ASD symptoms in adults with ADHD: a preliminary study using the ADOS-2

Area of Science:

• Neurodevelopmental Disorders
• Psychiatry
• Clinical Psychology

Background:

• Historically, Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) were considered mutually exclusive conditions.
• Emerging evidence highlights significant phenotypic and genetic overlaps between ADHD and ASD.
• Previous research on autistic traits in ADHD primarily focused on children using subjective reports.

Purpose of the Study:

• To objectively assess Autism Spectrum Disorder (ASD) symptoms in adults diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD) using direct measures.
• To investigate the prevalence and nature of ASD symptoms in adults with ADHD who do not have a clinical ASD diagnosis.
• To explore the overlapping and distinct characteristics between ADHD and ASD in an adult population.

Main Methods:

• Utilized the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2) Module 4 for objective ASD symptom evaluation.
• Included 56 adults (mean age 33.9 years, 35 males, IQ ≥ 85) diagnosed with ADHD per DSM-5 criteria.
• Administered Autism Spectrum Quotient (AQ), Conners' Adult ADHD Rating Scale (CAARS), and Wechsler Adult Intelligence Scale (WAIS)-III for supplementary assessments.

Main Results:

• 23.3% of adults with ADHD met the diagnostic criteria for ASD on the ADOS-2.
• Participants showed higher scores in social reciprocal interaction domains.
• Scores for restricted and repetitive behaviors were comparatively lower.

Conclusions:

• Objective assessment reveals a notable prevalence of ASD symptoms in adults with ADHD.
• Findings challenge the traditional view of ADHD and ASD as entirely separate conditions.
• The study underscores the importance of considering ASD in adult ADHD evaluations due to overlapping symptomatology.