Although the prevalence of childhood-onset schizophrenia is very low with only 1 in 100 people with schizophrenia developing the condition before the age of 13 the incidence of schizophrenia rises sharply between 12 and 14 and approximately 12-33% of individuals with the condition become ill before the age of 18. Early onset schizophrenia is usually more severe, can lead to significant, chronic, functional impairment and has a poor response to antipsychotic drugs. A review of studies into the effectiveness and side effects of antipsychotic medication in this young age group found that antipsychotic medication consistently reduced the severity of psychotic symptoms compared to a placebo. Clozapine was demonstrated to be superior to haloperidol and olanzapine. However, the studies showed that young people were more vulnerable to developing side effects than adults, in particular weight gain, and could be at greater risk of diabetes. The researchers say that there is an 'urgent need to develop therapeutic strategies to prevent and/or mitigate weight gain and diabetes early in the course of treatment in this population'
Kumra, Sanjiv ... [et al] - Efficacy and tolerability of second-generation antipsychotics in children and adolescents with schizophrenia Schizophrenia Bulletin January 2008, 34(1), 60-71