title: Improving working memory in children with attention-deficit/hyperactivity disorder: the separate and combined effects of incentives and stimulant medication.
abstract: Working memory (WM) is considered a core deficit in Attention-Deficit/ Hyperactivity Disorder (ADHD), with numerous studies demonstrating impaired WM among children with ADHD. We tested the degree to which WM in children with ADHD was improved by performance-based incentives, an analog of behavioral intervention. In two studies, WM performance was assessed using a visuo-spatial n-back task. Study 1 compared children (ages 9-12 years) with ADHD-Combined type (n = 24) to a group of typically developing (TD) children (n = 32). Study 1 replicated WM deficits among children with ADHD. Incentives improved WM, particularly among children with ADHD. The provision of incentives reduced the ADHD-control group difference by approximately half but did not normalize WM. Study 2 examined the separate and combined effects of incentives and stimulant medication among 17 children with ADHD-Combined type. Both incentives and a moderate dose of long-acting methylphenidate (MPH; ~0.3 mg/kg t.i.d. equivalent) robustly improved WM relative to the no-incentive, placebo condition. The combination of incentives and medication improved WM significantly more than either incentives or MPH alone. These studies indicate that contingencies markedly improve WM among children with ADHD-Combined type, with effect sizes comparable to a moderate dose of stimulant medication. More broadly, this work calls attention to the role of motivation in studying cognitive deficits in ADHD and in testing multifactorial models of ADHD.
authors.affiliation: Department of Psychology, University at Buffalo, SUNY, Buffalo, NY, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Strand
authors.forename: Larry W
authors.initials: LW
authors.lastname: Hawk
authors.forename: Michelle
authors.initials: M
authors.lastname: Bubnik
authors.forename: Keri
authors.initials: K
authors.lastname: Shiels
authors.forename: William E
authors.initials: WE
authors.lastname: Pelham
authors.forename: James G
authors.initials: JG
authors.lastname: Waxmonsky
mesh_terms: D000704:Analysis of Variance; D001289:Attention Deficit Disorder with Hyperactivity / Q000523:psychology / Q000628:therapy; D000697:Central Nervous System Stimulants / Q000627:therapeutic use*; D002648:Child; D003131:Combined Modality Therapy / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000209:etiology / Q000523:psychology / Q000628:therapy; D008570:Memory, Short-Term; D008774:Methylphenidate / Q000627:therapeutic use*; D009042:Motivation; D012054:Reinforcement, Psychology
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate