Autism vs ADHD: What Are the Differences?

Rear view of teenager sitting at home

Maskot/Getty Images

Table of Contents
View All
Table of Contents

Autism and attention deficit hyperactivity disorder (ADHD) are both neurodevelopmental disorders that develop in childhood. Autism and ADHD can be challenging to distinguish. This may be because both conditions share similar symptoms and can occur together.

Current research estimates that 50% to 70% of people with autism spectrum disorder also have ADHD. While both conditions are neurodevelopmental disorders, they are distinct conditions. In this article, you'll learn more about the differences between autism and ADHD and why knowing the difference in their symptoms and diagnosis is essential.

Symptoms 

There are several symptoms of autism and ADHD that overlap. Symptoms such as impulsivity, inattention, and hyperactivity are sometimes present in both conditions.

Although both conditions share inattention as a common symptom, doctors have found that while people with ADHD struggle with inattention in all aspects, autistic people can focus when they find a task that interests them. In fact, in some scenarios, they might even become hyper-fixated. 

Symptoms of Autism 

Symptoms of autism are typically marked by difficulty with social communication and exhibiting restricted or repetitive behaviors. Common examples of these symptoms include:

  • Trouble making or maintaining eye contact 
  • Being unresponsive when called 
  • Difficulty understanding people's emotional cues 
  • Speaking in an unusual tone of voice 
  • Repeating certain words or phrases more than typical 
  • Having a specific routine and being unable to function if it's disrupted 

Symptoms of ADHD 

On the other hand, ADHD symptoms consist of a combination of signs of inattention, hyperactivity, and impulsivity. Inattention symptoms make it difficult for people with the condition to be focused or organized.

With hyperactivity, you'll notice that a person with the disorder is constantly restless and fidgeting. Impulsivity makes it difficult for a person with this condition to exhibit self-control. Common ways in which these symptoms play out include: 

  • Being easily distracted 
  • Difficulty carrying out organized tasks and activities 
  • Being forgetful even with daily activities 
  • Speaking excessively 
  • Often interrupting others when they are speaking 
  • Having difficulty waiting their turn 
  • Being constantly on the go 

Causes 

One thing that autism and ADHD have in common is that it's unclear what exactly causes both conditions. What is clear is that a combination of genetic and environmental factors come into play with the development of both conditions. Both disorders also affect the brain, albeit in different ways. 

Causes of Autism 

There is no single cause of autism. Some research shows that autism could be caused by other developmental disorders such as Fragile X syndrome. It's clear that autism and ADHD can co-occur, but scientists don't know if either condition can cause the other to develop. Other risk factors that increase the likelihood of autism developing include: 

  • Having a sibling who has autism 
  • Pregnancy complications 
  • Being born to older parents 

Causes of ADHD 

Although it's unclear what causes ADHD. Certain things put people at a greater risk of developing the condition than others. Some of these risk factors include: 

  • Being born prematurely 
  • Early exposure to environmental toxins 
  • Substance abuse during pregnancy 
  • Low birth weight 
  • Brain injury 

Diagnosis 

A person can be diagnosed with both conditions. However, no specific medical or blood tests can be done to diagnose either disorder, which can make diagnosing both conditions challenging. 

Diagnosis of Autism

The American Psychiatric Association's Diagnostic and Statistical Manual (DSM-5-TR) provides specific criteria for the diagnosis of autism. According to the DSM-5-TR, for a person to be diagnosed with the condition, they must exhibit deficits in the following areas social communication and interaction. 

  • Persistent and unusual social interactions 
  • Difficulty forming and maintaining relationships with people 
  • Difficulty with non-verbal communication

They should also exhibit at least two forms of the following restricted and repetitive behaviors.

  • Repetitive behaviors with movement or speech
  • Having unusually fixated interests 
  • Being either too sensitive or under-sensitive to sensory stimuli 
  • Having inflexible routines and becoming distressed when it's disrupted 

The DSM-5 also provides that symptoms must be severe enough to disrupt daily functioning. 

Diagnosis of ADHD 

The DSM-5-TR is also used to help diagnose ADHD in children and adults. The manual provides a diagnostic standard to prevent misdiagnosis of the condition and help ensure people with the condition get the treatment they need as soon as possible.

It's established that people with ADHD exhibit inattention, hyperactivity, and impulsivity symptoms. The DSM-5-TR provides that children up to 16 are required to exhibit six or more symptoms of inattention. Five or more inattention symptoms should be present for children over 17 and adults.

The same rule applies to symptoms of hyperactivity and impulsivity. The signs should also occur in two or more locations. For instance, at home and in school, and be severe enough to interfere with daily functioning. 

Treatment 

Symptoms of both conditions are highly individual, affecting people differently. Treatment plans must be uniquely tailored to individuals with either or both conditions. In regards to psychotherapy, treatment for autism and ADHD is similar.

Cognitive behavioral therapy is typically used in alleviating symptoms of both disorders. Where treatment somewhat differs with both conditions is with medication.

Treatment of Autism 

While no known medicine can cure autism, certain medications can help reduce the severity of its symptoms. Several types of drugs are used to treat autism symptoms. Risperdal (risperidone) and Abilify (aripiprazole) are antipsychotics that the FDA has approved explicitly for treating severe irritability in people with this disorder.

Other medications that might be prescribed off-label include anti-anxiety medications, antidepressants, and anticonvulsants.

Treatment of ADHD 

Medication used for treating ADHD can be broadly split into stimulant and non-stimulant medications. These medications help improve symptoms of the condition and can be administered to children as young as six.

However, it's essential to understand that none of these medicines can cure the disorder. However, they help improve concentration, reduce symptoms of impulsivity and hyperactivity and help an individual live a fully functioning life despite their diagnosis: 

Prevention 

There is no known way to prevent either condition. While certain nutritional and environmental factors play significant roles in causing both conditions to develop, it's unclear if optimum environmental and dietary factors can help prevent the disorders from developing. 

A Word From Verywell

ADHD and autism are both neurodevelopmental disorders that affect the brain's development and cause people with both conditions to experience developmental delays. However, autism covers a spectrum of neurodevelopmental disorders that don't include ADHD.

Both conditions have different diagnostic criteria and different treatment approaches. It's also possible for both conditions to overlap. This means that some autistic people could also have ADHD. Treatment for both conditions must always be ongoing at home, school, or other locations.

12 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Hours C, Recasens C, Baleyte JM. ASD and ADHD comorbidity: what are we talking about? Front Psychiatry. 2022;13:837424. doi:10.3389/fpsyt.2022.837424

  2. National Institute of Mental Health (NIMH). Autism spectrum disorder. March 2022

  3. National Institute of Mental Health (NIMH). Attention-deficit/hyperactivity disorder. September 2021

  4. Ghirardi L, Pettersson E, Taylor MJ, et al. Genetic and environmental contribution to the overlap between ADHD and ASD trait dimensions in young adults: a twin study. Psychol Med. 2019;49(10):1713-1721. doi:10.1017%2FS003329171800243X

  5. Centers for Disease Control and Prevention (CDC). Basics about autism spectrum disorder (ASD). March 31, 2022

  6. Centers for Disease Control and Prevention. What is ADHD? September 23, 2021

  7. Centers for Disease Control and Prevention. Diagnostic Criteria Autism Spectrum Disorder (ASD). April 6, 2022

  8. Centers for Disease Control and Prevention. Symptoms and Diagnosis of ADHD. July 26, 2022

  9. National Institute of Child Health and Human Development. Medication Treatment for Autism. April 19, 2021

  10. National Library of Medicine. QELBREE- viloxazine hydrochloride capsule, extended-release. May 2, 2022

  11. Cleveland Clinic. ADHD Medication, Treatment & Stimulant Therapy. February 23, 2016

  12. Curtis LT, Patel K. Nutritional and environmental approaches to preventing and treating autism and attention deficit hyperactivity disorder (Adhd): a review. J Altern Complement Med. 2008;14(1):79-85.

By Toketemu Ohwovoriole
Toketemu has been multimedia storyteller for the last four years. Her expertise focuses primarily on mental wellness and women’s health topics.