Inhibitory function and working memory in attention deficit/hyperactivity disorder and pervasive developmental...

Area of Science:

• Neuropsychology
• Developmental Psychology
• Child Psychiatry

Background:

• Attention deficit/hyperactivity disorder (AD/HD) and pervasive developmental disorders (PDD) are distinct neurodevelopmental conditions.
• Understanding their overlapping and unique neuropsychological profiles is crucial for accurate diagnosis and intervention.
• Previous research suggests potential shared deficits in executive functions.

Purpose of the Study:

• To investigate the common features and differences in neuropsychological profiles between AD/HD and PDD.
• To examine the impact of comorbid AD/HD in PDD on executive function.
• To explore the relationship between symptom severity and executive function impairments.

Main Methods:

• A comparative study involving four groups of Japanese boys (aged 6-15): AD/HD, PDD with AD/HD (PDD+), PDD without AD/HD (PDD-), and typically developing controls.
• Executive function was assessed using verbal and visuospatial memory tasks, the Go/NoGo task, and the Stroop task.
• Both categorical and dimensional analyses were employed to evaluate diagnostic group effects and symptom scale correlations.

Main Results:

• AD/HD and PDD+ groups showed deficits in verbal working memory and response variability, correlated with inattentiveness.
• PDD+ and PDD- groups exhibited impaired interference control, linked to PDD symptom severity.
• Visuospatial working memory deficits were found in AD/HD and PDD- groups, but not PDD+.
• Inhibition of prepotent responses was impaired across all three disorder groups.

Conclusions:

• AD/HD and PDD share common neuropsychological features, particularly in executive functions.
• Each disorder presents a unique pattern of impairment, suggesting distinct underlying mechanisms.
• The findings lend partial support to the conceptualization of AD/HD and PDD existing on a developmental spectrum.