The effect of treatment on insight in psychotic disorders - A systematic review and meta-analysis.

BACKGROUND: For people with a psychotic disorder lack of insight can be detrimental on their condition and recovery. For this reason, insight has been considered as a target for therapy. We conducted a systematic review of the literature on pharmacological, psychological and other treatments to test the hypothesis that these interventions could improve insight.

METHODS: We performed a literature search (1970-2020) across the following databases: PubMed, EMBASE, PsychINFO, Medline and Web of Science. Within each database the following search terms and the associated Boolean operatives were used: "Insight AND (treatment OR therapy) AND (psychosis OR schizophrenia) AND (awareness or denial)". Further filters were applied to identify peer reviewed controlled trials on adults. Following assessment for bias and inclusion criteria, we calculated the effect size (Cohen's d) for each study and overall, using a random effects model with 95% confidence intervals.

RESULTS: Of 94 articles found in the initial literature search, 30 studies that examined the treatment of insight in psychosis met the initial selection criteria and were assessed for bias. A total of 21 studies were included in the final meta-analysis. The overall calculated mean effect size for all interventions was 0.441 (95% CI, 0.23-0.66), representing a medium effect size. The effect of psychoeducation studies alone was medium (0.613, 95% CI, -0.35-2.06), but not significant. The effect of CBT studies was small (0.235, 95% CI, 0.01-0.46), and significant. The effect of combined antipsychotic medication and psychosocial intervention was of medium size and significant (0.683, 95% CI = 0.54-0.83). Finally, tDCS over the left fronto-temporal cortex, produced a very large and significant improvement of insight 1.153 (95% CI = 0.61-1.70), which was present for at least a month after the intervention.

CONCLUSIONS: Despite the variation and small number and size of trials into possible interventions, the hypothesis that insight could be improved was confirmed. Whilst most research focuses on psychotherapies, there is scope and potential for pharmacological, as well as other interventions (e.g. physical exercise, self-video observation, Direct Current Stimulation) to improve insight over and above treatment as usual. Given the association of insight with illness severity and treatment adherence, it is important to direct efforts in therapies that target insight improvement in psychosis.