Sensory processing and reactivity were studied in 26 children with attention deficit hyperactivity disorder (ADHD) (mean age 8.3 years, 18 males, 8 females) and 30 normal controls at the University of Colorado Health Sciences Center, Denver, CO. Responses to repeated sensory stimuli (olfactory, visual, auditory, tactile, and vestibular) were measured by electrodermal (EDR) conductance. Parental observations of sensory, emotional, and attentional disorders were recorded by the Short Sensory Profile (SSP) test, the Leiter International Performance Scale-Revised, Parent Rating subscales, and a Child Behavor Checklist (CBCL) of Achenbach. Children with ADHD showed abnormalities in sensory modulations by both the laboratory EDR measures and parent reports. Variability in responses was also greater among ADHD subjects compared to controls. Levels of sensory modulation dysfunction (SMD), especially tactile sensitivity on the SSP, were highly correlated with measures of psychopathology on the CBCL, including aggressive and delinquent behavior and concerns about body and health. The authors propose two distinct sensory subgroups within ADHD, one with normal sensory responses and one with SMD. 
COMMENT. Sensory modulation is defined as the ability to regulate the degree and intensity of responses to sensory input, to optimize the performance and adaptation to the environment. Sensory modulation dysfunction (SMD) may present as sensation seeking or sensation avoiding behaviors. Seeking sensation behaviors include touching others too often or too hard, overactive and risky behavior, and repeated tapping or banging. Avoiding sensation behaviors are aggressive response or withdrawal from touch, fear of playground and car rides, over response to hugging and dislike for sports. Problems with sensitivity to stimuli such as touch may lead to emotional and behavior problems including aggressive responses. Treatments aimed at remediation of SMD among children with ADHD may prevent the development of comorbid oppositional defiance disorder.