Autism vs. ADHD: How Assessment Differentiates These Conditions

This post on Autism is written by Victoria Kaufman

---

Social media has made it easy to self-diagnose a wide range of mental health conditions, especially as creators frequently discuss diagnoses like autism spectrum disorder (ASD), ADHD, and more.

But what do these conditions really mean? How can we differentiate them, and how do we know if we might meet the criteria for one of them? 

The first step is understanding each diagnosis clearly.

What is Autism Spectrum Disorder (ASD)?

According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), autism spectrum disorder is a neurodevelopmental disorder characterized by persistent deficits in social communication and social interactions appearing across multiple contexts, along with restricted and repetitive behaviors, interests, or activities.

These symptoms must be present in early developmental periods and cause clinically significant impairment in social, occupational, or other important areas of functioning.

---

What is Attention Deficit Hyperactivity Disorder (ADHD)?

According to the DSM-5, ADHD is also a neurodevelopmental disorder, often presenting in childhood, that is characterized by persistent patterns of inattention and/or hyperactivity-impulsivity that interfere with functioning or development.

These symptoms must be present before age 12, occur in two or more settings, and negatively impact social, academic, or occupational performance.

How is ASD Assessed?

The gold standard way for assessing ASD is through the ADOS-2 (Autism Diagnostic Observation Schedule, Second Edition).

The ADOS-2 is a semi-structured and standardized assessment of social communication and play with individuals suspected of having ASD. The ADOS-2 is often used to evaluate individuals at different developmental levels and chronological ages.

The ADOS can be used from toddlers to adults, and from individuals with no speech to those who are verbally fluent. It takes about 30-45 minutes to administer, depending on the age and ability of the individual being tested.

To be diagnosed with ASD, an individual must meet all three of the following criteria: 

• Difficulties with social-emotional reciprocity, such as: 
  • Trouble initiating or maintaining conversations 
  • Difficulty sharing interests 
  • Challenges in expressing or understanding emotions 
• Deficits in nonverbal communication, including: 
  • Abnormal eye contact or body language 
  • Difficulty understanding facial expressions or gestures 
• Challenges in developing and maintaining relationships, such as: 
  • Limited interest in peers 
  • Struggles with adjusting behavior to different social contexts 
  • Difficulty in sharing imaginative play (CHOP, 2020)

Additionally, the ADOS-2 looks at whether an individual is demonstrating at least 2 of the following 4 restricted and repetitive behavior, interests, or activities: 

• Repetitive movements or speech, such as: 
  • Stereotyped speech 
  • Repetitive motor movements 
  • Echolalia (repeating phrases from others or TV shows) 
  • Unusual use of objects 
• Inflexibility or resistance to change, like: 
  • Insisting on the same routines 
  • Distress at small changes 
  • Ritualized patterns of behavior 
• Highly restricted, intense interests, such as: 
  • Strong attachment to unusual objects 
  • Obsessions (e.g., with train schedules) 
• Sensory sensitivities, including: 
  • Overreacting or underreacting to pain or sound 
  • Excessive touching or smelling objects 
  • Fascination with lights or spinning objects
    (CHOP, 2020) 

A clinical interview is also a crucial part of diagnosis. For children, this might involve a parent interview (e.g., the ADI-R); for adults, it can involve a direct interview with the individual.

The clinician will combine the results of the ADOS-2 and interviews to determine whether the individual meets diagnostic criteria for ASD. 

How is ADHD Assessed?

ADHD is primarily assessed through clinical interviews and standardized rating scales. One of the most used tools is the Conners Rating Scale, which gathers input from multiple sources, such as the individual, parents, and teachers, to provide a comprehensive understanding of symptoms across different environments. 

In addition, Conners offers a Continuous Performance Test (CPT) for individuals aged 8 and older. This objective, computerized assessment measures sustained attention and impulse control in real time. The CPT can serve as a valuable complement to the information gathered from questionnaires. 

Typically, ADHD is diagnosed through a comprehensive clinical evaluation, which may include interviews, rating scales, and performance-based measures like the CPT. It’s important to note that there is no single test that can confirm an ADHD diagnosis. A skilled clinician will integrate all available data to determine whether the symptoms observed are consistent with ADHD or may be better explained by other conditions.

In Summary

While there may be some overlapping characteristics, ASD and ADHD are distinct conditions. That said, they often co-occur, meaning an individual can meet criteria for both. At the SMart Center, we offer comprehensive assessments for both ASD and ADHD.

Our evaluations can help determine whether someone meets criteria for one, the other, or both conditions. If you’re curious about yourself or someone you care about, please reach out. We can help guide you toward the most appropriate assessment path.

Check out our other popular blog posts: