Explaining transitions over the hypothesized psychosis continuum.

OBJECTIVES: It is crucial to understand the psychological mechanisms that mediate transition from having one or two psychotic symptoms to becoming a patient with a psychotic disorder. This study investigated whether: (i) a delusional interpretation and/or a depressed response to hallucinatory experiences predicts the later onset of clinical psychotic disorder; and (ii) the presence of need for care in relation to psychotic disorder was associated with the use of particular coping strategies.
METHOD: A general population sample of 4672 individuals with no lifetime evidence of any psychotic disorder were interviewed with the Composite International Diagnostic Interview Schedule (CIDI) at baseline and 1 and 3 years later. At year 3, individuals with CIDI evidence of psychotic symptoms were interviewed by clinicians to identify onset of psychotic disorder with need for care. Coping, subjective distress with and perceived control over the psychotic experience were assessed using the Maastricht Assessment of Coping Strategies (MACS).
RESULTS: Given the presence of hallucinatory experiences at baseline, the increase in risk on the additive scale of having the psychosis outcome at T2 was higher in the group with delusional ideation at T1 than in those without delusional ideation at T1. Similarly, presence of depressed mood at T1 increased the risk of having the psychosis outcome at T2, but this effect overlapped partly with the risk-increasing effect of delusional ideation. Individuals with a need for care were much more likely to display symptomatic coping, whereas the presence of the other coping types was not different across the groups with and without need for care.
CONCLUSION: Transitions over the psychosis continuum are, at least in part, driven by the emotional, cognitive and behavioural responses to the initial psychotic or psychosis-like experiences. Individuals who react with a delusional interpretation, negative emotional states and/or a symptomatic coping style have an increased risk for developing clinical psychosis.