Differential therapeutic effects of atomoxetine and methylphenidate in childhood attention deficit/hyperactivity disorder as measured by near-infrared spectroscopy

Abstract

BackgroundThe stimulant methylphenidate (MPH) and the nonstimulant atomoxetine (ATX) are the most commonly-prescribed pharmacological treatments for attention deficit/hyperactivity disorder (ADHD). However, the drug-specific mechanism of action on brain function in ADHD patients is not well known. This study examined differences in prefrontal hemodynamic activity between MPH and ATX in children with ADHD as measured by near-infrared spectroscopy (NIRS) using the Stroop color-word task.MethodsThirty children with ADHD participated in the present study. We used 24-channel NIRS (ETG-4000) to measure the relative concentrations of oxyhemoglobin in the frontal lobes of participants in the drug-naïve condition and those who had received MPH (n = 16) or ATX (n = 14) for 12 weeks. Measurements were conducted every 0.1 s during the Stroop color-word task. We used the ADHD RS-IV-J (Home Version) to evaluate ADHD symptoms.ResultsTreatment with either MPH or ATX significantly reduced ADHD symptoms, as measured by the ADHD RS-IV-J, and improved performance on the Stroop color-word task in terms of number of correct words. We found significantly higher levels of oxyhemoglobin changes in the prefrontal cortex of participants in the ATX condition compared with the values seen at baseline (pre-ATX). In contrast, we found no oxyhemoglobin changes between pre- and post-treatment with MPH.ConclusionsThe present study suggests that MPH and ATX have differential effects on prefrontal hemodynamic activity in children with ADHD.

Intact Stimulus–Response Conflict Processing in ADHD—Multilevel Evidence and Theoretical Implications

“…From the point of view of medication, it has been suggested that atomoxetine (frequently used as second-line medication) may be more effective in reducing impulsivity than is the case for methylphenidate (first-line treatment), which may in turn be more beneficial in terms of reducing inattention [76,77]. Importantly, only atomoxetine has been shown to increase prefrontal activation during a Stroop task [78]. This effect may however crucially depend on different demographic factors and on individual differences in symptom severity [78].…”

“…Importantly, only atomoxetine has been shown to increase prefrontal activation during a Stroop task [78]. This effect may however crucially depend on different demographic factors and on individual differences in symptom severity [78]. Taken together, this suggests that it may indeed be very useful to take the individual pattern of cognitive deficits into account when developing treatment recommendations for individual patients [79].…”

Clinical Applications of Functional Near-Infrared Spectroscopy in Children and Adolescents with Psychiatric Disorders

“…In addition, after administration of MPH and atomoxetine, the hemodynamic activity of the right PFC was increased, and the right hemisphere was lateralized. Meanwhile, in the study by Nakanishi et al [ 22 ], there was no statistically significant change in hemodynamic changes after MPH administration. Studies by Nakanishi et al [ 22 ] and Sanefuji et al [ 23 ] found contradictory results from other studies [ 19 - 21 , 24 ], such as left-lateralized effect after pharmacotherapy.…”

“…Meanwhile, in the study by Nakanishi et al [ 22 ], there was no statistically significant change in hemodynamic changes after MPH administration. Studies by Nakanishi et al [ 22 ] and Sanefuji et al [ 23 ] found contradictory results from other studies [ 19 - 21 , 24 ], such as left-lateralized effect after pharmacotherapy. The results may differ depending on the research and statistical method; therefore, future research is needed to confirm consistent results.…”

Use of Virtual Reality Working Memory Task and Functional Near-Infrared Spectroscopy to Assess Brain Hemodynamic Responses to Methylphenidate in ADHD Children

“…Altogether, 23 right-handed Korean children with ADHD (age range, 7–16 years; mean age, 9.96 ± 2.82) and 12 healthy control (HC) children (age range, 7–14 years; mean age, 11.33 ± 2.93) participated in this study. The number of participants required for adequate statistical power was based on previous studies that investigated drug effects in ADHD patients through fNIRS ( 23 , 40 – 42 ) and a previous study that described the optimal design for functional brain imaging ( 43 ). The detailed demographic and clinical characteristics of subjects are listed in Table 1 .…”