725 The Influence of Risperidone on Attentional Functions in Children and Adolescents with Attention-Deficit/Hyperactivity Disorder and Co-Morbid Disruptive Behavior Disorder Thomas Günther, Ph.D., 1 Beate Herpertz-Dahlmann, M.D., 1 Jellemer Jolles, Ph.D., 2 and Kerstin Konrad, Ph.D. 1 ABSTRACT This study aims to examine the influence of risperidone on various attentional functions, in- cluding intensity and selectivity aspects of attention plus inhibitory control in children with attention deficit/hyperactivity disorder (ADHD) with co-morbid Disruptive Behavior Disor- ders (DBD) and normal IQ. Children with ADHD and DBD, aged 8–15 years, were treated with risperidone (mean daily dose: 1.5 mg; n = 23) and examined with three attentional para- digms before and after a 4-week treatment period. Age- and IQ-matched normal controls (n = 23) were also tested without medication on the same two occasions. No influence of the med- ication could be detected for any neuropsychological variable, neither as a positive enhance- ment nor as adverse side effects. However, clinical symptoms of ADHD and DBD assessed on the IOWA Conners Scale significantly improved after the 4-week treatment period. Diver- gent behavioral and cognitive effects of risperidone on ADHD symptoms were observed, with a significant reduction in behavioral symptoms, whereas no positive treatment effects were found on laboratory tasks of impulsivity. Thus, the cognitive effects of risperidone seem to differ from the cognitive effects of stimulant treatments in children with ADHD + DBD. However, no negative impact of risperidone was observed on attentional functions ei- ther, i.e., there was no slowing of cognitive speed. JOURNAL OF CHILD AND ADOLESCENT PSYCHOPHARMACOLOGY Volume 16, Number 6, 2006 Mary Ann Liebert, Inc. Pp. 725–735 1 Department of Child and Adolescent Psychiatry, Aachen University, Aachen, Germany. 2 Maastricht Brain & Behaviour Institute and Department of Psychiatry & Neuropsychology, Maastricht University, INTRODUCTION R ISPERIDONE IS AN ATYPICAL NEUROLEPTIC agent with combined serotonin and dopamine antagonism (Leysen et al. 1992). In child and adolescent psychiatry, risperidone is success- fully used to treat neuropsychiatric disorders like schizophrenia (Grcevich et al. 1996; Ar- menteros et al. 1997), bipolar disorder (Schreier 1998; Frazier et al. 1999), pervasive developmental disorder (Barnard et al. 2002; McCracken et al. 2002; King et al. 2003), tic dis- orders and obsessive-compulsive disorder (Sc- ahill et al. 2003; Gilbert et al. 2004), and disruptive behavior disorders (Barch et al. 2003; Aman et al. 2004; Aman et al. 2005a). Ag- gression is a common target symptom for which antipsychotics are prescribed to youths