Autism vs. ADHD: Understanding Where They Overlap and Diverge

Autism and ADHD are considered neurodevelopmental disorders, meaning they both affect the development of the nervous system and brain. ADHD and autism are distinct diagnoses that share some features, but each has distinct traits. Both autistic individuals and ADHDers are considered neurodivergent. This is a non-medical umbrella term for people with neurodevelopmental disabilities. It’s used to describe individuals whose brains work differently than what is expected for their age group.

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ADHD and autism can look similar. While the two conditions do share many traits and commonly co-occur, they are differentiated by a number of distinct features. Understanding these differences can equip neurodivergent people with more language to describe their experiences, helping them access resources, diagnoses and tailored support. This knowledge can also empower educators, employers, healthcare providers and other community members to introduce more supportive and inclusive practices for neurodivergent individuals.

Autism spectrum disorder (ASD) is a diagnosis associated with differences in communication, learning and ways of interacting with the world. Autistic individuals often:

• Approach social interactions differently
• Exhibit sensory differences from neurotypical peers
• Have a strong preference for routine and sameness 
• Have intense, sometimes limited interests

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Autistic people experience and engage with the world around them differently than neurotypical people, and differences in cognitive and sensory processing are common among autistics. The perspectives and approaches that come naturally to autistic people comprise a valuable part of human biodiversity; autistic individuals often notice things neurotypical people may not, excel at pattern recognition and are strong detail-oriented thinkers, among other strengths.

ADHD, or attention deficit hyperactivity disorder, is characterized clinically by three markers: inattention, hyperactivity, and impulsivity. Some individuals with ADHD, or ADHDers, experience predominantly inattention symptoms, while others experience mostly hyperactivity-impulsivity symptoms. Many experience varying degrees of both.

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For ADHDers, inattention symptoms can include difficulty maintaining focus and completing tasks, as well as challenges with working memory and losing items. Hyperactivity-impulsivity symptoms can entail fidgeting or increased movement, impatience and acting or speaking before careful consideration.

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ADHD is associated with sensory and cognitive processing differences from neurotypical brains. ADHDers may have variable, often slower reaction times to stimuli, and can experience both higher levels of distractibility as well as difficulty shifting tasks during times of hyperfocus. Like autistics, ADHDers possess many inherent strengths that contribute importantly to neurodiversity. People with ADHD tend to think outside the box, exhibit high levels of creativity, adapt deftly to change and can be excellent problem solvers.

While ADHD and autism are presently considered distinct diagnoses, there is increasing interest among researchers in the potential shared biological origins between the two. One team of researchers has even proposed that autism and ADHD are not different disorders, but two unique subtypes of one condition. 

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In addition to overlapping symptoms between the two conditions, research shows that relatives of either autistic or ADHD individuals exhibit an increased likelihood of having either, even if it is not the same diagnosis their relative has. These studies point to the potential for shared genetic indicators between autism and ADHD, but are not sufficient alone to establish the nature of the two conditions’ relationship.

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While the scientific community is far from consensus around a potential link between autism and ADHD, we do know the two diagnoses present with distinct characteristics and experiences. Understanding where they overlap and diverge is valuable regardless, informing how we support autistic people and ADHDers who benefit from different support strategies and clinical approaches.

Autism and ADHD share many traits. One experience common across autism and ADHD is executive dysfunction. While each individual may have different strengths and challenges around executive functioning, a 2023 research review suggests that both autistic and ADHD people experience similar executive functioning difficulties across “working memory, response inhibition, planning, cognitive flexibility, attention, processing speed and visuospatial abilities.”

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Though sensory differences tend to be associated most often with autism, they are also common among ADHDers. Compared to neurotypical people, ADHD individuals are more likely to experience hyper- or hyposensitivity to auditory, tactile, visual, olfactory and movement-based inputs. ADHD people can experience sensory overload as a result of hypersensitivity, and like autistic individuals, encounter greater difficulty in cognitive processing while overloaded.

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People with ADHD may also do what is known as stimming, or deliberately stimulating their own senses. Stimming is often associated with autism, and can be done as a response to sensory distress, to engage understimulated senses or to express other emotions, like happiness or anxiety.

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Emotional dysregulation is also widespread across autistic and ADHD individuals. Emotional dysregulation, for both neurotypes, can include feeling stronger emotional reactions than neurotypical peers, quick fluctuations in emotion and difficulty perceiving one’s own emotions. It can also mean that it feels more difficult to access known coping skills when emotions are heightened.

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People with ADHD and autism are also more likely to experience poorer mental health outcomes than neurotypical people. For example, anxiety and depression commonly co-occur with both autism and ADHD. While emotional dysregulation may predispose autistic and ADHD individuals to depressive and anxiety symptoms, the challenges of navigating an often unfriendly neurotypical world are likely drivers of this trend.

The differences between ADHD and autism are nuanced. There are a number of experiences that are shared among autistic people and ADHDers, but look and feel different across both neurotypes.

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Social skills

Though not generally associated with ADHD, both autistics and ADHDers can struggle with social skills and situations. Social differences, however, look different between ADHD and autistic people.  Autistic individuals don’t intuit social norms in the way neurotypical people do, and may struggle to identify which behaviors are typically expected. Autistic individuals may develop varying levels of social  understanding through observation and experience, and may mask their differences to a range of degrees.

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In contrast, ADHDers might grasp social norms and expectations more readily than autistic people. However, they may struggle to conform to them, changing topics abruptly, interrupting others, having a hard time paying attention or acting impulsively in ways others might find unusual. ADHDers without autism tend to be aware of these differences in the moment, whereas not all autistic people can readily pinpoint where their social behaviors diverge from expectations.

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Relationship to routine

Another area of nuanced difference between autism and ADHD is inflexible thinking. Though both neurotypes tend to be inclined towards rigid and black-and-white thinking, ADHDers are less likely to struggle with flexibility than autistic individuals. Autistic people tend to feel most comfortable with routine and prefer clear expectations for new situations. They struggle a great deal when routines or plans change, especially without warning. ADHD individuals, in contrast, are energized by spontaneity and may grow bored quickly with sameness. 

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Ability to pay attention

Like ADHDers, autistic people also experience attentional differences from neurotypicals, even though these symptoms are not included in diagnostic criteria for autism. While both neurotypes struggle with attention, each neurotype experiences its own nuances with inattention. Autistic individuals may struggle to focus when they are not interested in the subject matter at hand, but can often sustain attention longer than neurotypical people when engaged in the matter at hand.

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Both autistic and ADHD individuals, however, can struggle with shifting attention. Many autistic people and ADHDers experience hyperfocus, where they lock in on a task or stimulus, tuning out everything else. From a state of hyperfocus, it’s incredibly difficult to detach from the object of focus and redirect attention. Overall, however, individuals with ADHD tend to be more likely to lose attention abruptly or become distracted from their current area of focus than autistic people.

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Cognitive processing

Autistics and ADHDers also tend to exhibit some notable differences in cognitive processing. While autistic individuals are more likely to notice details but struggle with big-picture thinking, ADHDers are often strong big-picture thinkers but may bypass details more easily.

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While ADHD and autism are distinct conditions, they commonly co-occur. 50-70% of autistic people also have ADHD. Many individuals with both autism and ADHD refer to this co-occurrence as AuDHD, giving a name to the unique experiences, strengths, and challenges this intersection gives rise to.

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Rather than layering one on top of the other, co-occurring autism and ADHD diagnoses interact with each other. Symptoms shared across both neurotypes may be amplified, while conflicting traits can come into competition. This creates unique challenges and dissonance for AuDHDers. AuDHD individuals may feel a stronger drive to socialize than autistics who do not have ADHD, but will confront the same difficulties, anxieties and fatigue in social situations. AuDHD individuals might also struggle to balance desires for routine and familiarity with a need for novelty.

A mental health professional can diagnose and treat these two neurodevelopmental conditions. Diagnosis and treatment include the following. 

Diagnosis

Neither autism nor ADHD are diagnosed with a single test. To evaluate for either neurotype, clinicians rely on a patient’s self-report—as well as reports from people in the patient’s life, depending on the assessment given and the age of the patient. Numerous assessment questionnaires can be used to structure these reports. Diagnosing either ADHD or autism also involves some level of assessment for other diagnoses that might explain or contribute to the behaviors and experiences in question.

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In adults, an interview with the individual seeking assessment is the lynchpin of an evaluation for autism or ADHD. Because ADHD and autism are both classified as neurodevelopmental disorders, signs of either must be present during childhood in order for a clinician to diagnose either neurotype. Assessments of adults often incorporate the report of someone who knew the individual well during their childhood.

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Assessments for autism and ADHD in young children may also include medical and neurological exams, assessments of the child’s cognitive skills and behavioral observation of the child by the medical team leading the assessment.

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Treatment

Both autistic and ADHD people may seek multiple different forms of support and treatment. Therapy is an essential tool to support autistic and ADHD individuals’ wellbeing. When looking for a therapist, it’s important to find one who is neurodiversity-affirming. Neurodiversity-affirming therapists take a strengths-based approach to neurodivergence. They acknowledge the unique challenges that come with autism and ADHD, and will work with their patients to advance their unique individual goals for their wellbeing.

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Medication is also a tool that can be prescribed for both autistic and ADHD individuals. ADHDers are commonly prescribed stimulant medication to help with focus and executive functioning. However, these medications don’t work well for everyone with ADHD, and for some, cause undesirable side effects. Non-stimulant medication can be prescribed for those who don’t wish to take stimulants, or in tandem with stimulant medication, to treat similar symptoms.

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Sometimes, certain kinds of antidepressants like tricyclic antidepressants and bupropion (Wellbutrin), are prescribed as non-stimulant treatments for ADHD. There is evidence that these drugs reduce the severity of challenges ADHDers face with inattention and hyperactivity. Antidepressants can also treat co-occurring mental health disorders like anxiety and depression, which can improve the quality of life for ADHD individuals.

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Autistic people may also be prescribed antidepressants, such as selective serotonin reuptake inhibitors (SSRIs) and anxiety medications. These drugs are not intended to treat autism itself, but can treat co-occurring anxiety and depressive symptoms or disorders, aiming to improve overall mental health outcomes.

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When treating either autism, ADHD, or AuDHD, the wellbeing and needs of the individual should be the north star—not the feelings their caregivers or peers have about their behaviors. As with therapy, any intervention around autism and ADHD should strive to make life easier and more fulfilling for the individual, rather than to reduce the visibility of their symptoms to others. Therapy is a critical resource to this end, but the challenges autistic and ADHD people face are not individual ones; a larger cultural embrace of neurodiversity, a well-informed populace and social structures that accommodate different neurotypes would go a long way to reduce the need for treatment for either condition.

The relationship between ADHD and autism is far from fully explained, and is the subject of ongoing research. What we do know is that traits of autism and ADHD exist in a less-than-clear-cut Venn diagram: they have notable similarities and differences, with differences within the similarities and similarities within the differences.

Autism and ADHD must be understood holistically by advocates, medical providers, educators, community leaders and other decision-makers. Current diagnostic criteria do not paint a full picture of life with autism or ADHD, and neglecting their nuances is a disservice to the neurodivergent people in our lives. The lines that separate these two neurotypes can blur, but articulating this gray area and understanding the differences felt between them is necessary for a deeper embrace of neurodiversity and meaningful support of neurodivergent people.

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If you believe you may be autistic, or are unsure which diagnosis may apply to you, Prosper Health can help. Prosper Health offers autism assessments via telehealth that are tailored for adults and covered by insurance. Prosper Health also offers ongoing support for neurodivergent adults. Our therapists are neurodiversity-affirming and will work with you to help you achieve your individual goals for your wellbeing.