The notion that subtle cognitive, emotional, behavioral, and functional deviations from norms are present in many individuals several years before a formal diagnosis of schizophrenia has been around for almost a century. This notion has been at the base of the developmental hypothesis of schizophrenia and has been the impetus for the use of cognition as an endophenotype for studying the illness. The recent enthusiasm for prodromal research derives from two unrelated and controversial claims: that short duration of untreated psychosis is associated with better prognosis and that novel antipsychotic drugs have a better safety profile, supposedly enabling early intervention at a relatively lower risk of side effects to the patient.

At the current level of knowledge, the risk-benefit assessment of prodromal interventions turns out to be an almost unsolvable conundrum. On one hand, the age of onset of psychosis and schizophrenia, early and mid-ado-lescence, coincides with the age at which life-long social and vocational characteristics are shaped. Any intervention that could produce even minimal delay in onset of active psychosis or ameliorate its early course might have a life-long impact. Therefore, the idea of prodromal intervention cannot be easily dismissed. On the other hand, in absence of accurate markers for imminent psychosis and strong data indicating that treatment during the prodromal phase is effective, exposing adolescents to the stigma associated with the illness and the adverse effects of antipsychotics has raised serious hesitations among many researchers and clinicians.