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Specificity of basic information processing and inhibitory control in attention deficit hyperactivity disorder

  • G. A. Salum (a1) (a2), J. Sergeant (a3), E. Sonuga-Barke (a4) (a5), J. Vandekerckhove (a6), A. Gadelha (a1) (a7), P. M. Pan (a1) (a7), T. S. Moriyama (a1) (a7) (a8), A. S. Graeff-Martins (a1) (a8), P. Gomes de Alvarenga (a1) (a8), M. C. do Rosário (a1) (a7), G. G. Manfro (a1) (a2), G. Polanczyk (a1) (a8) and L. A. P. Rohde (a1) (a2) (a8)...
Abstract
Background

Both inhibitory-based executive functioning (IB-EF) and basic information processing (BIP) deficits are found in clinic-referred attention deficit hyperactivity disorder (ADHD) samples. However, it remains to be determined whether: (1) such deficits occur in non-referred samples of ADHD; (2) they are specific to ADHD; (3) the co-morbidity between ADHD and oppositional defiant disorder/conduct disorder (ODD/CD) has additive or interactive effects; and (4) IB-EF deficits are primary in ADHD or are due to BIP deficits.

Method

We assessed 704 subjects (age 6–12 years) from a non-referred sample using the Development and Well-Being Assessment (DAWBA) and classified them into five groups: typical developing controls (TDC; n = 378), Fear disorders (n = 90), Distress disorders (n = 57), ADHD (n = 100), ODD/CD (n = 40) and ADHD+ODD/CD (n = 39). We evaluated neurocognitive performance with a Two-Choice Reaction Time Task (2C-RT), a Conflict Control Task (CCT) and a Go/No-Go (GNG) task. We used a diffusion model (DM) to decompose BIP into processing efficiency, speed–accuracy trade-off and encoding/motor function along with variability parameters.

Results

Poorer processing efficiency was found to be specific to ADHD. Faster encoding/motor function differentiated ADHD from TDC and from fear/distress whereas a more cautious (not impulsive) response style differentiated ADHD from both TDC and ODD/CD. The co-morbidity between ADHD and ODD/CD reflected only additive effects. All ADHD-related IB-EF classical effects were fully moderated by deficits in BIP.

Conclusions

Our findings challenge the IB-EF hypothesis for ADHD and underscore the importance of processing efficiency as the key specific mechanism for ADHD pathophysiology.

Copyright
Corresponding author
* Address for correspondence: G. A. Salum, M.D. Hospital de Clínicas de Porto Alegre, Ramiro Barcelos, 2350, room 2202, 90035-003 Porto Alegre, RS, Brazil. (Email:gsalumjr@gmail.com)
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