“I SEE PEOPLE IN THEIR 20S WITH 20 CONDITIONS”: IS OVERDIAGNOSIS MAKING US SICKER?

Suzanne O’Sullivan, a neurologist of 25 years, believes we are overdiagnosing people. In her new book The Age of Diagnosis, she explores “sickness, health, and why medicine has gone too far.”

Covering everything from ADHD and autism to predictive screenings for dementia and cancer, her concern is not that people are getting softer but that, despite good intentions, excessive medical labeling may be harming us.

Overdiagnosis occurs when people are turned into patients by identifying problems that, if left undiagnosed, likely wouldn’t have caused harm. It’s a “better safe than sorry” approach that pathologises normal life.

It is a reason given for the apparently sudden ubiquity of conditions like ADHD, autism, chronic Lyme disease, hypermobile EDS, and PoTS. Over diagnosis may also be connected to the rise in preventative screening for cancer and dementia.

Recent data supports this: UK adult ADHD diagnoses have increased twentyfold; a 2021 study found a 787 per cent rise in autism diagnoses from 1998 to 2018; and in 2024, NHS cancer diagnoses rose by 5 per cent.

In the case of ADHD and autism, the inflation in diagnoses has come at the milder end of the spectrum – cases of people on the severe end, where the symptoms completely impair your ability to lead a normal life  has remained stable.

Why are we overdiagnosing people?

O’Sullivan (no relation to the journalist) outlines several reasons for this trend. “First of all, we had an underdiagnosis issue for a long time,” she explains. In the past, real suffering was either unrecognised or diagnosed too late. “We’re desperate to correct that, but I feel we’ve overcorrected based on the assumption that more diagnosis is good.”

Commercial interests also play a role – ADHD prescriptions have increased by 18 per cent annually since the pandemic – but she argues that scientists also have their own motivations. “When we create a new MRI scan, we want to use it widely. When we develop quick genetic tests, we want to see who else can benefit.”

Another factor is human nature. “People thirst for answers. Doctors like to please people, and if scientific culture allows it, they will provide them.” She calls this a “collusion between society, scientists, and doctors.”

She says this is especially evident in the explosion of neurodevelopmental disorder diagnoses. “Autism used to affect one in 2,500 children. Now, in Northern Ireland, it’s one in 20. You have to wonder what the hell is going on.”

The increase in autism and ADHD

One issue is “diagnostic creep”, where criteria broadens from more specific symptoms to include milder and milder iterations of those symptoms. “Some say mild autism was long overlooked, and I accept that. But in trying to correct it, we’ve loosened the criteria so much that we apply the label to people whose symptoms are so mild you wouldn’t even notice them.”

She doesn’t dispute individuals’ experiences but questions whether those particularly at the mild end of the spectrum benefit from diagnosis. Given the rise in diagnoses over 30 years, she argues we should see positive impacts, yet the evidence doesn’t support that.

Neurodivergent communities counter that the world isn’t built for them to thrive, but she believes this overlooks improvements. “I’m not saying the world is perfect, but despite special accommodations, we see no measurable improvement.”

She cites a Canadian study comparing children with ADHD who received accommodations and those who didn’t: while the accommodated children reported feeling helped, objective measures showed no actual improvement.

Beyond neurodevelopmental conditions, she highlights overdiagnosis in other areas. In her book, she explores long Covid as an example of how diagnoses can go wrong from the moment they are conceived.

Long Covid – the disease that started as a hashtag

Normally when you have a diagnosis it’s defined by something singular, and eventually you’ll find the spectrum of versions around that specific anchor. But long Covid came from a hashtag and moved quicker than it could be studied. O’Sullivan says: “Within a couple of months, everyone thought they knew what long Covid was but no one had ever studied it”.

She believes long Covid patients likely fall into distinct groups: those with post-viral syndrome, those with post-hospitalisation organ damage, and those experiencing something else. “As no one saw doctors during the pandemic, it’s inescapable that the period was a melting pot for psychosomatic conditions.”

She stresses she isn’t dismissing suffering. Throughout her book and interview, she emphasises that the search for diagnosis reflects real pain that deserves support. However, labelling can restrict people. In children, autism and ADHD diagnoses may limit development.

“My intention is in no way to say that people aren’t suffering. My intention is to say that people are suffering, but is medicalising those the best way to manage it?

“At the moment, society perceives that an ADHD or autism diagnosis is the best way to help a struggling child. What I’m advocating for is to recognise the child is suffering, and finding ways to help struggling people without the need for medical diagnosis.”

In this case, she is referring to people on the mild end of the spectrum who struggle but can manage, rather than those who cannot manage at all. “At the moment impairment is so poorly defined that it’s causing really big difficulties, even though the difference between someone who doesn’t feel he has a disorder but a difference, and someone who is non-verbal and needs constant support is miles apart,” she explains.

Read Next: Thousands of autistic people living with undiagnosed mental illnesses

For conditions involving bodily hyper-awareness, like long Covid, diagnosis can worsen symptoms. The more you focus on your body, the more you notice irregularities you’d otherwise ignore – a knee ache, fatigue. This creates a feedback loop where your brain anticipates and sustains symptoms.

This is a psychosomatic condition – a real, debilitating illness without a biological cause. “When I say long Covid is partly psychosomatic, I’m not dismissing suffering. Some of the sickest patients I see have psychosomatic conditions.

The difficulty we have is that psychosomatic illness is still so stigmatised. In putting these theories forward, I’m advocating that we take these problems more seriously and give them more respect.” Because psychosomatic illnesses are mental rather than biological, traditional medical care can reinforce rather than alleviate symptoms. They require careful therapeutic approaches instead.

When is a diagnosis helpful vs harmful?

But how do we determine whether ADHD or autism diagnoses are harmful? Many feel validated and relieved by diagnosis – is that not beneficial in itself?

“I completely get that people feel really validated and explained, and it gives people a great sense of relief,” she says. “But after that, what next? Once that moment of validation has gone, has this diagnosis really benefited you? Because I’m not 100 per cent convinced that the validation will last for a long time.”

She is particularly concerned about children, who are still developing their identities.

“The downside of diagnosis is that the minute you refer to yourself as neurodevelopmentally abnormal in some way, it’s like saying you have an insurmountable problem.

“And instead of maturing out of it or trying to overcome it or ignoring it, it focuses attention on what you cannot do.”

She believes a diagnosis might also influence how teachers and society treat these children, shaping expectations in ways that might be unhelpful.

O’Sullivan sees this pattern in her own work with epilepsy patients. Previously, those with dissociative seizures (psychological rather than neurological seizures) often went under the radar until their psychosomatic symptoms turned into seizures. Now, many young patients arrive with 20 other diagnoses: “I’ve seen people with dissociative seizures since I was a student. But what I never saw before was these patients arriving with a long list of medical diagnoses in their early twenties.”

Instead of in the past where she suspects patients would experience different symptoms until arriving at seizures, patients are now having each symptom diagnosed.

“I’m now seeing people in their twenties with long lists of symptoms and medical diagnoses. And it’s not just that they didn’t get the diagnosis 20 years ago – they didn’t have the symptoms 20 years ago. Through the medical system and through support groups, people are being shunted in a particular direction which has created a long list of symptoms, where we neither saw the symptoms accumulated or the labels in the past.”

Diagnosis is an art, not a science

She acknowledges that her views are contentious. “Pretty much everything I’ve written about will challenge someone. But these discussions are essential.”

The next step is rigorous scientific evaluation of how diagnosis affects outcomes. “No one has actually examined whether increased diagnosis has led to better health outcomes.”

On an individual level, she urges people not to rush into diagnosis or view it as definitive. “There’s enormous subjectivity in diagnosis, even with advanced technology. Medicine is an art, and the most important part is listening to the story, not just relying on tests.”

“If a diagnosis doesn’t come with a treatment that’s going to treat and cure you but rather turns you into a patient who focuses on their symptoms, perhaps it’s something you can do without. I really want people to know that these uncertainties exist so they can decide for themselves if the label that they’ve taken on is definitely helping them or could be holding them back.”

The Age of Diagnosis by Suzanne O’Sullivan is published by Hodder (£22).

2025-03-15T06:43:05Z