Executive Functions in Autism and ADHD: Shared Struggles

Two people say the same sentence: "I know I need to do it, I just can't sit down and do it."

One has an ADHD diagnosis, the other an autism diagnosis. The sentence is the same, the mechanism underneath is not, and this difference directly determines which solution will work.

I do not have an autism diagnosis, and I am not going to give myself one. I know the executive-function side through my own ADHD diagnosis; the autism side I relay from what I have read. I take care not to mix the two, because mixing them on this topic leads directly to the wrong method.

What executive functions are, exactly

A short refresher: executive functions are the set of mental operations that let you hold a goal and act toward it. Not a single ability, but a group of jobs.

Among them are: starting a task, holding information in working memory, directing attention, inhibiting an inappropriate response, planning and sequencing, switching from one rule to another, monitoring progress, regulating emotion.

I wrote the details of these headings in the article what are executive functions. The question here is narrower: which subdomains are strained in the two profiles?

What stands out on the ADHD side

The most discussed subdomain in ADHD is response inhibition. That is, stopping an inappropriate response.

Its everyday form looks like this: interrupting, saying whatever comes to mind, not waiting your turn, buying things that were not in the plan while shopping, writing the reply, sending it and then regretting it.

The second heading is initiation. You know what the task is, you know its importance, you know how long it takes, and you cannot start. We call this task paralysis, and it is the most misunderstood thing in ADHD, because from the outside it looks like laziness.

The third heading is time. Time blindness rots planning from the inside: duration estimates go off, a future task is not felt now.

The fourth is working memory. Walking into a room and forgetting why you came, losing what you were going to say in the middle of a sentence. The article working memory and forgetfulness covers this part.

The fifth is monitoring. Tracking how far you have progressed while doing a task, noticing that you have made a mistake and correcting course. When this is strained, the work gets finished but is not reviewed, or the opposite: the work does not get finished because the reviewing never stops. Both are two ends of the same mechanism.

What stands out on the autism side

The meta-analysis by Demetriou and colleagues (2018) reports a broad pattern of strain across the executive function domain in autism. That is, not in a single subdomain, but in many.

Two headings stand out in particular:

Cognitive flexibility. Moving from one rule to another, from one task to another, from one point of view to another. This is one explanation of the often-described state of "once I start, I can't stop" on the autism side.

Planning. Designing a multi-step task from the start, putting the steps in order and managing the intermediate goals.

The review by Craig and colleagues (2016) draws this distinction more clearly: the group in which both are present resembles the autism group on flexibility and planning, and the ADHD group on response inhibition. So the two patterns do not cancel each other out, they stack.

The same behavior, a different reason

This section is the part that helps most in practice.

Being unable to start a task. In ADHD the matter is usually arousal and reward: if the task is not interesting the motor does not run. On the autism side, what is often described is uncertainty: if what exactly the task is, how it will end and what it will look like are not clear, it cannot be started. In the first case the solution is to add stimulation, in the second the solution is to remove the uncertainty. Two different interventions for the same task.

Being unable to stop a task. In ADHD this goes by hyperfocus and is tied to interest and cannot be chosen. On the autism side it is more associated with the cost of transition: stopping means leaving the channel you are in. I went into the difference in more detail in the article special interest and hyperfocus.

Collapsing when the plan changes. In ADHD the problem is usually in the transition: the remnant of the old task stays in the mind and the new task cannot be moved to. On the autism side the problem is in the preparation: the mental preparation that was made collapses and has to be rebuilt. The article difficulty with transitions treats this mechanism separately.

Being unable to decide. In ADHD this often comes from the options looking equally weighted and the consequence not being felt now. On the autism side, incomplete information and the consequence being unpredictable come to the fore.

Where "I know but I can't do it" comes from

This sentence is the one most often said in both profiles, and this is where it is most misunderstood.

Executive function problems are not a knowledge problem but an application problem. Between knowing what to do and turning that knowledge into behavior there is a separate mechanism, and that is where the struggle is. This is why giving more information, giving more advice and explaining more does not work.

The most visible consequence of this is: someone looking from the outside sees the knowledge and assumes that what is missing is intention. The sentence "if they wanted to, they would" comes from here. Yet the intention is already there; the bridge between intention and behavior is what is strained.

The practical consequence is this: the interventions that work are structural, not persuasive. What makes a task doable is usually not a motivational talk but breaking the task into pieces, an external reminder, a person beside you or a setup that makes starting easier. I made this difference concrete in methods such as the visible place system and the two-minute rule.

Tests do not make a diagnosis

I made this caution a separate heading, because it is skipped very often.

Demetriou and colleagues (2018) emphasize that, although significant differences were found between groups, the clinical discriminating power of these tests is limited. That is, the scores of the group with an autism diagnosis and the comparison group overlap. A person doing well on the test does not rule out the diagnosis, and doing badly does not make one.

The same applies to ADHD. A neuropsychological test details the picture, it does not make the diagnosis. The diagnosis is made by clinical interview, developmental history and functioning. I described the process in the articles how adult ADHD is diagnosed and how autism is diagnosed in adulthood.

What you do in the testing room and what you have to do on Monday morning are not the same job. In the room there is silence, a single task and someone watching you. On Monday morning there is none of that.

Why good in the lab, bad in life

This contradiction is reported in both profiles, and its reason is understandable.

The test environment removes the conditions under which executive functions struggle most: what to do is told to you, a single task is given, the time is known, the room is quiet, there is an observer from outside. In real life you define what the task is, ten tasks are standing at once, the time is uncertain, the environment is noisy and nobody is watching.

For this reason, in an assessment your own report and the report of someone close to you can carry more information than the test result.

There is also its counterpart in daily life: the same person can be extraordinarily good in a crisis and completely nonfunctional on a calm Tuesday morning. Someone looking from the outside takes this for unwillingness, because they have seen once that the skill exists. But what was seen was not the skill; it was the external pressure that kicked in at that moment. This is called crisis performance, and it is a familiar pattern in both profiles.

The support side: which intervention where

The difference in mechanism translates into a difference in solution. Let me make it concrete.

If it comes from uncertainty: put the task in writing, write the steps one by one, define the finishing criterion ("when will this job count as done"), show an example, say how long it will take. These are arrangements often recommended on the autism side and they do no harm in ADHD either.

If it comes from arousal: shrink the task, put an external timer, bring someone next to you, move the reward forward. Body doubling is one of the methods that works best in this group.

If it comes from transition: set aside time for transitions, build an intermediate ritual, make the next task visible beforehand. Not leaving the moment of transition empty works on both sides.

If it comes from inhibition: put distance in between. A waiting rule before pressing send, a rule of not going outside the shopping list, waiting one round in an argument.

Antshel and Russo (2019) explain that in people with both present, a single approach is not enough and both directions need to be taken into account. This explains why a single method template does not work.

When building a system

If you want to build a system that takes both sides into account, the rule I have seen work is this: lower the uncertainty, leave the stimulus adjustable.

That is, let what the task is, when it will end and what it will look like be fixed and written. Let where you do it, with what music, in what order stay free. This is one of the rare solutions that handles both the side that needs predictability and the side that needs novelty at the same time.

I learned this while writing my thesis. I fixed the chapter headings and when each chapter would count as finished; I left free which chapter I would write on which day. The rigid schedules I had tried before lasted ten days; this setup went all the way to the end.

Let me add one caution: the distinctions in this article help you guess which mechanism is at work, but they do not give a diagnosis. Struggling with executive functions is very common and can have many causes, from sleep debt to depression, from anxiety to long-term stress. If there is a recurring pattern that truly restricts your life, assessment is the specialist's job.

I covered the picture where the two are together in the article on AuDHD, and the general differences between the two headings in the article are ADHD and autism the same thing.