J Neural Transm (2007) 114: 273–280 DOI 10.1007/s00702-006-0602-7 Printed in The Netherlands Weight gain associated with clozapine, olanzapine and risperidone in children and adolescents C. Fleischhaker 1 , P. Heiser 2 , K. Hennighausen 1 , B. Herpertz-Dahlmann 3 , K. Holtkamp 3 , C. Mehler-Wex 4 , R. Rauh 1 , H. Remschmidt 2 , E. Schulz 1 , A. Warnke 4 1 Department of Child and Adolescent Psychiatry and Psychotherapy, Albert Ludwig University, Freiburg, Germany 2 Clinic and Polyclinic for Psychiatry and Psychotherapy for Child and Adolescent Age Groups, Philipp University, Marburg, Germany 3 Clinic for Child and Adolescent Psychiatry, University Clinic, RWTH Aachen, Aachen, Germany 4 Clinic and Polyclinic for Child and Adolescent Psychiatry, Julius Maximilian University, Wuerzburg, Germany Received: May 26, 2005 = Accepted: December 5, 2005 = Published online: November 17, 2006 # Springer-Verlag 2006 Summary The study was aimed at the evaluation of weight gain associated with atypical antipsychotics and its clinical risk factors in children and adolescents. Weight and body mass index (BMI) of initially hospitalised patients treated with clozapine (n ¼ 15), olanzapine (n ¼ 15), and risperi- done (n ¼ 15) were prospectively monitored on a weekly basis for the first 6 weeks. Different clinical risk factors were tested for their association with weight gain in the three groups. All three groups experienced significant weight gain between baseline and endpoint (p < 0.0001). For all weight measures, planned comparisons were all significant between olanzapine vs. clozapine and risperidone, respectively. Average weight gain was signif- icantly higher for the olanzapine group (mean ¼ 4.6 kg, SD ¼ 1.9) than for the risperidone (mean ¼ 2.8 kg, SD ¼ 1.3) and clozapine (mean ¼ 2.5 kg, SD ¼ 2.9) groups. Olanzapine and risperidone, but not clozapine, caused a disproportionately higher weight gain in children and adolescents in com- parison to adults. Keywords: Weight gain, adolescents, atypical antipsychotics Introduction Neuroleptics, and particularly atypical antipsychotics, are frequently associated with substantial weight gain and pharmacologically induced obesity (Allison et al., 1999; Wirshing et al., 1999). In many patients, the different atyp- ical antipsychotics lead to varying severities of weight gain depending on the substance. This varying level of weight gain in adults taking different atypical antipsychotics has been shown in various meta-analyses and comparative in- vestigations (Allison et al., 1999; Wirshing et al., 1999). However, comparative investigations of atypical antipsycho- tics in adolescents are to a large extent still lacking (Kant et al., 2002; Ratzoni et al., 2002; Gothelf et al., 2003; Sikich et al., 2004). Several examinations with adult patients on weight gain induced by neuroleptics showed that the weight gain caused by antipsychotics is a frequent reason for non- compliance and for the discontinuation of the antipsychotic treatment. This therefore frequently results in a relapse of psychotic symptoms (Rockwell et al., 1983; Brady, 1989) Moreover, an excessive weight gain and substantial obesi- ty are associated with an increased morbidity in coronary heart disease, diabetes mellitus, hypertension, some kinds of cancer and sleep apnoea (Pi-Sunyer, 1993; Mukherjee et al., 1996). The cause of the weight gain has not yet been system- atically examined to any satisfactory extent. However, the causes are being discussed on the basis of varying hypoth- eses (Rison and Stanton, 1995). The patients frequently report on their inability to suppress their appetite even fol- lowing a full meal, which is best explained by a change in the feeling of repletion (Leadbetter et al., 1992). A general increase in appetite and a desire for carbohydrates is also reported (Klimke and Klieser, 1995). For these reasons, a close-meshed monitoring of weight is necessary under treatment with atypical antipsychotics, as well as an intensive therapy for weight control, induced Correspondence: Christian Fleischhaker, Department of Child and Adolescent Psychiatry and Psychotherapy, Albert Ludwig University, Hauptstraße 8, 79104 Freiburg, Germany e-mail: fleischhaker@psyallg.ukl.uni-freiburg.de