Human beings are naturally more varied than we’ve tended to assume, and perhaps it’s time our understanding of people reflected that reality.
Something a little different for this blog, and a little more with an academic bent as we head down another rabbit hole.
It started with what looked like a simple question. How many neurodivergent people are there really? Many of us have heard numbers around 15 to 20 percent. They get repeated often enough that we almost stop asking where they came from. The more I read, the more I listened to researchers, and the more I reflected on my own lived experience as someone who is autistic and ADHD, the more I couldn’t shake the feeling that we might be counting the wrong thing.
One of the things that sent me down this rabbit hole was the growing body of research into synaptic pruning, neural connectivity and brain development.
Another thought kept nagging at me. For the last couple of hundred years, society has increasingly rewarded consistency, repetition and conformity. Schools, factories and many workplaces were designed around those strengths. It made me wonder whether we’ve been measuring people against the needs of the industrial age, rather than simply recognising human diversity for what it has always been
While the science is still evolving, several studies have shown differences in synaptic density and pruning in autistic brains, raising a much bigger question in my mind. Are today’s diagnostic categories describing separate conditions, or are they different expressions of a broader underlying neural complexity that we simply don’t yet have the language to describe?
Before we go any further, let me make something clear.
This entry is not suggesting that 40 to 50 percent of the population is disabled. Quite the opposite. I’m exploring whether there may be a much larger group of highly capable, highly functional people who share a similar underlying neurodevelopmental architecture, but who have never needed or wanted a diagnosis. Disability and neurodevelopment are related conversations. They are not the same conversation.
The motivation for this rabbit hole isn’t to create another label. It’s almost the opposite. The more I’ve thought about it, the more I’ve come to wonder whether there really is such a thing as a ‘normal’ brain in the way we often imagine it.
Every one of us is unique. We have different strengths, different interests, different ways of learning, different ways of solving problems and different ways of connecting with other people. If this hypothesis turns out to have merit, perhaps the biggest takeaway isn’t that more people are neuro-complex than we thought. Perhaps it’s that human diversity is far more common than we’ve given ourselves permission to recognise.
That idea sits at the heart of why I wrote Weird is the New Normal. The book was never about celebrating diagnosis. It was about celebrating difference. Leadership, families, communities and businesses become stronger when different ways of thinking are welcomed rather than squeezed into one narrow definition of success.
So I grabbed a notebook.
Not because I thought I’d prove anything. Quite the opposite. I wanted to see whether the idea survived once I started putting some numbers against it. If the maths fell apart, great. I’d learnt something. If it didn’t, then perhaps there was a better question waiting to be asked.
The commonly quoted figure is around 15 to 20 percent. That seems a fair place to start because it broadly reflects recognised neurodevelopmental conditions. Those numbers largely come from people who have entered clinical systems, whether because they sought support, were identified through research, or met recognised diagnostic criteria. From there I started making adjustments, but only where there was a reasonable basis in research.
We know many adults remain undiagnosed. Some grew up before assessment was common. Some learnt to mask. Others simply function well enough that they have never seen a reason to seek a diagnosis.
Then I asked another question. What about the people who clearly think, learn and experience the world differently, yet live successful and meaningful lives? If they share a similar underlying neural complexity but never meet a clinical threshold, they won’t appear in today’s prevalence estimates either.
So, what did the notebook actually look like? Something like this. I wasn’t trying to prove the idea. I wanted to see whether it immediately fell apart once I started putting some numbers around it. Surprisingly, it didn’t. The simple model I ended up with looked like this:
N = D + U + F ? O
Where N is the estimated neuro-complex population, D is the currently recognised population, U is the likely undiagnosed population, F is the highly functional people who may never seek a diagnosis, and O removes the overlap between conditions so we don’t accidentally count the same people twice.
The model starts with the commonly quoted 15 to 20%, then allows for what we already know about underdiagnosis. From there, it asks a much bigger question. What if there is a large group of people who share a similar underlying neural complexity, but never meet a clinical threshold because they simply live successful lives without needing support? Further, I also considered what we already understand about the strong hereditary nature of many neurodevelopmental conditions and emerging research into synaptic pruning and differences in synaptic density. That isn’t a conclusion. It’s a hypothesis worth testing. When I modelled those scenarios, the numbers consistently landed somewhere between 30 and 50%, depending on which assumptions were used.
The important part isn’t whether the answer is exactly 32%, 41% or 47% as some sort of precise measure. The important part is that the model didn’t collapse or fall apart. It suggests we may have been measuring diagnosable conditions, when the more interesting question is whether we’ve been overlooking a much broader spectrum of human complexity hiding in plain sight. If nothing else, I hope this gives researchers, clinicians and wonderfully curious people another rabbit hole worth exploring.
If a broader underlying neural complexity exists beyond today’s diagnostic thresholds, then a possible population of 40 to 50 percent becomes mathematically plausible.
Notice my language here. Plausible. Not proven. Possible. Not established.
The interesting thing for me wasn’t that the numbers landed somewhere around 40 to 50 percent. It was what that possibility means. It reminds us to be very careful not to confuse neuro-complexity with disability.
For some people, autism, ADHD, dyslexia, dyspraxia and other neurodevelopmental conditions can be profoundly disabling. Those experiences are real and deserve understanding, support and accommodation.
For many others, those same underlying differences are simply part of who they are. They shape how they think, learn, create, build relationships, lead, innovate and contribute. They may create challenges in some environments and remarkable strengths in others.
That also raises another question I don’t think we’ve explored deeply enough.
If a very large proportion of the population is naturally neuro-complex, perhaps the real conversation isn’t about why neuro-complex people struggle to fit existing systems.
Perhaps we should also be asking whether many of the systems we’ve inherited from the industrial era (and others) were designed around a much narrower view of how people are expected to think, learn, work and succeed. That’s a conversation for another day, but I suspect it’s an important one.
So where does that leave us?
Not with a conclusion.
With a better question.
Have we spent decades estimating the prevalence of diagnosable neurodevelopmental conditions when what we really want to understand is the prevalence of underlying neural complexity?
Showing that people from many different walks of life think and process the world differently shouldn’t concern us. If anything, it should encourage us.
That’s one of the reasons this matters outside academia. Many people often say to me they see the world differently, that relationships are different, their ideas are different. In my own observations, different minded people often seem to gravitate towards one another. Perhaps that’s because there’s a level of understanding that doesn’t always need to be explained.
I am reminded of a quote courtesy of a recent Kaboose Divergent Discussion where the guest left a profound statement. If we design our world to be inclusive all in all, it works for all people regardless.
Imagine what our lives, families, communities, workplaces and businesses might look like if we genuinely designed them around that idea.
References
- Doyle, N. (2020) Neurodiversity at Work: A Biopsychosocial Model and the Impact on Working Adults.
- Faraone, S.V. et al. (2021) The World Federation of ADHD International Consensus Statement. Neuroscience & Biobehavioral Reviews.
- Happé, F. and Frith, U. (2020) Annual Research Review: Looking back to look forward. Journal of Child Psychology and Psychiatry.
- King’s College London (2023) Up to 90% of middle-aged and older autistic adults are undiagnosed in the UK.
- Lord, C. et al. (2020) Autism spectrum disorder. Nature Reviews Disease Primers.
- Centers for Disease Control and Prevention (2025) Autism Data and Statistics.
- Tang G, Gudsnuk K, Kuo S … Loss of mTOR-Dependent Macroautophagy Causes Autistic-like Synaptic Pruning Deficits Neuron, 2014; 83, 1131-1143
- 22 June 2026 – Kaboose – Michelle Ridsdale “Divergent Discussion: Navigating the Workplace as a Neurodivergent Human”
