How would it be if you woke up one morning around 4 am, consumed by an idea that felt like the Best Idea You Ever Had. You spend the next two hours fervently researching said idea, watching videos, reading in-depth articles, compiling a spreadsheet comparing costs, techniques and options, then buying a whole load of books and equipment, and signing up to courses to teach you how to bring this fantastic, life-changing idea to fruition. You book a viewing for the new house in a new country that you are going to buy after investigating climate, housing options and work opportunities. You book the flights for that trip, to a Pacific island, where you will learn to scuba dive and set up a business as a dive instructor having fully understood the tourism industry and its legal implications. You sign up for that master’s programme in hypnotherapy/mushroom-growing/road-building after comparing the cost and quality of all colleges offering these courses. Your research is deep, your conclusions well justified. These are all good choices.

Buzzing on your own brilliance at finding the answer to all of your problems, your true calling in life and, basically, frigging nirvana, you are desperate to wake your beloved, who is lying beside you, blissfully unaware that their world is about to be rocked. You think about waking them because you can’t contain all this excitement alone and need to share it, but it’s only 6 am and you know from experience that this wouldn’t end well. So you sit, fidgeting, watching the clock until 6:30 am. Surely, that’s late enough? Perhaps if you bring them coffee, they won’t be so mad. Yet how could they be mad, when what you’re about to reveal to them will make them say: ‘Why didn’t you wake me up sooner, you genius?’

But as you sit impatiently waiting for an acceptable hour to rouse your beloved and blow their mind, your whole self shifts sideways, like someone just turned the TV over to another channel or a changeling took over your mind. You suddenly realise that your previously designated Best Idea Ever is full of holes and is actually a Terrible Idea. You are puzzled that you didn’t see this sooner. What were you thinking? You can’t move house because your kids are in school here, you have a full-time job and bills to pay, and you don’t have the attention span to read your horoscope, let alone do a master’s. And you can’t even swim.

What idiot thought that any of this was a good idea? Oh… it was me. OK… time to cancel it all and hope that you didn’t lose too much money and that it will all be back in the bank account before ‘they’ wake up.

And hope that you don’t do the same thing again tonight.

Welcome to the world of AuDHD.

You will likely have come across the term AuDHD used as a shortcut to describe those given the dual diagnosis of autism and attention-deficit and hyperactivity disorder (ADHD). It is a relatively new label and for good reason – until recently, no one individual was clinically permitted to be given both diagnoses and therefore there was no one to whom the term ‘AuDHD’ could officially apply.

In 1994, a mere 32 years ago, the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV), included Asperger Syndrome for the first time. In 2013, the diagnosis was removed from the 5th edition (DSM-5) and subsumed under the broader category of ‘autism spectrum disorder’. Asperger Syndrome had identified individuals who met the social and behavioural aspects of the diagnostic criteria for autism but who did not have intellectual disability or the language-development differences then associated with an autism diagnosis. As a result, an autistic person reading this magazine today would have been unlikely to receive an autism diagnosis in the past: there was simply no diagnostic category that fit their profile. That helps to explain the huge rise in adult diagnoses in recent decades.

Autism and ADHD were long considered mutually exclusive

Alongside this, diagnosis of ADHD in adults has been a similarly recent arrival. Having been considered a predominantly childhood condition for most of its history, the idea that children can continue to experience ADHD features into adulthood was not seriously considered until the early 2000s. Earlier versions of the DSM required that symptoms had to have been present prior to the age of seven years, and focused almost entirely on childhood behaviours to form the diagnosis. In 2013, with the publication of the DSM-5, the onset age of ADHD symptoms was raised to 12 years, and fewer symptoms were required for adults to meet the diagnostic threshold – which took into account development changes and challenges within adult settings, such as work – thus opening up ADHD diagnosis to adults.

This means that a person without intellectual disability and with relatively typical language development has been eligible for an autism diagnosis for only 32 years. And the ADHD criteria have been explicitly adapted to better recognise the disorder in adults only since 2013. That history is one part of the AuDHD issue.

The second part is that autism and ADHD were long considered mutually exclusive. It was thought that their apparently contradictory traits of rigidity and impulsivity effectively cancelled each other out. This meant that a person – either child or adult – could not be officially diagnosed with both conditions until 13 years ago, when the DSM-5 removed this exclusion and allowed both diagnoses to be given to the same person – opening the way for what is now widely called AuDHD.

At first glance, existing diagnostic criteria for each condition may look like contradictions of each other. While a stereotypical autistic person may present as socially awkward, precise and cautious in language and behaviour, requiring predictability, sameness and calm, our ADHDer looks like the complete opposite. ADHD diagnostic criteria typically present as someone socially driven, scattered and impulsive in language and behaviour, seeking novelty, variety and stimulation. How can it be that both of these seemingly opposing traits can exist in one person, and what is it like for that person when they do?

Given the relatively recent formal recognition of this comorbid profile, research into its impact is unsurprisingly scarce and, aside from a small handful of papers, has been focused on children and adolescents. The earliest research into this overlap I could find was published in 1999; those investigators concluded that autistic features were common in those with ADHD, and that a dual diagnosis should be considered in some cases, even though this was not clinically permitted at the time. This overlap has been one of the most frequently studied aspects of AuDHD.

A 2023 systematic review identified 9,050 articles and ultimately included 23 studies; across these, estimates of the prevalence of ADHD symptoms in autistic young people without intellectual disability ranged from 2.6 per cent to 95.5 per cent. Another paper suggested that 50 to 70 per cent of autistic people present with comorbid ADHD. If you are reading this article with a diagnosis of autism or ADHD, you may want to think about whether you may be both, because it’s looking increasingly likely that you are.

Of course, there have always been differing opinions and concerns about the pathologising nature of diagnosis in neurodiversity. Where does one neurodivergent condition end and another begin? Can we really separate these aspects of ourselves into neat clinical categories – often deemed necessary to permit access to a particular support service, therapy, fund or setting to meet the often-disabling needs of being neurodivergent in a neurotypical world? The reality is that no one knows the answers, so here we are with our rigid clinical diagnostic criteria, which – as we can see from the alterations in the DSM-5 – are changing as understanding grows. Forgive me for working within these uncomfortable neat boxes, but they are all we have right now; and, for at least some people, they can be a helpful way of understanding the contradictions of living with AuDHD.

My former life had failed to meet my autistic need for routine but had satisfied my ADHD need for novelty

The example at the top of the article is one from my own life and it has resonated with many of the 69 AuDHD adults and parents of AuDHD children whose stories and words I had the privilege to gather for my new book, The Complete Guide to AuDHD (2026).

My own AuDHD story is a typical one. I was diagnosed as autistic in my 40s after having written five books on autism and neurodiversity and achieving an MA in autism – I knew my stuff, and myself, or at least I thought I did. Yet I had led a chaotic life of multiple jobs, house moves and plans and schemes of one kind or another – I am known for it by those who know me; they take bets on how long I will stay in one place/job/course/project – which upsets me, but which is hard, logically, to take umbrage at.

I had never considered that I would meet the criteria for ADHD diagnosis because I was too logical, too organised and too set in my ways. I am the Queen of the Spreadsheet, the Mistress of the Plan. After bringing up two kids, I worked as a trainer and speaker for 15 years, travelling the country and overseas on a crazy schedule of driving, hotels and public speaking. Not surprisingly, I crashed horribly into years of panic attacks, agoraphobia and severe physical and mental burnout. Eventually, I gave it all up and began working locally and remotely, removing 90 per cent of the stress and unpredictability of my former life. At first, it was wonderful, I remembered what it was like to wake up without a brick of dread and anxiety on my chest. I slept in the same bed every night and knew what each day would bring. Perfect. Until… a few weeks into this blissful new existence I recall a feeling that I verbalised at the time as ‘I feel like I’m dead.’ I felt flat, blank, nothing, emotionless. Over a period of reflection, I realised that I had never actually sat still my whole life. While my former parenting and working lives had failed to meet my autistic need for routine and predictability, they had entirely satisfied – what I now understood to be – my ADHD need for constant dopamine in the form of novelty, variety and excitement.

Those who have the same experience of a second diagnosis of either autism or ADHD share the same feeling I did – it’s the final piece of the puzzle. The first diagnosis made sense of a lot, but it didn’t explain it all. There were questions and gaps: ‘I’m too social to be autistic.’ ‘I need too much order to be ADHD.’

This sense of two selves, of the push and pull of opposing wants and needs, is the core of the experience

Since the dual diagnosis of the two conditions is fairly recent, it is still unusual for both diagnoses to occur at the same time, with most adults currently having received one diagnosis first and the second at some point later, as did I. And although autism and ADHD were deemed contradictory for much of their joint history, both sets of diagnostic criteria need to be met for each diagnosis to be given: there is no allowance made for ADHD characteristics masking those of autism, for example – which they often do – during the diagnostic assessment.

Which diagnosis comes first varies from person to person, with either autism or ADHD often appearing as the primary profile. Perhaps ADHD appears more ‘visible’ for a child challenged by sitting still at school, or autism for an adult struggling with the social and flexibility requirements of a job – with the other lurking behind ready to throw a spanner in the works or offer a helping hand. Given that the second diagnosis was simply not an option for so long, the thought of it was generally never given the time of day, although a number of AuDHD people I have assessed often say they’d felt that the first diagnosis had answered some of the questions they’d had throughout their lives about why they were different, but not all. For others, it was a complete surprise. As one person I interviewed for my book explained:

My ADHD assessor said: ‘Many of these symptoms could be explained by the autism,’ to which I replied: ‘What autism?’

For many, this ‘primary’ profile is not fixed. Female hormones are known to affect the severity of ADHD. The time of day and associated stress and fatigue play a role. And the impact depends on the activity contemplated – does it require speed and creativity, or accuracy and focus?

The idea of the autistic and ADHD selves as separate entities is hardly definitive, and experts differ here. Some research finds autism and ADHD symptoms to be largely segregated along existing diagnostic boundaries; others that they have overlapping features; while others suggest that the co-occurrence of autism and ADHD may represent a distinct combined phenotype. Regardless of the thoughts of academics, this sense of two selves, of conflict and contradiction and the push and pull of opposing wants and needs, is one that formed the core and essence of the experience of the participants in my own research.

An article by Siân Boyle in The Guardian in 2024 described this contradiction in the AuDHD label as one of ‘oxymoronic nature, perpetual internal war and rollercoaster of needs’, which nicely sums things up.

The realisation that there is a name and an explanation for the persistent inconsistency that accompanies the AuDHD lived experience can be liberating – it’s a relief to know that you are not actually crazy, because that’s the way it can feel. In the words of my research participants, it is:

Having to keep two different beasts fed and cared for, after having spent most of my life being told by others that neither beast existed.

A lightbulb moment when I realised that my hectic brain being pulled in two different directions at all times throughout my whole life actually had a reason and it wasn’t that I was stupid or incapable as I always believed before.

Despite this sense of contradiction, the two conditions do share some characteristics. Both are highly heritable and run through families. As far back as 2009, a team led by the child and adolescent psychiatrist Aisling Mulligan at Trinity College Dublin found that autistic traits in children with ADHD ran in families, along with the ADHD itself. More recent research shows that mothers with ADHD are six times more likely to have a child with ADHD – and 2.5 times as likely to have an autistic child. Other studies suggest a shared genetic base between autism and ADHD, explaining the high prevalence of both conditions in the same families. Twin studies provide further evidence of this genetic overlap.

People with either autism or ADHD may find it challenging to read subtle social nuances and engage in reciprocal conversation, making it harder to sustain friendships and relationships. Both often have intense passions and interests, although these tend to last longer in autism than in ADHD. And while sensory features are not mentioned in the diagnostic criteria for ADHD, both groups may have atypical sensory profiles. As a very broad generalisation, autistic people find sensory experiences overwhelming, leading them to avoid some sensations and seek out comfort. On the other hand, ADHD people may seek sensory input and stimulation to feel grounded and focused. Although it is early days for research and the number of papers looking at AuDHD are small and focused almost entirely on children and adolescents, the general consensus is that the combination of autism and ADHD makes things worse socially, adaptively, behaviourally and mentally. I could not find any research-based evidence that sought or found examples of the dual diagnosis making life better. It seems that, in academic studies, questions relating to the advantages and joys of AuDHD were not asked, and that the focus was entirely on problems, challenges and deficit, as is often, disappointingly, the case.

Every day needs to be filled with entertainment and stability, learning and fun

The inconsistency brought by these apparently opposing sets of features does cause considerable frustration for the typical AuDHDer, who lives switching – often rapidly – between seeking both order and disruption, sameness and variety, impulsivity and risk-aversion, social motivation and solitude, single focus and multi-focus. When needs and wants shift so quickly and vary so wildly, decision-making and balance can feel impossible, leading to a far more chaotic life than would be expected from someone with an autism diagnosis. As one of the research participants said:

For my child, it’s like living with Bert and Ernie from Sesame Street in his head at one time. Bert wants quiet but Ernie needs noise… The internal tension is real.

Yet the participants in my own research reported the joys of AuDHD as well. For me, the combination of the detail and diligence of autism and the creativity and impulsivity of ADHD have likely led to my deeply interesting and varied life, because I couldn’t have tolerated it any other way. Every day needs to be filled with entertainment and stability, learning and fun. Others in my research agree:

The absolute chaos and rhizome-like thinking enables me to be very creative in all aspects of my life and see things in a way that others don’t. The ability to feel and see so much; a complete all-encompassing joy over very small tiny things and details that most other people miss, sometimes it feels like I can almost see or feel an extra dimension compared to those around me, and it brings me so much joy.

For me, it feels like a life of two halves, like living as a pair of twins who argue a lot but now and again will sit on the couch together and watch a movie. We know we have to have a schedule, eat the same foods and get things done. We know we have to physically move – a lot – keep switching tasks, and force ourselves to stop when we’re just done. We know we find it hard to begin, hard to keep going and hard to stop, and we’re continually developing ways to work with all of that at any given time in all given circumstances.

And although Autism has to step in to keep ADHD in check, and force it to sit down and do the dull, important things for a few minutes – rather than spending all day watching videos about giant tortoises on the Galápagos Islands – ADHD also needs to break through the rigidity of Autism’s need for productivity, tell it to lighten up – and come watch some of these great videos on giant tortoises on the Galápagos Islands. And then, once ADHD has piqued Autism’s interest with today’s Best Idea Ever, Autism can become a world authority on tortoises, research the climate, food, cheapest flights and best hotel on the islands, and build a spreadsheet to get this trip on the road. What a team!

We only have to hope that Autism knows where the passport is.