The readers of this journal will be familiar with the fact that schizophrenia has the nosological status of a clinical syndrome.13 As such, the diagnosis of schizophrenia will encompass clinical outcomes that derive from many different etiological pathways. Heterogeneity is to be expected, and just as clinicians are comfortable with substantial variation in outcomes in individuals diagnosed with schizophrenia, researchers should expect that etiological processes will also be heterogeneous. Thus, it is implausible that any one intervention will be sufficient to “prevent” the full syndrome of schizophrenia.
On a related issue, many individuals in the community report isolated psychotic-like experiences,14 and psychotic symptoms can also be associated with a range of other clinical disorders (eg, mood disorders).15 Currently, there is debate about the utility of including an “At Risk” diagnostic category in Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition.16 The boundaries of schizophrenia will need to be kept under continuous revision in response to advances in psychiatric research. With respect to the prevention of schizophrenia, it is feasible that future interventions designed to target the syndrome of schizophrenia may result in benefits in a wider range of adverse health outcomes. While lack of specificity between an exposure and an outcome can weaken the case that the variables of interest are causally related,17 from a public health perspective, interventions that have nonspecific benefits are particularly attractive.1