Is Attention Deficit Hyperactivity Disorder (ADHD) commonly comorbid with Autism Spectrum Disorder (ASD)?

ADHD and Autism Spectrum Disorder Comorbidity

Yes, ADHD is highly comorbid with autism spectrum disorder, with 50-70% of individuals with ASD also meeting diagnostic criteria for ADHD. 1

Prevalence and Clinical Significance

The comorbidity between ADHD and ASD is remarkably common and clinically significant:

• ADHD is one of the most frequent comorbid conditions in ASD, affecting the majority of individuals on the autism spectrum 2
• The 2019 American Academy of Pediatrics clinical practice guideline explicitly lists autism spectrum disorder among the developmental conditions that must be screened for when evaluating any child for ADHD 3
• This comorbidity became formally diagnosable with DSM-5, which removed the previous exclusion criteria that prevented clinicians from diagnosing both conditions simultaneously 4

Diagnostic Framework

When evaluating either condition, clinicians must systematically screen for the other:

• The American Academy of Pediatrics mandates screening for autism spectrum disorders in all ADHD evaluations as a Grade B strong recommendation 3, 5
• Information must be obtained from multiple sources (parents, teachers, school personnel, mental health clinicians) to document symptoms across settings 6, 5
• The majority of both boys and girls with ADHD meet diagnostic criteria for another mental disorder, with ASD being a prominent comorbidity 3

Overlapping and Distinct Features

The relationship between these disorders involves both shared and unique characteristics:

• Both conditions share genetic heritability and demonstrate impairments in social functioning and executive functioning 7
• However, quantitative and qualitative differences exist in how these impairments present phenotypically 7
• Research reveals overlapping cognitive deficits that may reflect shared etiological underpinnings, while nonoverlapping deficits indicate why some children develop ADHD despite enhanced risk for ASD 8

Critical Diagnostic Pitfall

A major clinical caveat: attentional impairment in ASD patients may actually represent impaired joint attention (a core ASD trait) rather than true ADHD attention deficit 1:

• Agitation in ASD may be a consequence of joint attention impairment or physical restlessness etiologically different from ADHD hyperactivity 1
• The neurobiological reality of ASD-ADHD comorbidity remains debated, and amphetamine-based ADHD treatments can have paradoxical or undesirable effects in the ASD population 1
• This diagnostic complexity underscores why careful differentiation is essential before initiating treatment 1

Comorbidity Subtypes

Research identifies distinct clinical presentations when both conditions co-occur:

• Two subtypes exist: ADHD[+ASD] (ADHD prominent with some ASD features) and ASD[+ADHD] (ASD prominent with some ADHD features) 8
• These subtypes likely require different clinical approaches and treatment strategies 8
• Children with both conditions show more impaired cognitive functioning than those with ADHD alone 8

Treatment Implications

For ASD interventions to be maximally efficacious, comorbid ADHD must be identified and addressed (and vice versa) 7:

• The presence of comorbid ASD alters the treatment approach for ADHD 3
• Effective assessment, diagnosis, and management of ADHD in ASD patients is essential for quality of life 2
• The American Academy of Pediatrics recommends managing complex ADHD (including ADHD with comorbid developmental conditions like ASD) following chronic care model principles 3

Clinical Management Approach

When both conditions are present:

• Screen for additional comorbidities including anxiety, depression, learning disabilities, language disorders, sleep disorders, and tics, as these frequently compound the clinical picture 3, 5
• Obtain comprehensive information across multiple settings to distinguish true ADHD symptoms from ASD-related attentional difficulties 6, 5
• Consider that behavioral interventions may need modification when ASD is present, as standard ADHD treatments may not translate directly 1
• Monitor medication responses carefully, as stimulant medications may produce atypical effects in individuals with ASD 1