Prediction of psychosis. A step towards indicated prevention of schizophrenia

The identification of people at high risk of becoming psychotic within the near future creates opportunities for early intervention prior to the onset of psychosis to prevent or minimise later ill-health. The present study combines current knowledge about risk factors for schizophrenia with our knowledge of psychotic prodromes in an attempt to identify a group particularly vulnerable to impending psychosis. We wanted to identify people with high likelihood of transition to psychosis within a follow-up period of 12 months, and to determine the rate of transition to psychosis in this group.

Various state and trait risk factors for psychosis were used alone and in combination to operationally define a putatively high-risk group. Operationalised criteria for onset of psychosis were established. The individuals were assessed monthly on measures of psychopathology for six months.

Eight out of 20 people made the transition to frank psychosis within a six-month follow-up period. Follow-up of this group is still in progress, and the 12 month transition rate might prove to be higher still.

We have demonstrated that it is possible to identify individuals with a high likelihood of onset of psychosis within a brief follow-up period. This lays the foundation for early treatment in an attempt to prevent, delay or minimise the severity of first onset of schizophrenia.