When the Diagnosis Doesn't Explain Everything

One of the hardest things about parenting a neurodivergent child is knowing when to accept an explanation and when to keep asking questions.

In our case, my son's autism was initially masked by his intelligence and ADHD. Once we understood the autism, however, something else happened: autism became a very convenient explanation for almost everything that remained difficult.

For years we made the changes you are supposed to make when an autistic child is severely dysregulated. We changed his environment, his schooling, our expectations, sensory input and the way demands were presented. We tried to understand rather than punish behaviour. Yet despite years of adaptations, the fundamental picture barely changed. The extreme dysregulation, low mood, lack of motivation, difficulty moving, poor executive functioning and constant desire to lie down remained.

Eventually, the lack of improvement became a clue in itself.

This article is not medical advice and is not a diagnosis of anyone else's child. It is a parent's account of remaining curious when one explanation stopped being enough.

When One Diagnosis Masks Another

Neurodivergence is better imagined as a tree than a collection of tidy boxes. Autism, ADHD, executive function, sensory processing, interoception, sleep, anxiety, intellectual ability and physical health can branch and intersect in countless combinations. Two children with the same diagnoses can therefore function completely differently.

Research into neurodevelopment and many of these overlaps is also relatively young. Professionals can be extremely knowledgeable while still working in areas where the evidence is incomplete, particularly when a child has an unusual combination of characteristics. Rare or less-recognised presentations are inevitably easier to miss.

In our case, behaviours such as constantly lying down, not wanting to move, struggling to exercise, poor concentration, nausea, temperature regulation problems and severe dysregulation could all be explained through autism, ADHD, burnout, executive dysfunction or mood. None of those explanations was unreasonable, which is precisely why we didn't immediately see another possibility.

Then my son told us something interesting: he can focus much better when he is lying down.

That made us look differently at something he had been doing for years.

Why Might Lying Down Matter?

The autonomic nervous system controls many processes we don't consciously manage, including heart rate, blood pressure, circulation, digestion and temperature regulation.

When we become upright, gravity causes blood to shift towards the lower body. The body normally compensates automatically by adjusting blood vessels, heart rate and circulation so that adequate blood flow is maintained. When this system does not regulate appropriately, remaining upright can become physiologically demanding.

This broad area includes autonomic dysfunction (dysautonomia) and orthostatic intolerance, while POTS is one specific syndrome within it.

Importantly, this does not always look like the stereotypical child who stands up, becomes dizzy and faints. A child may instead experience fatigue, nausea, exercise intolerance, cognitive difficulties, headaches, temperature problems or a strong desire to sit or lie down. Those symptoms have many possible causes, but in an autistic or ADHD child they are particularly easy to absorb into an existing neurodevelopmental explanation.

It doesn't mean that meltdowns, executive dysfunction or autistic burnout are secretly POTS. It means that once a child has a diagnosis, we should be careful not to make that diagnosis responsible for every subsequent difficulty.

If Nothing Seems to Work, Ask Different Questions

Parents don't need to diagnose their children, but we are in a unique position to notice patterns. A professional may see our child for an hour; we have watched them across thousands of hours, different environments, illnesses, school terms, holidays, good days and terrible ones.

If something continues not to make sense, these are the questions I think are worth asking:

The purpose isn't to turn every behaviour into a medical symptom. It is to remain curious when the existing explanation repeatedly fails to explain what you are seeing.

When You Feel Fobbed Off

This can be one of the loneliest parts of parenting a complex child. You have watched a pattern hundreds of times, but you have fifteen minutes to communicate it to someone who may meet your child on a relatively good day. Being told that something is “common in autism” can close the conversation very quickly.

Rather than having to convince a professional of your own diagnosis, ask them to explain theirs:

• “What makes us confident this is caused by autism rather than a co-occurring condition?”
• “What alternative explanations have been considered?”
• “If autism wasn't already on his record, how would you investigate these symptoms?”

Those are not anti-doctor questions. They are exactly the kinds of questions that complicated cases sometimes require.

Good assessment needs all three.

Our investigation into autonomic dysfunction may or may not ultimately explain every part of my son's difficulties, and that isn't the point. The lesson for me has been much broader.

If you have spent years making thoughtful, appropriate changes and nothing seems to work, trust that observation enough to ask what might be missing.

Final Thought

A diagnosis can be a door. It can give language, support and a way of understanding a child more kindly. The risk is when it becomes a lid: something that closes the conversation just when a more complete picture is still needed.

If you are holding a pattern that still does not add up, you are not being difficult by asking again. You are doing the work that complicated children often need someone to do.

Related reading: Beyond Labels, Your Child Isn't “Struggling”, and How to Help Your Child Feel Calmer, More Focused and in Control.