Today a landmark study has been published on the efficacy of psychological interventions for people distressed by psychotic experiences such as hearing voices or profound fears about their safety. This ‘network meta-analysis’ (NMA), published in World Psychiatry, was prepared by a group of authors more commonly known for their influential Lancet meta-analyses on antipsychotic and antidepressant medication efficacy. NMA represents an important new approach to evidence synthesis. Its principal advantage over more traditional meta-analysis is that it allows for conclusions to be drawn about the relative efficacy of treatments that have yet to be compared directly in randomised controlled trials. The underlying logic is that if intervention A has been compared to intervention B, and intervention B has been compared to intervention C, then we might be able to use this data to make claims about the differences between interventions A and C.
The debate about the effectiveness of psychological interventions for psychosis, in particular cognitive behavioural therapy (CBT) has been heated and fractious. In recent years a group of researchers who are known to be highly vocal in their animosity towards these interventions published three traditional meta-analyses, where they concluded that CBT did not work for psychosis when examined in trials where those assessing participant progress were ‘masked’ to which group they were in. Indeed, one of these authors – Keith Laws, a Professor of Neuropsychology at the University of Hertfordshire – took the unusual step of calling for CBT to no longer be offered to people distressed by their psychotic experiences.
However, the authors of this new NMA are themselves regarded as neutral in this debate. Moreover, their paper represents the largest synthesis of evidence since the NICE guideline on schizophrenia was published in 2008. It included 53 RCTs and data from over 4,000 people with psychosis. Unlike almost all previous researchers, critics and non-critics alike, these authors pre-registered their meta-analysis in the public domain, thus reducing the risk of their own biases influencing their methods or interpretation.
They found that CBT did help to “reduce the positive symptoms of psychosis”, regardless of whether usual care or non-specific ‘supportive therapy’ was the control condition. Most importantly, they did not find that the apparent efficacy of CBTp was simply a consequence of assessor bias or researcher allegiance. Overall, their work means people distressed by psychotic experiences and their clinicians can now be confident that CBT represents an effective and acceptable non-pharmacological approach to helping with distressing experiences such as intrusive voices and persecutory fears.
We suggest there now ought to be an important debate as to why those who have been highly critical of CBT for psychosis found such a different result to the present authors, and whether this has led to people who are distressed by experiences such as hearing voices or other experiences of psychosis being less likely to have been offered an effective intervention for several years as a direct consequence.