Abstract Details

Title Motor Cortex Physiology and Stop Signal Reaction Times as Predictors and Correlates of Atomoxetine Responses in Children with ADHD

Topic Clinical Neurophysiology

Presentation(s) IN11 - (-)

Poster/Presentation
Number 008

Objective

Background ADHD symptoms of inattention and/or hyperactivity/impulsivity likely involve inefficient neurophysiological function in frontal cortex. Mechanisms of clinical improvement on atomoxetine are unclear.

Design/Methods Assessments of motor cortex physiology using Transcranial Magnetic Stimulation (TMS) and Response Inhibition using the Stop Signal Reaction Time (SSRT) task were performed pre- and post- treatment, blinded to symptom ratings and clinical responses. Treatment combined a single-dose, double-blind, placebo-controlled design, with pre- and post-dose physiology, and a 4-week open-label design, with baseline versus one month measures. In this interim analysis, we report data on 83 children. Clinical responses (yes, partial, no) were categorized based on pre-specified criteria. Group univariate comparisons were performed using one-way ANOVA using SAS v9.3 (Cary, NC) with p < .05 considered significant.

Results 74 children (51 males; 47 Caucasian, 18 African American, 5 Asian, 4 Mixed; Mean Age 9.2 years) completed both visits, of whom 40 were responders (69% mean improvement in ADHD rating scale scores), 22 non-responders (15% improvement), and 12 partial responders (45% improvement). Stop Signal Reaction Time was greater at baseline in nonresponders (mean 530.1ms; SD 187.3 ms) than in responders and partial responders (combined mean 372.1ms; SD 146.8 ms) (F2,68 = 6.5; p = .003). TMS-evoked motor cortex physiology at baseline did not strongly predict clinical responses. However, one-month changes in paired pulse TMS short interval cortical inhibition (p = .01) and intracortical facilitation (p = .09) were greater in clinical responders.

Conclusions Atomoxetine nonresponders had worse baseline stop signal reaction times. Changes in paired pulse TMS-evoked motor cortex inhibition may elucidate atomoxetine response pathways but do not appear to predict them.

Authors/Disclosures
Tina Chen PRESENTER	No disclosure on file
Steve Wu, MD (Cincinnati Children'S Hospital Medical Center)	The institution of Dr. Wu has received research support from Tourette Association of America.
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
Donald Gilbert, MD, FAAN (Cincinnati Children's Hospital Med. Ctr.)	Dr. Gilbert has received personal compensation in the range of $500-$4,999 for serving as a Consultant for PTC Therapeutics. Dr. Gilbert has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Illumina. Dr. Gilbert has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Emalex Biosciences. The institution of Dr. Gilbert has received research support from NIMH. The institution of Dr. Gilbert has received research support from Emalex Biosciences. The institution of Dr. Gilbert has received research support from PTC Therapeutics. The institution of Dr. Gilbert has received research support from Department of Defense. The institution of Dr. Gilbert has received research support from Quince Therapeutics. Dr. Gilbert has received publishing royalties from a publication relating to health care. Dr. Gilbert has received publishing royalties from a publication relating to health care. Dr. Gilbert has received personal compensation in the range of $500-$4,999 for serving as a Medical Second Opinion Expert with Teldoc/Advanced Medical. Dr. Gilbert has received personal compensation in the range of $10,000-$49,999 for serving as a Medical Expert with Department of Health and Human Services/Vaccine Injury Compensation Program.
Opeolu Adeoye	No disclosure on file

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