Visual search in ADHD, ASD and ASD + ADHD: overlapping or dissociating disorders?

Area of Science:

• Neurodevelopmental Disorders
• Cognitive Neuroscience
• Comparative Psychology

Background:

• Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) are frequently debated for potential overlaps.
• Past research has often studied these neurodevelopmental disorders in isolation.
• Systematic comparisons are needed, investigating markers of each disorder concurrently.

Purpose of the Study:

• To directly compare cognitive markers of ADHD and ASD in children aged 10-13 years.
• To investigate superior local processing (associated with ASD) and increased Intra-Subject Variability (ISV, associated with ADHD).
• To examine these markers in groups with ADHD, ASD (with and without comorbid ADHD), and typically developing controls.

Main Methods:

• A visual search task involving paired words was administered to 85 participants (ADHD, ASD-, ASD+, and typically developing).
• Performance was assessed based on overall search accuracy and trial-to-trial variability (ISV).
• Scanpath analysis using Recurrence Quantification Analysis (RQA) and the Multi-Match Model was employed.

Main Results:

• The ASD- group (ASD without comorbid ADHD) demonstrated superior search performance.
• Increased ISV was observed exclusively in groups exhibiting ADHD symptoms (ADHD and ASD+).
• These findings indicate distinct cognitive profiles for ASD and ADHD.

Conclusions:

• The study reveals a double dissociation between ASD and ADHD regarding specific cognitive markers.
• Superior local processing is specific to ASD, while increased ISV is specific to ADHD.
• Evidence argues against a significant cognitive overlap between ASD and ADHD at this level of analysis.