Placebo-controlled Trial in Subjects at Ultra-high Risk for Psychosis With Omega-3 Fatty Acids in Europe

Inclusion Criteria: * Written informed consent of the subject. For individuals younger than 18 years of age the parents / legal representatives need to give consent, and the subject can provide assent (whether the latter is required depends on local laws and regulations). * UHR diagnosis as made using the Comprehensive Assessment of At-Risk Mental States (CAARMS) (Yung et al., 2005). Subjects have to meet one or more of the following criteria: (a) attenuated psychotic symptoms, (b) brief limited intermittent psychotic symptoms (a history of one or more episodes of frank psychotic symptoms that resolved spontaneously within 1 week in the past year), or (c) either the presence of schizotypal personality disorder or a family history of psychosis in a first-degree relative, all three together with a recent decline in function. Exclusion Criteria: * Any clinically significant medical condition that may influence the results of the trial or affect the ability to take part in a trial. * Laboratory screening values considered clinically relevant by a medical doctor for transaminases, thyroid hormones or coagulation parameters * Current or past DSM-IV diagnosis of psychosis, as measured with K-SADS-PL * Current treatment with an antipsychotic or mood-stabilising agent * Intake of an antipsychotic or mood-stabilising agent in the two weeks prior to study inclusion * Intake of an antipsychotic agent equivalent to a total haloperidol use of \>50 mg in the six months prior to study inclusion * A first-degree relative (i.e. parents, offspring or siblings) participating in this study * UHR diagnosis on the basis of attenuated psychotic symptoms that are entirely explained by acute intoxication * Current aggression or dangerous behaviour (PANSS G14 score 5 or above) * Current suicidality / self-harm (PANSS G6 score 7) * Current DSM-IV diagnosis of alcohol or substance dependence as measured with K-SADS-PL * Any current or previous neurological disorder, including epilepsy * History of head injury resulting in unconsciousness lasting at least 1 hour * IQ \< 70 * More than 4 weeks of regular omega-3 supplementation (\>2 daily capsules standard strength providing \>600 mg combined EPA/DHA) within the last 6 months.