Participants Were Recruited from a Variety of Sources Including Local Schools, Pediatricians

Appendix e-1

Methods

Participants

Participants were recruited from a variety of sources including local schools, pediatricians’ offices, outpatient clinics at the Kennedy Krieger Institute and Cincinnati Children’s Hospital Medical Center, from advertisements posted in local communities, and also through local chapters of Children and Adults with Attention Deficit/Hyperactivity Disorder (CHADD).

Intellectual disability, seizures, traumatic brain injury or other neurological illnesses were excluded via phone screening.

In person evaluations were conducted by research personnel (psychologist or psychometrician) trained to administer psychiatric interviews and parent questionnaires. To be included, full scale IQ, as assessed using the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV)e1 had to be > 80 and Word Reading subtest scores from the Wechsler Individual Achievement Test, Second Edition (WIAT-II)e2 had to be > 85. Right-handedness was confirmed based on both the Edinburgh Inventorye3 and the PANESSe4.

Diagnosis of ADHD was determined by the Diagnostic Interview for Children and Adolescents-IV (DICA-IV)e5.Three subtypes of ADHD were included: combined (n=19, 10 girls), inattentive (n=five, two girls), and hyperactive/impulsive (n=one, zero girls). Children were excluded if they met criteria for diagnosis of conduct, mood, generalized anxiety, separation anxiety or obsessive-compulsive disorders on DICA-IV. Diagnoses of oppositional defiant disorder (ODD) and simple phobias were allowed. While findings from studies suggest that ADHD associated with conduct disorder may be a distinct subtype, this is not the case for ADHD associated with ODDe6,e7. Of the 25 children included with ADHD, eight were comorbid ODD (5 girls), two of which were also diagnosed with a simple phobia (1 girl). Parents completed the Conners’ Parent Rating Scales-Revised (CPRS-R)e8 and the ADHD Rating Scale-IV, home and school versions (ADHDRS)e9. Inclusion in ADHD was made based on the following criteria: (1) DSM-IV-TR diagnosis of ADHD based on positive scores on at least one of the parent rating scales (i.e. T-score of 65 or higher on scale L (DSM-IV: inattentive) or M (DSM-IV: hyperactive-impulsive) on the CPRS-R Long Form or children receiving scores of 2 or 3 on at least 6/9 items on the Inattentive or Hyperactivity/Impulsivity scales of the ARS); and (2) confirmation of ADHD diagnosis by DICA-IV psychiatric interview. Children were excluded if they were taking non-stimulant longer-acting psychoactive medications. Parents of children with ADHD taking stimulants were asked to withhold medication the day prior and the day of testing.

Typically developing (TD) controls could not be diagnosed with ADHD or have a first degree relative diagnosed with ADHD. In addition, parent reports on CPRS-R and ARS had to be below clinical cutoff scores, and they could not meet diagnostic criteria for any psychiatric disorder, other than simple phobias, based on DICA-IV.

e-References

e1. Wechsler DL. Wechsler intelligence scale for children, fourth edition, San Antonio, TX: The Psychological Corporation; 2003.

e2. Wechsler DL. Wechsler individual achievement test-ii, San Antonio, TX: The Psychological Corporation; 2002.

e3. Oldfield RC. The assessment and analysis of handedness: The edinburgh inventory. Neuropsychologia 1971;9:97-113.

e4. Denckla MB. Revised neurological examination for subtle signs. Psychopharmacology Bulletin 1985;21:773-779.

e5. Reich W, Welner Z and Herjanic B. The diagnostic interview for children and adolescents-iv, North Tonawanda: Multi-Health Systems; 1997.

e6. Biederman J, Faraone SV and Lapey KA. In: Weiss G, editors. Comorbidity of diagnosis in attention deficit disorder. Philadelphia: W.B. Saunders; 1992:

e7. Faraone SV, Biederman J, Chen WJ, Milberger S, Warburton R and Tsuang MT. Genetic heterogeneity in attention deficit hyperactivity disorder (adhd): Gender, psychiatric comorbidity, and maternal adhd. J Abnorm Psychol 1995;104:334-345.

e8. Conners CK. Conners' rating scales - revised, North Tonawanda, New York: Multi-Health Systems Inc.; 1997.

e9. DuPaul GJ, Power TJ, Anastopoulos AD and Reid R. Adhd rating scale-iv, New York: Guilford Press; 1998.