Autism and ADHD in Adults: Differentiating Between Neurotypes
Autism and ADHD are two different neurotypes that share similar characteristics, but that does not make them the same.
In order to differentiate between the two, we will take a look at where they overlap and the important aspects that make each of them unique.
Executive function
In order to highlight how ADHD differs from autism, it is important to talk about executive functioning first.
Executive functioning is responsible for many of our daily tasks:
planning and organizing;
prioritizing and staying on track;
time management and focus;
starting and stopping tasks;
shifting between various tasks;
tuning out irrelevant stimuli;
working memory, and much more.
Perhaps less talked about portion of executive functioning - yet vitally important - is inhibition control, both behavioral and emotional.
Behavioral inhibition control may look like regulating the impulse to engage in a more fun/interesting task and maintaining focus on the task at hand. The classic example of this would be a student who leaves homework behind to go play with their friends.
Emotional inhibition control means not becoming easily overwhelmed by emotions, having higher tolerance for frustration and experiencing emotions at an expected intensity level. This may look like not becoming frustrated two minutes into starting a new task because we don’t know how to execute it or be perfect at it right away.
Meaning that executive functioning is also responsible for impulse control and emotional regulation.
ADHD and the brain
As @LesleyPsyD - a clinical psychologist specializing in autism and ADHD - describes it, ADHD is a neurotype that centers around difference in the executive functioning part of the brain.
Folks with ADHD are likely to struggle with the many, if not all, executive functions outlined above.
They will have difficulty starting and stopping a task, switching between two tasks, remembering steps in a sequence of tasks, maintaining attention on a needed topic, and having a different processing speed when it comes to incoming stimuli. They also likely have difficulty managing frustrations and regulating emotions, becoming easily irritated, overwhelmed, and shut down when not knowing how to do a task.
Having difficulty in inhibiting behavior also impacts social relationships, where a person may not be able to control the impulse to jump into a conversation while others are still talking, take turns listening and speaking, miss context of social situations or become too focused on other’s reactions.
As executive functioning is also responsible for filtering out unnecessary stimuli, it means folks with ADHD will suffer from sensory issues due to the brain’s inability to filter out unnecessary input, whether it’s someone’s chewing or a persistently dripping faucet.
The difference between ADHD and autism lies here in the executive functioning center of the brain. Other aspects of their functioning may be affected as well, such as sensory perception and social interactions, but it stems from this core - the executive functioning part of the brain and the multitude of things it is responsible for.
Autism and the brain
Autism is a neurotype that affects a person more broadly in how they view and interact with the world. It encompasses many different brain functions together: sensory perception, social and communication abilities, motor function, language, learning abilities and executive functioning.
The difference is more global rather than localized (as with ADHD, for example, where it is local to the executive functioning part of the brain).
Autism is characterized by differences in social communication and interaction across multiple contexts, repetitive movements or behaviors, strict adherence to routines, sensory issues and intense interests. These differences are typically present from early childhood and on, however for many adults autistic traits will go unnoticed for many years before a stressor or a big life event will diminish masking abilities and coping to a point where autistic traits become more pronounced.
Many, if not all, of the above characteristics can also be explained by monotropism - the idea that austistic brains are wired to prefer one channel of input over many. It explains why autistic folks prefer to deeply focus on one thing - one conversation, one project, one activity, etc. - and miss much of what may be going on outside of that.
What the medical and pathology model calls “rigidity” is simply a brain’s preference and desire to focus on only one source of input at a time (if you want to learn more about this topic, here is a great article to read).
ADHD vs. Autism
One of the biggest differences between ADHD versus autistic brains is that autistic brains thrive on order, predictability, routine and repetition. Whether it is eating the same breakfast every day or having a detailed plan of what activities to anticipate that day, autistic brains gain comfort from knowing what is coming around the corner.
ADHD brains, on the contrary, like newness, adventure and spontaneity. They may become easily bored by doing the same task over and over again, or lose interest in an activity that is highly rigid and outlined.
Living on the spectrum put together a very helpful graphic comparing the two neurotypes that contrasts the differences well, while outlining the similarities.
Source: Living on the Spectrum
Co-occurence of ADHD and Autism
Research shows that there are high levels of co-occurrence between ADHD and autism, meaning that autistic folks are highly likely to also have ADHD and vice versa.
One study found that 61% of their participants who were autistic met the criteria for an attention disorder, with 76.8% specifically meeting the criteria for combined form of ADHD (combined meaning both inattentive and hyperactive types).
It will be important for us to continue monitoring new research, as many of these topics are under-researched and need further investigation and review. Yet we already have a strong basis for seeing how these two neurotypes can frequently occur together.
In discussing the differences and similarities of ADHD and autism, I would like to once again highlight the fact that these two neurotypes are simply different ways of viewing, perceiving and interacting with the world.
As a neurodivergence-affirming therapist I do not believe in labeling natural diversity in brain development a “disorder” and encourage you to do the same by engaging with more reading material on the topic, listening to neurodivergent voices and advocating for a kinder and more accommodating world.