Biological Child and Adolescent Psychiatry - Original Article

Journal of Neural Transmission

, Volume 117, Issue 5, pp 655-662

Preliminary fMRI findings on the effects of event rate in adults with ADHD

  • Libbe KooistraAffiliated withBehavioral Research Unit, Department of Pediatrics, Alberta Children’s Hospital, University of CalgaryFoothills Academy Email author 
  • , Jaap J. van der MeereAffiliated withDepartment of Clinical Neuropsychology, University of Groningen
  • , Jodi D. EdwardsAffiliated withSeaman Family MR Research Centre, The Hotchkiss Brain Institute
  • , Bonnie J. KaplanAffiliated withBehavioral Research Unit, Department of Pediatrics, Alberta Children’s Hospital, University of Calgary
  • , Susan CrawfordAffiliated withBehavioral Research Unit, Department of Pediatrics, Alberta Children’s Hospital, University of Calgary
  • , Bradley G. GoodyearAffiliated withSeaman Family MR Research Centre, The Hotchkiss Brain InstituteDepartments of Radiology and Clinical Neurosciences, University of Calgary

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Abstract

Inhibition problems in attention deficit hyperactivity disorder (ADHD) are sensitive to stimulus event rate. This pilot study explores the neural basis of this increased susceptibility to event rate in ADHD. Event-related functional magnetic resonance imaging was used in conjunction with the administration of a fast (1.5 s) and a slow (7 s) Go/No-Go task. Brain activity patterns and reaction times of ten young male adults with ADHD (two of whom were in partial remission) and ten healthy male controls were compared. The ADHD group responded slower than controls with greater variability but with similar number of errors. Accurate response inhibition in the ADHD group in the slow condition was associated with widespread fronto-striatal activation, including the thalamus. For correct Go trials only, the ADHD group compared with controls showed substantial under-activation in the slow condition. The observed abnormal brain activation in the slow condition in adults with ADHD supports a fronto-striatal etiology, and underlines a presumed activation regulation deficit. Larger sample sizes to further validate these preliminary findings are needed.

Keywords

ADHD Adults Neuroimaging Event rate Inhibition Activation regulation