Lessons from psychotherapy research for psychological interventions for people with schizophrenia.

This article argues that psychological interventions for people with schizophrenia could be developed by being informed by research from the wider psychotherapy literature. We specifically argue that research on these interventions has ignored two key themes from this wider literature: first, the contention that differing models of intervention broadly result in similar outcomes, known as the 'equivalent outcomes paradox'; and second, the phenomenon of 'investigator allegiance' whereby the conclusions that may safely be drawn from comparative research are compromised by researchers' unwitting bias. We present evidence indicating that both these themes from the wider literature may be applicable to the literature on psychological interventions for schizophrenia and that schizophrenia treatment research should incorporate some of the lessons already learned in studies of other disorders. We conclude by arguing that psychological interventions for people with schizophrenia should be based on unbiased evidence and that interpretation of the evidence base should not be hindered by dogma or ideology from any quarter.