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The Age of Diagnosis

Are Medical Labels Doing Us More Harm Than Good?

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The Age of Diagnosis

By: Suzanne O’Sullivan
Narrated by: Suzanne O’Sullivan
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From autism to allergies, ADHD to long Covid, more people are being labelled with medical conditions than ever before. Are we actually becoming less healthy? Or are we medicalising normal human differences?

Includes chapters on:
-ADHD
-Autism
-Long Covid
-Lyme Disease
-Genetic screening
-Cancer screening
-Huntington's Disease

The boundaries between sickness and health are being redrawn. Mental health categories are shifting and expanding all the time, radically altering what we consider to be 'normal'. Genetic tests can now detect pathologies decades before people experience symptoms, and sometimes before they're even born.

An accurate diagnosis can bring greater understanding and of course improved treatment. But many diagnoses aren't as definitive as we think. And in some cases they risk turning healthy people into patients.

Drawing on the stories of real people, as well as decades of clinical practice and the latest medical research, Dr Suzanne O'Sullivan overturns long held assumptions and transforms how we think about illness and health.

Praise for The Age of Diagnosis:
'Revelatory. Slices through the contradictions.' - CHRIS VAN TULLEKEN
'So well-written... critically important.' - RANGAN CHATTERJEE
'A doctor's brilliant study of the dangers of overdiagnosis' - GUARDIAN
'Compassionate and bracingly independent thinking' - THE TIMES
'Exceptional. Chapter by brilliant chapter, it raises fundamental questions we should all be asking.' - NEW STATESMAN

*As heard on Radio 4 Book of the Week, Today, Good Morning Britain, Sky News and more.*©2025 Suzanne O’Sullivan Biological Sciences Brain & Nervous System Medicine & Health Care Industry Physical Illness & Disease Physician & Patient Science Health Mental Health Thought-Provoking Medicine
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Critic reviews

The Age of Diagnosis covers so many topics that have been troubling me but which I hadn't been able to resolve myself. It slices through the confusion and the contradictions that have tied me in knots - both as a parent and as a clinician - with grace, elegance and compassion. It is scholarly and human, but an absolutely absorbing read from start to finish. There are very few people who could write this so straightforwardly and yet with endless compassion. I really cannot say good enough things about it. (Chris van Tulleken, author of ULTRA-PROCESSED PEOPLE)
Wow... So well-written, there's deep compassion behind the words... raising awareness of something critically important. (RANGAN CHATTERJEE)
O'Sullivan is brave to take this subject on, and she hits the target... she is an excellent, fluid writer, and an eloquent speaker... In a world where medical misinformation and disinformation flourish, and people die as a result, it takes courage to counter them without pandering to stereotypes. But that is what The Age of Diagnosis does so well... Its overall message is clear: diagnosis is a tool to be wielded with the utmost caution, and tolerance for difference and for imperfection can go a long way in keeping us healthy. (Adam Rutherford)
'Exceptional... Chapter by brilliant chapter, [The Age of Diagnosis] raises fundamental questions we should all be asking when thinking about illness, be it cancer or genetic disorders, never shying away from difficult truths.' (Hannah Barnes)
'The neurologist takes eloquent aim at a medical culture that, although well intentioned, is too quick to assign clinical labels to aspects of the human condition... A brave and compassionate book.'
How does she carry off that high wire act, being so technical and expert and grounded in data, while telling stories in a way that makes them utterly addictive? I love the way she listens to people talking. It's a really important, intelligent, compassionate and brave book, and it speaks very eloquently to things happening in our ideas about ourselves. (Tessa Hadley)
A humane and thoughtful observer of the oddities of the human mind... full of intriguing case studies and wise observations. Her new book ranges widely, taking in the drawbacks of mass screening for illnesses as well as the perils of overextending mental health categories... We make people sicker by by the simple act of diagnosing them with a medical problem. A fascinating book. (Robbie Millen)
A brave and deeply compassionate book with a very important message. (Henry Marsh)
The neurologist Suzanne O'Sullivan has written insightful books about psychosomatic conditions. Here she turns her attention to the perils of over-diagnosis - including autism, allergies, ADHD and long Covid. Be prepared for compassionate and bracingly independent thinking.
All stars
Most relevant
In an age of binary certainty and having all the answers, a book that acknowledges where we are and asks questions about the need for absolutes. I feel I have been so lucky in finding some amazing books recently and this is right up there with the best of them. It is so brave for a doctor to ask the questions asked in the modern world. It’s an amazing book.

The antidote to modern madness

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This is what, today, we call 'a brave book' but which, 25 years ago, we would have called 'a book'. I haven't heard the abridged BBC version, which I imagine is high quality and full of important information and challenging opinions. But I can't think of anything in the unabridged version which is superfluous, so I would recommend just taking the plunge and getting the book. If only some of our policymakers and/or opinion formers (particularly the contemporary media which seems to just accept 'science' without understanding that it's possible to be supportive whilst always needing to be objective and inquisitive - this is definitely NOT a book for the anti-vaxxers and conspiracy theorists) would read/listen and take note.

A 'must read' for anyone with an open mind

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Informed me so much that I take into my place of work. Information and easy to listen to

Brilliant

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I work in diagnostic medicine and I absolutely loved this book and how it explains that more is not always better. My lab is always chasing the best and most expensive technologies and it has me thinking have we lost sight of what is best for the patient. A really enjoyable read.

a fascinating read

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Fantastic book, incredibly thought provoking and questions many different diagnosis’s.
As someone with a psychosomatic illness I find it fascinating and mind boggling

Kind explanations and questions medicine

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