Summary: A new study in Journal of Neurophysiology reveals children with ADHD perform worse on tests of tactile functioning than those without the disorder.
Children with attention deficit hyperactive disorder (ADHD) are likely to also have trouble with touch (tactile) processing. A new study finds that children with ADHD fare worse on several tests of tactile functioning, including reaction time and detecting a weak stimulus on the skin (detection threshold). The article, published ahead of print in the Journal of Neurophysiology, was chosen as an APSselect article for October.
Two groups of children (ages 8 to 12) participated in a series of tests in which researchers administered tactile stimulation (low-frequency vibrations) to the skin of their fingers. One group of children had ADHD, and the other group was typically developing (control). The children reported when they felt the weakest amount of stimulation, which stimulus was stronger or faster, or the order in which they felt two stimuli applied to two fingers (temporal order judgment).
When compared to the control group, the ADHD group was significantly slower to react when instructed to click a button as soon as they felt sensation on their hand or fingers. The children with ADHD also had more difficulty detecting weak stimuli and performed worse on temporal order judgment tasks.
However, children with ADHD did not perform worse on all tasks, suggesting that poor performance on sensory activities is not only due to the inattention issues that are a hallmark of ADHD, but possibly also due to low levels of the neurotransmitters that calm nerve activity, the research team explained. “There is likely a complex interplay of different factors, which need further investigation. Understanding these mechanisms may provide a potential target for future therapies to address sensory symptoms, both through pharmacological and behavioral interventions,” the researchers wrote.
Source: Stacy Brooks – APS
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Original Research: Abstract for “Altered tactile sensitivity in children with Attention Deficit Hyperactive Disorder” by NICOLAAS A J PUTS, Ashley D Harris, Mark Mikkelsen, Mark Tommerdahl, Richard AE Edden, and Stewart H Mostofsky in Journal of Neurophysiology. Published online August 2 2017 doi:10.1152/jn.00087.2017
Altered tactile sensitivity in children with Attention Deficit Hyperactive Disorder
ADHD is characterized by an inability to concentrate, heightened activity, and hypermotoric behavior, but sensory, e.g. tactile, problems are common. The literature on tactile impairments in ADHD is limited, with most work employing clinical observations or questionnaires. Here, we study tactile processing in children with ADHD, and hypothesize that children with ADHD show reduced performance in tasks closely linked to inhibition. Sixty seven children with ADHD and 62 typically developing children performed a battery of tasks grouped in domains: simple and choice reaction time; static and dynamic detection threshold (probing feed-forward inhibition); amplitude discrimination without adaptation, and with dual, and single-site adaptation (probing lateral inhibition and adaptation); sequential and simultaneous frequency discrimination (previously linked to GABA); and temporal order judgment with and without a synchronous carrier stimulus. Children with ADHD could discriminate different amplitudes without adaptation suggesting lateral inhibition is intact, but were negatively affected in all adaptation conditions whereas TDC were only affected during single-site adaptation. Children with ADHD also showed normal frequency discrimination. Children with ADHD showed slower reaction times and higher detection threshold, likely driven by IQ and inattention, as reaction time and detection thresholds correlated with IQ and subtle motor signs. Children with ADHD show a pattern of altered tactile processing on specific tasks, suggesting that higher cognitive function and cortical mechanisms related to adaptation are affected in ADHD, but no clear conclusion can be drawn towards impaired inhibition.
“Altered tactile sensitivity in children with Attention Deficit Hyperactive Disorder” by NICOLAAS A J PUTS, Ashley D Harris, Mark Mikkelsen, Mark Tommerdahl, Richard AE Edden, and Stewart H Mostofsky in Journal of Neurophysiology. Published online August 2 2017 doi:10.1152/jn.00087.2017