'At-risk' for psychosis research: Where are we heading?

The 'at-risk' criteria are a useful paradigm for investigating the psychological, neurocognitive, neurobiological and genetic risk factors for psychosis, specifically schizophrenia. To date, the primary outcome of interest in at-risk research has been the development of psychotic disorder, whereby patients are categorized as either having 'transitioned' or 'not transitioned'. Despite the acceptance of this dichotomy, it is important to consider that the threshold at which psychotic symptoms progress from attenuated to frank 'psychotic disorder' is arbitrary and may be incorrect or meaningless in terms of neurobiological and functional changes associated with psychosis. This has implications for clinical care and the search for markers of schizophrenia. We present recent research suggesting that the term 'outcome' needs to be broadened to incorporate non-psychotic diagnoses, functioning and negative symptoms. Shifting the traditional notion of outcome is the future challenge for at-risk research, but the inclusion of outcomes other than psychosis is likely to result in better aetiological models of psychotic illness.