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Children with ADHD exhibit poorer touch processing

Children with ADHD exhibited poorer tactile functioning, including reaction time and detection threshold, compared with typically developing children.

“Sensory problems (eg, touch processing abnormalities) in children with ADHD are relatively common — Ben-Sasson et al. suggest that one in six children with ADHD has sensory impairments that have a negative impact on everyday function,” Nicolaas A.J. Puts, PhD, of Johns Hopkins University School of Medicine, Baltimore, and colleagues wrote. “Tactile processing in specific is important in development, as it supports exploration of the physical world, as well as playing an important role in forming physical relationships and development of communication. Altered tactile processing could therefore contribute to the developmental issues observed in ADHD.”

To assess tactile processing in ADHD, researchers evaluated 67 children with ADHD and 62 typically developing children. Study participants completed a battery of tasks that assessed simple and choice reaction time; static and dynamic detection threshold; amplitude discrimination without adaptation and with dual and single-site adaptation; sequential and simultaneous frequency discrimination; and temporal order judgment with and without a synchronous carrier stimulus.

Children with ADHD were able to discriminate different amplitudes without adaptation, suggesting intact lateral inhibition. However, they were negatively affected in all adaptation conditions, while typically developing children were only affected during single-site adaptation.

Children with ADHD exhibited normal frequency discrimination.

Further, children with ADHD had slower reaction times and higher detection thresholds, possibly due to IQ and inattention, according to researchers.

“We show altered tactile sensitivity in children with ADHD, but these alterations appear to be restricted to the modulation of repetitive tactile information or ‘adaptation,’ potentially reflecting reduced signal-to-noise related to stimulus encoding and dysfunctional mechanisms underlying habituation. Further work is needed to investigate how this is related to inattention and hyperactivity,” the researchers wrote.

“These results point to a complex picture where specific aspects of tactile (possibly primary somatosensory) function are affected in ADHD,” they concluded. “The link between altered adaptation, its’ effect on attention and other clinical metrics, and the link to GABAergic function need further study.” – by Amanda Oldt

Disclosures: Puts reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.