22 Although the existence of such indicators of developmental vulnerability could in theory be used to initiate a selective prevention program, it soon became clear that although group differences were detectable between preschizophrenia children and their peers as early as 2 years of age, these differences were very small, with the great majority of preschizophrenia children scoring well

within the normal range. This would make it all but impossible to predict prospectively, on the basis of such developmental indicators, if a child would develop schizophrenia.23 For example, if, in a cohort Inhibitors,research,lifescience,medical of 5000 children, 20 children (0.4%) out of a total of 30 destined to develop schizophrenia have a value on a motor development variable below 40 on a scale of 1 to 100, and the children share this feature on the developmental motor variable with 2000 (40%) other children in the cohort, it can be readily seen that – although significant- the predictive Inhibitors,research,lifescience,medical value of this score Inhibitors,research,lifescience,medical will be too low for the purpose of screening and prevention. The only way to remedy this situation is to introduce, with the wisdom of hindsight, some post hoc selection criterion24 that nevertheless would not have been available prospectively25 Research on mental state Tubastatin A vulnerabilities close to onset The

Inhibitors,research,lifescience,medical second line of research should not be seen in isolation from the first, but a crucial difference is that the focus now is not so much on indicators of vulnerability expressed in parameters of motor, social, or cognitive development, but on parameters related to mental state and Inhibitors,research,lifescience,medical functioning in the period closer to the onset of the disorder, which, in the case of an actual illness onset, can retrospectively be labeled as prodromes of the illness. Careful follow-back studies

of first-episode schizophrenia patients using instruments like the Interview for Retrospective Assessment of Schizophrenia (IRAOS)26 have established that the great Thymidine kinase majority of first-episode patients displayed evidence of signs and symptoms up to 6 years prior to onset of the psychotic disorder.27 Given the high rate of detectable prodromes in patients, the question arises of whether these prodromes could not have been used to identify individuals in the very early throes of psychosis, so that early treatment would have possibly aborted their further transition to full-blown psychotic disorder. In other words, if it is not possible to practice selective prevention in the developmental phase, would it be possible to practice indicated prevention in the prodromal phases Figure 2? Figure 2. Prevention of full-blown psychotic disorder.