Does the ADHD Autism Overlap Cause Overdiagnosis?

PostedOctober 9, 2025

UpdatedOctober 9, 2025

ByMy Patient Advice

Author: Avery Lombardi, MSc | Reviewed by: Dr. Rebecca Fernandez, MBBS

Yes, the ADHD autism overlap can contribute to overdiagnosis, particularly when symptoms of both conditions are present or misinterpreted. Autism Spectrum Disorder (ASD) and ADHD share several behavioural traits, such as impulsivity, social difficulties, and challenges with focus and attention. However, because the conditions manifest differently, it’s crucial to properly differentiate between the two.

In cases where ADHD and autism symptoms overlap, clinicians may mistakenly diagnose one condition when both are present, leading to misdiagnosis or an incomplete understanding of a person’s challenges. Co-occurring conditions like ADHD and autism are common, but distinguishing between them requires careful differential diagnosis. Without a thorough evaluation, there is a risk that ADHD will be overdiagnosed, while other critical aspects of the individual’s condition, such as autism-related social or communication difficulties, may be overlooked.

Why ADHD and Autism Overlap Can Lead to Overdiagnosis

Here’s how the ADHD autism overlap can cause issues:

Shared symptoms

Both conditions involve attention issues, hyperactivity, and impulsivity, which can lead to an ADHD diagnosis when autism may also be present.

Difficulty with differentiation

Professionals may focus on behavioural symptoms without fully assessing for the nuanced traits of autism, leading to incomplete or inaccurate diagnoses.

Missed co-occurring conditions

Without a comprehensive evaluation, ADHD might be diagnosed in individuals who also have autism, leading to treatment that doesn’t address all the factors at play.

In conclusion, a comprehensive assessment that considers both ADHD and autism is essential for proper diagnosis and treatment. Proper diagnostic clarity ensures both conditions are managed effectively, improving long-term outcomes.

Visit providers like ADHD Certify for personal consultations and expert guidance tailored to your unique situation.

For a deeper dive into the science, diagnosis, and full treatment landscape, read our complete guide to Overdiagnosis vs. Underdiagnosis in ADHD.

Avery Lombardi, MSc

Author

Avery Lombardi is a clinical psychologist with a Master’s in Clinical Psychology and a Bachelor’s in Psychology. She has professional experience in psychological assessment, evidence-based therapy, and research, working with both child and adult populations. Avery has provided clinical services in hospital, educational, and community settings, delivering interventions such as CBT, DBT, and tailored treatment plans for conditions including anxiety, depression, and developmental disorders. She has also contributed to research on self-stigma, self-esteem, and medication adherence in psychotic patients, and has created educational content on ADHD, treatment options, and daily coping strategies.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the author's privacy.

Dr. Rebecca Fernandez, MBBS

Reviewer

Dr. Rebecca Fernandez is a UK-trained physician with an MBBS and experience in general surgery, cardiology, internal medicine, gynecology, intensive care, and emergency medicine. She has managed critically ill patients, stabilised acute trauma cases, and provided comprehensive inpatient and outpatient care. In psychiatry, Dr. Fernandez has worked with psychotic, mood, anxiety, and substance use disorders, applying evidence-based approaches such as CBT, ACT, and mindfulness-based therapies. Her skills span patient assessment, treatment planning, and the integration of digital health solutions to support mental well-being.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the reviewer's privacy.