Effects of methylphenidate on working memory components: influence of measurement.
BACKGROUND
To investigate the effects of methylphenidate (MPH) on components of working memory (WM) in attention-deficit hyperactivity disorder (ADHD) and determine the responsiveness of WM measures to MPH.


METHODS
Participants were a clinical sample of 50 children and adolescents with ADHD, aged 6 to 16 years old, who participated in an acute randomized, double-blind, placebo-controlled, crossover trial with single challenges of three MPH doses. Four components of WM were investigated, which varied in processing demands (storage versus manipulation of information) and modality (auditory-verbal; visual-spatial), each of which was indexed by a minimum of two separate measures.


RESULTS
MPH improved the ability to store visual-spatial information irrespective of instrument used, but had no effects on the storage of auditory-verbal information. By contrast, MPH enhanced the ability to manipulate both auditory-verbal and visual-spatial information, although effects were instrument specific in both cases.


CONCLUSIONS
MPH effects on WM are selective: they vary as a function of WM component and measurement.
Bedard
Anne-Claude
AC
Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.
Jain
Umesh
U
Johnson
Sheilah Hogg
SH
Tannock
Rosemary
R
D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy*; D000697:Central Nervous System Stimulants / Q000494:pharmacology* / Q000627:therapeutic use*; D002648:Child; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000187:drug effects*; D008774:Methylphenidate / Q000494:pharmacology* / Q000627:therapeutic use*; D012720:Severity of Illness Index
D000697:Central Nervous System Stimulants; D008774:Methylphenidate