Journal of the American Academy of Child & Adolescent Psychiatry
Volume 44, Issue 4 , Pages 377-384, April 2005

A Meta-Analysis of Working Memory Impairments in Children With Attention-Deficit/Hyperactivity Disorder

Ms. Martinussen is with the Institute of Medical Science, University of Toronto; Dr. Hayden is with the University of Toronto and the Institute for Work and Health, Toronto; Dr. Hogg-Johnson is with the Institute for Work and Health, Toronto; Dr. Tannock is with The Hospital for Sick Children and the University of Toronto, Toronto

Accepted 2 November 2004.

ABSTRACT 

Objective

To determine the empirical evidence for deficits in working memory (WM) processes in children and adolescents with attention-deficit/hyperactivity disorder (ADHD).

Method

Exploratory meta-analytic procedures were used to investigate whether children with ADHD exhibit WM impairments. Twenty-six empirical research studies published from 1997 to December, 2003 (subsequent to a previous review) met our inclusion criteria. WM measures were categorized according to both modality (verbal, spatial) and type of processing required (storage versus storage/manipulation).

Results

Children with ADHD exhibited deficits in multiple components of WM that were independent of comorbidity with language learning disorders and weaknesses in general intellectual ability. Overall effect sizes for spatial storage (effect size = 0.85, CI = 0.62 − 1.08) and spatial central executive WM (effect size = 1.06, confidence interval = 0.72-1.39) were greater than those obtained for verbal storage (effect size = 0.47, confidence interval = 0.36-0.59) and verbal central executive WM (effect size = 0.43, confidence interval = 0.24-0.62).

Conclusion:

Evidence of WM impairments in children with ADHD supports recent theoretical models implicating WM processes in ADHD. Future research is needed to more clearly delineate the nature, severity, and specificity of the impairments to ADHD.

Key Words:  attention-deficit/hyperactivity disorder , working memory , reading disorder

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 This research was funded by a Canadian Institute of Health Research (CIHR) Doctoral Fellowship (Ms. Martinussen), a CIHR Postdoctoral Fellowship (Dr. Hayden), and a CIHR operating grant (Dr. Tannock).Article Plus (online only) materials for this article appear on the Journal's Web site: www.jaacap.com.Correspondence to Dr. Rosemary Tannock, Brain and Behavior Research, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8; e-mail: rosemary.tannock@sickkids.ca.Disclosure: Dr. Tannock has received research funding from, is a consultant for, and is on the speaker's bureau for Eli Lilly. She is also on the advisory board for Shire and has received funding (for placebo control) from Novartis. The other authors have no financial relationships to disclose.

PII: S0890-8567(09)61489-1

doi:10.1097/01.chi.0000153228.72591.73

Journal of the American Academy of Child & Adolescent Psychiatry
Volume 44, Issue 4 , Pages 377-384, April 2005

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