Understanding the Overlap of Autism and ADHD

In recent years, there’s been growing awareness around neurodivergence — especially Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD). Since April is Autism Awareness Month and I’ve seen increasing numbers of teens and young adults asking if they have autism because they recognize traits in themselves, I thought it a great time to delve into overlap of ASD and ADHD and how to recognize symptoms that deserve further investigation.

While each condition has its own diagnostic criteria, research now shows that they can and often do co-exist. Despite this frequent overlap, a dual diagnosis of ADHD and ASD was not formally permitted until the revision of Diagnostic and Statistical Manual of Mental Disorders in 2013 with the 5th edition. This means there are potentially many people diagnosed with one or the other prior to 2013 who did not receive the diagnosis of the other due to diagnostic criteria of the time. If you received a diagnosis over 12 years ago and you notice traits of another condition, it might be helpful to talk to your physician about a referral to a neuropsychologist.

Studies show that ADHD co-exists in 30–80% of people with ASD, and ASD is present in 20–50% of people with ADHD. This overlap can make it difficult to distinguish between the two, especially when relying on online checklists or social media content for self-diagnosis. That’s why understanding the similarities, differences, and the value of a professional evaluation is essential.

The co-existence of ADHD and ASD is a relatively new field of study. They have been largely investigated in separate research fields and with a focus on childhood. There is still much to be learned, especially through the years of brain development of adolescence into adulthood.

Shared Symptoms, Different Roots

ASD and ADHD share several behavioral traits, which can lead to confusion during the diagnostic process. These overlapping symptoms often have different causes and meanings depending on the condition.

• Sensory Sensitivities (heightened sensitivity or reduced sensitivity to various sensory stimuli like sounds, textures, tastes, and smells)

  • When a person has difficulty with sensory processing they may feel frustrated, anxious, or angry. Overwhelming sensory input can trigger meltdowns, with intense emotional distress, difficulty communicating, and even potentially self-injurious behaviors.

  • Sensory challenges are a core diagnostic criterion for ASD, and people with autism often have a broader range and more significant degree of sensory sensitivities and avoidances compared to those with ADHD.

  • Sensory issues are not part of the ADHD diagnostic criteria but many people with ADHD also experience them. For more on these differences, see Making Sense of Sensory Overload in Autism and ADHD: When are symptoms "sensory" versus ASD or ADHD? by Dr. Benjamin Cheyette and Dr. Sarah Cheyette.

• Social challenges: 

  • A child with ADHD may lack the ability to reliably use social skills that they have due to problems with impulse control and other executive functioning deficits. Social skills training is often not sufficient for those with ADHD because it teaches skills but does not address inefficient use of existing skills. Medication can lead to changes in the executive function of the brain and may help children with ADHD more reliably use the social skills they have learned. For example, they may know that they should wait until someone is finished talking before they say something, but if they may impulsively interrupt if their executive functioning is not under control. They might want to say something now because they worry they’ll forget it in a few minutes when the speaker is done due to working memory problems.

  • A child with ASD may struggle with social skills due to challenges with understanding social cues or conversational norms. Children with ASD may prefer solitary activities or have unique interests, which impacts their ability to engage with peers. Many with ASD struggle with expressive and receptive language skills, making it challenging to express their thoughts, feelings, and needs effectively. Difficulties in initiating and maintaining conversations, understanding figurative language or sarcasm, and taking turns during communication can create barriers to social communication skills. They may struggle to interpret and use nonverbal cues such as facial expressions, body language, gestures, tone of voice, and eye contact. The ability to understand and share others' emotions can be impaired in people with ASD. This does not mean that those with ASD lack compassion or the desire to connect with others, but they may struggle with accurately identifying and responding to other people’s emotional states. Strategies to improve social skills include breaking down social interactions into smaller steps, providing clear instructions, role playing, social stories, and using positive reinforcement.

• Feelings of Justice (a strong sense of fairness and a need to address perceived injustices):

  • People with neurodivergence (both ASD and ADHD) as well as those in minority communities experience traumatic events, abuse, and discrimination at a higher rate than the rest of the population. These experiences can cause some people to focus on stopping discrimination and mistreatment and contributes to why people in these communities may become justice sensitive.

  • Children with ASD may prioritize adherence to rules and social norms and often focus on issues of social fairness and inclusion. They may focus on the details of the situation and try to understand why things are not fair. Some may hyperfocus on topics or problems until they find a solution. Their communication challenges can make it difficult for them to advocate for themselves or others in situations of injustice.

  • Children with ADHD may be more inclined to react impulsively. They may feel significant distress related to perceived rejection or being overlooked, but their impulsivity and emotional regulation difficulties can sometimes lead them to act out in ways that may not be helpful in addressing injustices.

• Executive functioning (skills that help individuals plan, focus attention, remember instructions, and manage multiple tasks):

  • People with ASD may experience difficulties with executive functions, especially those associated with cognitive flexibility, but including:

    • Attention and Focus - might not be able to concentrate on a topic that falls outside of their narrow scope of interests. Social interaction and communication challenges may also interfere with their ability to sustain attention. Conversely, they may be able to focus intently on things that they are interested in and not recognize other things going on around them.

    • Planning and Organization - may struggle with multi-step instructions, time management, and prioritizing tasks.

    • Cognitive Flexibility - may have difficulty adapting to changes in routine, unexpected events, or new situations.

    • Emotional Regulation - may experience heightened emotional responses, struggle with understanding and managing emotions, and have difficulty regulating their behaviors.

    • Memory - many people with autism struggle to remember faces as well as with general memory issues. They may be unable to complete a series of tasks because they forget what they are supposed to do or they may seem impatient due to working memory problems. For example, if they are told when their turn would come within a group, but that information is quickly forgotten, they may feel confused and frustrated.

  • People with ADHD struggle with many of the same executive functions ADHD, often linked to difficulties with response inhibition and sustained attention:

    • Attention and Focus - may struggle to pay attention to non-preferred tasks yet can be immersed in preferred tasks. They may be able to focus for hours on a video game or whatever they enjoy, but struggle to read a paragraph of a topic that bores them because their mind wanders while reading.

    • Planning and Prioritization - may struggle to break down tasks into smaller steps, set priorities, or plan ahead, leading to difficulties in managing time and completing projects.

    • Working Memory - may have problems related to the ability to temporarily hold and use information, making it hard to follow instructions, remember steps in a process, or manage multiple tasks simultaneously.

    • Organization and Time Management - may find it difficult to keep track of belongings, appointments, and deadlines, and to manage time effectively.

    • Inhibition and Self-Regulation - difficulties with the ability to control impulses and delay gratification can lead to impulsive behaviors and challenges with self-regulation.

    • Emotional Regulation - may find it difficult to manage emotions, such as frustration or anger, which can impact behavior and relationships.

    • Flexibility and Adaptability - may struggle with flexibility and adaptability, making it challenging to adjust to unexpected changes or shift between different tasks or activities.

• Routines:

  • A child with ASD might resist change due to a need for routine and predictability. They often rely on routines and rituals to create predictability and reduce anxiety. While routines can provide structure and comfort, they may also contribute to social interaction difficulties. Insistence of following specific routines or difficulty adapting to changes in plans can affect social flexibility and spontaneous interactions.

  • A change in routine can lead to increased stress, anxiety, and difficulties with focus and behavior in children with ADHD. These children often rely on predictable schedules and routines, which help them manage executive functions like planning, organizing, and self-regulation. Disruptions to these routines can disrupt these cognitive processes, making it harder for them to adjust and leading to behavioral challenges.

Differentiating the Two — and Recognizing Both

Autism is primarily characterized by differences in social communication and interaction, along with restricted and repetitive patterns of behavior or interests. On the other hand, ADHD is characterized by problems regulating attention, impulsive behaviors, and/or hyperactivity that interferes with daily functioning.

When both conditions co-occur, a person might show a complex combination of behaviors. For example, someone might experience the intense interests and social communication challenges typical of autism while also having the impulsivity and distractibility of ADHD.

Unfortunately, many people receive only one diagnosis — especially if their symptoms are subtle, masked, or misunderstood. This is especially common among girls, women, and people of color, whose traits may not fit the traditional stereotypes.

With the explosion of online mental health content, it’s easy to find checklists and self-assessments like these for ASD and ADHD. While these tools can help people recognize that their experiences are valid and worth exploring, they are not diagnostic.

These quizzes often oversimplify complex conditions and fail to capture the nuances that professionals consider during evaluations. They may lead to self-diagnosis without a full understanding of co-occurring conditions or how other mental health issues — like anxiety, trauma, or learning disorders — can present with similar symptoms.

A professional evaluation, ideally by someone who understands the nuances of ASD and ADHD, offers a comprehensive look at cognitive, emotional, and behavioral functioning. It helps uncover not only whether a person meets the criteria for ASD or ADHD, but also if there are other contributing factors, such as sleep deprivation, anxiety, depression, trauma history, or learning differences.

Unfortunately there are professionals who rely solely upon diagnostic surveys and do not account for personal reflections and parent recollections of struggles and behaviors they notice. If you feel that a diagnosis is missed with initial evaluations, it may be worth it to see someone with more experience evaluating for the condition(s) you suspect.

A professional diagnosis can:

• Provide clarity and validation: Understanding the full picture helps people make sense of their struggles and strengths.

• Inform treatment: Accurate diagnoses lead to targeted interventions, whether that’s medication, therapy, social skills training, coaching, or educational accommodations.

• Support access: Schools, workplaces, and insurance providers often require a formal diagnosis for accommodations or support services.

Encouragement, Not Discouragement

If you’ve taken an online quiz or stumbled across relatable content on social media, don’t dismiss it — but don’t stop there. Let that be your starting point, not your finish line.

If your results raised questions about whether you might have ADHD, ASD, or both, it’s worth seeking out a professional for a thorough evaluation. Some clinicians will diagnose ADHD but not ASD, and it is appropriate to do that evaluation first, since those who diagnose ASD are limited and waiting periods can be long. Delaying a diagnosis of ADHD while awaiting one for ASD delays the important treatments you can start for ADHD if it is affecting the person.

The goal isn’t to label, but to understand. When we better understand ourselves or our children, we’re more equipped to advocate for the right support and build environments where neurodivergent minds can thrive. Appropriate diagnosis and management may lead to fewer labels and less trauma to the person because they’re better able to manage daily tasks with appropriate interventions.

In Summary:

• ADHD and ASD often co-exist and share overlapping traits.

• Despite similarities, each has distinct core features and needs.

• Online quizzes can spark awareness but are no substitute for a professional evaluation.

• A thorough diagnostic process provides clarity and opens the door to better support.

Understanding is the first step toward empowerment. Whether for yourself, your child, or someone you love, take the step toward a clearer path forward by speaking with a professional who understands neurodevelopmental differences.

As always, remember: You’ve got this!