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Methylphenidate Does Not Ease Overactivated Visual Perception of Children With ADHD
The contextual visual perception of children with attention-deficit/hyperactivity disorder (ADHD) was not affected by a single dose of methylphenidate, according to study findings published in the European Archives of Psychiatry and Clinical Neuroscience.
“The pathogenesis of overactivated visual perception in ADHD remains unclear, which is interpreted as a cognitive compensation,” explained a research team in China. “The existing studies have proposed that perceptual abnormalities in neurodevelopmental disorders are associated with dysfunction of the contextual knowledge system, which influences the development and formation of perception.”
In the current study, researchers investigated differences in the contextual visual perception of children with and without ADHD, and then evaluated the effects of a single dose of methylphenidate in those with ADHD.
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For the first part of the study, 135 children — 70 with ADHD and 65 without, matched for age and sex — performed a visual spatial search task while undergoing electroencephalogram (EEG) monitoring. The task involved reporting on the position of an object while ignoring distracting objects around it.
In the second part of the study, 19 children with ADHD participated in the same visual spatial search task before, and then after, a single dose of methylphenidate. Again, EEG monitoring captured electrical activity in the children’s brains.
“Pre-stimulus alpha oscillations and P1 activity were significantly greater in children with ADHD than in the controls,” researchers reported in the study. “Overactivated pre-stimulus alpha positively predicted P1. Both pre-stimulus alpha and P1 overactivation have beneficial effects on cognitive performance in children with ADHD. No intervening effect of a single dose of methylphenidate on the compensatory activation of pre-stimulus alpha and P1 were observed.”
Researchers believe that overactive contextual visual perception during cognitive tasks causes children with ADHD to be distracted by extraneous stimuli in the environment. Although the single dose of methylphenidate improved the children’s speed and consistency on the study task, it had no effect on their contextual visual perception.
“Our findings extended the perceptual activation to the contextual knowledge system, suggesting that compensatory perception in children with ADHD is more likely to be a top-down regulated cognitive operational process,” researchers concluded.
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