Understanding Flexible Thinking: Why Autistic and ADHD Young People Can Become Rigid — and Vulnerable to Outside Influence
When we talk about autism and ADHD, one of the most misunderstood areas is flexible thinking. Families often describe the same pattern:
“He won’t change his mind, even when the evidence is clear.”
“She listens to strangers online more than her parents.”
“He gets stuck on one idea and nothing can shift him.”
This can be confusing and frustrating for families, especially when the rigid belief puts the young person at risk — like refusing medication, following extreme diets, trusting questionable advice, or making decisions that impact their health, education, or wellbeing.
But none of this is about being stubborn.
It’s not about attitude.
And it’s not about a lack of intelligence.
It is neurobiology.
Understanding why this happens is the key to supporting autistic and ADHD young people safely and compassionately.
What Is Flexible Thinking?
Flexible thinking is an executive function skill that helps us:
shift between ideas
see another perspective
adapt when things change
update a belief when new information appears
let go of something that isn’t working
For many autistic and ADHD individuals, this skill is naturally weaker because of how their brains process information, emotion, and uncertainty.
This means the brain can become “stuck” — not out of choice, but because shifting mental gears is genuinely harder.
Why Autistic People May Struggle with Flexible Thinking
1. Predictability reduces stress
The autistic nervous system often feels calmer when things are consistent.
Changing a belief or plan creates uncertainty — and uncertainty triggers anxiety.
2. Deep, logical thinking becomes rigid
Autistic thinking is often detail-oriented and structured.
Once something makes sense to them, it becomes the way.
3. Social and emotional noise is filtered out
Autistic young people may discount emotional arguments (“because we care about you”) and respond only to logic — but their logic, not yours.
4. Black-and-white thinking
Clear rules feel safe.
Grey areas feel uncomfortable.
So when someone tells them:
“Don’t take medication — just follow this diet, it’s healthier and more natural,”
this can feel simple, logical, and predictable — even if it’s medically incorrect.
Why ADHD Young People Become Rigid in Their Own Way
ADHD rigidity looks different, but it’s still linked to flexible thinking.
1. Hyperfocus
Once they lock onto an idea, changing direction feels like stopping a moving train.
2. Emotional reactivity
If someone challenges them, the emotional response overrides the logical one.
3. Difficulty switching mental tracks
They may know something isn’t working — but still can’t shift away from it easily.
4. Attraction to quick fixes
ADHD brains crave certainty and speed.
If someone offers a simple solution, they may latch onto it instantly.
This makes them vulnerable to bold, confident voices — especially online.
The Double Vulnerability: Autistic AND ADHD
When someone is both autistic and ADHD, they get:
autism’s rigidity,
ADHD’s impulsivity,
autism’s difficulty evaluating social motives,
ADHD’s tendency to trust the newest idea,
autism’s anxiety around uncertainty,
ADHD’s fear of failure and desire for fast improvement.
This is why a young person can:
ignore parents
reject medical advice
adopt an extreme diet
follow a stranger’s opinion
insist they are right even when evidence is overwhelming
It is not because they are careless.
It is because they are neurologically vulnerable to both rigidity and influence.
An Example: When Health Information Becomes a Risk
Many families see this play out with health decisions.
A young autistic/ADHD person might:
receive medication from the GP
hear from a peer or online influencer, “You don’t need meds, just follow this diet”
instantly adopt the idea
refuse treatment even when it’s important or medically necessary
Not because they want to be difficult, but because:
The new idea feels simple.
It gives them a sense of control.
It avoids the anxiety of uncertainty.
It fits their logical style (“natural = good”).
It feels like independence from parents.
Meanwhile the practical reality — time, cost, evidence, safety — gets lost in the rigid tunnel of belief.
How to Support Them Without Triggering More Rigidity
Telling them they are wrong will not work.
It will make them grip tighter.
A better approach is:
1. Validate the logic they see
“You want to do what’s healthiest for your skin — I get that.”
2. Add information, not correction
“Can I show you what dermatologists actually recommend for your type of acne?”
3. Offer choice, not control
“You can try diet changes alongside medication. You don’t have to choose one or the other.”
4. Use practical reasoning
“Your work schedule makes strict diets really hard. I don’t want you running out of energy when you’re bricklaying.”
5. Preserve their autonomy
“You’re in charge of your health decisions. My job is just to make sure you have safe information.”
When a young person feels respected, not cornered, their thinking genuinely becomes more flexible.
The Big Message for Families
Autistic and ADHD young people are not rigid because they want to be.
They are rigid because:
their brain struggles to shift
change feels unsafe
new information is overwhelming
the world is confusing
they want to feel independent
And at the same time, they are more vulnerable to influence because:
simple solutions feel soothing
confident voices sound trustworthy
they often don’t recognise misinformation
they desperately want control over their lives
Understanding this helps families respond with compassion rather than conflict.
Final Thought
If your autistic/ADHD young adult is following an extreme idea, refusing treatment, or rejecting professional advice — it doesn’t mean they’re being awkward. It means they’re trying to cope with a complex world using the skills they have.
Our goal is not to override them, but to help them build the flexible thinking they need to stay safe, confident, and informed.
