Clinical correlates of working memory deficits in youth with and without ADHD: A controlled study

ABSTRACT

Objective: Both working memory (WM; a brain system that provides temporary storage and manipulation of the information) and attention-deficit/hyperactivity disorder (ADHD) have been associated with educational deficits. Since WM deficits are prevalent in children with ADHD, the main aim of the present study was to examine whether educational deficits are driven by working memory deficits or driven by the effect of ADHD itself. Method: Participants were referred youth with (N = 276) and without (N = 241) ADHD ascertained from pediatric and psychiatric sources. Assessment included measures of psychiatric, psychosocial, educational, and cognitive functioning. Education deficits were defined as grade retention or placement in special classes and were assessed using interviews and written rating scales. Working memory was assessed using the Wechsler Intelligence Scale for Children–Revised (WISC–R) Freedom from Distractibility (FFD) factor based on Digit Span, Arithmetic, and Coding. Results: Significantly more youth with ADHD had WM deficits than controls (31.9% vs. 13.7%, p < .05). In ADHD children, WM deficits were significantly (p < .01) associated with an increased risk for grade retention and placement in special classes as well as lower scores on reading and math achievement tests than for ADHD children without WM deficits. In contrast, no other differences were noted in other areas of functioning. Although WM deficits also had some adverse impact on educational and cognitive correlates in non-ADHD controls, these differences failed to attain statistical significance. Conclusion: WM deficits significantly and selectively increase the risk for academic deficits and cognitive dysfunction in children with ADHD beyond those conferred by ADHD. Screening for WM deficits may help identify children with ADHD at high risk for academic and cognitive dysfunction.

KEYWORDS:

• Attention deficit hyperactivity disorder
• neuropsychology
• executive function
• working memory
• children

Disclosure statement

Ronna Fried is currently receiving research support from the following sources: Lundbeck. In 2015, Ronna Fried received honoraria from the MGH Psychiatry Academy for tuition-funded continuing medical education (CME) courses. In previous years, Ronna Fried received research support from the National Institutes of Health (NIH) and Shire. In the past year, Stephen Faraone received income, travel expenses, and/or research support from and/or has been on an Advisory Board for Pfizer, Ironshore, Shire, Akili Interactive Labs, CogCubed, Alcobra, VAYA Pharma, Neurovance, Impax, and NeuroLifeSciences and has received research support from NIH. With his institution, he has U.S. patent US20130217707 A1 for the use of sodium–hydrogen exchange inhibitors in the treatment of attention-deficit/hyperactivity disorder (ADHD). In previous years, he received consulting fees or was on Advisory Boards or participated in CME programs sponsored by: Shire, Alcobra, Otsuka, McNeil, Janssen, Novartis, Pfizer, and Eli Lilly. Stephen Faraone receives royalties from books published by Guilford Press: Straight Talk about Your Child’s Mental Health; Oxford University Press: Schizophrenia: The Facts; and Elsevier: ADHD: Non-Pharmacologic Treatments. Joseph Biederman is currently receiving research support from the following sources: The Department of Defense, Food & Drug Administration, Ironshore, Lundbeck, Magceutics Inc., Merck, PamLab, Pfizer, Shire Pharmaceuticals Inc., SPRITES, Sunovion, Vaya Pharma/Enzymotec, and NIH. In 2015, Joseph Biederman received honoraria from the MGH Psychiatry Academy for tuition-funded CME courses. He has a U.S. Patent Application pending (Provisional Number 61/233,686) through MGH corporate licensing, on a method to prevent stimulant abuse. In 2014, Joseph Biederman received honoraria from the MGH Psychiatry Academy for tuition-funded CME courses. He received research support from the American Academy of Child and Adolescent Psychiatry, Alcobra, Forest Research Institute, and Shire Pharmaceuticals Inc. Joseph Biederman received departmental royalties from a copyrighted rating scale used for ADHD diagnoses, paid by Ingenix, Prophase, Shire, Bracket Global, Sunovion, and Theravance; these royalties were paid to the Department of Psychiatry at MGH. In 2013, Joseph Biederman received an honorarium from the MGH Psychiatry Academy for a tuition-funded CME course. He received research support from American Professional Society of ADHD and Related Disorders, ElMindA, McNeil, and Shire. Joseph Biederman received departmental royalties from a copyrighted rating scale used for ADHD diagnoses, paid by Shire and Sunovion; these royalties were paid to the Department of Psychiatry at MGH. In 2012, Joseph Biederman received an honorarium from the MGH Psychiatry Academy and The Children’s Hospital of Southwest Florida/Lee Memorial Health System for tuition-funded CME courses. James Chan, Leah Feinberg, Amanda Pope, and Yvonne Woodworth do not have any financial relationships to disclose.

Additional information

Funding

This work was supported by the National Institutes of Health (NIH) [grant number R01MH050657], [grant number R01HD036317] to J. Biederman; and by the Pediatric Psychopharmacology Research Council Fund.