Autism and ADHD: The myth of co-occurring conditions

It’s a very poorly kept secret that many people who are given a diagnosis of autism also meet the criteria for a diagnosis of ADHD. One could be forgiven for assuming this means that people who meet the criteria for both (often termed AuDHD) have two co-occurring conditions. Unfortunately, nothing in life is simple, and the actual answer to this situation is far more complex.

Co-occurring disorders refer to two separate conditions that are occurring at the same time. For example, one might be both asthmatic and diabetic simultaneously. I have chosen this particular example because I want to explore the disconnect between physical health and psychiatric diagnoses.

Diagnosis is a two part system. Step one is research. Clusters of symptoms are matched up to biological signs (known as biomarkers). Where a meaningful relationship can be found between symptoms and biomarkers, you have a disorder. In psychiatry, however, it does not go this smoothly. We can identify clusters of symptoms, usually behaviour or thoughts and feelings that have been deemed troublesome or pathological by those with the privilege of not being oppressed. The problem comes when we try to find a meaningful link with biomarkers.

Despite decades of research, we are not any closer to finding a quantifiable difference in the human body. The research that does exist has been largely inconclusive.

So here’s where autism and ADHD come in. Many of us meet the criteria for both diagnoses. This is because diagnostic manuals specify lists of traits, and if you meet enough of them, you get diagnosed. The problem is that much like pseudoscientific personality tests, humans don’t fit neatly into categories. The criteria for many diagnoses overlap and mic together.

The point I’m trying to make is that AuDHD’ers do not have two conditions simultaneously. In fact, according to the neurodivesity paradigm, there is nothing medically quantifiable. Humans have individual sets of traits that are diverse and interlinked. Remember the saying “if you’ve met one Autistic person, you’ve met one Autistic person”?

That’s because autism doesn’t actually exist. It’s not a physical abnormality, it has no presence. Autistic people exist, and being Autistic is an identity based on shared culture and language. So, what is far more likely is that Autistic and ADHD people are more likely to share particular clusters of traits. You don’t have two conditions, your particular flavour of diversity just happens to tick the right boxes for both.

One could argue that this means a separate diagnosis should be created for people who meet both criteria or that classification should be changed to have them listed as part of a shared spectrum. The problem is that current diagnostic models are unreliable and prone to mistakes. We often find our diagnosis changing from doctor to doctor.

This isn’t necessarily because doctors are bad at their job. It’s because we are trying to pathologise human experience and identity. You can’t measure psychiatric conditions with a blood test, doctors know this, and they’ve been trying to do it for many years. This means that not just diagnosis, but the criteria themselves are at the whim of individuals. Experts and professionals bring their own individual biases to the table, and each one will interpret traits differently.

This is why it’s important that we move towards a demedicalised approach to neurodiversity. We need to stop assigning people fixed identities through diagnosis and instead explore the very real fact that everything about us, including our neurology, changes with time.

People should be allowed to explore their identity and try on whatever labels they feel are right for them.

If this has intrigued you I highly recommend the Neuroqueer series that I co-author with Katie Munday and the interview I recently has with Dr. Nick Walker for my podcast.