Developmental differences in intra-individual variability in children with ADHD and ASD.

Area of Science:

• Neurodevelopmental disorders
• Cognitive neuroscience
• Developmental psychology

Background:

• Intra-individual variability (IIV) reflects performance fluctuations within an individual.
• Children with ADHD and ASD exhibit higher IIV than typically developing children.
• IIV decreases significantly with age during development, suggesting a link to neural maturation.

Purpose of the Study:

• To investigate developmental changes in IIV in children with ADHD and ASD.
• To explore IIV as a potential marker of atypical neurodevelopmental trajectories.

Main Methods:

• Propensity score matching used for a sample of 405 children (aged 6-19) with ADHD, ASD, and controls.
• Ex-Gaussian distribution parameters (sigma and tau) characterized IIV in fast and slow responses.

Main Results:

• Response times decreased similarly with age across all groups.
• Autism Spectrum Disorder (ASD) showed a significantly slower rate of change in variability parameters (sigma and tau) with age compared to ADHD and controls.
• Attention-Deficit/Hyperactivity Disorder (ADHD) exhibited higher IIV (sigma and tau) but with a similar age-related decrease rate as controls.

Conclusions:

• Developmental trajectories of IIV differ among children with ADHD, ASD, and controls.
• IIV's differential developmental patterns support its role as a marker of neurodevelopmental changes in these disorders.