This unfavourable outcome highlights the importance of preventive treatment for schizophrenia and related psychoses. The notion of early pharmacological intervention during the prodromal phase of these disorders has a dual aim: 1) to treat active prodromal symptoms and 2) to prevent further deterioration and progression toward the full-blown disorder and chronicity. Overall, it raises the possibility of preventing, delaying or ameliorating the onset of the diagnosable disorder. This type of intervention, although already in use in other medical branches and potentially ground-breaking for mental health delivery systems, has not been systematically assessed in the past. Recently, the development of improved criteria for detecting individuals at high risk for developing schizophrenia and related psychoses, has led to the first clinical trials that assessed the role of atypical antipsychotics (i.e., risperidone and olanzapine) for these subjects. The results of these studies indicate that significant clinical benefits nay be derived from early intervention but also point to the drawbacks of exposing patients at a very early stage of illness to antipsychotic drugs that are associated with debilitating (i.e. motor, metabolic) side effects.