title: Atomoxetine could improve intra-individual variability in drug-naïve adults with attention-deficit/hyperactivity disorder comparably with methylphenidate: A head-to-head randomized clinical trial.
abstract: Intra-individual variability in reaction time (IIV-RT) is common in individuals with attention-deficit/hyperactivity disorder (ADHD). It can be improved by stimulants. However, the effects of atomoxetine on IIV-RT are inconclusive. We aimed to investigate the effects of atomoxetine on IIV-RT, and directly compared its efficacy with methylphenidate in adults with ADHD.
  
  
  
  An 8-10 week, open-label, head-to-head, randomized clinical trial was conducted in 52 drug-naïve adults with ADHD, who were randomly assigned to two treatment groups: immediate-release methylphenidate (n=26) thrice daily (10-20 mg per dose) and atomoxetine once daily (n=26) (0.5-1.2 mg/kg/day). IIV-RT, derived from the Conners' continuous performance test (CCPT), was represented by the Gaussian (reaction time standard error, RTSE) and ex-Gaussian models (sigma and tau). Other neuropsychological functions, including response errors and mean of reaction time, were also measured. Participants received CCPT assessments at baseline and week 8-10 (60.4±6.3 days).
  
  
  
  We found comparable improvements in performances of CCPT between the immediate-release methylphenidate- and atomoxetine-treated groups. Both medications significantly improved IIV-RT in terms of reducing tau values with comparable efficacy. In addition, both medications significantly improved inhibitory control by reducing commission errors.
  
  
  
  Our results provide evidence to support that atomoxetine could improve IIV-RT and inhibitory control, of comparable efficacy with immediate-release methylphenidate, in drug-naïve adults with ADHD. Shared and unique mechanisms underpinning these medication effects on IIV-RT awaits further investigation.
authors.affiliation: Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan Department of Psychiatry, Chang Gung Memorial Hospital at Linkou, Taiwan.
authors.forename: Hsing-Chang
authors.initials: HC
authors.lastname: Ni
authors.affiliation: Graduate Institute of Behavioral Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan.
authors.forename: Shoou-Lian
authors.initials: SL
authors.lastname: Hwang Gu
authors.affiliation: Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Hsiang-Yuan
authors.initials: HY
authors.lastname: Lin
authors.affiliation: Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan Department of Psychiatry, Far Eastern Memorial Hospital, Taipei, Taiwan Department of Psychiatry, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Yu-Ju
authors.initials: YJ
authors.lastname: Lin
authors.affiliation: Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan Department of Psychiatry, Beitou Branch, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Li-Kuang
authors.initials: LK
authors.lastname: Yang
authors.affiliation: Department of Child and Adolescent Psychiatry, Taoyaun Psychiatric Center, Ministry of Health and Welfare, Taoyuan County, Taiwan.
authors.forename: Hui-Chun
authors.initials: HC
authors.lastname: Huang
authors.affiliation: Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan Department of Psychiatry, College of Medicine, National Taiwan University, Taipei, Taiwan Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan gaushufe@ntu.edu.tw.
authors.forename: Susan Shur-Fen
authors.initials: SS
authors.lastname: Gau
mesh_terms: D018759:Adrenergic Uptake Inhibitors / Q000627:therapeutic use*; D000328:Adult; D000069445:Atomoxetine Hydrochloride / Q000627:therapeutic use*; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy*; D000697:Central Nervous System Stimulants / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000627:therapeutic use*; D011930:Reaction Time
chemical_list: D018759:Adrenergic Uptake Inhibitors; D000697:Central Nervous System Stimulants; D008774:Methylphenidate; D000069445:Atomoxetine Hydrochloride
keywords: Adult; atomoxetine; attention-deficit/hyperactivity disorder; ex-Gaussian distribution; intra-individual variability in reaction time; methylphenidate