harmed marginalised communities—including the neurodivergent population.
Let's address some of the concerning claims and examine what the research actually tells us.
On ADHD: "I'm far from convinced that ADHD is a single disease"
Dr. O'Sullivan states she doesn't believe adult ADHD is the same condition as childhood ADHD and suggests there's no biological basis for the condition.
What the research actually shows:
Biological evidence is substantial: Contrary to O'Sullivan's claim that "if you take a person with very severe ADHD and you do a brain scan for abnormalities, you will not find any abnormalities," numerous neuroimaging studies have found consistent differences in ADHD brains. A 2023 meta-analysis published in Molecular Psychiatry examined data from 83 studies involving over 4,000 participants with ADHD, finding consistent structural differences in regions associated with attention and impulse control.
Genetic evidence is overwhelming: ADHD has a heritability of approximately 74%, making it one of the most heritable neurodevelopmental conditions. Over 12 different genes have been consistently implicated in ADHD, particularly those involved in dopamine transport and reception.
On adult diagnosis: Longitudinal research from the past two decades definitively shows that ADHD persists into adulthood in approximately 65% of cases. Dr. Russell Barkley's 25-year follow-up study demonstrated that ADHD doesn't simply disappear with age but rather manifests differently as executive function demands change in adulthood.
On medication efficacy: When Dr. O'Sullivan claims "there is a Cochrane review that has shown no benefit to adults," she's either misinterpreting or misrepresenting the data. The most recent Cochrane reviews show that stimulant medications demonstrate significant efficacy in reducing core ADHD symptoms in adults, with effect sizes comparable to those seen in children.
On Autism: "We think you are autistic, but there is nothing that you can't do"
Dr. O'Sullivan suggests that diagnosis of milder autism is potentially harmful because people "unconsciously take on the features of that label."
What the research actually shows:
Late diagnosis improves outcomes: Multiple studies, including a comprehensive 2021 review in the *Journal of Autism and Developmental Disorders*, found that receiving an autism diagnosis in adolescence or adulthood led to improved self-understanding, reduced anxiety and depression, and better life outcomes—even for those with "milder" presentations.
The "autism epidemic" explained: The tripling of autism diagnoses that O'Sullivan mentions is largely explained by three factors: expanded diagnostic criteria that better capture the full spectrum, improved screening practices, and greater awareness among healthcare providers. A landmark 2022 study in *JAMA Pediatrics* found that approximately 80% of the increase in autism prevalence can be attributed to these factors rather than a true increase in incidence.
On masking and late diagnosis: Research by Dr. Francesca Happé and colleagues has demonstrated that many autistic individuals, particularly women and girls, develop sophisticated masking strategies that delay diagnosis until life stressors exceed their compensation abilities—exactly the scenario O'Sullivan describes but misinterprets as over diagnosis.
The Fallacy of "Psychosomatic" Explanations for Long COVID
When Dr. O'Sullivan suggests that long COVID is largely psychosomatic and represents "the perfect storm for a psychosomatic epidemic," she ignores mounting biological evidence.
What the research actually shows:
Biological markers exist: Multiple studies have identified distinct physiological abnormalities in long COVID patients, including microclot formation, persistent viral reservoirs, and dysregulated immune responses. A 2023 study in *Nature Communications* identified over 20 distinct biological markers present in long COVID patients but absent in recovered controls.
Not explained by psychology: While psychological factors can exacerbate any chronic condition (including cancer or diabetes), research published in *Cell* and other top journals has failed to find any correlation between pre-existing psychological conditions and likelihood of developing long COVID.
The harmful history of "psychosomatic" labelling: Conditions like multiple sclerosis, lupus, and myalgic encephalomyelitis were all once dismissed as psychosomatic before biological markers were discovered. This pattern disproportionately affects conditions that predominantly impact women and marginalised communities.
The Harm of Dismissing Lived Experience
Perhaps most concerning in O'Sullivan's arguments is the dismissal of lived experience. When she questions whether adults who say they benefit from ADHD diagnosis and treatment are experiencing anything more than placebo effects, she's dismissing decades of research showing improved quality of life, reduced substance abuse risk, lower accident rates, and better relationship stability among treated adults with ADHD.
Why This Matters So Much
For the neurodivergent community, books like "The Age of Diagnosis" don't exist in a vacuum. They influence medical practice, insurance coverage, educational accommodations, and public perception. When prominent doctors promote views that contradict established research, real harm follows:
Delayed diagnosis and treatment: The average wait time for adult ADHD assessment in many countries is already 2+ years. Attitudes like O'Sullivan's contribute to this barrier.
Internalised shame: Many late-diagnosed adults report decades of shame and self-blame before diagnosis, believing they were simply "lazy" or "not trying hard enough."
Reduced access to accommodations: When conditions are framed as over diagnosed, it becomes harder to secure necessary workplace and educational accommodations.
A Better Way Forward: Evidence-Based Inclusion
Rather than worrying about "over diagnosis," we should be focused on:
Improving diagnostic accuracy: This means better training for clinicians, not raising diagnostic thresholds.
Reducing stigma: Neurodevelopmental conditions are variations in brain function, not character flaws or excuses.
Supporting neurodivergent people: Diagnosis should be the beginning of support, not merely a label.
Listening to lived experience: The neurodivergent community has been saying for decades what research is only now confirming.
The suggestion that we're simply "labeling" normal variations as medical conditions represents a fundamental misunderstanding of neurodevelopmental differences. The scientific evidence overwhelmingly supports the biological basis of conditions like ADHD and autism, their persistence across the lifespan, and the benefits of appropriate diagnosis and support.
While I appreciate Dr. O'Sullivan's concern about medicalization, dismissing the lived experiences of millions of neurodivergent people and contradicting established science does more harm than good. The real problem isn't overdiagnosis—it's the continued barriers to appropriate recognition, understanding, and support that many neurodivergent people face.
For those of us who spent decades wondering what was "wrong" with us before finding answers through diagnosis, books like "The Age of Diagnosis" feel like a step backward into an era when differences were dismissed rather than understood.
Real progress comes not from raising diagnostic barriers but from creating a world that better accommodates neurological diversity in all its forms.
What has your experience been with diagnosis? Has it helped or harmed your understanding of yourself? Share your thoughts in the comments below.
So important! Thanks for this.