The past 15 years have seen a growing interest in early intervention and detection of psychosis before the onset of the first episode. Recent proposals to include a psychosis risk syndrome (PRS) in DSM 5 have focused attention on the evidence base achieved to date in this field.

This article aims to (1) review the underlying principles of early identification and intervention during the pre-psychotic phase, (2) summarise the naturalistic follow-up studies conducted to date in this ‘at-risk’ population, (3) discuss the identified clinical risk factors for transition to psychosis, (4) summarise the interventional studies both psychological and pharmacological completed to date and (5) briefly discuss the controversy around the proposed inclusion of the PRS in DSM 5.

Electronic databases EmBase, MedLine and PsychInfo were searched using the keywords ultra-high risk/at-risk mental state/risk syndrome/pre-psychotic/prodrome/prodromal and psychosis/schizophrenia.

The evidence suggests that it is possible to identify individuals who may be at risk of developing psychosis. Results from intervention studies, mostly involving second-generation antipsychotics and cognitive behavioural therapy, are currently insufficient to make treatment recommendations for this group. The emerging research with regard to possible neuroprotective factors such as omega fatty acids is promising, but will require replication in larger cohorts before it can be recommended.