ABSTRACT. Background: According to the DSM-IV there are three subtypes of Attention Deficit Hyperactivity Disorder (ADHD): ADHD, Predominantly Inattentive Type (ADHD-I), ADHD, Combined Type (ADHD-C), and ADHD, Predominantly Hyperactive-Impulsive Type (ADHD-H/I). The central nervous system physiological distinctions between these categories remain unclear.

Objective: To assess children with ADHD diagnosed at a university ADHD clinic on peripheral and EEG psychophysiologic measures to determine if psychophysiology is distinctive across diagnostic categories and experimental conditions.

Methods: The CWRU Child Psychiatry Clinic determined 20 children to meet criteria for one of three diagnostic categories: 9 had ADHD-I (7 males), 7 had ADHD-C (5 males), and 4 had ADHD-I and were borderline for ADHD-C (all males). These children underwent psychophysiologic monitoring while experiencing three conditions: talking for three minutes, reading age appropriate material for three minutes, and performing a computerized Braintrain Intermediate Visual and Auditory (IVA) Continuous Performance Test (CPT). Their hand skin temperature, bilateral hand skin conductance, heart rate, and EEG from the Cz site were recorded using the Procomp+/Biograph program (Thought Technology,Ltd.). The psychophysiologic data was exported to Excel and analyzed by two-way ANOVA, using STATIT software (Statware, Inc.)

Results: The children, as a whole, demonstrated significant changes in EEG theta amplitude between the talking and CPTconditions (p=.0133) and in EEG theta/beta amplitude ratios among all conditions (p<.0001). The groups' skin conductances, heart rate, and certain EEG parameters (theta, beta amplitudes and theta/beta amplitude ratios) were not significantly different when compared across groups. Skin temperature showed a significant interaction effect between groups and conditions (p=.0409). SMR (13-15 hz) amplitudes had significant group differences (p=.043) for the comparison between the talking and CPT conditions.

Conclusions: Children with ADHD show evidence of change in neurophysiologic status when exposed to talking, reading, and CPT conditions. Further research is needed to determine if peripheral skin temperature and EEG Cz site SMR amplitude distinguishes among ADHD diagnostic categories.