What to Know About Comorbid Autism and ADHD (AuDHD)

Attention-deficit/hyperactivity disorder and autism spectrum disorder are both neurodevelopmental diagnoses in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Both diagnoses represent neurodivergence that can lead to challenges, though neurodiversity reflects a variety of strengths among humanity.

While approximately 10% of the population has ADHD, some research has shown that 40% of autistic people have ADHD, with other studies suggesting that the rate may be closer to 70%. Conversely, while 2-3% of people are autistic, 20-50% of those with ADHD are also autistic.

In this article, we discuss the connection between ADHD and autism and how these diagnoses present when they co-exist.

The Connection Between Autism and ADHD

As the statistics above indicate, people with ADHD are significantly more likely to be autistic compared to those who do not have ADHD, and vice versa. However, prior to 2013, the Diagnostic and Statistical Manual of Mental Disorders indicated that an individual could not meet the diagnostic criteria for both diagnoses. Despite this requirement, the comorbidity rate of diagnosing both autism and ADHD was 45% at this time.

Despite the overlap, though, current research indicates that ADHD and autism are distinct, separate diagnoses rather than one neurotype on the same spectrum.

Complications of Autism and ADHD

Due to symptom overlap, autistic individuals who also have ADHD might have more difficulty receiving an accurate diagnosis. Many diagnostic scales emphasize symptoms as they tend to manifest when the individual only meets the criteria for autism or ADHD rather than both diagnoses. So a unique combination of symptoms that may not neatly fit into just one diagnostic “box” can be overlooked or misunderstood.

Sometimes, autistic people with ADHD may have difficulty functioning in a world created for neurotypical brains. Sensory issues and executive dysfunction can make many daily tasks challenging. If you are struggling, look into what support services might be available to you.

Diagnosing Autism and ADHD

ADHD and autism can both be diagnosed by certain medical and mental health professionals. Although many people have both diagnoses, providers may not evaluate for both unless you request it. A qualified evaluator will use a variety of diagnostic tools when determining if someone meets the diagnostic criteria for ADHD, autism, or both.

Most psychological evaluations for any diagnosis will include a diagnostic interview, during which they will ask several questions about history, symptoms, mental health, and traits that might be consistent with ADHD or autism. Since neurodevelopmental diagnoses like ADHD and autism occur from birth or early childhood, this interview will likely include questions about early developmental years.

Diagnosing ADHD

Measures commonly used to diagnose ADHD include:

• Conners Rating Scales: There are Conners forms for ages 2 to 6 (Conners Early Childhood), 6 to 18 (Conners 4), and 18+ (Conners Adult ADHD Rating Scales). Depending on your age, there are self-report and observer rating scales that yield information about your symptoms and how closely those symptoms correlate with the diagnostic criteria for ADHD.
• Tests of Sustained Attention: Many different attention tasks exist, such as the Test of Variable Attention. These tasks require an individual to demonstrate their ability to focus on a task.
• Behavior Rating Inventory of Executive Functioning (BRIEF): There are child and adult versions of this form, which assesses the individual’s ability to break down large projects, complete tasks, and sustain attention.

Diagnosing Autism

Measures used to diagnose autism include:

• Autism Diagnostic Observation Schedule. This test utilizes a series of tasks, which the evaluator uses to assess thought processes, behavior, and communication style for consistency with the diagnostic criteria for autism.
• Autism Spectrum Rating Scales. This observational form takes data from parents and teachers or childcare professionals to determine if a child’s behaviors are consistent with autism. It does not have a self-report form.
• Monteiro Interview Guidelines for Diagnosing the Autism Spectrum. This structured interview gathers history and current information about adults to determine if they meet the criteria for autism.

Depending on your presenting concerns, an evaluator might also complete a cognitive assessment (also known as an IQ test). Some autistic people or those with ADHD have learning difficulties, and the IQ test may provide valuable information about how to support your learning.

They may also administer screeners for various other mental health issues, like anxiety or depression, that can co-occur with autism and ADHD.

Support for Autistic People With ADHD

Since the world is not set up for autistic and ADHD brains, many people with either or both diagnoses need support for daily living, work, finances, or other areas. Traditionally, “treatment” for autism and ADHD has emphasized making the person act or appear neurotypical rather than supporting their needs. This has led to increased burnout and trauma symptoms.

These organizations offer more information on supporting autistic people with ADHD or for finding support regarding your own diagnoses:

• The Autistic Self-Advocacy Network: Created by and for the autistic community, ASAN provides educational information about autism and advocates for autistic-affirming policy changes.
• Neuroclastic: This online non-profit organization elevates autistic voices and stories as well as advocates for a neurodiversity-affirming world.
• CHADD: This organization provides information and community support for people with ADHD and their loved ones.
• ADDitude Mag: This magazine and blog provides medically accurate and community-based information about ADHD.