ADHD vs. Autism: Understanding the nuances and overlap of the two

Attention-deficit/hyperactivity disorder (ADHD) and autism often have several overlapping characteristics and frequently co-occur. The overlapping traits and similarities are often misunderstood and misinterpreted by healthcare professionals who do not specialize in adult ADHD and autism. 

What is attention-deficit/hyperactivity disorder (ADHD)?

ADHD is a neurodevelopmental condition that is typically diagnosed in childhood. Recently, more adults have begun to pursue ADHD assessment, diagnosis, and treatment. ADHD involves persistent issues, including difficulty focusing, hyperactivity, impulsivity, and/or challenges with executive functioning. An estimated 8% of children and 2% of adults have been diagnosed with ADHD, though many remain undiagnosed into adulthood. 

ADHD is more frequently diagnosed and treated in people assigned male at birth (AMAB) than people assigned female at birth (AFAB). AFAB individuals are consistently underidentified and underdiagnosed, and age at diagnosis tends to be later. This disparity is likely due to a combination of gender bias, differences in symptom presentation, and commonly held misconceptions and stereotypes about ADHD. AMAB individuals often present with more externalized characteristics while AFAB individuals experience more internalized characteristics. 

Some of the most common traits of ADHD include:

• Daydreaming

• Difficulty initiating a task, staying on task or completing a task

• Difficulty listening

• Forgetfulness or losing things

• Fidgeting

• Difficulty waiting to take turns, may interrupt frequently

• Hyperfocus/hyperfixation

• Talking in excess, oversharing, or lacking a “filter”

• Making frequent mistakes

• Engaging in risky or impulsive actions 

• Difficulty making or maintaining friendships

• Difficulty getting along with peers

• Executive functioning issues 

• Difficulty remaining still (physically or mentally)

• Impulsivity
  
   

The DSM-5-TR categorizes ADHD into three main types:

• Predominantly inattentive type — Inattentive presentation can show difficulty in organizing, beginning, or completing a task; paying attention to details; or following verbal directions or conversations. This person is easily distracted, struggles to listen or forgets information. 

• Predominantly Hyperactive-impulsive type — This presentation can manifest through fidgeting and excessive talking. It is hard for this person to remain still; they may feel restless and impulsive. They may need more constant mental stimulation. They may be prone to accidents and injuries.

• Combined type — A combined presentation occurs when a person has a combination of inattentiveness and hyperactivity-impulsivity. 

Despite being one of the most widely studied conditions, the exact cause of ADHD is unknown. Research has found several possible contributing factors including genetics, brain anatomy and function, significant traumatic brain injuries, prematurity at birth, and exposure to toxins in utero. There is no evidence to support the role of immunizations, diet, or screen time as causative factors.

According to the DSM-5-TR criteria for ADHD, symptoms must be present prior to age 12. While some evaluations require collateral information from a family member or loved one, NeuroSpark Health only includes this information if you would like it to be included. That’s because we believe neurodivergent adults are the experts of their own experiences. Read more about our ADHD assessment process.   

If diagnosed, ADHD may be addressed through coaching, therapy, lifestyle changes, medication, accommodations, or a combination of these depending on individual preferences. The goal of treatment is to improve the person’s overall well-being by helping them improve functioning at home, school, and/or work. 

What is autism, and why is it sometimes missed or misdiagnosed?

Autism is another neurotype, characterized by social, communication, sensory, and information-processing differences. Autism can be diagnosed at any age, but as a developmental condition, it is typically diagnosed in early childhood. 

Many late-identified autistic people have adapted to mask their autistic behaviors. The term “masking” refers to the act of camouflaging or suppressing autistic traits, or mimicking neurotypical behaviors, even if it means the person is hiding their authentic self. For example, studies have shown that autistic women tend to mask their behaviors by forcing eye contact and smiling more frequently to maintain a neurotypical appearance. Masking is also used not only as a social strategy, but as a survival strategy for marginalized groups who may be targeted for their differences. 

Characteristics of autism may be noticed as early as one-year-old but are most often recognized between the ages of 2 to 3. In some cases, autistic characteristics are not apparent until school age, and other times, they may not be recognized until adulthood. Traits associated with autism may include:

• Stimming

• Difficulty identifying or expressing emotions (referred to as alexitymia)

• Difficulty making eye contact

• Having difficulty using or understanding nonverbal gestures

• Insistence on sameness or difficulty coping with change

• Hyperfixations on specific topics, activities or interests

• Hyper- or hypo-sensitivity to sensory/proprioceptive input

• Arranging things in a particular manner (e.g., lining up toys) 

For adults who have been misdiagnosed, overlooked or undiagnosed, signs of autism can include:

• Struggling with social reciprocity or the back-and-forth of social interactions

• Experiencing difficulties with nonverbal communication, or hyperfixation on social cues

• Having difficulties with making and maintaining relationships 

• Feeling drained by social interactions; needing more time to recover after social demands

• Engaging in stimming behaviors that may not be as obvious to others

• Insisting on sameness or having trouble with change

• Having a special and intense interest that may appear to be typical interests 

• Being sensitive to sensory input but tolerating the intense discomfort in an attempt to mask needs

There is no known cause of autism. While genetics are often implicated, the research is complex and unclear. However, research is clear when it comes to what does not cause autism. Autism is not caused by vaccines, and it is not caused by bad parenting.  

In children, autism may be diagnosed based on a specialized evaluation involving interviewing the parent/caregiver, observing and interacting with the child, and additional testing to rule out the possibility of other conditions. In adults, family feedback may not be accessible or desired in some contexts. At NeuroSpark, the assessment process instead aims to gather important information from the person’s lived experience. It is imperative that an autism assessment is conducted by a qualified, neuroaffirming provider who specializes in late-identified autism and understands how autism may present within marginalized groups, such as women or people of color.

When ADHD and autism overlap

While ADHD and autism are two distinct neurotypes, a person can have both ADHD and autism, also known by the community as AuDHD. It is estimated that up to 80% of autistic children also meet the diagnostic criteria for ADHD, while up to 50% of children with ADHD show signs of also being autistic. Both conditions involve developmental differences that affect the way the brain processes information. Current studies are investigating the overlap of the conditions. Many adults who seek diagnostic evaluation for AuDHD do so for the purpose of understanding their unique brainstyle and identity as well as determining how autism and ADHD each manifest in their lives. Understanding how autism and ADHD overlap for you personally can be a very enlightening and informative process. 

NeuroSpark can help you understand your neurodivergence, whether it’s autism, ADHD or both 

At NeuroSpark, we are pleased to offer a dual-assessment option to evaluate for both autism and ADHD. We understand the overlap and distinctions between the two conditions and hope to help you gain clarity on your unique neurotype. We also offer neurodiversity-affirming therapy and coaching for adults. 

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Looking for more information? Read our AuDHD advice and AuDHD assessment lived-experience