Delusional disorder is commonly considered to be difficult to treat. Antipsychotic medications are frequently used and there is growing interest in a potential role for psychological therapies such as cognitive behavioural therapy (CBT) in the treatment of delusional disorder.
To evaluate the effectiveness of medication (antipsychotic medication, antidepressants, mood stabilisers) and psychotherapy, in comparison with placebo in delusional disorder.
We searched the Cochrane Schizophrenia Group's Trials Register (28 February 2012).
Relevant randomised controlled trials (RCTs) investigating treatments in delusional disorder.
All review authors extracted data independently for the one eligible trial. For dichotomous data we calculated risk ratios (RR) and their 95% confidence intervals (CI) on an intention-to-treat basis with a fixed-effect model. Where possible, we calculated illustrative comparative risks for primary outcomes. For continuous data, we calculated mean differences (MD), again with a fixed-effect model. We assessed the risk of bias of the included study and used the GRADE approach to rate the quality of the evidence.
Only one randomised trial met our inclusion criteria, despite our initial search yielding 141 citations. This was a small study, with 17 people completing a trial comparing CBT to an attention placebo (supportive psychotherapy) for people with delusional disorder. Most participants were already taking medication and this was continued during the trial. We were not able to include any randomised trials on medications of any type due to poor data reporting, which left us with no usable data for these trials. For the included study, usable data were limited, risk of bias varied and the numbers involved were small, making interpretation of data difficult. In particular there were no data on outcomes such as global state and behaviour, nor any information on possible adverse effects.A positive effect for CBT was found for social self esteem using the Social Self-Esteem Inventory (1 RCT, n = 17, MD 30.5, CI 7.51 to 53.49, very low quality evidence), however this is only a measure of self worth in social situations and may thus not be well correlated to social function. More people left the study early if they were in the supportive psychotherapy group with 6/12 leaving early compared to 1/6 from the CBT group, but the difference was not significant (1 RCT, n = 17, RR 0.17, CI 0.02 to 1.18, moderate quality evidence). For mental state outcomes the results were skewed making interpretation difficult, especially given the small sample.
Despite international recognition of this disorder in psychiatric classification systems such as ICD-10 and DSM-5, there is a paucity of high quality randomised trials on delusional disorder. There is currently insufficient evidence to make evidence-based recommendations for treatments of any type for people with delusional disorder. The limited evidence that we found is not generalisable to the population of people with delusional disorder. Until further evidence is found, it seems reasonable to offer treatments which have efficacy in other psychotic disorders. Further research is needed in this area and could be enhanced in two ways: firstly, by conducting randomised trials specifically for people with delusional disorder and, secondly, by high quality reporting of results for people with delusional disorder who are often recruited into larger studies for people with a variety of psychoses.