Antidepressant, antipsychotic and psychological interventions in subjects at high clinical risk for psychosis: OASIS 6-year naturalistic study

Background. Recent randomized controlled trials suggest some efficacy for focused interventions in subjects at high risk (HR) for psychosis. However, treating HR subjects within the real-world setting of prodromal services is hindered by several practical problems that can significantly make an impact on the effect of focused interventions.

Method. All subjects referred to Outreach and Support in South London (OASIS) and diagnosed with a HR state in the period 2001-2012 were included (n = 258). Exposure to focused interventions was correlated with sociodemographic and clinical characteristics at baseline. Their association with longitudinal clinical and functional outcomes was addressed at follow-up.

Results. In a mean follow-up time of 6 years (S.D. = 2.5 years) a transition risk of 18% was observed. Of the sample, 33% were treated with cognitive behavioural therapy (CBT) only; 17% of subjects received antipsychotics (APs) in addition to CBT sessions. Another 17% of subjects were prescribed with antidepressants (ADs) in addition to CBT. Of the sample, 20% were exposed to a combination of interventions. Focused interventions had a significant relationship with transition to psychosis. The CBT + AD intervention was associated with a reduced risk of transition to psychosis, as compared with the CBT + AP intervention (hazards ratio = 0.129, 95% confidence interval 0.030-0.565, p = 0.007).

Conclusions. There were differential associations with transition outcome for AD v. AP interventions in addition to CBT in HR subjects. These effects were not secondary to baseline differences in symptom severity.